Polymer Matrix Drives Dual Phosphorescence in Dispersed Chromophores

Polymer Matrix Drives Dual Phosphorescence in Dispersed Chromophores | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Polymer Matrix Drives Dual Phosphorescence in Dispersed Chromophores Pakkirisamy Thilagar, Subhajit Ghosh Ghosh, Rajendra Nandi, Silvano Geremia, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5794027/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 19 Feb, 2026 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract Poly(methyl methacrylate) (PMMA) matrix has been extensively explored for decades to achieve efficient room-temperature phosphorescence in blue-to-red regions from dispersed chromophores. Isolated chromophores at low-weight concentrations in the polymer matrix eliminate the inter-chromophore interactions. However, the impact of the polymer matrix on the optical characteristics of chromophores remains elusive. Herein, we analyze the dual phosphorescence behavior of three chromophores molecularly dispersed (1 wt.% concentration) in the PMMA matrix. We employ second-order Algebraic Diagrammatic Construction (ADC2) excited state calculations to show that the dual phosphorescence observed in BANHPh and BANMePh does not stem from the T 1 and T 2 electronic states. Instead, this phenomenon arises from matrix-assisted, room-temperature accessible conformers within the T 1 state (T 1 H and T 1 L ). The PMMA matrix creates an asymmetric environment around the chromophores, inducing structural and electronic modulations that result in spectral tuning of the singlet and triplet manifolds. In conclusion, conformation-dependent dual phosphorescence is unlikely to occur without the PMMA matrix. These matrix-induced dual phosphorescent emitters have been demonstrated to be highly competent in the application of fingerprint recognition, information encryption, and afterglow display. Physical sciences/Chemistry/Materials chemistry/Optical materials Physical sciences/Materials science/Soft materials/Organic molecules in materials science Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Controlling the nature of dual phosphorescence demands a comprehensive understanding of triplet excited state behavior. The triplet-state involved afterglow has been utilized for several advanced applications such as bioimaging 1 , 2 , sensing 3 , organic light-emitting diodes 4 – 6 , lasers 7 and anticounterfeiting 8 , 9 . The organic room temperature phosphorescence (RTP) emitter efficiency has been shown to improve by introducing hetero-atoms 10 , aromatic carbonyl group substitution 11 , engineering resonance linkage 12 , and through-space charge-transfer (TSCT) motif 13 to facilitate the intersystem crossing (ISC) process from the lowest excited singlet state (S 1 ) to the triplet state (T n ). Lately, it has been demonstrated that exciton spin-flip between singlet and triplet excited states can also be accelerated by sp 2 -boron localized (σ, Bp) → (π, Bp) transition 14 . On the other hand, crystal engineering 15 , 16 , molecular aggregations 17 , 18 , and molecularly dispersed polymer matrix 19 – 21 have been successfully explored to suppress the oxygen quenching and molecular vibration-caused non-radiative deactivation of triplet excitons. Among these, RTP from the organic chromophores embedded in polymer matrices (such as polyvinyl alcohol 22 , polystyrene 23 , and polyacrylamide 24 ) has received a momentous research interest in a target to improve the stability of triplet excitons. Physical dispersion of simple luminophores in different polymer matrices at variable ratios enables better flexibility to tune the RTP properties than the challenging and tedious chemical synthesis of complex chromophores. 25 Poly(methyl methacrylate) (PMMA) is the most commonly used polymer matrix to achieve afterglow emission from molecularly dispersed organic chromophores owing to suitable mechanical properties, amorphous state, chemical stability, and facile film processing technique. Furthermore, the oxygen sensitivity of the PMMA matrix has been explored for several photo-induced phosphorescence 25 , 26 . Most of the dopant-matrix systems exhibit excellent features of a single phosphorescence band owing to a suitable matrix environment. Nevertheless, there are several reports demonstrating stimuli-dependent dual phosphorescence features by virtue of the strategic structural design of chromophores molecularly dispersed in a matrix environment 27 – 30 . The dual phosphorescence feature is currently in demand in promising applications such as the development of white light emitters from single chromophore 31 , 32 , and stimuli-responsive materials for anti-counterfeiting applications 33 . Molecular dual phosphorescence can arise due to either rarely observed multiple T n -S 0 (n = 1 and n ≥ 2 for anti-Kasha emission) radiative decay 30 or emission from molecular conformation-dependent multiple accessible triplet excited states 27 , 28 . Li et al . reported that dual phosphorescence of benzophenone-containing difluoroboronβ-diketonate derivatives embedded in phenyl benzoate matrix was originated due to radiative decay of T n (n ≥ 2) states 30 . Wang et al . explained that multiple emissive triplet excited states result from excitonic coupling caused by molecular aggregates in the polymer matrix. Although several experiments have been conducted on dual phosphorescence in matrix environments, the chemistry behind the role of the matrix for triplet state dynamics of emitter has remained unclear. Our group has been actively involved in developing organic RTP systems derived from the molecular dispersion of chromophores in PMMA matrix 34 , 35 . As part of the ongoing program, we set out to investigate the impact of the asymmetric environment created by the PMMA matrix to understand the origin of dual phosphorescence from the dispersed chromophore. In this target, we have selected borylaniline derivatives comprising the amine donor and -BMes 2 acceptor as the model compounds. We sought to decipher the influence of rigid matrix on the conformational isomerism of chromophores to gain insights into the underlying mechanism of dual phosphorescence. Accordingly, the molecules are rationally designed with locked geometry around the boron center, allowing conformational freedom only to N-C(xylyl) bond (Fig. 1 a). This approach simplified the system by eliminating the possibility of multiple dihedral angle variation. In a matrix environment, the side-chain ester group and α-methyl group of the PMMA chain may induce specific steric and electrostatic interaction with chromophore, leading to different spatial arrangements of the conformers at each fixed dihedral angle. These factors govern the relative stability of the conformers, which are related to distinct triplet energy levels (Fig. 1 a, b). This feature resulted in temperature dependent dual phosphorescence behavior of the emitter at 1 wt.% of the chromophore concentration in the PMMA matrix. Two room temperature accessible conformers at the T 1 state are mainly responsible for the dual phosphorescence behavior of the emitters. Further, control photophysical studies have been carried out in poly(butyl methacrylate) (PBMA) matrix to validate the matrix influence on dual phosphorescence. Thereafter, the theoretical investigation of the influence of the polymer (PMMA) matrix on the electronic energy levels of the dispersed chromophore confirms our anticipation. We observe an extraordinary finding where the PMMA matrix lifts the degeneracy of the conformers in the T 1 state by providing an asymmetric environment. However, similar degeneracy lifting is not likely to happen in the absence of the matrix surroundings. We further corroborate our experimental findings with the wavefunction-based second-order Algebraic Diagrammatic Construction (ADC2) excited state calculations performed on the compounds explicitly in the presence of the matrix to validate our hypothesis (Fig. 4). The present results can be utilized for temperature sensing from the ratiometric phosphorescence afterglow colour change-over in a short energy range. These emitters (1 wt.% BANHPh@PMMA and 1 wt.% BANH2@PMMA) have also been successfully explored for anti-counterfeiting applications and promising afterglow materials. Results Molecular design and characterization The chromophores were designed by changing the substituent at the nitrogen center of 4-(dimesitylboraneyl)-3,5-dimethylaniline (BANH2), keeping the core structure intact. A secondary amine derivative (BANHPh) was designed to enable the feasibility of non-degenerate conformers under external stimuli. The methylated derivative (BANMePh) was synthesized to investigate the photo-physics of the system in the absence of the H-bonding channel present in the secondary amine derivative. The unsubstituted derivative (BANH2) was explored to examine the photophysical properties without the interference of non-degenerate conformational isomers. The presence of mesityl and xylyl groups provides kinetic protection to electron-deficient boron center (Fig. 1 ). The compound 4-(dimesitylboraneyl)-3, 5-dimethylaniline were synthesized following a literature reported elsewhere 36 . The detailed synthesis techniques were described in the supplementary information. The compounds were characterized by 1 H, 13 C, and 11 B nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HRMS) techniques (Supplementary Figs. 1–8). The molecular structures of the compounds were further confirmed by single crystal X-ray diffraction (SC-XRD) technique (Fig. 1 c and Supplementary Figs. 9, 10). Powder X-ray diffraction spectra indicated the crystalline nature of the pristine compounds. However, thin films of the compounds at 1 wt.% concentration in the PMMA matrix were found to be amorphous in nature (Supplementary Figs. 11, 12). The pristine compounds are stable under ambient conditions. Thermogravimetric analysis (TGA) showed that the decomposition temperature of the final compounds was in the range of 245°C − 302°C indicating good thermal stability of the compounds (Supplementary Fig. 13). Moreover, differential scanning calorimetry (DSC) data exhibited that there was no phase transformation except the melting point for BANHPh and BANMePh whereas BANH2 showed additional crystallization process during cooling cycle (Supplementary Fig. 14). Single-Crystal XRD Analysis The impact of temperature on the molecular structure was investigated through SCXRD data from 100 K to 300 K (Supplementary Tables 1–7). Molecule BANHPh showed one independent molecule in the asymmetric unit. The dihedral angles between the mean plane of the xylyl carbon atoms and the mean plane of the phenyl carbon atoms remained constant with respect to temperature (Fig. 1 c). In fact, the values of 58.42(3) at 100 K and 58.47(4) at 300 K were the same within experimental error. Similar observations were also found for other temperatures as well. In the case of BANMePh, there were two independent molecules in the asymmetric unit. These two molecules exhibited a significant difference in the dihedral angles formed by the mean planes of the xylyl ring and the phenyl ring (Fig. 1 c). This could be attributed to differences in crystal packing environments of the two independent molecules (Supplementary Fig. 10). For both molecules of BANMePh, there was a reduction in dihedral angles across the temperature range from 100 K to 300 K; however, the values for each molecule did not lie within the range of the standard uncertainty (Fig. 1 c). Similar results were found for BANH2, and the variation was less than 1° across the temperature range 100 K to 275 K (Supplementary Fig. 9, 10). Therefore, the temperature-dependent variation of the dihedral angle of the molecular structures in the crystal lattice appeared to be insignificant. Optoelectronic investigation in PMMA matrix To analyze the influence of the PMMA matrix on molecular properties, photo physics was investigated for encapsulated chromophores in the PMMA matrix. At first, the emission characteristics of the compounds were conducted in the matrix at low weight concentrations (1 wt.%) to obtain the molecular property of the compound with negligible influence from intermolecular interactions among the chromophores. The higher energy absorption band ( 350 nm) presents amine to boryl intramolecular charge transfer (ICT) transition (Fig. 2 b and Supplementary Fig. 15). This is corroborated from the photophysical studies in dilute solution state (conc. 10 µM). The intermolecular interactions among the chromophores in dilute solution are also expected to be non-operative as 1 wt.% thin film. The higher energy absorption bands ( 350 nm) showed weak solvent dielectric dependency, which indicates the weakly polar electronic ground state of these compounds (Supplementary Figs. 16–18). The steady-state photoluminescence (PL) spectrum of the 1 wt.% compound@PMMA showed a structureless emission band (λ PL = 445–455 nm) with an associated lifetime of 6.5–10 ns (Fig. 2 a, and Supplementary Tables 10, 13, 16). The ICT characteristics of the steady-state PL band of the emitters were confirmed from the solution state studies. The steady-state emission band of the compounds is susceptible to solvent polarity, which explains the ICT feature of the band (Supplementary Figs. 16, 17 and Tables 8–9). However, the time-gated measurements indicated the absence of phosphorescence in the solution state. This can be due to thermally induced vibrational relaxation of the triplet excited state in a dilute solution. The rigid polymer (PMMA) matrix eliminates the possibility of vibrational relaxation-caused quenching of excited state species. Time-gated PL measurement of 1 wt.% BANHPh@PMMA (50 µs delay time) at room temperature showed a structureless broad emission band at 450 nm (Fig. 2 a). The delayed emission band was found to exhibit bi-exponential decay (λ (450nm) 298 K : τ A1 = 23 ms, τ A2 = 103 ms) for the emission maxima. The delayed emission band (λ = 450 nm) was slightly lower in energy than the prompt emission band (λ = 445 nm), as depicted in Fig. 2 a and 2 h. Moreover, the strong oxygen sensitivity and faster decay of delayed emission at elevated temperatures featured the possibility of room temperature phosphorescence (RTP) rather than thermally activated delayed fluorescence (TADF) (Fig. 2 d and Supplementary Fig. 24, 26). The temperature-dependent photophysical property investigation of 1 wt.% BANHPh@PMMA revealed a bathochromic spectral shift of phosphorescence maxima from 450 nm at 298 K to 482 nm at 77 K (Fig. 2 c and Supplementary Fig. 23a). Although there was a negligible change in the steady-state PL maxima at different temperatures. The energy difference (Δλ PH max = 32 nm) between the lower-energy phosphorescence (LEP) band at 77 K and higher-energy phosphorescence (HEP) band at 298 K indicated the involvement of two different triplet excited states in this phenomenon. The LEP band of the emitter was found to exhibit remarkably long bi-exponential decay (λ (482nm) 77 K : τ A1 = 587 ms, τ A2 = 1087 ms) (Supplementary Table 11). A comparison of LEP and HEP spectra inferred that the HEP band comprised the phosphorescence from both the high-lying triplet state (T H ) and the low-lying triplet excited state (T L ). However, there was an insignificant contribution of the HEP band (λ = 450 nm) in the LEP spectrum at low temperature (77 K). The HEP band arose progressively with thermal energy above 200 K with a concomitant decrease in intensity of the LEP band (Fig. 2 c). In addition, the different peak position of excitation spectra for 450 nm and 482 nm phosphorescence band further corroborates the involvement of different emissive states (Fig. 2 b and Supplementary Fig. 19). The tail fitting of the phosphorescence lifetime decay profile (for both HEP and LEP bands) at each temperature revealed a bi-exponential component with gradual variation in the amplitude value with temperature (Supplementary Table 11). Interestingly, there was an abnormal elevation of total phosphorescence quantum yield from 77 K (Φ 77 K = 13%) to 298 K (Φ 298 K = 16%), which inferred that temperature-induced non-radiative deactivation of triplet excitons was unlikely in this case (Supplementary Table 12). The area-deconvolution of the phosphorescence spectrum at 298 K showed that the HEP band majorly contributed to the RTP quantum yield (Φ RTP Cum (16%) = Φ HEP 450 (11%) + Φ LEP 482 (5%)). In fact, there was gradual change in the phosphorescence quantum yield with temperature for both LEP and HEP band (Fig. 2 g). Furthermore, the excited state kinetics of dual phosphorescence was analyzed by time-resolved phosphorescence spectra at 225 K (in millisecond time scale) (Fig. 2 f and Supplementary Fig. 31). Area normalization of time-resolved phosphorescence bands exhibited the attenuation of higher energy phosphorescence band (λ = 450 nm) intensity at longer time range. The time-dependent intensity variation of emission bands further confirms the phosphorescence nature of the dual emission bands 37 . To elucidate the controlling parameters of dual phosphorescence behavior, photophysical studies were conducted for BANMePh and BANH2 at 1 wt.