Theoretical investigation on phosphorescent platinum complexes based on two tetradentate bipyridine ligands

Theoretical investigation on phosphorescent platinum complexes based on two tetradentate bipyridine ligands | 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 Research Article Theoretical investigation on phosphorescent platinum complexes based on two tetradentate bipyridine ligands Hadj MEZOUAR, Houari BRAHIM, Mostefa BOUMEDIENE, Fatima YAHIA CHERIF, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3921913/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 25 Mar, 2024 Read the published version in Theoretical Chemistry Accounts → Version 1 posted 4 You are reading this latest preprint version Abstract In this work, the geometrical, optical, and phosphorescence properties of four complexes with general formula [dRpypy―C(OCH3)R′―dRpypy]Pt, with Pt-1 (R = F, R′=methyl), Pt-2 (R = F, R′=hexyl), Pt-3 (R = methoxy, R′=methyl) and Pt-4 (R = methoxy, R′=hexyl) were studied using the B3PW91 and TD-B3PW91 methods. The effect of the double substitution R and R′ on the electronic properties of the four complexes has been investigated. Replacing the two fluorine atoms with the two methoxy groups modifies the shape of the UV-vis spectra and red shift the phosphorescence spectra, while the substituents on the linker R′ do not induces changes in both spectra. Normal modes involved in the vibronic structure were identified and analyzed using adiabatic Hessian approaches according to the Franck-Condon approximation. The computed phosphorescence wavelengths agree with the observed ones and indicate that the fluorinated complexes exhibit a bright light blue color, while the methoxy complexes display a light spring green color. TD-DFT platinum complexes absorption phosphorescence Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Cyclometalated iridium and platinum complexes have been extensively studied in the last two decades owing principally to their applications in phosphorescent organic light-emitting diodes (OLEDs) and also in photocatalysts [ 1 – 5 ]. Octahedral iridium complexes, with C^N bidentate ligands in particular phenylpyridine, phenylpyrazole, and acetylacetonate ligands showed a high luminescence quantum yield and short luminescent lifetime into the microsecond range at room temperature [ 6 – 9 ]. These remarkable properties have made these complexes highly preferable in OLED applications as phosphorescent emitters. Square planar geometry around the metal has also been widely considered due to the different coordination possibilities that can develop between the ligands and the metal in this geometry [ 10 – 13 ]. The easy synthesis of square planar complexes and the flexibility of their geometrical structures have allowed the use of various cyclometalating ligands such as bidentate, tridentate, or tetradentate [ 14 – 16 ]. In recent years, several studies have shown that Pt square planar complexes can be considered as an excellent alternative to the usual octahedral iridium complexes [ 17 – 19 ]. Square planar Pt complexes based on tetradentate ligands have recently been of great interest due to their rigid structures and due to their efficiency in OLED applications [ 20 – 22 ]. Chiheon Lee et al have synthesized and characterized a new series of four square Pt(II) complexes based on two tetradentate bipyridine ligands (pypy) linked by C(OCH 3 )R′ group [ 23 ]. The four complexes have general formula [dRpypy―C(OCH 3 )R′―dRpypy]Pt, with Pt-1 (R = F, R′=methyl), Pt-2 (R = F, R′=hexyl), Pt-3 (R = methoxy, R′=methyl) and Pt-4 (R = methoxy, R′=hexyl). The authors studied the effects of the substituents methyl or hexyl at the linker and the effects of the introduction of an electron-donating/withdrawing fragment (fluorine or methoxy) on the structure and the phosphorescence properties of the four complexes. In this work, we studied geometrical structure, optical and phosphorescence properties of the four complexes using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. Our study provides detailed investigation on structural and electronic properties of both ground state and excited triplet state of the four complexes. The emission spectra were modeled using the Franck-Condon (FC) approximation taking into account the vibrational structure contributions to S0-T1 transition. Computational details Starting from X-ray geometries, all studied complexes were fully optimized in dichloromethane (CH 2 Cl 2 ) using hybrid exchange–correlation functional B3PW91 [ 24 – 26 ]. We have employed LANL2DZ base set [ 27 , 28 ] for all atoms augmented with d polarization functions on C, N, S, and O, and augmented with f polarization functions on Pt. The "relativistic" HayWat pseudo-potential associated with LANL2DZ basis set was used to describe the inner electron of the Pt. The solvent effects were introduced using the polarizable continuum model PCM [ 29 , 30 ] implemented in Gaussian [ 31 ]. The low-lying excited states were studied using the TD-DFT method in term of natural transition orbitals (NTOs) [ 32 ]. All spectra were simulated with gaussian function (FWHM = 0.35 eV) using GaussSum GUI application [ 33 ]. S 0 geometries were used as starting point to optimize the first triplet excited states T 1 of all studied complexes by unrestricted DFT (UB3PW91) in CH 2 Cl 2 with the same basis sets cited above. Frequency calculations were performed to confirm that both S 0 and T 1 geometries of all complexes correspond to true minima on the Potential Energy Surface (PES). Phosphorescence wavelengths were calculated according to ΔSCF vert and ΔSCF adiab procedures. 0–0 wavelengths were calculated taking into account zero-point vibrational energy (ZPVE) corrections. To simulate the phosphorescence spectra, the vibrational structure contributions to the T 1 -S 0 electronic transition were studied using adiabatic Hessian (AH) and adiabatic shift (AS) approaches according to the FC approximation. Emission spectra were plotted using VMS program [ 34 ]. All calculations were performed by Gaussian 09. We have use Avogadro-1 [ 35 ] to get isosurface orbitals and to visualizing geometric structures. Results and discussions Ground-state study Ground state geometries (S 0 ) of the four complexes were fully optimized in CH 2 Cl 2 using B3PW91 functional. Selected bond lengths and angles are given in Table 1 together with available experimental data (data not available for complex Pt-3 ). As the crystal structures, all optimized geometry complexes display a distorted square planar geometry around the metal (Fig. 1 ). As shown in Table 1 , computed bond lengths and bond angles agree with experimental values. For all complexes, Pt − N bond lengths are slightly longer than Pt − C bond lengths. Pt − N 1 and Pt-N 2 bond lengths are closes in each complex, which means that N 1 and N 2 coordinate similarly with Pt. Same conclusion for Pt − C 1 and Pt − C 2 . Replacing methyl with hexyl and/or fluorine atoms with methoxy groups does not affect Pt-ligand bonds lengths. Table 1 Selected o ptimized and experimental bond lengths (in Å) and bond angles (in °) of the four studied complexes calculated with B3PW91. Pt-1 Pt-2 Pt-3 Pt-4 B3PW91 Exp [23] B3PW91 Exp [23] B3PW91 B3PW91 Exp [23] Pt – N 1 2.079 2.064 2.079 2.068 2.075 2.080 2.057 Pt – N 2 2.093 2.077 2.093 2.075 2.080 2.075 2.054 Pt – C 1 1.988 1.995 1.988 1.987 1.989 1.988 1.980 Pt – C 2 1.987 1.996 1.986 1.993 1.988 1.988 1.997 N 1 – Pt-N 2 93.3 93.9 92.9 93.6 95.4 95.2 96.0 N 1 – Pt-C 1 80.7 80.8 80.7 80.9 81.6 81.1 80.8 C 2 – Pt-C 1 104.0 103.8 104.3 103.6 101.8 102.9 102.1 C 2 – Pt-N 2 81.3 81.0 81.3 81.4 81.8 81.4 81.3 C 2 – Pt-N 1 167.5 171.1 167.2 168.9 170.0 169.6 171.1 C 1 – Pt-N 2 173.4 173.5 172.7 173.7 174.8 174.8 176.5 Frontier molecular orbitals (FMOs) of the four complexes were studied using B3PW91 functional. Energy levels, energy gaps and the composition selected FMOs in term of orbital fragments are depicted in Scheme 1 . Energy levels of fluorinated complexes ( Pt-1 and Pt-2 ) are lower than those of Pt-3 and Pt-4 containing methoxy groups instead fluorine atoms due to the electron withdrawing character of fluorine atoms. While replacing methyl with hexyl at the linker do not affect the energies and the compositions of FMOs of Pt-1 and Pt-3 . The five highest occupied orbitals (HOMO — H-5) of Pt-1 and Pt-2 are delocalized over pypy ligands and dPt orbitals with different percentages. The proportion of dPt orbitals are dominated only in H-2 orbitals in both Pt-1 and Pt-2 . For the complexes Pt-3 and Pt-4 , the two highest occupied orbitals HOMO and H-1 are delocalized only over pypy orbitals while the four orbitals H-2, H-3, H-4 and H-5 are contributed with dPt and pypy orbitals. The lowest unoccupied orbitals of the four complexes (Scheme 1 ) are delocalized in pypy orbitals without any contribution of