% concentration in the PMMA matrix (Supplementary Figs. 20–30 and Table 13–18). Structural manipulation can change the electronic and steric environment of the chromophore in the matrix environment. Temperature-dependent steady-state PL and phosphorescence spectra of the BANMePh emitter showed similar spectral behavior to the first emitter (Supplementary Figs. 23b, 25a, 27 and Table 14). The phosphorescence spectrum showed a 36 nm bathochromic spectral shift on changing temperature from 298 K to 77 K. Further time-resolved phosphorescence spectra inferred the kinetics between the triplet excited states (Supplementary Figs. 32, 33). The methyl substitution resulted in a slight bathochromic shift in the LEP band for BANMePh (λ = 486 nm) relative to the BANHPh emitter (λ = 482 nm). Similar photophysical behavior of methyl derivative compared to secondary amine derivative indicated no such dominant role of non-covalent interactions in the secondary amine derivative for dual phosphorescence behavior. For the BANH2 emitter, the absence of a phenyl group linked to the nitrogen center resulted in a different photo-physics than the other two emitters. Temperature-dependent phosphorescence spectra exhibited a transition of the phosphorescence band maxima from lower-energy to higher-energy region with increasing temperature. However, phosphorescence spectral shift (Δλ PH max = 20 nm) was found to be smaller relative to the other two emitters (Supplementary Fig. 25b). The HEP and LEP bands showed comparatively different energy values for the triplet states (λ HEP = 455 nm and λ LEP = 475 nm) (Fig. 2 a). Unlike the previous two emitters, the LEP band at lower temperatures (< 200 K) showed the emission contribution from both low and high-lying triplet states (Supplementary Fig. 25b). In addition, the RTP lifetime was found to be shorter (λ (455nm) 298 K : τ A1 = 13 ms, τ A2 = 60 ms) than the other two emitters (Supplementary Figs. 26–28 and Supplementary Tables 11, 14, 17). As hypothesized vide supra, the absence of a phenyl group changed the emissive electronic state, leading to different phosphorescence behavior. Intermolecular interactions effect on dual phosphorescence The influence of intermolecular interactions between the chromophores on phosphorescence behavior was studied by embedding the compound at 10 wt.% concentration in the PMMA matrix (Fig. 3 b, Supplementary Figs. 34–40 and Tables 19–27). Time-gated measurements at variable temperatures for 10 wt.% of BANHPh@PMMA (Δλ PH max = 35 nm) exhibited a similar spectral shift between HEP and LEP bands relative to 1 wt.% emitter (Δλ PH max = 32 nm) (Fig. 3 b, 2 c). However, the steady-state PL band and phosphorescence bands (HEP and LEP) for the 10 wt.% of BANHPh@PMMA were found to be red-shifted compared to the 1 wt.% of BANHPh@PMMA (Fig. 3 c and Supplementary Fig. 41a). The high dispersion concentration in matrix resulted in a shorter lifetime for both LEP (λ (497nm) 77K : τ A1 = 964 ms, τ A2 = 469 ms) and HEP (λ (462nm) 298 K : τ A1 = 45 ms, τ A2 = 9.1 ms) bands as well as diminished phosphorescence quantum yield (Φ PH Cum(77 K) = 7.1% and Φ PH Cum(298 K) = 8%) (Fig. 3 d, 3 e and Supplementary Tables 11, 12, 20, 21). This can be attributed to the diffusion of excitons towards several non-radiative deactivation channels, which reduces the lifetime and quantum yield value 38 . A similar observation was found for 10 wt.% of BANMePh@PMMA and 10 wt.% BANH2@PMMA (Supplementary Figs. 34–40, 41–44, and Tables 22–27). Both the 10 wt.% emitter (BANMePh and BANH2) exhibited a red shifting of phosphorescence band on decreasing temperature from 298 K to 77 K as depicted in supplementary Figs. 41 and 42 (Δλ PH(BANMePh) max = 35 nm and Δλ PH(BANH2) max = 25 nm). Although the growth in the intermolecular interactions of chromophores modulated the electronic energy level of the 10 wt.% emitter, it demonstrated a negligible impact on the origin of dual phosphorescence in the matrix environment as a function of temperature. Steric effect of PBMA matrix on dual phosphorescence Further optical studies have been carried out in a rigid poly (butyl methacrylate) (PBMA) matrix to verify the matrix-dependent triplet state behavior of these emitters (Fig. 3 f, Supplementary Figs. 45–50, and Tables 28–30). Both PMMA and PBMA polymers possess similar electronic nature but provide a different steric environment to the dispersed chromophore (Fig. 3 a). Temperature dependent steady-state PL and phosphorescence behavior were found to be different in PBMA matrix environment (Figs. 3 g-i, and Supplementary Figs. 51–54). The 1 wt.% BANHPh@PBMA emitter showed a shifting of the phosphorescence band with temperature; however, there was a gradual destabilization of the emissive state at higher temperatures (Fig. 3 f). The ratio-metric change of HEP and LEP band with temperature exhibited a non-linear relationship for PMMA and PBMA matrix-based emitter (Fig. 3 i). In addition, PBMA matrix emitter of BANHPh (λ (445nm) 298 K : τ A1 = 5 ms, τ A2 = 17 ms) displayed relatively faster lifetime than PMMA matrix emitter (λ (450nm) 298 K : τ A1 = 23 ms, τ A2 = 103 ms) (Fig. 3 h and supplementary Fig. 54). The reduced phosphorescence performance in PBMA matrix can be due to the larger n-butyl group mediated non-radiative relaxation of emissive states at higher temperatures. Further, photophysical properties were investigated for the other two chromophores (BANMePh and BANH2) in the PBMA matrix. The 1 wt.% emitter of BANMePh exhibited analogous behavior to BANHPh in the PBMA matrix. However, 1 wt.% BANH2@PBMA exhibited a more stable emissive state for the HEP band compared to the other two emitters (Fig. 3 f, and Supplementary Fig. 47). This might be due to reduced steric interaction at higher temperatures in the absence of bulky phenyl group for BANH2 molecule. The lifetime decay profile of both the emitters (BANH2 and BANMePh) exhibited a shorter lifetime in the PBMA matrix than in the PMMA matrix (Supplementary Fig. 54). This experiment supported the significant role of matrix environment in controlling the stability of different triplet states in the dispersed chromophore. Origin of dual phosphorescence We performed quantum chemical calculations to elucidate the electronic origins of dual phosphorescence and tested two hypotheses for this phenomenon: (a) phosphorescence arising from low-lying triplet states (i.e., T 2 → S 0 , T 1 → S 0 ) and (b) the presence of room-temperature accessible conformers in the T 1 state. Accordingly, we explored the influence of the PMMA and PBMA matrices on the electronic properties of these compounds. The second hypothesis is supported by the variation in the dihedral angle between the xylyl and phenyl groups in the molecular structure (Supplementary Fig. 60, Tables 31–32). In this study, we employed the second-order Algebraic Diagrammatic Construction (ADC(2)) 39 method to compute excited state energetics, which has been shown to yield superior results for similar systems. First, we calculated the low-energy spectrum of all compounds using their fully optimized geometries in the presence of the matrix. Both PMMA and PBMA matrices were modeled as linear polymeric chains that fully encapsulate the compound (see Fig. 4a-c) (see computational methodology for details). For BANHPh@PMMA (Fig. 4d), we found the T 1 state (2.98 eV) lower in energy than the S 1 state (3.28 eV), while the T 2 state (3.39 eV) was slightly higher, suggesting that phosphorescence primarily arises from the T 1 state (Table 1 , Supplementary Table 33–34). The spin-orbit couplings (SOC) between S 0 –T 1 and S 0 –T 2 were 0.803 cm⁻¹ and 0.222 cm⁻¹, respectively, further supporting the dominant role of the T 1 state in the observed dual phosphorescence. However, the calculated T 1 –T 2 energy gap (0.41 eV) is larger than the experimentally determined value (0.19 eV). We observed similar trends for BANMePh@PMMA, where the T 1 state (2.95 eV) was lower than the S 1 state (3.18 eV), and the T 2 state (3.39 eV) was slightly higher, resulting in a T 1 –T 2 energy gap of 0.44 eV (Table 1 , Supplementary Table 35–37). We observed a similar dominant role of T 1 in phosphorescence in BANMePh. Interestingly, for BANH2@PMMA, both the T 1 (3.18 eV) and T 2 (3.48 eV) states were found below the S 1 state (3.50 eV), with a T 1 –T 2 energy gap of 0.30 eV. In this case, the SOC for T 2 –S 0 (0.75 cm⁻¹) was higher than for T 1 –S 0 (0.34 cm⁻¹), indicating that both T 1 and T 2 may contribute to the observed dual phosphorescence. (Supplementary Table 38–40) Overall, our excited-state calculations reveal the possible role of two distinct conformational states along the T1 in the dual phosphorescence in both BANHPh and BANMePh compounds in the presence of the PMMA matrix. However, for BANH2, both T 1 and T 2 states may be involved in the dual phosphorescence behavior. We note that for BANHPh@PMMA, the T 1 and T 2 states experienced a blue shift (0.088 eV) and redshift (0.065 eV), respectively, upon embedding in the PMMA matrix, resulting in an overall lowering of the T 1 –T 2 gap (from 0.56 eV to 0.41 eV). Similarly, for BANH2, the T 1 –T 2 gap decreased from 0.4 eV to 0.3 eV (see Table 1 ). Interestingly, spectral shifts in the low-energy spectrum were observed upon embedding in the PBMA matrix (Fig. 4e and Supplementary Table 32–33, 35–36, 38–39) This serves as a robust proof of the principle that polymeric matrix effects must be explicitly included in such calculations, as the matrix tunes the energetics of the frontier molecular orbitals (see Fig. 4f-g and supplementary Fig. 61) involved in the excitations, ultimately influencing the excitation energies. We further tested the second hypothesis regarding the existence of T 1 conformers. A CREST 40 conformational search (in the gas phase, for both T 1 and S 0 states) was conducted on all compounds, revealing that both BANHPh@PMMA and BANMePh@PMMA possess multiple conformers with flexible dihedral angles between the xylyl and phenyl groups. Based on these findings, we performed relaxed potential energy surface (PES) calculations (using GFN2-xTB) 41 for both the S 0 and T 1 states in the gas phase and within the PMMA matrix. For the T 1 state of BANHPh@PMMA, we identified five nearly isoenergetic conformers (all within 0–0.3 kcal/mol) in the gas phase, with the PES minimum showing a dihedral angle of 155° between the xylyl and phenyl groups. This suggests that all conformational states are thermally accessible at room temperature in the T 1 state (Fig. 4h). However, this result alone does not fully explain the observed gap of 0.19 eV (4.4 kcal/mol) between T 1 H and T 1 L . Upon embedding in the PMMA matrix, we found that the degeneracy of the conformers is lifted, with the minimum structure displaying a dihedral angle of 320°. The second minimum along the PES was 5.7 kcal/mol higher, with a dihedral angle of 272°. PMMA provides a unique compound-matrix interface, inducing molecular strain and electronic tuning that alters the properties of these compounds compared to their behavior in homogeneous solvents. Interestingly, a similar lifting of degeneracy was observed for BANMePh, with the PES minimum showing a dihedral angle of 325° between the xylyl and phenyl groups in the PMMA matrix, compared to 140° in the gas phase (see Fig. 4h). These results strongly suggest that the conformers of the T 1 state in BANHPh and BANMePh, when embedded in the PMMA matrix, could give rise to dual RTP. Temperature effects may provide the activation energy required for phenyl group rotation and subsequently lead to a population of high-energy conformational states. We also conducted similar PES scans for BANHPh and BANMePh in the S 0 state (Supplementary Fig. 62), observing a comparable lifting of conformational degeneracy. The degeneracy lifting relative to the gas phase is also observed in the case of the relaxed scans performed in the PBMA matrix for both BANHPh and BANMePh; however, unlike PMMA, only one minimum is found along the S 0 and T 1 . This clearly shows how different matrix environments tune the PES of these compounds. Table 1 Vertical excitation energies of low-lying singlet (S) and triplet (T) excited states for BANHPh, BANMePh and BANH2 computed using the ADC(2)/def2-TZVP level of theory. The fully optimized ground state singlet geometry, in the presence of an explicit PMMA matrix, was utilized. The nature of the excited states on a canonical basis and their weights are also depicted, and the oscillator strength ( f ) for the singlet excitation is shown. All energy values are in electron volts (eV). Compound S 1 T 1 T 2 With PMMA Gas-phase With PMMA Gas-phase With PMMA Gas-phase BANHPh 3.28 ( f = 0.32) H→ L 85.8% 3.16 ( f = 0.30) H→ L 87.0% 2.98 H→ L 79.1% 2.89 H→ L 79.1% 3.39 H-1→ L 77.3% 3.45 H-1→ L 78.2% BANMePh 3.18 ( f = 0.23) H→ L 87.9% 2.99 ( f = 0.20) H→ L 87.3% 2.95 H→ L 79.8% 2.81 H→ L 80.4% 3.39 H-1→ L 78.4% 3.42 H-1→ L 75.4% BANH2 3.50 (0.19) H→ L 91.7% 3.43 (0.18) H→ L 92.1% 3.18 H→ L 83.8% 3.12 H→ L 84.3% 3.48 H-1→ L 74.0% 3.52 H-1→ L 58.1% Our CREST conformational search in the case of BANH2 along the T 1 state suggests mainly two distinct structures (see Supplementary Fig. 63); however, their high energy gap (13.4 kcal mol − 1 ~ 0.6 eV) does not align with the experimental gap of 0.12 eV. Hence, the role of the T 1 conformers in the dual phosphorescence in the case of BANH2 can be ruled out, and this result goes in line with the earlier conclusion, based on excitation energetics results with possible involvement of both T 2 and T 1 in the dual phosphorescence. 31 . The rigidity of the PMMA matrix restricts the higher temperature, promoting vibronic coupling between the triplet excited states and the ground state. Therefore, the ascending of non-radiative rate constants ( k nr ) at higher temperatures for both the phosphorescence bands signify the faster interconversion rate of excitons ( k nr(482nm) 298 K = 9.36 s − 1 and k nr(482nm) 77 K = 0.79 s − 1 for BANHPh) between the triplet excited states (T 1 H and T 1 L ) (Supplementary Tables 12, 15, 18). The up-conversion (UC, T 1 L →T 1 H ) and down-conversion (DC, T 1 H →T 1 L ) rates are directly proportional to the non-radiative rate constant of T 1 L and T 1 H , respectively. The experimental activation energy for the interconversion of triplet excited states is calculated from the Arrhenius plot of the logarithm of the non-radiative rate constant varying with the Reciprocal of temperature. The activation energy of the up-conversion and down-conversion process is 2.4 Kcal/mol and 3.7 Kcal/mol, respectively for BANHPh emitter (Fig. 5 and Supplementary Fig. 55). The methyl incorporation in the BANMePh emitter enhanced the activation energy barriers for both up-conversion (3.9 Kcal/mol) and down-conversion (3.2 Kcal/mol) processes (Supplementary Figs. 56, 57). The relative activation energy of the emitters coincides with the theoretically estimated interconversion barriers of the thermally accessible conformers at the T 1 state. A similar trend in activation energy for the BANH2 emitter was found in the Arrhenius plot (Supplementary Figs. 58, 59). The different molecules create alternative heterogeneity in the matrix environment, which develops variations in the activation barriers between the triplet state interconversions. The relative activation energy determines the nature of the dual phosphorescence. Potential applications of the emitters Polymer-dispersed RTP emitters exhibit diverse technical applications owing to compatible mechanical strength and easy film processability procedures. The variable temperature dual-phosphorescence spectra showed a considerable spectral shift in the afterglow emission maxima for 1 wt.% (Δλ max : 32 nm) and 10 wt.% (Δλ max : 35 nm) of BANHPh @PMMA at different temperatures (Fig. 2 c, 3 b). The 1 wt.% emitter exhibited better phosphorescence properties than the 10 wt.% emitter (Fig. 3 d, 3 e). The phosphorescence color change of these emitters from light green at 77 K to blue at 298 K can be utilized as a useful temperature sensor for diverse applications (Fig. 6 a). In addition, the suitable RTP lifetime and phosphorescence quantum yield (PhQY) of 1 wt.% of BANHPh @PMMA and 1 wt.% of BANH2 @PMMA was explored for anticounterfeiting application using universal Morse cipher. As depicted in Fig. 6 b, the dichloromethane solution of 1 wt.% of BANHPh @PMMA and 1 wt.