dPt orbitals. Replacing methyl with hexyl at the linker don’t affect the energy gaps, indeed Pt-1 and Pt-2 have very close energy gaps 4.02 and 4.03 eV respectively also Pt-3 and Pt-4 have almost same energy gaps (ΔE ≈ 3.72 eV). While, the energy gaps of the fluorinated complexes ( Pt-1 and Pt-2) are larger than Pt-3 and Pt-4 containing dimethoxy-pypy ligands. UV–vis absorption spectra Singlet excited states of the four complexes were studied using B3PW91 functional in CH 2 Cl 2 . Absorption spectra were simulated using gaussian band shape with a fixed full width at half-minimum (FWHM) of 0.33 eV (Fig. 2 ). Wavelengths, oscillator strengths and character of selected S 0 -S n absorptions are reported together with experimental data in Table 2 ( Pt-1 and Pt-3 ) and Table S1 ( Pt-2 and Pt-4 ). As shown in Fig. 2 , B3PW91 gives acceptable results compared to the experience and reproduces the main characteristic of the observed spectra. A comparison between Pt-1 and Pt-2 spectrum and between Pt-3 and Pt-4 spectrum, shows that the replacement of methyl group with hexyl group do not change the shape of both simulated and experimental spectra. While replacing the four fluorine atoms of Pt-1 and Pt-2 by four methoxy groups to get Pt-3 and Pt-4 affects the spectrum shapes. Indeed, Pt-1 and Pt-2 spectrum contain multiple bands between 250 and 400 nm unlike Pt-3 and Pt-4 spectrum which contain two distinctive bands. The singlet excited states of Pt-1 and Pt-3 reported in Table 2 are quasi similar with those of Pt-2 and Pt-4 respectively. For this reason, we only studied the excited states of Pt-1 and Pt-3 in terms of NTOs (Tables 3 and S2). S 0 -S 1 ( f = 0.01) and S 0 -S 2 ( f = 0.06) absorptions of Pt-1 calculated at 370 and 349 nm respectively correspond to single hole-electron transition which occurs principally from dPt to pypy ligand orbitals and to intra-pypy ligands charge transfer. We can assign these absorptions to the weak band observed at 350–390 nm. The weak band simulated at the region 325–350 nm is contributed with S 0 -S 3 ( f = 0.13) and S 0 -S 4 ( f = 0.11) absorptions calculated at 321 and 314 nm. S 0 -S 3 contains double hole-electron transitions, the first (weight = 0.66) correspond to a mixed character MLCT/LLCT while the second (weight = 0.33) principally to LLCT transition. S 0 -S 4 absorption contains one hole-transition and corresponds to MLCT/ILCT character. The tow absorptions S 0 -S 3 and S 0 -S 4 can be attributed to the two absorptions observed at 332 and 306 nm respectively. The intense band simulated at ~ 300 nm is contributed with S 0 -S 5 and S 0 -S 6 absorptions with significant oscillator strengths f = 0.27 and f = 0.23 respectively. Table 2 Wavelengths (λ cal and λ exp ), oscillator strengths and the character of selected singlet excited states of Pt-1 and Pt-3 . λ cal f Transition λ exp [23] Character Pt-1 S 1 370 0.01 H-1→LUMO (95%) MLCT/LLCT S 2 349 0.06 H-2→LUMO (79%) 377 MLCT/LLCT S 3 321 0.13 HOMO→L + 1 (52%) H-3→LUMO (31%) 332 MLCT/LLCT S 4 314 0.11 H-4→LUMO (78%) 306 LLCT S 5 285 0.27 H→L + 2 (36%) H-3→L + 1 (31%) LLCT/MLCT S 6 279 0.23 H-3→L + 1 (45%) H-2→L + 1 (25%) 273 LLCT/MLCT S 7 250 0.22 H-3→L + 3 (46%) H-2→L + 3 (20%) LLCT/MLCT Pt-3 S 1 405 0.06 HOMO→LUMO (82%) 421 MLCT/LLCT S 2 356 0.16 H-2→LUMO (61%) 356 MLCT/LLCT S 3 334 0.21 H-4→LUMO (69%) HOMO→L + 1 (20%) MLCT/LLCT S 4 309 0.22 H-4→L + 1 (15%) HOMO→L + 2 (64%) LLCT S 5 290 0.39 H-4→L + 1 (34%) H-1→L + 3 (18%) 295 LLCT/MLCT S 6 281 0.14 H-4→L + 2 (10%) H-4→L + 3 (11%) H-3→L + 3 (47%) 272 LLCT/MLCT NTO analyzes show that the two absorptions are composed with two hole-electron transitions, with two different proportions corresponding to MLCT/LLCT characters. The two absorptions are assigned to the most intense band observed experimentally above 270 nm. For Pt-3 , S 0 -S 1 absorption computed at 405 nm containing one NTO pair transition correspond to a mixed character MLCT/LLCT and can be assigned to the weak band observed at ~420 nm. The band simulated at 320-350 nm is attributed principally with two absorptions S 0 -S 2 ( f =0.16) and S 0 -S 3 ( f =0.21). NTO analysis show that the two absorptions correspond to transitions from dPt and pypy ligand orbitals to pypy ligand orbitals. The two absorptions are assigned to the band observed at 330-380 nm. The two most intense absorptions S 0 -S 4 ( f =0.22) and S 0 -S 5 ( f =0.39) computed at 309 and 290 nm are assigned to the intense band observed at ~295 nm. S 0 -S 4 and S 0 -S 5 contain two hole-electron transitions, one dominant and the second minority corresponding both to MLCT/LLCT characters (Table 3). First triplet excited state study The first triplet excited states T 1 of the studied complexes were optimized in CH 2 Cl 2 using UB3PW91 functional. Frequency calculations were performed to check that T 1 obtained correspond to true global minimum. A comparison between T 1 of the four complexes show that introducing substituents methyl or hexyl at the linker between the two pypy ligands does not change T 1 bond lengths (Table 4 and S3). While, the substituents on the two pyridine ligands (fluorine or methoxy), cause a slight modification around Pt and on intra-pypy ligand bonds. A comparative study between S 0 and T 1 geometries are reported in Table 4 ( Pt-1 and Pt-3 ) and in Table S3 ( Pt-2 and Pt-4 ). Only bond lengths with significant |T 1 -S 0 | are reported and classified in descending order. In Pt-1 and Pt-2 , Pt-N and Pt-C bonds of one pypy ligand are the most affected bonds around Pt. Indeed, the two pyridines of pypy become closer to Pt through N and C by 0.044 and 0.022Å respectively. Pt-N and Pt-C bond lengths between Pt and the second pypy ligand don’t change significantly (~ 0.003Å) after S 0 -T 1 transition. For intra-ligand bond lengths, the most affected bonds are located in pyridine rings of one pypy ligand which shows that during T 1 relaxation the electronic redistribution occurs only on this ligand (colored bonds in Fig. 1 ). For the methoxy complexes ( Pt-3 and Pt-4) , Pt-N and Pt-N reducing by 0.035 and 0.034Å after S 0 -T 1 transition, are the most affected bonds around the metal. For ligand bond lengths, the most important deformations occur over the two pypy ligands. Visualizations of the singly occupied natural orbital (SONO) pairs of all T1 show that charge density distribution are localized in one pypy ligand for Pt-1 and Pt-2 and delocalized over the two pypy ligands for Pt-3 and Pt-4 . Table 4 A comparison between S 0 and T 1 geometries of Pt-1 and Pt-3 complexes. Bond length colors are depicted in Fig. 1 . Pt-1 Pt-3 S 0 T 1 |T 1 -S 0 | S 0 T 1 |T 1 -S 0 | Pt-N 2 2.093 2.049 0.044 Pt-N 1 2.075 2.040 0.035 Pt-C 2 1.987 1.965 0.022 Pt-N 2 2.080 2.046 0.034 Pt-N 1 2.079 2.076 0.003 Pt-C 1 1.989 1.975 0.014 Pt-C 1 1.988 1.991 0.003 Pt-C 2 1.988 1.976 0.012 C-C red 1.47 1.398 0.072 N-C green 1.373 1.403 0.03 N-C green 1.362 1.426 0.064 N-C green 1.375 1.403 0.028 C-C blue 1.400 1.453 0.053 C-C red 1.463 1.435 0.028 C-C yellow 1.436 1.483 0.047 C-C red 1.463 1.435 0.028 C-C orange 1.402 1.437 0.035 C-C blue 1.415 1.441 0.026 C-C black 1.396 1.428 0.032 C-C blue 1.416 1.442 0.026 N-C purple 1.319 1.293 0.026 C-C yellow 1.434 1.453 0.019 N-C brown 1.321 1.346 0.025 C-C yellow 1.434 1.452 0.018 C-C pink 1.392 1.369 0.023 C-C pink 1.391 1.408 0.017 Phosphorescence properties Phosphorescence spectra of the four studied complexes were modelled using AH method and superposed with experimental spectra for comparison (Fig. 3 ). Normal modes with frequencies low than 150 cm − 1 were cleared to get sufficient spectrum progressions (> 95% for all complexes). Simulated phosphorescence wavelengths of most intense band of all spectra are given in Table 5 together with experimental data. Simulated phosphorescence spectra of the four complexes reproduce nicely the experimental ones. Introducing the substituent hexyl with methyl at the linker doesn’t change the shape of Pt-1 and Pt-3 spectra. While replacing fluorine atoms with methoxy groups red shifts the phosphoresce spectra of Pt-1 and Pt-2 . Normal modes involved in the vibronic structure are reported in Table 6 . For Pt-1 and Pt-2 , the most intense band simulated at 470 nm is not contributed by 0–0 transition but with the modes 118 and 115 for Pt-1 and with 153 and 150 for Pt-2 , which have intense stick near to 470 nm. All these modes correspond to in-plane vibrations localized in one pypy ligand assigned to the breathing of the pypy rings and to C-H bending, and are assigned to the intense band observed in Pt-1 and Pt-2 spectra. The shoulder simulated at ~ 500 nm is contributed by the modes |118 2 〉 and |118 1 |115 1 〉 for Pt-1 and by the modes |153 2 〉 and |153 1 |150 1 〉 for Pt-2 . Noting that | n 2 〉 corresponds to the case where the vibration mode n is at v = 2 and | n 1 | m 1 〉 is a combination of the vibration mode n at v = 1 with