% of BANH2 @PMMA were used as ink to mark for ‘•’ and ‘─’ respectively on a glass plate. Both the emitters showed similar Commission Internationale de l´Eclairage (CIE) coordinates for the prompt emission [BANHPh: (0.15, 0.07) and BANH2: (0.19, 0.12)] and RTP bands [BANHPh: (0.15, 0.11) and BANH2: (0.15, 0.12)] (Fig. 6 b, right side spectra). However, these displayed different RTP lifetime values for phosphorescence maxima (λ (450) BANHPh : τ A1 = 23 ms, τ A2 = 103 ms; λ (455) BANH2 : τ A1 = 13 ms, τ A2 = 60 ms) (Fig. 6 b, right side decay profile) and this feature had been applied for storing confidential data. True information could not be observed when the UV light was on since both the emitters showed similar prompt emissions. The information did not even appear in the instantaneous UV light switch-off. The afterglow intensity of both the emitters was found to be reduced with time. The BANH2 emitter exhibited a shorter afterglow and stopped after 500 ms of UV light was turned off, revealing the position of the ‘─’ symbol. At this stage, the RTP of only the BANHPh emitter was visible with reduced phosphorescence intensity, which indicated the position of the ‘•’ symbol. The corresponding location of the symbols ‘•’ and ‘─’ signified the integrated Morse code. The comparison of the symbols with the Morse code index provided the encrypted information “S C I E N C E”. Thus, these RTP emitters with variation in PL lifetime can be utilized to improve the strength of the hidden data to make the information more confidential. The photostability of the 1 wt.% BANHPh @PMMA emitter was examined at different cycles after exposure to 365 nm UV light excitation (Fig. 6 c). No detectable photobleaching was observed in the naked eye, even after 15 cycles of UV light exposure. The afterglow intensity remained almost intact throughout all the cycles. The photostability and afterglow brightness of the designed phosphorescent material encourages future innovative applications using this phosphorescent material. Discussion We report intriguing findings on lifting triplet-state degeneracy in organic chromophores embedded in a PMMA matrix. A strategic design of the chromophores and a suitable combination of polymer matrix resulted in the rare phenomenon of thermally promoted phosphorescence with efficient quantum yield. The molecular dispersion (1 wt.%) of the chromophore in the PMMA matrix provides favorable crossover energies of triplet excited states to maintain the thermal equilibrium of emissive states. We showcased a robust proof-of-principle that polymeric matrices can tune the geometric structure and spectroscopic properties of chromophores using advanced quantum chemical approaches. These polymeric matrices provide an asymmetric environment, distinct from homogeneous solvents, which imposes greater steric control over the compound. This observation parallels findings in biological systems, where pigments such as chlorophylls embedded in protein matrices modulate functional properties. A key example is the Photosystem II reaction center 42 , where chlorophylls are embedded in a protein matrix. It is well established that the protein matrix 43 plays a crucial role in lowering the charge-transfer state energetics, a factor essential for the charge-separation event and overall enzymatic efficiency. The ideal approach would involve molecular dynamics-based conformational sampling of the compound-matrix binary solution using periodic boundary conditions. We are currently working on implementing this method in future studies. Nevertheless, the current model provides solid proof that the matrix plays a critical role in the geometric and electronic tuning of chromophores. Finally, these emitters have been successfully explored for anti-counterfeiting applications using Morse cipher. Moreover, this concept holds the potential for better future innovative applications in dynamic multilevel encryption of information against the traditional understanding of device design. Methods Measurements 1 H, 13 C{ 1 H}, and 11 B NMR spectra were recorded at 25°C on a Bruker Advance 400 MHz NMR Spectrometer operating at a frequency of 400 MHz for 1 H, 100 MHz for 13 C and 128 MHz for 11 B using deuterated solvent (CDCl 3 ). 1 H NMR and 13 C NMR spectra were referenced to the residual solvent signal, and 11B NMR spectra were referenced to the standard boron signal of BF 3 ·Et 2 O. High-resolution mass spectra (HRMS) were recorded on a Micromass Q-ToF High-Resolution Mass Spectrometer by electrospray ionization (ESI) method. Powder X-ray diffraction patterns of the pristine compounds and thin films were collected from a XD-D1 Shimadzu X-ray diffractometer. Thermogravimetric analysis (TGA) was examined using TA Instrument Q50 TGA thermogravimetric analyzer at a 10°C/min heating rate under an argon atmosphere. The decomposition temperature for TGA curves was determined at a threshold of 10% weight loss. DSC was performed using METTLER-TOLEDO and TA instruments at a heating and cooling rate of 10°C/min under an argon atmosphere. The absorption measurements were carried out at room temperature by SHIMADAZU UV-2600 spectrophotometer. The steady-state emission, excitation, and lifetime spectra were measured using an Edinburgh Instrument FLS980 spectrometer equipped with a xenon arc lamp and microsecond flash lamp. Time-gated emission spectra were recorded using the same FLS980 spectrometer coupled with a time-gated circuit to the photomultiplier tube (PMT) detector. The steady-state and time-gated emission spectra were recorded using a xenon arc lamp and pulsed microsecond Flashlamp (µF1, pulse width of 1.1 µS) as excitation sources, respectively. Temperature-dependent measurements were performed using an Oxford Instruments OPTISTAT DN2 cryostat controlled by an Oxford Instruments Mercury iTC temperature controller connected to the FLS980 spectrometer. Samples were allowed to reach uniform temperature distribution before conducting any measurement. Photophysical studies of thin films were recorded under vacuum conditions unless otherwise mentioned. The fluorescence quantum yields of the solutions and thin films were measured under ambient conditions using a calibrated integrating sphere from Horiba combined with the Horiba JOBIN YVON Fluoromax-4 spectrometer. Preparation of Thin Films The chromophores, poly(methyl methacrylate) (PMMA), and poly(butyl methacrylate) (PBMA) were dissolved in HPLC dichloromethane solvent to prepare the stock solutions at a concentration of 1 mg/ml. The stock solutions were mixed in a particular proportion to obtain 1 wt.% and 10 wt.% of compound concentration in the polymer solution. The wt.% indicates the weight percentage of the compound relative to the total weight content of the polymer. Each film was prepared by spin-coating the compound/PMMA solution on a quartz substrate at 25°C. Computational Methodology The PMMA matrix around each chromophore was constructed using chem3D 20.1.1 software 44 . The system sizes for BANHPh, BANMePh, and BANH2 consisted of 651, 654, and 641 atoms, respectively. All compounds were first optimized within the PMMA matrix in their S 0 and T 1 states using the GFN2-xTB approach 41 , which resolved any geometric clashes within the system. Relaxed potential energy scans for both the S 0 and T 1 states were conducted using GFN2-xTB by varying the dihedral angle between the xylyl and phenyl groups. The conformational sampling for compounds (along the T 1 state) was computed using the CREST program 45 . Vertical excitation energies were calculated using the second-order Algebraic Diagrammatic Construction (ADC(2)) 39 Method, combined with the def2-TZVP all-atom basis set, via the Turbomole 7.5 suite 46 . The matrix effect on the excited state calculations was incorporated using point charges (derived from the Merz-Kollman Restrained Electrostatic Potential), where the contributions of the charges were explicitly included in the one-electron matrices and nuclear repulsion terms. We note that the geometries obtained via GFN2-xTB were highly consistent with those from full optimization at the B3LYP/def2-TZVP level of theory, with an RMSD of 0.0358 Å. For benchmarking, we also compared the ADC(2) excitation energies for BANHPh geometries optimized using both GFN2-xTB and B3LYP/def2-TZVP, and found similar excited state energetics, state ordering, and orbital contributions in the canonical basis. The spin-orbit coupling (SOC) matrix elements 47 were calculated using time-dependent density functional theory (TDDFT) at the B3LYP/def2-TZVP level, with TDDFT computations performed using the ORCA 5.2 program 48 . Declarations Data availability The data supporting the findings of the work are available in the supplementary information file of this article. The X-ray crystallographic coordinates for structures reported in this study have been deposited at the Cambridge Crystallographic Data Centre (CCDC), under deposition numbers 2402229, 2402230, 2402231, 2402232, 2402233, 2402233, and 2402235 for BANHPh at different temperatures; 2403250, 2403251, 2403252, 2403253, 2403254, 2403255, and 2403256 for BANMePh at different temperatures; 2403348, 2403349, 2403350, 2403351, 2403352, and 2403353 for BANH2 at various temperatures. Source data are provided with this paper. Competing interests The authors declare no competing interests. Author contributions P.T. designed the research works. S.G. carried out the synthesis of the chromophores, film preparation, characterization, photophysical studies, and application studies. R.P.N. contributed to the synthesis. N.H. and S.G. performed the SCXRD analysis. A.S. carried out the theoretical calculations and contributed to manuscript writing. All the authors commented on the manuscript. P.T. organized the entire project and approved the final version of the manuscript. Acknowledgments This work was supported by the Science and Engineering Research Board (SERB), India (EEQ/2023/000903 (P.T.)); Prime Minister Research Fellowship (PM/MHRD-20-17748.03 (S.G.)) and Indian Institute of Science research fellowship (R.P.N). All the authors thank IISc and the IPC department for instrumental and computational support. References Zhang KY et al (2018) Dual-Phosphorescent Iridium(III) Complexes Extending Oxygen Sensing from Hypoxia to Hyperoxia. J Am Chem Soc 140:7827–7834 Yang J et al (2018) The influence of the molecular packing on the room temperature phosphorescence of purely organic luminogens. Nat Commun 9:840 Zhou Y et al (2019) Long-Lived Room-Temperature Phosphorescence for Visual and Quantitative Detection of Oxygen. Angew Chem 131:12230–12234 Wang T et al (2019) Aggregation-Induced Dual-Phosphorescence from Organic Molecules for Nondoped Light-Emitting Diodes. Adv Mater 31:1904273 Liu X et al (2021) An Electroactive Pure Organic Room-Temperature Phosphorescence Polymer Based on a Donor-Oxygen-Acceptor Geometry. Angew Chem Int Ed 60:2455–2463 Tao P et al (2016) Facile Synthesis of Highly Efficient Lepidine-Based Phosphorescent Iridium(III) Complexes for Yellow and White Organic Light-Emitting Diodes. Adv Funct Mater 26:881–894 Yu Z et al (2017) Organic Phosphorescence Nanowire Lasers. J Am Chem Soc 139:6376–6381 Sun H et al (2014) Smart responsive phosphorescent materials for data recording and security protection. Nat Commun 5:3601 Yang Z et al (2016) Intermolecular Electronic Coupling of Organic Units for Efficient Persistent Room-Temperature Phosphorescence. Angew Chem 128:2221–2225 Zhao W et al (2018) Highly sensitive switching of solid-state luminescence by controlling intersystem crossing. Nat Commun 9:3044 He Z et al (2019) Achieving Persistent, Efficient, and Robust Room-Temperature Phosphorescence from Pure Organics for Versatile Applications. Adv Mater 31:1807222 Tao Y et al (2022) Resonance-Induced Stimuli-Responsive Capacity Modulation of Organic Ultralong Room Temperature Phosphorescence. J Am Chem Soc 144:6946–6953 Liang X et al (2019) Organic Room-Temperature Phosphorescence with Strong Circularly Polarized Luminescence Based on Paracyclophanes. Angew Chem Int Ed 58:17220–17225 Wu Z et al (2020) Persistent Room Temperature Phosphorescence from Triarylboranes: A Combined Experimental and Theoretical Study. Angew Chem Int Ed 59:17137–17144 An Z et al (2015) Stabilizing triplet excited states for ultralong organic phosphorescence. Nat Mater 14:685–690 Cheng Z et al (2018) Ultralong Phosphorescence from Organic Ionic Crystals under Ambient Conditions. Angew Chem Int Ed 57:678–682 Jia X et al (2019) Photoexcitation-controlled self-recoverable molecular aggregation for flicker phosphorescence. Proc. Natl. Acad. Sci. 116, 4816–4821 Du M et al (2022) White Emissions Containing Room Temperature Phosphorescence from Different Excited States of a D–π–A Molecule Depending on the Aggregate States. Adv Sci 9:2104539 Zhang Y et al (2021) Large-Area, Flexible, Transparent, and Long-Lived Polymer-Based Phosphorescence Films. J Am Chem Soc 143:13675–13685 Ma D-X et al (2024) Nylons with Highly-Bright and Ultralong Organic Room-Temperature Phosphorescence. Nat Commun 15:4402 Zou X et al (2023) Narrowband Organic Afterglow via Phosphorescence Förster Resonance Energy Transfer for Multifunctional Applications. Adv Mater 35:2210489 Wang Z et al (2020) Color-Tunable Polymeric Long-Persistent Luminescence Based on Polyphosphazenes. Adv Mater 32:1907355 Ogoshi T et al (2018) Ultralong Room-Temperature Phosphorescence from Amorphous Polymer Poly(Styrene Sulfonic Acid) in Air in the Dry Solid State. Adv Funct Mater 28:1707369 Wu H et al (2021) Tailoring Noncovalent Interactions to Activate Persistent Room-Temperature Phosphorescence from Doped Polyacrylonitrile Films. Adv Funct Mater 31:2101656 Zhang X et al (2023) A Class of Organic Units Featuring Matrix-Controlled Color-Tunable Ultralong Organic Room Temperature Phosphorescence. Adv Sci 10:2206482 Wang Y et al (2021) New Phenothiazine Derivatives That Exhibit Photoinduced Room-Temperature Phosphorescence. Adv Funct Mater 31:2101719 Wang T, De J, Wu S, Gupta AK, Zysman-Colman E (2022) Thermally Activated and Aggregation-Regulated Excitonic Coupling Enable Emissive High-Lying Triplet Excitons. Angew Chem Int Ed 61:e202206681 Wang T et al (2021) Thermochromic aggregation-induced dual phosphorescence via temperature-dependent sp3-linked donor-acceptor electronic coupling. Nat Commun 12:1364 She P et al (2022) Single-Component Molecular Dual Persistent Room Temperature Phosphorescence from Low- and High-Lying Triplet States. Adv Opt Mater 10:2102706 Li J et al (2023) A direct observation of up-converted room-temperature phosphorescence in an anti-Kasha dopant-matrix system. Nat Commun 14:1987 He Z et al (2017) White light emission from a single organic molecule with dual phosphorescence at room temperature. Nat Commun 8:416 Zhou C et al (2018) Ternary Emission of Fluorescence and Dual Phosphorescence at Room Temperature: A Single-Molecule White Light Emitter Based on Pure Organic Aza-Aromatic Material. Adv Funct Mater 28:1802407 Jiang K et al (2020) Carbon Dots with Dual-Emissive, Robust, and Aggregation-Induced Room-Temperature Phosphorescence Characteristics. Angew Chem Int Ed 59:1263–1269 Nandi RP, Kalluvettukuzhy NK, Pagidi S, Thilagar P (2023) Molecular Persistent Room-Temperature Phosphorescence from Tetraarylaminoboranes. Inorg Chem 62:1122–1134 Arumugam R et al (2024) Regioisomers containing triarylboron-based motifs as multi-functional photoluminescent materials: from dual-mode delayed emission to pH-switchable room-temperature phosphorescence. Chem Sci 15:18364–18378 Sudhakar P, Mukherjee S, Thilagar P (2013) Revisiting Borylanilines: Unique Solid-State Structures and Insight into Photophysical Properties. Organometallics 32:3129–3133 Ma Z et al (2021) Converting molecular luminescence to ultralong room-temperature phosphorescence via the excited state modulation of sulfone-containing heteroaromatics. Chem Sci 12:14808–14814 Hertel T, Himmelein S, Ackermann T, Stich D, Crochet J (2010) Diffusion Limited Photoluminescence Quantum Yields in 1-D Semiconductors: Single-Wall Carbon Nanotubes. ACS Nano 4:7161–7168 Schirmer J (1982) Beyond the random-phase approximation: A new approximation scheme for the polarization propagator. Phys Rev A 26:2395–2416 Pracht P, Bohle F, Grimme S (2020) Automated exploration of the low-energy chemical space with fast quantum chemical methods. Phys Chem Chem Phys 22:7169–7192 Bannwarth C, Ehlert S, Grimme S (2019) GFN2-xTB—An Accurate and Broadly Parametrized Self-Consistent Tight-Binding Quantum Chemical Method with Multipole Electrostatics and Density-Dependent Dispersion Contributions. J Chem Theory Comput 15:1652–1671 Umena Y, Kawakami K, Shen J-R, Kamiya N (2011) Crystal structure of oxygen-evolving photosystem II at a resolution of 1.9 Å. Nature 473:55–60 Sirohiwal A, Neese F, Pantazis DA (2020) Protein Matrix Control of Reaction Center Excitation in Photosystem II. J Am Chem Soc 142:18174–18190 Zielesny A (2005) Chemistry Software Package ChemOffice Ultra 2005. J Chem Inf Model 45:1474–1477 Pracht P et al (2024) CREST—A program for the exploration of low-energy molecular chemical space. J Chem Phys 160:114110 Balasubramani SG et al (2020) Modular program suite for ab initio quantum-chemical and condensed-matter simulations. J Chem Phys 152:184107 de Souza B, Farias G, Neese F, Izsák R (2019) Predicting Phosphorescence Rates of Light Organic Molecules Using Time-Dependent Density Functional Theory and the Path Integral Approach to Dynamics. J Chem Theory Comput 15:1896–1904 Neese F (2018) Software update: the ORCA program system, version 4.0. WIREs Comput Mol Sci 8:e1327 Additional Declarations There is NO Competing Interest. Supplementary Files Sourcedata.xlsx Supplementary Dataset 1 SI.docx SI Cite Share Download PDF Status: Published Journal Publication published 19 Feb, 2026 