the vibration mode m at v = 1. These vibration modes can be assigned to the weak band observed at 495 nm ( Pt-1 ) and 500 nm ( Pt-2 ). The bands simulated at 442 nm ( Pt-1 ) and 444 nm ( Pt-2 ) which have not been recorded experimentally, are contributed with 0–0 transition and the mode 28 ( Pt-1 ) and 36 ( Pt-2 ). For the methoxy complexes, the intense band simulated at 486 nm ( Pt-3 ) and at 484 nm ( Pt-4 ) are contributed principally with 0–0 transition. Additional modes near to 0–0 transition with non-negligible intensity contribute to this intense band, in particular modes 41 ( Pt-3 ) and 72 ( Pt-4 ) assigned mainly to in-plane vibrations of pypy fragment. The shoulder in 500–550 nm region of Pt-3 and Pt-4 spectra can be assigned to the vibrational signatures of two modes (87, 156) and (124, 135) in Pt-3 and Pt-4 spectra respectively (Table 6 ). Table 5 Computed and experimental phosphorescence wavelengths of the studied complexes. Pt-1 Pt-2 Pt-3 Pt-4 AH Exp [23] AH Exp [23] AH Exp [23] AH Exp [23] λ/nm 498/470/442 495/466 500/473/444 500/466 510/486 515/494 510/484 515/490 CIE(x,y) (0.17,0.22) (0.15,0.26) (0.17,0.24) (0.17,0.29) (0.17,0.47) (0.16,0.46) (0.17,0.50) (0.20,0.47) Phosphorescence colors of the four complexes were studied according to CIE-1931 color system. Color-calculator program was used to generate the CIE (x,y) coordinates from simulated (FC/AH) spectra and also from digitized experimental spectra for comparison (Table 6 ). As depicted in the CIE chromaticity diagram (Fig. 4 ), simulated and experimental (x,y) coordinates are located in the same color region of the horseshoes. Which mean that AH/FC method reproduces nicely the observed phosphorescence colors of all complexes. The fluorinated complexes Pt-1 and Pt-2 exhibit light bright blue color while the two methoxy complexes Pt-2 and Pt-3 exhibit light spring green color. Replacing methyl with hexyl group does not significantly change the CIE (x,y) coordinates of Pt-1 and Pt-3 and therefore don’t affects the their phosphoresce colors. Conclusion In this study, the geometrical, optical, and phosphorescence properties of the four complexes were investigated using the B3PW91 and TD-B3PW91 methods. The computed bond lengths and bond angles align with experimental data. Analysis of S 0 and T 1 for all complexes indicates that the introduction of methyl or hexyl substituents in the linker, as well as the replacement of fluorine atoms with methoxy groups, does not lead to significant modifications in S 0 and T 1 bond lengths. Furthermore, the electronic relaxation of T 1 occurs principally on one pypy ligand for fluorinated complexes and over the two pypy ligands for methoxy complexes. B3PW91 provides acceptable results compared to experimental data and reproduces the main characteristics of both absorption and phosphorescence spectra. The substituents on the linker do not affect the spectra, while the replacement of fluorine atoms with methoxy groups on the pyridine ligands modifies the shape of the UV-vis spectra and induces a red shift in the phosphorescence spectra. NTO analyses show that the most intense absorptions, simulated in the 250–300 nm region, correspond to MLCT/LLCT character. Normal modes near to the 0–0 transition involved in the vibronic structure were identified and analyzed. The fluorinated complexes exhibit light bright blue color while the methoxy complexes display light spring green color. Moreover, replacing the two methyl groups with two hexyl groups doesn't affect the phosphorescent colors. Declarations Conflict of interest statement On behalf of all authors, the corresponding author states that there is no conflict of interest. Author Contribution Author contributionsHM : Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Resources, Software, Visualization, Writing – original draft. HB and DH : Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. MB and FYC : Conceptualization, Data curation, Formal analysis, Methodology, Resources, Software, Validation, Visualization. AG : Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – review & editing. Acknowledgements This work is part of Projets de Recherche Formation-Universitaire (PRFU, MESRS, Algeria) supported by the directorate general for scientific research and technological development (DGRSDT, www.dgrsdt.dz ) and the thematic research agency in science and technology (ATRST, www.atrst.dz ). PRFU code: B00L01UN200120230005. All the authors thank DGRSDT. References Yu, T.; Zhang, C.; Zhao, Y.; Guo, S.; Liu, P.; Li, W.; Fan, D. Synthesis, Crystal Structure and Photoluminescence of a Cyclometalated Iridium(III) Coumarin Complex. J. Fluoresc. 