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5794027","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":404694993,"identity":"38ae3bfc-f08a-4d50-96b5-650d3df614bc","order_by":0,"name":"Pakkirisamy Thilagar","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIiWNgGAWjYDACCcbGAyCan5mxASLCTEAHjwRjA1iLZDPxWhgYwFoMDhDrLnvp5oYDP37Z5RsfZ27+8IPBTp6BnRe/bh6Zgw0He/uSLbcdZmyT7GFINmxg5ksg4LDEhgO8PcwGZkAtQF8wJzAw8xgQ1HLwb0+9gXEzY/NnBoZ64rQc5vlx2MAAGMjSDAyHidByA6hFtuG4gQTYLwbHDdsIaWGfkf7w4Zs/1Qb8/ccff/hRUS3Pz38GvxYwYGyDsYCK2QirB4E/xCkbBaNgFIyCEQoAK6U/GcZWB28AAAAASUVORK5CYII=","orcid":"","institution":"Indian Institute of Science","correspondingAuthor":true,"prefix":"","firstName":"Pakkirisamy","middleName":"","lastName":"Thilagar","suffix":""},{"id":404694994,"identity":"7f9aae1e-d6ad-473a-8fa4-17c38ad5a4a2","order_by":1,"name":"Subhajit Ghosh Ghosh","email":"","orcid":"https://orcid.org/0009-0004-6776-5240","institution":"Indian Institute of Science, Bangalore, INDIA","correspondingAuthor":false,"prefix":"","firstName":"Subhajit","middleName":"Ghosh","lastName":"Ghosh","suffix":""},{"id":404694995,"identity":"fcf226b7-1c3a-42b1-aa20-565ac2f489f3","order_by":2,"name":"Rajendra Nandi","email":"","orcid":"","institution":"IISc","correspondingAuthor":false,"prefix":"","firstName":"Rajendra","middleName":"","lastName":"Nandi","suffix":""},{"id":404694996,"identity":"8cb5b01a-74b0-4437-90d2-112d2a88ebe7","order_by":3,"name":"Silvano Geremia","email":"","orcid":"","institution":"University of Trieste","correspondingAuthor":false,"prefix":"","firstName":"Silvano","middleName":"","lastName":"Geremia","suffix":""},{"id":404694997,"identity":"295376d7-eddd-4fdc-bc6b-6320c1f58c91","order_by":4,"name":"Neal Hickey","email":"","orcid":"","institution":"University of Trieste","correspondingAuthor":false,"prefix":"","firstName":"Neal","middleName":"","lastName":"Hickey","suffix":""},{"id":404694998,"identity":"d55ab30e-e89d-4e3d-9e51-a05996000604","order_by":5,"name":"Abhishek Sirohiwal","email":"","orcid":"","institution":"Indian Institute of Science, Bangalore, INDIA","correspondingAuthor":false,"prefix":"","firstName":"Abhishek","middleName":"","lastName":"Sirohiwal","suffix":""}],"badges":[],"createdAt":"2025-01-09 07:15:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5794027/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5794027/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41467-026-69664-x","type":"published","date":"2026-02-19T05:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":76189204,"identity":"00f168e1-3132-4cd2-b8e4-e905f7de0e70","added_by":"auto","created_at":"2025-02-13 09:15:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":922473,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRational design of chromophores and schematic illustration of triplet state degeneracy lifting\u003c/strong\u003e. \u003cstrong\u003ea\u003c/strong\u003e Chemical structures of chromophores. \u003cstrong\u003eb\u003c/strong\u003e The representation of triplet state degeneracy lifting due to temperature promoted conformational isomerism in the presence of a PMMA matrix surrounding it. \u003cstrong\u003ec\u003c/strong\u003e SCXRD obtained molecular structures at 100 K and 300 K, representing the dihedral angle (DA) between the mean plane of the phenyl ring (thick bond) and xylyl ring (thick bond) for each molecule.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-5794027/v1/7e2ee0fdc9c95795563bea55.png"},{"id":76189409,"identity":"f3d944c4-9af6-478b-a4a0-505d472cbafa","added_by":"auto","created_at":"2025-02-13 09:23:16","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1473933,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eInvestigation on dual phosphorescence property of 1 wt.% compound in PMMA matrix.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e Steady-state PL and phosphorescence (50 μs delay) spectra for 1 wt.% of BANHPh (λ\u003csub\u003eex\u003c/sub\u003e = 390 nm) (bottom); 1 wt.% of BANMePh (λ\u003csub\u003eex\u003c/sub\u003e = 380 nm) (middle) and 1 wt.% of BANH2 (λ\u003csub\u003eex\u003c/sub\u003e = 365 nm) (top) in the PMMA matrix. \u003cstrong\u003eb\u003c/strong\u003e Absorbance and excitation spectra of 1 wt.% BANHPh@PMMA. \u003cstrong\u003ec\u003c/strong\u003e Temperature-dependent phosphorescence spectra (50 μs delay) from 77 K to 298 K of 1 wt.% BANHPh@PMMA. \u003cstrong\u003ed\u003c/strong\u003e Lifetime decay profiles of 1 wt.% BANHPh@PMMA at 298 K for 450 nm phosphorescence band and 77 K for 482 nm phosphorescence band. \u003cstrong\u003ee\u003c/strong\u003e Temperature-dependent variation of lifetime of 1 wt.% BANHPh@PMMA at 450 nm and 482 nm phosphorescence band. \u003cstrong\u003ef\u003c/strong\u003e Time resolved area-normalized emission spectra at 225 K for 1 wt.% BANHPh@PMMA. \u003cstrong\u003eg\u003c/strong\u003e Temperature-dependent variation of phosphorescence quantum yield of 1 wt.% BANHPh@PMMA for 450 nm and 482 nm phosphorescence band. \u003cstrong\u003eh\u003c/strong\u003e The representation of S\u003csub\u003e1\u003c/sub\u003e, T\u003csup\u003eL \u003c/sup\u003eand T\u003csup\u003eH\u003c/sup\u003e energy levels appraised from the emission spectra of 1 wt.% BANHPh@PMMA.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-5794027/v1/9eec45a34de410086bdc6b2d.png"},{"id":76189205,"identity":"10ab1d86-23ba-4285-9eb1-e0e2cd705d7f","added_by":"auto","created_at":"2025-02-13 09:15:16","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1576447,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eInfluence of intermolecular interactions and matrix environments on Dual phosphorescence. a\u003c/strong\u003e. Chemical structure of PMMA and PBMA polymers. \u003cstrong\u003eb\u003c/strong\u003e Temperature-dependent phosphorescence spectra (50 μs delay) from 77 K to 298 K of 10 wt.% BANHPh@PMMA. \u003cstrong\u003ec\u003c/strong\u003e Relative phosphorescence spectra at 77 K and 298 K for 1 wt.% and 10 wt.% BANHPh@PMMA. \u003cstrong\u003ed\u003c/strong\u003e Comparison of lifetime decay profile at 298 K (λ\u003csub\u003emax\u003c/sub\u003e) and 77 K (λ\u003csub\u003emax\u003c/sub\u003e) for 1 wt.% and 10 wt.% BANHPh@PMMA. \u003cstrong\u003ee\u003c/strong\u003e Histograms of total phosphorescence quantum yield at 298 K and 77 K for 1 wt.% and 10 wt.% BANHPh@PMMA. \u003cstrong\u003ef\u003c/strong\u003e Temperature-dependent phosphorescence spectra (50 μs delay) of 1 wt.% BANHPh@PBMA. \u003cstrong\u003eg\u003c/strong\u003e Relative phosphorescence spectra at 77 K and 298 K for 1 wt.% BANHPh@PMMA and 1 wt.% BANHPh@PBMA. \u003cstrong\u003eh \u003c/strong\u003eComparison of lifetime decay profile at 298 K (λ\u003csub\u003emax\u003c/sub\u003e) and 77 K (λ\u003csub\u003emax\u003c/sub\u003e) for 1 wt.% BANHPh@PMMA and 1 wt.% BANHPh@PBMA. \u003cstrong\u003ei \u003c/strong\u003eRelative intensity of LEP and HEP bands at different temperatures for 1 wt.% emitter of BANHPh in PMMA and PBMA matrix; (λ\u003csub\u003eex\u003c/sub\u003e =390 nm).\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-5794027/v1/8dc5e19958da8ac189244abe.png"},{"id":76189208,"identity":"cf9b34a4-3156-47e9-a4d7-8f56b33a0fcf","added_by":"auto","created_at":"2025-02-13 09:15:17","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":758259,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTheoretical calculations to understand the origin of dual phosphorescence in PMMA matrix\u003c/strong\u003e. \u003cstrong\u003ea\u003c/strong\u003e Molecular structure of the compound embedded in a PMMA matrix. The inset shows the unique interface between the compound and the matrix, including the formation of a hydrogen bond between the compound and the side-chain carbonyl moiety of the polymer chain. \u003cstrong\u003eb, c\u003c/strong\u003e Molecular structures of BANHPh and BANMePh, highlighting atoms (rendered with a larger radius) involved in the dihedral angle between the rotating xylyl and phenyl groups. \u003cstrong\u003ed, e\u003c/strong\u003e Energy levels of S\u003csub\u003e1\u003c/sub\u003e, T\u003csub\u003e2\u003c/sub\u003e, and T\u003csub\u003e1\u003c/sub\u003e relative to the S\u003csub\u003e0\u003c/sub\u003e state, computed using the ADC(2)/def2-TZVP level of theory for all three compounds embedded in the PMMA and PBMA matrices. Matrix effects are included in all calculations. The T\u003csub\u003e2\u003c/sub\u003e-T\u003csub\u003e1\u003c/sub\u003e energy gap and the spin-orbit coupling parameters (η) for T1/T2-S1 andT1/T2-S0 are also shown. \u003cstrong\u003ef, g\u003c/strong\u003e Frontier molecular orbitals of BANHPh and BANMePh, with yellow and red isosurfaces representing positive and negative phases, respectively. \u003cstrong\u003eh\u003c/strong\u003e Relaxed potential energy scans (T\u003csub\u003e1\u003c/sub\u003e state) of phenyl group rotation, varying the dihedral angle with the xylyl group for BANHPh and BANMePh embedded in the PMMA matrix.\u0026nbsp; \u003cstrong\u003eh\u003c/strong\u003e Relaxed potential energy scans (T\u003csub\u003e1\u003c/sub\u003e state) of phenyl group rotation, varying the dihedral angle with the xylyl group for BANHPh and BANMePh embedded in the PBMA matrix.\u0026nbsp;\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-5794027/v1/cddb03d5a80547a50667dfe9.png"},{"id":76189209,"identity":"52a29134-9aac-4057-814e-2a10b5fc5554","added_by":"auto","created_at":"2025-02-13 09:15:17","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":501586,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCrossover energies for triplet excited states for 1 wt.% emitter.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e Up-conversion (UC) and down-conversion (DC) process of triplet excited states for 1 wt.% BANHPh@PMMA. \u003cstrong\u003eb\u003c/strong\u003e Temperature dependence of 450 nm (T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eH\u003c/sup\u003e) to 482 nm (T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eL\u003c/sup\u003e) down-conversion rate constant (k\u003csub\u003eDC \u003c/sub\u003e≈ k\u003csub\u003enr\u003c/sub\u003e\u003csup\u003e450\u003c/sup\u003e). \u003cstrong\u003ec\u003c/strong\u003e Temperature dependence of 482 nm (T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eL\u003c/sup\u003e) to 450 nm (T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eH\u003c/sup\u003e) up-conversion rate constant (k\u003csub\u003eUC \u003c/sub\u003e≈ k\u003csub\u003enr\u003c/sub\u003e\u003csup\u003e482\u003c/sup\u003e) for 1 wt.% BANHPh@PMMA emitter.\u003c/p\u003e\n\u003cp\u003e* The activation energy (E\u003csub\u003eA\u003c/sub\u003e) is not calculated for 10 wt.% compound@PMMA and 1 wt.% compound@PBMA in the matrix due to intermolecular interaction effects in non-radiative rate constants at higher temperatures.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-5794027/v1/28470bf134c1c85b1ef4b4c2.png"},{"id":76189216,"identity":"91063fb9-5c43-4502-b2a0-e45db26c3b86","added_by":"auto","created_at":"2025-02-13 09:15:17","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1373283,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eApplications of phosphorescent emitters.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e Temperature-dependent phosphorescence afterglow of 1 wt.% and 10 wt.% BANHPh @PMMA. \u003cstrong\u003eb\u003c/strong\u003e Demonstration of encryption application with Morse code. Right side: Relative phosphorescence decay profile (above) and comparison of phosphorescence spectra (below) of BANHPh and BANH2 at 1 wt.% conc. In the PMMA matrix. \u003cstrong\u003ec\u003c/strong\u003e Afterglow emitting material with different cycles of photoirradiation.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-5794027/v1/d0e503f600280cbf92bbd1c4.png"},{"id":105618276,"identity":"95812b06-2893-4c4a-b70c-a45ce788022a","added_by":"auto","created_at":"2026-03-28 07:12:50","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7804490,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5794027/v1/1b9ad81c-7157-4707-8645-cbfc6df27ce2.pdf"},{"id":76189207,"identity":"e5f6072c-574a-4426-8c74-dd0683f93e8a","added_by":"auto","created_at":"2025-02-13 09:15:16","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":411336,"visible":true,"origin":"","legend":"Supplementary Dataset 1","description":"","filename":"Sourcedata.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-5794027/v1/e4a5fb14c0ce7a259976cf81.xlsx"},{"id":76190410,"identity":"14e272f4-ecbb-4037-ae03-4f604cf115ae","added_by":"auto","created_at":"2025-02-13 09:31:17","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":9445208,"visible":true,"origin":"","legend":"SI","description":"","filename":"SI.docx","url":"https://assets-eu.researchsquare.com/files/rs-5794027/v1/ed2aa2c96725f97901acce60.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Polymer Matrix Drives Dual Phosphorescence in Dispersed Chromophores","fulltext":[{"header":"Introduction","content":"\u003cp\u003eControlling the nature of dual phosphorescence demands a comprehensive understanding of triplet excited state behavior. The triplet-state involved afterglow has been utilized for several advanced applications such as bioimaging\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e, sensing\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e, organic light-emitting diodes\u003csup\u003e\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e, lasers\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e and anticounterfeiting\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. The organic room temperature phosphorescence (RTP) emitter efficiency has been shown to improve by introducing hetero-atoms\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e, aromatic carbonyl group substitution\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e, engineering resonance linkage\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e, and through-space charge-transfer (TSCT) motif\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e to facilitate the intersystem crossing (ISC) process from the lowest excited singlet state (S\u003csub\u003e1\u003c/sub\u003e) to the triplet state (T\u003csub\u003en\u003c/sub\u003e). Lately, it has been demonstrated that exciton spin-flip between singlet and triplet excited states can also be accelerated by sp\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e-boron localized (σ, Bp) \u0026rarr; (π, Bp) transition\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. On the other hand, crystal engineering\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e, molecular aggregations\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e, and molecularly dispersed polymer matrix\u003csup\u003e\u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e have been successfully explored to suppress the oxygen quenching and molecular vibration-caused non-radiative deactivation of triplet excitons. Among these, RTP from the organic chromophores embedded in polymer matrices (such as polyvinyl alcohol\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e, polystyrene\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e, and polyacrylamide\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e) has received a momentous research interest in a target to improve the stability of triplet excitons. Physical dispersion of simple luminophores in different polymer matrices at variable ratios enables better flexibility to tune the RTP properties than the challenging and tedious chemical synthesis of complex chromophores.\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003ePoly(methyl methacrylate) (PMMA) is the most commonly used polymer matrix to achieve afterglow emission from molecularly dispersed organic chromophores owing to suitable mechanical properties, amorphous state, chemical stability, and facile film processing technique. Furthermore, the oxygen sensitivity of the PMMA matrix has been explored for several photo-induced phosphorescence\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e. Most of the dopant-matrix systems exhibit excellent features of a single phosphorescence band owing to a suitable matrix environment. Nevertheless, there are several reports demonstrating stimuli-dependent dual phosphorescence features by virtue of the strategic structural design of chromophores molecularly dispersed in a matrix environment\u003csup\u003e\u003cspan additionalcitationids=\"CR28 CR29\" citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. The dual phosphorescence feature is currently in demand in promising applications such as the development of white light emitters from single chromophore\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e,\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e, and stimuli-responsive materials for anti-counterfeiting applications\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. Molecular dual phosphorescence can arise due to either rarely observed multiple T\u003csub\u003en\u003c/sub\u003e-S\u003csub\u003e0\u003c/sub\u003e (n\u0026thinsp;=\u0026thinsp;1 and n\u0026thinsp;\u0026ge;\u0026thinsp;2 for anti-Kasha emission) radiative decay\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e or emission from molecular conformation-dependent multiple accessible triplet excited states\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e. Li \u003cem\u003eet al\u003c/em\u003e. reported that dual phosphorescence of benzophenone-containing difluoroboronβ-diketonate derivatives embedded in phenyl benzoate matrix was originated due to radiative decay of T\u003csub\u003en\u003c/sub\u003e (n\u0026thinsp;\u0026ge;\u0026thinsp;2) states\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. Wang \u003cem\u003eet al\u003c/em\u003e. explained that multiple emissive triplet excited states result from excitonic coupling caused by molecular aggregates in the polymer matrix. Although several experiments have been conducted on dual phosphorescence in matrix environments, the chemistry behind the role of the matrix for triplet state dynamics of emitter has remained unclear. Our group has been actively involved in developing organic RTP systems derived from the molecular dispersion of chromophores in PMMA matrix\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e,\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. As part of the ongoing program, we set out to investigate the impact of the asymmetric environment created by the PMMA matrix to understand the origin of dual phosphorescence from the dispersed chromophore.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn this target, we have selected borylaniline derivatives comprising the amine donor and -BMes\u003csub\u003e2\u003c/sub\u003e acceptor as the model compounds. We sought to decipher the influence of rigid matrix on the conformational isomerism of chromophores to gain insights into the underlying mechanism of dual phosphorescence. Accordingly, the molecules are rationally designed with locked geometry around the boron center, allowing conformational freedom only to N-C(xylyl) bond (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). This approach simplified the system by eliminating the possibility of multiple dihedral angle variation. In a matrix environment, the side-chain ester group and α-methyl group of the PMMA chain may induce specific steric and electrostatic interaction with chromophore, leading to different spatial arrangements of the conformers at each fixed dihedral angle. These factors govern the relative stability of the conformers, which are related to distinct triplet energy levels (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, b). This feature resulted in temperature dependent dual phosphorescence behavior of the emitter at 1 wt.% of the chromophore concentration in the PMMA matrix. Two room temperature accessible conformers at the T\u003csub\u003e1\u003c/sub\u003e state are mainly responsible for the dual phosphorescence behavior of the emitters. Further, control photophysical studies have been carried out in poly(butyl methacrylate) (PBMA) matrix to validate the matrix influence on dual phosphorescence. Thereafter, the theoretical investigation of the influence of the polymer (PMMA) matrix on the electronic energy levels of the dispersed chromophore confirms our anticipation. We observe an extraordinary finding where the PMMA matrix lifts the degeneracy of the conformers in the T\u003csub\u003e1\u003c/sub\u003e state by providing an asymmetric environment. However, similar degeneracy lifting is not likely to happen in the absence of the matrix surroundings. We further corroborate our experimental findings with the wavefunction-based second-order Algebraic Diagrammatic Construction (ADC2) excited state calculations performed on the compounds explicitly in the presence of the matrix to validate our hypothesis (Fig.\u0026nbsp;4). The present results can be utilized for temperature sensing from the ratiometric phosphorescence afterglow colour change-over in a short energy range. These emitters (1 wt.% BANHPh@PMMA and 1 wt.% BANH2@PMMA) have also been successfully explored for anti-counterfeiting applications and promising afterglow materials.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eMolecular design and characterization\u003c/h2\u003e\n \u003cp\u003eThe chromophores were designed by changing the substituent at the nitrogen center of 4-(dimesitylboraneyl)-3,5-dimethylaniline (BANH2), keeping the core structure intact. A secondary amine derivative (BANHPh) was designed to enable the feasibility of non-degenerate conformers under external stimuli. The methylated derivative (BANMePh) was synthesized to investigate the photo-physics of the system in the absence of the H-bonding channel present in the secondary amine derivative. The unsubstituted derivative (BANH2) was explored to examine the photophysical properties without the interference of non-degenerate conformational isomers. The presence of mesityl and xylyl groups provides kinetic protection to electron-deficient boron center (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). The compound 4-(dimesitylboraneyl)-3, 5-dimethylaniline were synthesized following a literature reported elsewhere\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e. The detailed synthesis techniques were described in the supplementary information. The compounds were characterized by \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003eH, \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003eC, and \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003eB nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HRMS) techniques (Supplementary Figs. 1\u0026ndash;8). The molecular structures of the compounds were further confirmed by single crystal X-ray diffraction (SC-XRD) technique (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec and Supplementary Figs.\u0026nbsp;9, 10). Powder X-ray diffraction spectra indicated the crystalline nature of the pristine compounds. However, thin films of the compounds at 1 wt.% concentration in the PMMA matrix were found to be amorphous in nature (Supplementary Figs.\u0026nbsp;11, 12). The pristine compounds are stable under ambient conditions. Thermogravimetric analysis (TGA) showed that the decomposition temperature of the final compounds was in the range of 245\u0026deg;C \u0026minus;\u0026thinsp;302\u0026deg;C indicating good thermal stability of the compounds (Supplementary Fig.\u0026nbsp;13). Moreover, differential scanning calorimetry (DSC) data exhibited that there was no phase transformation except the melting point for BANHPh and BANMePh whereas BANH2 showed additional crystallization process during cooling cycle (Supplementary Fig.\u0026nbsp;14).\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eSingle-Crystal XRD Analysis\u003c/h3\u003e\n\u003cp\u003eThe impact of temperature on the molecular structure was investigated through SCXRD data from 100 K to 300 K (Supplementary Tables\u0026nbsp;1\u0026ndash;7). Molecule BANHPh showed one independent molecule in the asymmetric unit. The dihedral angles between the mean plane of the xylyl carbon atoms and the mean plane of the phenyl carbon atoms remained constant with respect to temperature (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec). In fact, the values of 58.42(3) at 100 K and 58.47(4) at 300 K were the same within experimental error. Similar observations were also found for other temperatures as well. In the case of BANMePh, there were two independent molecules in the asymmetric unit. These two molecules exhibited a significant difference in the dihedral angles formed by the mean planes of the xylyl ring and the phenyl ring (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec). This could be attributed to differences in crystal packing environments of the two independent molecules (Supplementary Fig.\u0026nbsp;10). For both molecules of BANMePh, there was a reduction in dihedral angles across the temperature range from 100 K to 300 K; however, the values for each molecule did not lie within the range of the standard uncertainty (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec). Similar results were found for BANH2, and the variation was less than 1\u0026deg; across the temperature range 100 K to 275 K (Supplementary Fig.\u0026nbsp;9, 10). Therefore, the temperature-dependent variation of the dihedral angle of the molecular structures in the crystal lattice appeared to be insignificant.\u003c/p\u003e\n\u003ch3\u003eOptoelectronic investigation in PMMA matrix\u003c/h3\u003e\n\u003cp\u003eTo analyze the influence of the PMMA matrix on molecular properties, photo physics was investigated for encapsulated chromophores in the PMMA matrix. At first, the emission characteristics of the compounds were conducted in the matrix at low weight concentrations (1 wt.%) to obtain the molecular property of the compound with negligible influence from intermolecular interactions among the chromophores. The higher energy absorption band (\u0026lt;\u0026thinsp;350 nm) of 1 wt.% chromophore@PMMA originates because of \u0026pi;-\u0026pi;*/n-\u0026pi;* transitions and the low energy band (\u0026gt;\u0026thinsp;350 nm) presents amine to boryl intramolecular charge transfer (ICT) transition (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb and Supplementary Fig.\u0026nbsp;15). This is corroborated from the photophysical studies in dilute solution state (conc. 10 \u0026micro;M). The intermolecular interactions among the chromophores in dilute solution are also expected to be non-operative as 1 wt.% thin film. The higher energy absorption bands (\u0026lt;\u0026thinsp;350 nm) are almost insensitive to solvent polarity. Whereas the lower energy band (\u0026gt;\u0026thinsp;350 nm) showed weak solvent dielectric dependency, which indicates the weakly polar electronic ground state of these compounds (Supplementary Figs.\u0026nbsp;16\u0026ndash;18).\u003c/p\u003e\n\u003cp\u003eThe steady-state photoluminescence (PL) spectrum of the 1 wt.% compound@PMMA showed a structureless emission band (\u0026lambda;\u003csub\u003ePL\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;445\u0026ndash;455 nm) with an associated lifetime of 6.5\u0026ndash;10 ns (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea, and Supplementary Tables 10, 13, 16). The ICT characteristics of the steady-state PL band of the emitters were confirmed from the solution state studies. The steady-state emission band of the compounds is susceptible to solvent polarity, which explains the ICT feature of the band (Supplementary Figs. 16, 17 and Tables 8\u0026ndash;9). However, the time-gated measurements indicated the absence of phosphorescence in the solution state. This can be due to thermally induced vibrational relaxation of the triplet excited state in a dilute solution. The rigid polymer (PMMA) matrix eliminates the possibility of vibrational relaxation-caused quenching of excited state species. Time-gated PL measurement of 1 wt.% BANHPh@PMMA (50 \u0026micro;s delay time) at room temperature showed a structureless broad emission band at 450 nm (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea). The delayed emission band was found to exhibit bi-exponential decay (\u0026lambda;\u003csub\u003e(450nm)\u003c/sub\u003e\u003csup\u003e298 K\u003c/sup\u003e: \u0026tau;\u003csub\u003eA1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;23 ms, \u0026tau;\u003csub\u003eA2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;103 ms) for the emission maxima. The delayed emission band (\u0026lambda;\u0026thinsp;=\u0026thinsp;450 nm) was slightly lower in energy than the prompt emission band (\u0026lambda;\u0026thinsp;=\u0026thinsp;445 nm), as depicted in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea and \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eh. Moreover, the strong oxygen sensitivity and faster decay of delayed emission at elevated temperatures featured the possibility of room temperature phosphorescence (RTP) rather than thermally activated delayed fluorescence (TADF) (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ed and Supplementary Fig. 24, 26).\u003c/p\u003e\n\u003cp\u003eThe temperature-dependent photophysical property investigation of 1 wt.% BANHPh@PMMA revealed a bathochromic spectral shift of phosphorescence maxima from 450 nm at 298 K to 482 nm at 77 K (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec and Supplementary Fig.\u0026nbsp;23a). Although there was a negligible change in the steady-state PL maxima at different temperatures. The energy difference (\u0026Delta;\u0026lambda;\u003csub\u003ePH\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;32 nm) between the lower-energy phosphorescence (LEP) band at 77 K and higher-energy phosphorescence (HEP) band at 298 K indicated the involvement of two different triplet excited states in this phenomenon. The LEP band of the emitter was found to exhibit remarkably long bi-exponential decay (\u0026lambda;\u003csub\u003e(482nm)\u003c/sub\u003e\u003csup\u003e77 K\u003c/sup\u003e: \u0026tau;\u003csub\u003eA1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;587 ms, \u0026tau;\u003csub\u003eA2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1087 ms) (Supplementary Table\u0026nbsp;11). A comparison of LEP and HEP spectra inferred that the HEP band comprised the phosphorescence from both the high-lying triplet state (T\u003csup\u003eH\u003c/sup\u003e) and the low-lying triplet excited state (T\u003csup\u003eL\u003c/sup\u003e). However, there was an insignificant contribution of the HEP band (\u0026lambda;\u0026thinsp;=\u0026thinsp;450 nm) in the LEP spectrum at low temperature (77 K). The HEP band arose progressively with thermal energy above 200 K with a concomitant decrease in intensity of the LEP band (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec). In addition, the different peak position of excitation spectra for 450 nm and 482 nm phosphorescence band further corroborates the involvement of different emissive states (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb and Supplementary Fig.\u0026nbsp;19).\u003c/p\u003e\n\u003cp\u003eThe tail fitting of the phosphorescence lifetime decay profile (for both HEP and LEP bands) at each temperature revealed a bi-exponential component with gradual variation in the amplitude value with temperature (Supplementary Table\u0026nbsp;11). Interestingly, there was an abnormal elevation of total phosphorescence quantum yield from 77 K (\u0026Phi;\u003csup\u003e77 K\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;13%) to 298 K (\u0026Phi;\u003csup\u003e298 K\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;16%), which inferred that temperature-induced non-radiative deactivation of triplet excitons was unlikely in this case (Supplementary Table\u0026nbsp;12). The area-deconvolution of the phosphorescence spectrum at 298 K showed that the HEP band majorly contributed to the RTP quantum yield (\u0026Phi;\u003csub\u003eRTP\u003c/sub\u003e\u003csup\u003eCum\u003c/sup\u003e (16%) = \u0026Phi;\u003csub\u003eHEP\u003c/sub\u003e\u003csup\u003e450\u003c/sup\u003e (11%) + \u0026Phi;\u003csub\u003eLEP\u003c/sub\u003e\u003csup\u003e482\u003c/sup\u003e (5%)). In fact, there was gradual change in the phosphorescence quantum yield with temperature for both LEP and HEP band (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eg). Furthermore, the excited state kinetics of dual phosphorescence was analyzed by time-resolved phosphorescence spectra at 225 K (in millisecond time scale) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ef and Supplementary Fig.\u0026nbsp;31). Area normalization of time-resolved phosphorescence bands exhibited the attenuation of higher energy phosphorescence band (\u0026lambda;\u0026thinsp;=\u0026thinsp;450 nm) intensity at longer time range. The time-dependent intensity variation of emission bands further confirms the phosphorescence nature of the dual emission bands\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eTo elucidate the controlling parameters of dual phosphorescence behavior, photophysical studies were conducted for BANMePh and BANH2 at 1 wt.% concentration in the PMMA matrix (Supplementary Figs.\u0026nbsp;20\u0026ndash;30 and Table\u0026nbsp;13\u0026ndash;18). Structural manipulation can change the electronic and steric environment of the chromophore in the matrix environment. Temperature-dependent steady-state PL and phosphorescence spectra of the BANMePh emitter showed similar spectral behavior to the first emitter (Supplementary Figs.\u0026nbsp;23b, 25a, 27 and Table\u0026nbsp;14). The phosphorescence spectrum showed a 36 nm bathochromic spectral shift on changing temperature from 298 K to 77 K. Further time-resolved phosphorescence spectra inferred the kinetics between the triplet excited states (Supplementary Figs.\u0026nbsp;32, 33). The methyl substitution resulted in a slight bathochromic shift in the LEP band for BANMePh (\u0026lambda;\u0026thinsp;=\u0026thinsp;486 nm) relative to the BANHPh emitter (\u0026lambda;\u0026thinsp;=\u0026thinsp;482 nm). Similar photophysical behavior of methyl derivative compared to secondary amine derivative indicated no such dominant role of non-covalent interactions in the secondary amine derivative for dual phosphorescence behavior. For the BANH2 emitter, the absence of a phenyl group linked to the nitrogen center resulted in a different photo-physics than the other two emitters. Temperature-dependent phosphorescence spectra exhibited a transition of the phosphorescence band maxima from lower-energy to higher-energy region with increasing temperature. However, phosphorescence spectral shift (\u0026Delta;\u0026lambda;\u003csub\u003ePH\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;20 nm) was found to be smaller relative to the other two emitters (Supplementary Fig.