2013 , 23 (4), 777-783. DOI: 10.1007/s10895-013-1214-x. 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Physical Review B 1986 , 33 (12), 8822-8824. DOI: 10.1103/physrevb.33.8822. Becke, A. D. Density-functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 1993 , 98 (7), 5648. DOI: 10.1063/1.464913. Perdew, J. P.; Burke, K.; Wang, Y. Generalized gradient approximation for the exchange-correlation hole of a many-electron system. Physical Review B 1996 , 54 (23), 16533-16539. DOI: 10.1103/physrevb.54.16533. Hay, P. J.; Wadt, W. R. Ab initio effective core potentials for molecular calculations. Potentials for the transition metal atoms Sc to Hg. J. Chem. Phys. 1985 , 82 (1), 270. DOI: 10.1063/1.448799. Hay, P. J.; Wadt, W. R. Ab initio effective core potentials for molecular calculations. Potentials for K to Au including the outermost core orbitals. J. Chem. Phys. 1985 , 82 (1), 299. DOI: 10.1063/1.448975. Cancès, E.; Mennucci, B.; Tomasi, J. A new integral equation formalism for the polarizable continuum model: Theoretical background and applications to isotropic and anisotropic dielectrics. J. Chem. Phys. 1997 , 107 (8), 3032. DOI: 10.1063/1.474659. Cossi, M.; Barone, V.; Mennucci, B.; Tomasi, J. Ab initio study of ionic solutions by a polarizable continuum dielectric model. Chem. Phys. Lett. 1998 , 286 (3-4), 253-260. DOI: 10.1016/s0009-2614(98)00106-7. M.J. Frisch, G. W. T., H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato,X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M. Hada,M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda,O. Kitao, H. Nakai, T. Vreven, J.A. Montgomery Jr., J.E. Peralta, F. Ogliaro, M.Bearpark, J.J. Heyd, E. Brothers, K.N. Kudin, V.N. Staroverov, R. Kobayashi, J.Normand, K. Raghavachari, A. Rendell, J.C. Burant, S.S. Iyengar, J. Tomasi, M.Cossi, N. Rega, J.M. Millam, M. Klene, J.E. Knox, J.B. Cross, V. Bakken, C. Adamo,J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C.Pomelli, J.W. Ochterski, R.L. Martin, K. Morokuma, V.G. Zakrzewski, G.A. Voth,P. Salvador, J.J. Dannenberg, S. Dapprich, A.D. Daniels, J.B. Foresman, J.V. Ortiz,J. Cioslowski, D.J. Fox. Gaussian 09, Gaussian, Inc., Wallingford CT 2009 . Martin, R. L. Natural transition orbitals. The Journal of Chemical Physics 2003 , 118 (11), 4775-4777. DOI: 10.1063/1.1558471. O'Boyle, N. M.; Tenderholt, A. L.; Langner, K. M. cclib: A library for package-independent computational chemistry algorithms. J. Comput. Chem. 2008 , 29 (5), 839-845. DOI: 10.1002/jcc.20823. Licari, D.; Baiardi, A.; Biczysko, M.; Egidi, F.; Latouche, C.; Barone, V. Implementation of a graphical user interface for the virtual multifrequency spectrometer: The VMS-Draw tool. J. Comput. Chem. 2014 , 36 (5), 321-334. DOI: 10.1002/jcc.23785. Hanwell, M. D.; Curtis, D. E.; Lonie, D. C.; Vandermeersch, T.; Zurek, E.; Hutchison, G. R. Avogadro: an advanced semantic chemical editor, visualization, and analysis platform. J. Cheminform. 2012 , 4 (1), 17. DOI: 10.1186/1758-2946-4-17. Tables Tables 3 and 6 are available in the Supplementary Files section. Schemes Scheme 1 is available in the Supplementary Files section Additional Declarations No competing interests reported. Supplementary Files SI.docx Scheme1.png Scheme 1. Energy levels (in eV), energy gaps (in eV) and the composition selected FMOs in term of orbital fragments obtained with B3PW91. 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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-3921913","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":270936231,"identity":"6d345c72-41e7-4457-bd50-038004a7b299","order_by":0,"name":"Hadj MEZOUAR","email":"","orcid":"","institution":"University of Saida - Dr Moulay Tahar","correspondingAuthor":false,"prefix":"","firstName":"Hadj","middleName":"","lastName":"MEZOUAR","suffix":""},{"id":270936232,"identity":"e4b68636-433d-4192-9298-2536e7381ebd","order_by":1,"name":"Houari BRAHIM","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAzUlEQVRIiWNgGAWjYBACAwYGNoYEBoYEfhDvAViAWC2SDQyMDQlEawGCBIMDxGoxlz787MHDHIY84+M95g8SKmyMGdgPH92AT4tlX5q5QeI2hmKzM2cMGxLOpJkx8KSl3cDrsDMMZhJALYnbbuQYNiS2HbZhkOAxI6CF/RtYy+YZxGvhgdiyQQKixYygFssenjKgFonEGWeOFc4A+sWYjZBfzHnYt0n+3GaT2N/evOHDhwobw372w8fwaoECCQSTjQjlo2AUjIJRMAoIAABT50mTGPAtuAAAAABJRU5ErkJggg==","orcid":"","institution":"University