\u0026nbsp;25b). The HEP and LEP bands showed comparatively different energy values for the triplet states (\u0026lambda;\u003csub\u003eHEP\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;455 nm and \u0026lambda;\u003csub\u003eLEP\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;475 nm) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea). Unlike the previous two emitters, the LEP band at lower temperatures (\u0026lt;\u0026thinsp;200 K) showed the emission contribution from both low and high-lying triplet states (Supplementary Fig.\u0026nbsp;25b). In addition, the RTP lifetime was found to be shorter (\u0026lambda;\u003csub\u003e(455nm)\u003c/sub\u003e\u003csup\u003e298 K\u003c/sup\u003e: \u0026tau;\u003csub\u003eA1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;13 ms, \u0026tau;\u003csub\u003eA2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;60 ms) than the other two emitters (Supplementary Figs.\u0026nbsp;26\u0026ndash;28 and Supplementary Tables\u0026nbsp;11, 14, 17). As hypothesized vide supra, the absence of a phenyl group changed the emissive electronic state, leading to different phosphorescence behavior.\u003c/p\u003e\n\u003ch3\u003eIntermolecular interactions effect on dual phosphorescence\u003c/h3\u003e\n\u003cp\u003eThe influence of intermolecular interactions between the chromophores on phosphorescence behavior was studied by embedding the compound at 10 wt.% concentration in the PMMA matrix (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb, Supplementary Figs.\u0026nbsp;34\u0026ndash;40 and Tables\u0026nbsp;19\u0026ndash;27). Time-gated measurements at variable temperatures for 10 wt.% of BANHPh@PMMA (\u0026Delta;\u0026lambda;\u003csub\u003ePH\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;35 nm) exhibited a similar spectral shift between HEP and LEP bands relative to 1 wt.% emitter (\u0026Delta;\u0026lambda;\u003csub\u003ePH\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;32 nm) (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb, \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec).\u003c/p\u003e\n\u003cp\u003eHowever, the steady-state PL band and phosphorescence bands (HEP and LEP) for the 10 wt.% of BANHPh@PMMA were found to be red-shifted compared to the 1 wt.% of BANHPh@PMMA (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ec and Supplementary Fig.\u0026nbsp;41a). The high dispersion concentration in matrix resulted in a shorter lifetime for both LEP (\u0026lambda;\u003csub\u003e(497nm)\u003c/sub\u003e\u003csup\u003e77K\u003c/sup\u003e: \u0026tau;\u003csub\u003eA1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;964 ms, \u0026tau;\u003csub\u003eA2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;469 ms) and HEP (\u0026lambda;\u003csub\u003e(462nm)\u003c/sub\u003e\u003csup\u003e298 K\u003c/sup\u003e: \u0026tau;\u003csub\u003eA1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;45 ms, \u0026tau;\u003csub\u003eA2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;9.1 ms) bands as well as diminished phosphorescence quantum yield (\u0026Phi;\u003csub\u003ePH\u003c/sub\u003e\u003csup\u003eCum(77 K)\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;7.1% and \u0026Phi;\u003csub\u003ePH\u003c/sub\u003e\u003csup\u003eCum(298 K)\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;8%) (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ed, \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ee and Supplementary Tables\u0026nbsp;11, 12, 20, 21). This can be attributed to the diffusion of excitons towards several non-radiative deactivation channels, which reduces the lifetime and quantum yield value\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. A similar observation was found for 10 wt.% of BANMePh@PMMA and 10 wt.% BANH2@PMMA (Supplementary Figs.\u0026nbsp;34\u0026ndash;40, 41\u0026ndash;44, and Tables\u0026nbsp;22\u0026ndash;27). Both the 10 wt.% emitter (BANMePh and BANH2) exhibited a red shifting of phosphorescence band on decreasing temperature from 298 K to 77 K as depicted in supplementary Figs.\u0026nbsp;41 and 42 (\u0026Delta;\u0026lambda;\u003csub\u003ePH(BANMePh)\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;35 nm and \u0026Delta;\u0026lambda;\u003csub\u003ePH(BANH2)\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;25 nm). Although the growth in the intermolecular interactions of chromophores modulated the electronic energy level of the 10 wt.% emitter, it demonstrated a negligible impact on the origin of dual phosphorescence in the matrix environment as a function of temperature.\u003c/p\u003e\n\u003ch3\u003eSteric effect of PBMA matrix on dual phosphorescence\u003c/h3\u003e\n\u003cp\u003eFurther optical studies have been carried out in a rigid poly (butyl methacrylate) (PBMA) matrix to verify the matrix-dependent triplet state behavior of these emitters (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ef, Supplementary Figs.\u0026nbsp;45\u0026ndash;50, and Tables\u0026nbsp;28\u0026ndash;30). Both PMMA and PBMA polymers possess similar electronic nature but provide a different steric environment to the dispersed chromophore (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea). Temperature dependent steady-state PL and phosphorescence behavior were found to be different in PBMA matrix environment (Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eg-i, and Supplementary Figs.\u0026nbsp;51\u0026ndash;54). The 1 wt.% BANHPh@PBMA emitter showed a shifting of the phosphorescence band with temperature; however, there was a gradual destabilization of the emissive state at higher temperatures (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ef). The ratio-metric change of HEP and LEP band with temperature exhibited a non-linear relationship for PMMA and PBMA matrix-based emitter (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ei). In addition, PBMA matrix emitter of BANHPh (\u0026lambda;\u003csub\u003e(445nm)\u003c/sub\u003e\u003csup\u003e298 K\u003c/sup\u003e: \u0026tau;\u003csub\u003eA1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;5 ms, \u0026tau;\u003csub\u003eA2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;17 ms) displayed relatively faster lifetime than PMMA matrix emitter (\u0026lambda;\u003csub\u003e(450nm)\u003c/sub\u003e\u003csup\u003e298 K\u003c/sup\u003e: \u0026tau;\u003csub\u003eA1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;23 ms, \u0026tau;\u003csub\u003eA2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;103 ms) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eh and supplementary Fig.\u0026nbsp;54). The reduced phosphorescence performance in PBMA matrix can be due to the larger n-butyl group mediated non-radiative relaxation of emissive states at higher temperatures. Further, photophysical properties were investigated for the other two chromophores (BANMePh and BANH2) in the PBMA matrix. The 1 wt.% emitter of BANMePh exhibited analogous behavior to BANHPh in the PBMA matrix. However, 1 wt.% BANH2@PBMA exhibited a more stable emissive state for the HEP band compared to the other two emitters (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ef, and Supplementary Fig.\u0026nbsp;47). This might be due to reduced steric interaction at higher temperatures in the absence of bulky phenyl group for BANH2 molecule. The lifetime decay profile of both the emitters (BANH2 and BANMePh) exhibited a shorter lifetime in the PBMA matrix than in the PMMA matrix (Supplementary Fig.\u0026nbsp;54). This experiment supported the significant role of matrix environment in controlling the stability of different triplet states in the dispersed chromophore.\u003c/p\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eOrigin of dual phosphorescence\u003c/h2\u003e\n \u003cp\u003eWe performed quantum chemical calculations to elucidate the electronic origins of dual phosphorescence and tested two hypotheses for this phenomenon: (a) phosphorescence arising from low-lying triplet states (i.e., T\u003csub\u003e2\u003c/sub\u003e \u0026rarr; S\u003csub\u003e0\u003c/sub\u003e, T\u003csub\u003e1\u003c/sub\u003e \u0026rarr; S\u003csub\u003e0\u003c/sub\u003e) and (b) the presence of room-temperature accessible conformers in the T\u003csub\u003e1\u003c/sub\u003e state. Accordingly, we explored the influence of the PMMA and PBMA matrices on the electronic properties of these compounds. The second hypothesis is supported by the variation in the dihedral angle between the xylyl and phenyl groups in the molecular structure (Supplementary Fig.\u0026nbsp;60, Tables\u0026nbsp;31\u0026ndash;32).\u003c/p\u003e\n \u003cp\u003eIn this study, we employed the second-order Algebraic Diagrammatic Construction (ADC(2))\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e method to compute excited state energetics, which has been shown to yield superior results for similar systems. First, we calculated the low-energy spectrum of all compounds using their fully optimized geometries in the presence of the matrix. Both PMMA and PBMA matrices were modeled as linear polymeric chains that fully encapsulate the compound (see Fig.\u0026nbsp;4a-c) (see computational methodology for details).\u003c/p\u003e\n \u003cp\u003eFor BANHPh@PMMA (Fig.\u0026nbsp;4d), we found the T\u003csub\u003e1\u003c/sub\u003e state (2.98 eV) lower in energy than the S\u003csub\u003e1\u003c/sub\u003e state (3.28 eV), while the T\u003csub\u003e2\u003c/sub\u003e state (3.39 eV) was slightly higher, suggesting that phosphorescence primarily arises from the T\u003csub\u003e1\u003c/sub\u003e state (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, Supplementary Table\u0026nbsp;33\u0026ndash;34). The spin-orbit couplings (SOC) between S\u003csub\u003e0\u003c/sub\u003e\u0026ndash;T\u003csub\u003e1\u003c/sub\u003e and S\u003csub\u003e0\u003c/sub\u003e\u0026ndash;T\u003csub\u003e2\u003c/sub\u003e were 0.803 cm⁻\u0026sup1; and 0.222 cm⁻\u0026sup1;, respectively, further supporting the dominant role of the T\u003csub\u003e1\u003c/sub\u003e state in the observed dual phosphorescence. However, the calculated T\u003csub\u003e1\u003c/sub\u003e\u0026ndash;T\u003csub\u003e2\u003c/sub\u003e energy gap (0.41 eV) is larger than the experimentally determined value (0.19 eV). We observed similar trends for BANMePh@PMMA, where the T\u003csub\u003e1\u003c/sub\u003e state (2.95 eV) was lower than the S\u003csub\u003e1\u003c/sub\u003e state (3.18 eV), and the T\u003csub\u003e2\u003c/sub\u003e state (3.39 eV) was slightly higher, resulting in a T\u003csub\u003e1\u003c/sub\u003e\u0026ndash;T\u003csub\u003e2\u003c/sub\u003e energy gap of 0.44 eV (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, Supplementary Table\u0026nbsp;35\u0026ndash;37). We observed a similar dominant role of T\u003csub\u003e1\u003c/sub\u003e in phosphorescence in BANMePh. Interestingly, for BANH2@PMMA, both the T\u003csub\u003e1\u003c/sub\u003e (3.18 eV) and T\u003csub\u003e2\u003c/sub\u003e (3.48 eV) states were found below the S\u003csub\u003e1\u003c/sub\u003e state (3.50 eV), with a T\u003csub\u003e1\u003c/sub\u003e\u0026ndash;T\u003csub\u003e2\u003c/sub\u003e energy gap of 0.30 eV. In this case, the SOC for T\u003csub\u003e2\u003c/sub\u003e\u0026ndash;S\u003csub\u003e0\u003c/sub\u003e (0.75 cm⁻\u0026sup1;) was higher than for T\u003csub\u003e1\u003c/sub\u003e\u0026ndash;S\u003csub\u003e0\u003c/sub\u003e (0.34 cm⁻\u0026sup1;), indicating that both T\u003csub\u003e1\u003c/sub\u003e and T\u003csub\u003e2\u003c/sub\u003e may contribute to the observed dual phosphorescence. (Supplementary Table\u0026nbsp;38\u0026ndash;40)\u003c/p\u003e\n \u003cp\u003eOverall, our excited-state calculations reveal the possible role of two distinct conformational states along the T1 in the dual phosphorescence in both BANHPh and BANMePh compounds in the presence of the PMMA matrix. However, for BANH2, both T\u003csub\u003e1\u003c/sub\u003e and T\u003csub\u003e2\u003c/sub\u003e states may be involved in the dual phosphorescence behavior.\u003c/p\u003e\n \u003cp\u003eWe note that for BANHPh@PMMA, the T\u003csub\u003e1\u003c/sub\u003e and T\u003csub\u003e2\u003c/sub\u003e states experienced a blue shift (0.088 eV) and redshift (0.065 eV), respectively, upon embedding in the PMMA matrix, resulting in an overall lowering of the T\u003csub\u003e1\u003c/sub\u003e\u0026ndash;T\u003csub\u003e2\u003c/sub\u003e gap (from 0.56 eV to 0.41 eV). Similarly, for BANH2, the T\u003csub\u003e1\u003c/sub\u003e\u0026ndash;T\u003csub\u003e2\u003c/sub\u003e gap decreased from 0.4 eV to 0.3 eV (see Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Interestingly, spectral shifts in the low-energy spectrum were observed upon embedding in the PBMA matrix (Fig.\u0026nbsp;4e and Supplementary Table\u0026nbsp;32\u0026ndash;33, 35\u0026ndash;36, 38\u0026ndash;39) This serves as a robust proof of the principle that polymeric matrix effects must be explicitly included in such calculations, as the matrix tunes the energetics of the frontier molecular orbitals (see Fig.\u0026nbsp;4f-g and supplementary Fig.\u0026nbsp;61) involved in the excitations, ultimately influencing the excitation energies.\u003c/p\u003e\n \u003cp\u003eWe further tested the second hypothesis regarding the existence of T\u003csub\u003e1\u003c/sub\u003e conformers. A CREST\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e conformational search (in the gas phase, for both T\u003csub\u003e1\u003c/sub\u003e and S\u003csub\u003e0\u003c/sub\u003e states) was conducted on all compounds, revealing that both BANHPh@PMMA and BANMePh@PMMA possess multiple conformers with flexible dihedral angles between the xylyl and phenyl groups. Based on these findings, we performed relaxed potential energy surface (PES) calculations (using GFN2-xTB)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e for both the S\u003csub\u003e0\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e states in the gas phase and within the PMMA matrix.\u003c/p\u003e\n \u003cp\u003eFor the T\u003csub\u003e1\u003c/sub\u003e state of BANHPh@PMMA, we identified five nearly isoenergetic conformers (all within 0\u0026ndash;0.3 kcal/mol) in the gas phase, with the PES minimum showing a dihedral angle of 155\u0026deg; between the xylyl and phenyl groups. This suggests that all conformational states are thermally accessible at room temperature in the T\u003csub\u003e1\u003c/sub\u003e state (Fig.\u0026nbsp;4h). However, this result alone does not fully explain the observed gap of 0.19 eV (4.4 kcal/mol) between T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eH\u003c/sup\u003e and T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eL\u003c/sup\u003e. Upon embedding in the PMMA matrix, we found that the degeneracy of the conformers is lifted, with the minimum structure displaying a dihedral angle of 320\u0026deg;. The second minimum along the PES was 5.7 kcal/mol higher, with a dihedral angle of 272\u0026deg;. PMMA provides a unique compound-matrix interface, inducing molecular strain and electronic tuning that alters the properties of these compounds compared to their behavior in homogeneous solvents.\u003c/p\u003e\n \u003cp\u003eInterestingly, a similar lifting of degeneracy was observed for BANMePh, with the PES minimum showing a dihedral angle of 325\u0026deg; between the xylyl and phenyl groups in the PMMA matrix, compared to 140\u0026deg; in the gas phase (see Fig.\u0026nbsp;4h). These results strongly suggest that the conformers of the T\u003csub\u003e1\u003c/sub\u003e state in BANHPh and BANMePh, when embedded in the PMMA matrix, could give rise to dual RTP. Temperature effects may provide the activation energy required for phenyl group rotation and subsequently lead to a population of high-energy conformational states. We also conducted similar PES scans for BANHPh and BANMePh in the S\u003csub\u003e0\u003c/sub\u003e state (Supplementary Fig.\u0026nbsp;62), observing a comparable lifting of conformational degeneracy. The degeneracy lifting relative to the gas phase is also observed in the case of the relaxed scans performed in the PBMA matrix for both BANHPh and BANMePh; however, unlike PMMA, only one minimum is found along the S\u003csub\u003e0\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e. This clearly shows how different matrix environments tune the PES of these compounds.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003e\u003cstrong\u003eVertical excitation energies of low-lying singlet (S) and triplet (T) excited states for BANHPh, BANMePh and BANH2 computed using the ADC(2)/def2-TZVP level of theory. The fully optimized ground state singlet geometry, in the presence of an explicit PMMA matrix, was utilized. The nature of the excited states on a canonical basis and their weights are also depicted, and the oscillator strength (\u003c/strong\u003e\u003cstrong\u003ef\u003c/strong\u003e\u003cstrong\u003e) for the singlet excitation is shown. All energy values are in electron volts (eV).\u003c/strong\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth rowspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eCompound\u003c/p\u003e\n \u003c/th\u003e\n \u003cth colspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth colspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth colspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eT\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWith PMMA\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGas-phase\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWith PMMA\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGas-phase\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWith PMMA\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGas-phase\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eBANHPh\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.28 (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.32)\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 85.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.16 (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.30)\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 87.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.98\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 79.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.89\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 79.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.39\u003c/p\u003e\n \u003cp\u003eH-1\u0026rarr; L 77.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.45\u003c/p\u003e\n \u003cp\u003eH-1\u0026rarr; L 78.2%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eBANMePh\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.18 (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.23)\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 87.9%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.99 (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.20)\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 87.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.95\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 79.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.81\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 80.4%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.39\u003c/p\u003e\n \u003cp\u003eH-1\u0026rarr; L 78.4%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.42\u003c/p\u003e\n \u003cp\u003eH-1\u0026rarr; L 75.4%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eBANH2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.50 (0.19)\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 91.7%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.43 (0.18)\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 92.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.18\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 83.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.12\u003c/p\u003e\n \u003cp\u003eH\u0026rarr; L 84.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.48\u003c/p\u003e\n \u003cp\u003eH-1\u0026rarr; L 74.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.52\u003c/p\u003e\n \u003cp\u003eH-1\u0026rarr; L 58.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eOur CREST conformational search in the case of BANH2 along the T\u003csub\u003e1\u003c/sub\u003e state suggests mainly two distinct structures (see Supplementary Fig.\u0026nbsp;63); however, their high energy gap (13.4 kcal mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e ~ 0.6 eV) does not align with the experimental gap of 0.12 eV. Hence, the role of the T\u003csub\u003e1\u003c/sub\u003e conformers in the dual phosphorescence in the case of BANH2 can be ruled out, and this result goes in line with the earlier conclusion, based on excitation energetics results with possible involvement of both T\u003csub\u003e2\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e in the dual phosphorescence.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eThe rigidity of the PMMA matrix restricts the higher temperature, promoting vibronic coupling between the triplet excited states and the ground state. Therefore, the ascending of non-radiative rate constants (\u003cem\u003ek\u003c/em\u003e\u003csub\u003enr\u003c/sub\u003e) at higher temperatures for both the phosphorescence bands signify the faster interconversion rate of excitons (\u003cem\u003ek\u003c/em\u003e\u003csub\u003enr(482nm)\u003c/sub\u003e\u003csup\u003e298 K\u003c/sup\u003e= 9.36 s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and \u003cem\u003ek\u003c/em\u003e\u003csub\u003enr(482nm)\u003c/sub\u003e\u003csup\u003e77 K\u003c/sup\u003e= 0.79 s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for BANHPh) between the triplet excited states (T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eH\u003c/sup\u003e and T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eL\u003c/sup\u003e) (Supplementary Tables\u0026nbsp;12, 15, 18). The up-conversion (UC, T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eL\u003c/sup\u003e\u0026rarr;T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eH\u003c/sup\u003e) and down-conversion (DC, T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eH\u003c/sup\u003e\u0026rarr;T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eL\u003c/sup\u003e) rates are directly proportional to the non-radiative rate constant of T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eL\u003c/sup\u003e and T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eH\u003c/sup\u003e, respectively. The experimental activation energy for the interconversion of triplet excited states is calculated from the Arrhenius plot of the logarithm of the non-radiative rate constant varying with the Reciprocal of temperature. The activation energy of the up-conversion and down-conversion process is 2.4 Kcal/mol and 3.7 Kcal/mol, respectively for BANHPh emitter (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e and Supplementary Fig.\u0026nbsp;55). The methyl incorporation in the BANMePh emitter enhanced the activation energy barriers for both up-conversion (3.9 Kcal/mol) and down-conversion (3.2 Kcal/mol) processes (Supplementary Figs.\u0026nbsp;56, 57). The relative activation energy of the emitters coincides with the theoretically estimated interconversion barriers of the thermally accessible conformers at the T\u003csub\u003e1\u003c/sub\u003e state. A similar trend in activation energy for the BANH2 emitter was found in the Arrhenius plot (Supplementary Figs.\u0026nbsp;58, 59). The different molecules create alternative heterogeneity in the matrix environment, which develops variations in the activation barriers between the triplet state interconversions. The relative activation energy determines the nature of the dual phosphorescence.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003ePotential applications of the emitters\u003c/h3\u003e\n\u003cp\u003ePolymer-dispersed RTP emitters exhibit diverse technical applications owing to compatible mechanical strength and easy film processability procedures. The variable temperature dual-phosphorescence spectra showed a considerable spectral shift in the afterglow emission maxima for 1 wt.% (\u0026Delta;\u0026lambda;\u003csup\u003emax\u003c/sup\u003e: 32 nm) and 10 wt.% (\u0026Delta;\u0026lambda;\u003csup\u003emax\u003c/sup\u003e: 35 nm) of BANHPh @PMMA at different temperatures (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec, \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb). The 1 wt.% emitter exhibited better phosphorescence properties than the 10 wt.% emitter (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ed, \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ee). The phosphorescence color change of these emitters from light green at 77 K to blue at 298 K can be utilized as a useful temperature sensor for diverse applications (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea).\u003c/p\u003e\n\u003cp\u003eIn addition, the suitable RTP lifetime and phosphorescence quantum yield (PhQY) of 1 wt.% of BANHPh @PMMA and 1 wt.% of BANH2 @PMMA was explored for anticounterfeiting application using universal Morse cipher. As depicted in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eb, the dichloromethane solution of 1 wt.% of BANHPh @PMMA and 1 wt.% of BANH2 @PMMA were used as ink to mark for \u0026lsquo;\u0026bull;\u0026rsquo; and \u0026lsquo;─\u0026rsquo; respectively on a glass plate. Both the emitters showed similar Commission Internationale de l\u0026acute;Eclairage (CIE) coordinates for the prompt emission [BANHPh: (0.15, 0.07) and BANH2: (0.19, 0.12)] and RTP bands [BANHPh: (0.15, 0.11) and BANH2: (0.15, 0.12)] (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eb, right side spectra). However, these displayed different RTP lifetime values for phosphorescence maxima (\u0026lambda;\u003csub\u003e(450) BANHPh\u003c/sub\u003e: \u0026tau;\u003csub\u003eA1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;23 ms, \u0026tau;\u003csub\u003eA2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;103 ms; \u0026lambda;\u003csub\u003e(455) BANH2\u003c/sub\u003e: \u0026tau;\u003csub\u003eA1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;13 ms, \u0026tau;\u003csub\u003eA2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;60 ms) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eb, right side decay profile) and this feature had been applied for storing confidential data. True information could not be observed when the UV light was on since both the emitters showed similar prompt emissions. The information did not even appear in the instantaneous UV light switch-off. The afterglow intensity of both the emitters was found to be reduced with time. The BANH2 emitter exhibited a shorter afterglow and stopped after 500 ms of UV light was turned off, revealing the position of the \u0026lsquo;─\u0026rsquo; symbol. At this stage, the RTP of only the BANHPh emitter was visible with reduced phosphorescence intensity, which indicated the position of the \u0026lsquo;\u0026bull;\u0026rsquo; symbol. The corresponding location of the symbols \u0026lsquo;\u0026bull;\u0026rsquo; and \u0026lsquo;─\u0026rsquo; signified the integrated Morse code. The comparison of the symbols with the Morse code index provided the encrypted information \u0026ldquo;S C I E N C E\u0026rdquo;. Thus, these RTP emitters with variation in PL lifetime can be utilized to improve the strength of the hidden data to make the information more confidential. The photostability of the 1 wt.% BANHPh @PMMA emitter was examined at different cycles after exposure to 365 nm UV light excitation (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ec). No detectable photobleaching was observed in the naked eye, even after 15 cycles of UV light exposure. The afterglow intensity remained almost intact throughout all the cycles. The photostability and afterglow brightness of the designed phosphorescent material encourages future innovative applications using this phosphorescent material.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eWe report intriguing findings on lifting triplet-state degeneracy in organic chromophores embedded in a PMMA matrix. A strategic design of the chromophores and a suitable combination of polymer matrix resulted in the rare phenomenon of thermally promoted phosphorescence with efficient quantum yield. The molecular dispersion (1 wt.%) of the chromophore in the PMMA matrix provides favorable crossover energies of triplet excited states to maintain the thermal equilibrium of emissive states. We showcased a robust proof-of-principle that polymeric matrices can tune the geometric structure and spectroscopic properties of chromophores using advanced quantum chemical approaches. These polymeric matrices provide an asymmetric environment, distinct from homogeneous solvents, which imposes greater steric control over the compound. This observation parallels findings in biological systems, where pigments such as chlorophylls embedded in protein matrices modulate functional properties. A key example is the Photosystem II reaction center\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e, where chlorophylls are embedded in a protein matrix. It is well established that the protein matrix\u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e plays a crucial role in lowering the charge-transfer state energetics, a factor essential for the charge-separation event and overall enzymatic efficiency. The ideal approach would involve molecular dynamics-based conformational sampling of the compound-matrix binary solution using periodic boundary conditions. We are currently working on implementing this method in future studies. Nevertheless, the current model provides solid proof that the matrix plays a critical role in the geometric and electronic tuning of chromophores. Finally, these emitters have been successfully explored for anti-counterfeiting applications using Morse cipher. Moreover, this concept holds the potential for better future innovative applications in dynamic multilevel encryption of information against the traditional understanding of device design.\u003c/p\u003e "},{"header":"Methods","content":" \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003eMeasurements\u003c/h2\u003e \u003cp\u003e \u003csup\u003e \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e \u003c/sup\u003eH, \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003eC{\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003eH}, and \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003eB NMR spectra were recorded at 25\u0026deg;C on a Bruker Advance 400 MHz NMR Spectrometer operating at a frequency of 400 MHz for \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003eH, 100 MHz for \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003eC and 128 MHz for \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003eB using deuterated solvent (CDCl\u003csub\u003e3\u003c/sub\u003e). \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003eH NMR and \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003eC NMR spectra were referenced to the residual solvent signal, and 11B NMR spectra were referenced to the standard boron signal of BF\u003csub\u003e3\u003c/sub\u003e\u0026middot;Et\u003csub\u003e2\u003c/sub\u003eO. High-resolution mass spectra (HRMS) were recorded on a Micromass Q-ToF High-Resolution Mass Spectrometer by electrospray ionization (ESI) method. Powder X-ray diffraction patterns of the pristine compounds and thin films were collected from a XD-D1 Shimadzu X-ray diffractometer. Thermogravimetric analysis (TGA) was examined using TA Instrument Q50 TGA thermogravimetric analyzer at a 10\u0026deg;C/min heating rate under an argon atmosphere. The decomposition temperature for TGA curves was determined at a threshold of 10% weight loss. DSC was performed using METTLER-TOLEDO and TA instruments at a heating and cooling rate of 10\u0026deg;C/min under an argon atmosphere.\u003c/p\u003e \u003cp\u003eThe absorption measurements were carried out at room temperature by SHIMADAZU UV-2600 spectrophotometer. The steady-state emission, excitation, and lifetime spectra were measured using an Edinburgh Instrument FLS980 spectrometer equipped with a xenon arc lamp and microsecond flash lamp. Time-gated emission spectra were recorded using the same FLS980 spectrometer coupled with a time-gated circuit to the photomultiplier tube (PMT) detector. The steady-state and time-gated emission spectra were recorded using a xenon arc lamp and pulsed microsecond Flashlamp (\u0026micro;F1, pulse width of 1.1 \u0026micro;S) as excitation sources, respectively. Temperature-dependent measurements were performed using an Oxford Instruments OPTISTAT DN2 cryostat controlled by an Oxford Instruments Mercury iTC temperature controller connected to the FLS980 spectrometer. Samples were allowed to reach uniform temperature distribution before conducting any measurement. Photophysical studies of thin films were recorded under vacuum conditions unless otherwise mentioned. The fluorescence quantum yields of the solutions and thin films were measured under ambient conditions using a calibrated integrating sphere from Horiba combined with the Horiba JOBIN YVON Fluoromax-4 spectrometer.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of Thin Films\u003c/h2\u003e \u003cp\u003eThe chromophores, poly(methyl methacrylate) (PMMA), and poly(butyl methacrylate) (PBMA) were dissolved in HPLC dichloromethane solvent to prepare the stock solutions at a concentration of 1 mg/ml. The stock solutions were mixed in a particular proportion to obtain 1 wt.% and 10 wt.% of compound concentration in the polymer solution. The wt.% indicates the weight percentage of the compound relative to the total weight content of the polymer. Each film was prepared by spin-coating the compound/PMMA solution on a quartz substrate at 25\u0026deg;C.