of Saida - Dr Moulay Tahar","correspondingAuthor":true,"prefix":"","firstName":"Houari","middleName":"","lastName":"BRAHIM","suffix":""},{"id":270936233,"identity":"047ac9d8-19ab-4cbc-b8c1-1ecbf33baf01","order_by":2,"name":"Mostefa BOUMEDIENE","email":"","orcid":"","institution":"University of Tiaret – Ibn Khaldoun","correspondingAuthor":false,"prefix":"","firstName":"Mostefa","middleName":"","lastName":"BOUMEDIENE","suffix":""},{"id":270936234,"identity":"13080455-5a9d-4403-ae86-3c1334a95172","order_by":3,"name":"Fatima YAHIA CHERIF","email":"","orcid":"","institution":"University of Saida - Dr Moulay Tahar","correspondingAuthor":false,"prefix":"","firstName":"Fatima","middleName":"YAHIA","lastName":"CHERIF","suffix":""},{"id":270936235,"identity":"82d49296-7ecb-4db3-bf76-f8cb4ee40fb1","order_by":4,"name":"Djebar HADJI","email":"","orcid":"","institution":"University of Saida - Dr Moulay Tahar","correspondingAuthor":false,"prefix":"","firstName":"Djebar","middleName":"","lastName":"HADJI","suffix":""},{"id":270936236,"identity":"53ccc2ed-5eb8-4686-a0c1-3d151bcf37d4","order_by":5,"name":"Abdelkrim GUENDOUZI","email":"","orcid":"","institution":"University of Saida - Dr Moulay Tahar","correspondingAuthor":false,"prefix":"","firstName":"Abdelkrim","middleName":"","lastName":"GUENDOUZI","suffix":""}],"badges":[],"createdAt":"2024-02-02 18:59:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3921913/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3921913/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00214-024-03107-y","type":"published","date":"2024-03-25T15:01:06+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":50706036,"identity":"752768f4-45c1-4a9d-910f-54fd77ef63c1","added_by":"auto","created_at":"2024-02-06 06:10:36","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":135099,"visible":true,"origin":"","legend":"\u003cp\u003eGeometric structures (S\u003csub\u003e0\u003c/sub\u003e) of the studied complexes optimized with B3PW91.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3921913/v1/ab0641652ebb6e15744ff173.png"},{"id":50705703,"identity":"3439d028-b53b-40d3-a5ba-1cae3dddeccd","added_by":"auto","created_at":"2024-02-06 06:02:36","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":273521,"visible":true,"origin":"","legend":"\u003cp\u003eExperimental (blue) and simulated (black) electronic absorption spectra of the four complexes\u003cstrong\u003e. \u003c/strong\u003eExperimental spectra digitized from [23].\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3921913/v1/1cbc037a32d000c8a22b8344.png"},{"id":50706551,"identity":"3098b0c9-a690-4083-8411-ca0c34810396","added_by":"auto","created_at":"2024-02-06 06:18:36","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":384596,"visible":true,"origin":"","legend":"\u003cp\u003eSimulated and experimental phosphorescence spectra of the studied complexes with normal modes involved in the vibronic structure.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3921913/v1/b5cbea4570a9be3162ec913a.png"},{"id":50705708,"identity":"20c2c8ac-b37a-4ac2-aba6-8f4bc195a26f","added_by":"auto","created_at":"2024-02-06 06:02:36","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":309447,"visible":true,"origin":"","legend":"\u003cp\u003eCIE chromaticity diagram of \u003cstrong\u003ePt-1\u003c/strong\u003e (orange), \u003cstrong\u003ePt-2\u003c/strong\u003e (red), \u003cstrong\u003ePt-3\u003c/strong\u003e (violet) and \u003cstrong\u003ePt-4\u003c/strong\u003e (black). AH/FC coordinates in circle and exp coordinates in square (Exp\u003csup\u003e[23]\u003c/sup\u003e).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3921913/v1/172dd76400ceb29593766f3e.png"},{"id":53869570,"identity":"456ea8d2-1c3a-4adb-ae65-1a095f66b35f","added_by":"auto","created_at":"2024-04-01 15:10:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1389891,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3921913/v1/80ac8146-6f6f-4a6b-97f9-73e43a2152e3.pdf"},{"id":50705706,"identity":"543893c9-b21e-4353-a810-d9d180cc8d5e","added_by":"auto","created_at":"2024-02-06 06:02:36","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":386238,"visible":true,"origin":"","legend":"","description":"","filename":"SI.docx","url":"https://assets-eu.researchsquare.com/files/rs-3921913/v1/0e09786ad3d28f8456c65a97.docx"},{"id":50706034,"identity":"7f05dc86-a3ca-4eee-818f-0c6a031e2106","added_by":"auto","created_at":"2024-02-06 06:10:36","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":76931,"visible":true,"origin":"","legend":"\u003cp\u003eScheme 1. Energy levels (in eV), energy gaps (in eV) and the composition selected FMOs in term of orbital fragments obtained with B3PW91.