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eComputational Methodology\u003c/h2\u003e \u003cp\u003eThe PMMA matrix around each chromophore was constructed using chem3D 20.1.1 software\u003csup\u003e\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e. The system sizes for BANHPh, BANMePh, and BANH2 consisted of 651, 654, and 641 atoms, respectively. All compounds were first optimized within the PMMA matrix in their S\u003csub\u003e0\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e states using the GFN2-xTB approach\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e, which resolved any geometric clashes within the system. Relaxed potential energy scans for both the S\u003csub\u003e0\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e states were conducted using GFN2-xTB by varying the dihedral angle between the xylyl and phenyl groups. The conformational sampling for compounds (along the T\u003csub\u003e1\u003c/sub\u003e state) was computed using the CREST program\u003csup\u003e\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eVertical excitation energies were calculated using the second-order Algebraic Diagrammatic Construction (ADC(2))\u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e Method, combined with the def2-TZVP all-atom basis set, via the Turbomole 7.5 suite\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e. The matrix effect on the excited state calculations was incorporated using point charges (derived from the Merz-Kollman Restrained Electrostatic Potential), where the contributions of the charges were explicitly included in the one-electron matrices and nuclear repulsion terms.\u003c/p\u003e \u003cp\u003eWe note that the geometries obtained \u003cem\u003evia\u003c/em\u003e GFN2-xTB were highly consistent with those from full optimization at the B3LYP/def2-TZVP level of theory, with an RMSD of 0.0358 \u0026Aring;. For benchmarking, we also compared the ADC(2) excitation energies for BANHPh geometries optimized using both GFN2-xTB and B3LYP/def2-TZVP, and found similar excited state energetics, state ordering, and orbital contributions in the canonical basis.\u003c/p\u003e \u003cp\u003eThe spin-orbit coupling (SOC) matrix elements\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e were calculated using time-dependent density functional theory (TDDFT) at the B3LYP/def2-TZVP level, with TDDFT computations performed using the ORCA 5.2 program\u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e "},{"header":"Declarations","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eThe data supporting the findings of the work are available in the supplementary information file of this article. The X-ray crystallographic coordinates for structures reported in this study have been deposited at the Cambridge Crystallographic Data Centre (CCDC), under deposition numbers 2402229, 2402230, 2402231, 2402232, 2402233, 2402233, and 2402235 for BANHPh at different temperatures; 2403250, 2403251, 2403252, 2403253, 2403254, 2403255, and 2403256 for BANMePh at different temperatures; 2403348, 2403349, 2403350, 2403351, 2403352, and 2403353 for BANH2 at various temperatures. Source data are provided with this paper.\u003c/p\u003e \u003c/div\u003e\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor contributions\u003c/h2\u003e \u003cp\u003eP.T. designed the research works. S.G. carried out the synthesis of the chromophores, film preparation, characterization, photophysical studies, and application studies. R.P.N. contributed to the synthesis. N.H. and S.G. performed the SCXRD analysis. A.S. carried out the theoretical calculations and contributed to manuscript writing. All the authors commented on the manuscript. P.T. organized the entire project and approved the final version of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eThis work was supported by the Science and Engineering Research Board (SERB), India (EEQ/2023/000903 (P.T.)); Prime Minister Research Fellowship (PM/MHRD-20-17748.03 (S.G.)) and Indian Institute of Science research fellowship (R.P.N). All the authors thank IISc and the IPC department for instrumental and computational support.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eZhang KY et al (2018) Dual-Phosphorescent Iridium(III) Complexes Extending Oxygen Sensing from Hypoxia to Hyperoxia. J Am Chem Soc 140:7827\u0026ndash;7834\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang J et al (2018) The influence of the molecular packing on the room temperature phosphorescence of purely organic luminogens. Nat Commun 9:840\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou Y et al (2019) Long-Lived Room-Temperature Phosphorescence for Visual and Quantitative Detection of Oxygen. Angew Chem 131:12230\u0026ndash;12234\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang T et al (2019) Aggregation-Induced Dual-Phosphorescence from Organic Molecules for Nondoped Light-Emitting Diodes. Adv Mater 31:1904273\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu X et al (2021) An Electroactive Pure Organic Room-Temperature Phosphorescence Polymer Based on a Donor-Oxygen-Acceptor Geometry. Angew Chem Int Ed 60:2455\u0026ndash;2463\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTao P et al (2016) Facile Synthesis of Highly Efficient Lepidine-Based Phosphorescent Iridium(III) Complexes for Yellow and White Organic Light-Emitting Diodes. Adv Funct Mater 26:881\u0026ndash;894\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYu Z et al (2017) Organic Phosphorescence Nanowire Lasers. J Am Chem Soc 139:6376\u0026ndash;6381\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSun H et al (2014) Smart responsive phosphorescent materials for data recording and security protection. Nat Commun 5:3601\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang Z et al (2016) Intermolecular Electronic Coupling of Organic Units for Efficient Persistent Room-Temperature Phosphorescence. Angew Chem 128:2221\u0026ndash;2225\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao W et al (2018) Highly sensitive switching of solid-state luminescence by controlling intersystem crossing. Nat Commun 9:3044\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHe Z et al (2019) Achieving Persistent, Efficient, and Robust Room-Temperature Phosphorescence from Pure Organics for Versatile Applications. Adv Mater 31:1807222\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTao Y et al (2022) Resonance-Induced Stimuli-Responsive Capacity Modulation of Organic Ultralong Room Temperature Phosphorescence. J Am Chem Soc 144:6946\u0026ndash;6953\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang X et al (2019) Organic Room-Temperature Phosphorescence with Strong Circularly Polarized Luminescence Based on Paracyclophanes. Angew Chem Int Ed 58:17220\u0026ndash;17225\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWu Z et al (2020) Persistent Room Temperature Phosphorescence from Triarylboranes: A Combined Experimental and Theoretical Study. Angew Chem Int Ed 59:17137\u0026ndash;17144\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAn Z et al (2015) Stabilizing triplet excited states for ultralong organic phosphorescence. Nat Mater 14:685\u0026ndash;690\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCheng Z et al (2018) Ultralong Phosphorescence from Organic Ionic Crystals under Ambient Conditions. Angew Chem Int Ed 57:678\u0026ndash;682\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJia X et al (2019) Photoexcitation-controlled self-recoverable molecular aggregation for flicker phosphorescence. \u003cem\u003eProc. Natl. Acad. Sci.\u003c/em\u003e 116, 4816\u0026ndash;4821\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDu M et al (2022) White Emissions Containing Room Temperature Phosphorescence from Different Excited States of a D\u0026ndash;π\u0026ndash;A Molecule Depending on the Aggregate States. Adv Sci 9:2104539\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Y et al (2021) Large-Area, Flexible, Transparent, and Long-Lived Polymer-Based Phosphorescence Films. J Am Chem Soc 143:13675\u0026ndash;13685\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMa D-X et al (2024) Nylons with Highly-Bright and Ultralong Organic Room-Temperature Phosphorescence. Nat Commun 15:4402\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZou X et al (2023) Narrowband Organic Afterglow via Phosphorescence F\u0026ouml;rster Resonance Energy Transfer for Multifunctional Applications. Adv Mater 35:2210489\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang Z et al (2020) Color-Tunable Polymeric Long-Persistent Luminescence Based on Polyphosphazenes. Adv Mater 32:1907355\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOgoshi T et al (2018) Ultralong Room-Temperature Phosphorescence from Amorphous Polymer Poly(Styrene Sulfonic Acid) in Air in the Dry Solid State. Adv Funct Mater 28:1707369\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWu H et al (2021) Tailoring Noncovalent Interactions to Activate Persistent Room-Temperature Phosphorescence from Doped Polyacrylonitrile Films. Adv Funct Mater 31:2101656\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang X et al (2023) A Class of Organic Units Featuring Matrix-Controlled Color-Tunable Ultralong Organic Room Temperature Phosphorescence. Adv Sci 10:2206482\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang Y et al (2021) New Phenothiazine Derivatives That Exhibit Photoinduced Room-Temperature Phosphorescence. Adv Funct Mater 31:2101719\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang T, De J, Wu S, Gupta AK, Zysman-Colman E (2022) Thermally Activated and Aggregation-Regulated Excitonic Coupling Enable Emissive High-Lying Triplet Excitons. Angew Chem Int Ed 61:e202206681\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang T et al (2021) Thermochromic aggregation-induced dual phosphorescence via temperature-dependent sp3-linked donor-acceptor electronic coupling. Nat Commun 12:1364\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShe P et al (2022) Single-Component Molecular Dual Persistent Room Temperature Phosphorescence from Low- and High-Lying Triplet States. Adv Opt Mater 10:2102706\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi J et al (2023) A direct observation of up-converted room-temperature phosphorescence in an anti-Kasha dopant-matrix system. Nat Commun 14:1987\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHe Z et al (2017) White light emission from a single organic molecule with dual phosphorescence at room temperature. Nat Commun 8:416\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou C et al (2018) Ternary Emission of Fluorescence and Dual Phosphorescence at Room Temperature: A Single-Molecule White Light Emitter Based on Pure Organic Aza-Aromatic Material. Adv Funct Mater 28:1802407\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJiang K et al (2020) Carbon Dots with Dual-Emissive, Robust, and Aggregation-Induced Room-Temperature Phosphorescence Characteristics. Angew Chem Int Ed 59:1263\u0026ndash;1269\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNandi RP, Kalluvettukuzhy NK, Pagidi S, Thilagar P (2023) Molecular Persistent Room-Temperature Phosphorescence from Tetraarylaminoboranes. Inorg Chem 62:1122\u0026ndash;1134\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eArumugam R et al (2024) Regioisomers containing triarylboron-based motifs as multi-functional photoluminescent materials: from dual-mode delayed emission to pH-switchable room-temperature phosphorescence. Chem Sci 15:18364\u0026ndash;18378\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSudhakar P, Mukherjee S, Thilagar P (2013) Revisiting Borylanilines: Unique Solid-State Structures and Insight into Photophysical Properties. Organometallics 32:3129\u0026ndash;3133\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMa Z et al (2021) Converting molecular luminescence to ultralong room-temperature phosphorescence via the excited state modulation of sulfone-containing heteroaromatics. Chem Sci 12:14808\u0026ndash;14814\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHertel T, Himmelein S, Ackermann T, Stich D, Crochet J (2010) Diffusion Limited Photoluminescence Quantum Yields in 1-D Semiconductors: Single-Wall Carbon Nanotubes. ACS Nano 4:7161\u0026ndash;7168\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchirmer J (1982) Beyond the random-phase approximation: A new approximation scheme for the polarization propagator. Phys Rev A 26:2395\u0026ndash;2416\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePracht P, Bohle F, Grimme S (2020) Automated exploration of the low-energy chemical space with fast quantum chemical methods. Phys Chem Chem Phys 22:7169\u0026ndash;7192\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBannwarth C, Ehlert S, Grimme S (2019) GFN2-xTB\u0026mdash;An Accurate and Broadly Parametrized Self-Consistent Tight-Binding Quantum Chemical Method with Multipole Electrostatics and Density-Dependent Dispersion Contributions. J Chem Theory Comput 15:1652\u0026ndash;1671\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUmena Y, Kawakami K, Shen J-R, Kamiya N (2011) Crystal structure of oxygen-evolving photosystem II at a resolution of 1.9 \u0026Aring;. Nature 473:55\u0026ndash;60\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSirohiwal A, Neese F, Pantazis DA (2020) Protein Matrix Control of Reaction Center Excitation in Photosystem II. J Am Chem Soc 142:18174\u0026ndash;18190\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZielesny A (2005) Chemistry Software Package ChemOffice Ultra 2005. J Chem Inf Model 45:1474\u0026ndash;1477\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePracht P et al (2024) CREST\u0026mdash;A program for the exploration of low-energy molecular chemical space. J Chem Phys 160:114110\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBalasubramani SG et al (2020) Modular program suite for ab initio quantum-chemical and condensed-matter simulations. J Chem Phys 152:184107\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Souza B, Farias G, Neese F, Izs\u0026aacute;k R (2019) Predicting Phosphorescence Rates of Light Organic Molecules Using Time-Dependent Density Functional Theory and the Path Integral Approach to Dynamics. J Chem Theory Comput 15:1896\u0026ndash;1904\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNeese F (2018) Software update: the ORCA program system, version 4.0. WIREs Comput Mol Sci 8:e1327\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-5794027/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5794027/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePoly(methyl methacrylate) (PMMA) matrix has been extensively explored for decades to achieve efficient room-temperature phosphorescence in blue-to-red regions from dispersed chromophores. Isolated chromophores at low-weight concentrations in the polymer matrix eliminate the inter-chromophore interactions. However, the impact of the polymer matrix on the optical characteristics of chromophores remains elusive. Herein, we analyze the dual phosphorescence behavior of three chromophores molecularly dispersed (1 wt.% concentration) in the PMMA matrix. We employ second-order Algebraic Diagrammatic Construction (ADC2) excited state calculations to show that the dual phosphorescence observed in BANHPh and BANMePh does not stem from the T\u003csub\u003e1\u003c/sub\u003e and T\u003csub\u003e2\u003c/sub\u003e electronic states. Instead, this phenomenon arises from matrix-assisted, room-temperature accessible conformers within the T\u003csub\u003e1\u003c/sub\u003e state (T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eH\u003c/sup\u003e and T\u003csub\u003e1\u003c/sub\u003e\u003csup\u003eL\u003c/sup\u003e). The PMMA matrix creates an asymmetric environment around the chromophores, inducing structural and electronic modulations that result in spectral tuning of the singlet and triplet manifolds. In conclusion, conformation-dependent dual phosphorescence is unlikely to occur without the PMMA matrix. These matrix-induced dual phosphorescent emitters have been demonstrated to be highly competent in the application of fingerprint recognition, information encryption, and afterglow display.\u003c/p\u003e","manuscriptTitle":"Polymer Matrix Drives Dual Phosphorescence in Dispersed Chromophores","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-13 09:15:11","doi":"10.21203/rs.3.rs-5794027/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"6e1fd922-c04f-4b41-94d9-10200765875a","owner":[],"postedDate":"February 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":43144215,"name":"Physical sciences/Chemistry/Materials chemistry/Optical materials"},{"id":43144216,"name":"Physical sciences/Materials science/Soft materials/Organic molecules in materials science"}],"tags":[],"updatedAt":"2026-03-28T07:12:44+00:00","versionOfRecord":{"articleIdentity":"rs-5794027","link":"https://doi.org/10.1038/s41467-026-69664-x","journal":{"identity":"nature-communications","isVorOnly":false,"title":"Nature Communications"},"publishedOn":"2026-02-19 05:00:00","publishedOnDateReadable":"February 19th, 2026"},"versionCreatedAt":"2025-02-13 09:15:11","video":"","vorDoi":"10.1038/s41467-026-69664-x","vorDoiUrl":"https://doi.org/10.1038/s41467-026-69664-x","workflowStages":[]},"version":"v1","identity":"rs-5794027","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5794027","identity":"rs-5794027","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}