\u003c/p\u003e","description":"","filename":"Scheme1.png","url":"https://assets-eu.researchsquare.com/files/rs-3921913/v1/c3d3737f4d269917133368a5.png"},{"id":50705704,"identity":"2d6eccd7-8cf2-4564-a77d-2b46e57ac437","added_by":"auto","created_at":"2024-02-06 06:02:36","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":2813706,"visible":true,"origin":"","legend":"","description":"","filename":"Table3and6.docx","url":"https://assets-eu.researchsquare.com/files/rs-3921913/v1/4cb693f73283f638a4c7b6b5.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Theoretical investigation on phosphorescent platinum complexes based on two tetradentate bipyridine ligands","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCyclometalated iridium and platinum complexes have been extensively studied in the last two decades owing principally to their applications in phosphorescent organic light-emitting diodes (OLEDs) and also in photocatalysts [\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Octahedral iridium complexes, with C^N bidentate ligands in particular phenylpyridine, phenylpyrazole, and acetylacetonate ligands showed a high luminescence quantum yield and short luminescent lifetime into the microsecond range at room temperature [\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. These remarkable properties have made these complexes highly preferable in OLED applications as phosphorescent emitters. Square planar geometry around the metal has also been widely considered due to the different coordination possibilities that can develop between the ligands and the metal in this geometry [\u003cspan additionalcitationids=\"CR11 CR12\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The easy synthesis of square planar complexes and the flexibility of their geometrical structures have allowed the use of various cyclometalating ligands such as bidentate, tridentate, or tetradentate [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In recent years, several studies have shown that Pt square planar complexes can be considered as an excellent alternative to the usual octahedral iridium complexes [\u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Square planar Pt complexes based on tetradentate ligands have recently been of great interest due to their rigid structures and due to their efficiency in OLED applications [\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Chiheon Lee et al have synthesized and characterized a new series of four square Pt(II) complexes based on two tetradentate bipyridine ligands (pypy) linked by C(OCH\u003csub\u003e3\u003c/sub\u003e)R\u0026prime; group [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The four complexes have general formula [dRpypy―C(OCH\u003csub\u003e3\u003c/sub\u003e)R\u0026prime;―dRpypy]Pt, with \u003cb\u003ePt-1\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;F, R\u0026prime;=methyl), \u003cb\u003ePt-2\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;F, R\u0026prime;=hexyl), \u003cb\u003ePt-3\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;methoxy, R\u0026prime;=methyl) and \u003cb\u003ePt-4\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;methoxy, R\u0026prime;=hexyl). The authors studied the effects of the substituents methyl or hexyl at the linker and the effects of the introduction of an electron-donating/withdrawing fragment (fluorine or methoxy) on the structure and the phosphorescence properties of the four complexes.\u003c/p\u003e \u003cp\u003eIn this work, we studied geometrical structure, optical and phosphorescence properties of the four complexes using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. Our study provides detailed investigation on structural and electronic properties of both ground state and excited triplet state of the four complexes. The emission spectra were modeled using the Franck-Condon (FC) approximation taking into account the vibrational structure contributions to S0-T1 transition.\u003c/p\u003e"},{"header":"Computational details","content":"\u003cp\u003eStarting from X-ray geometries, all studied complexes were fully optimized in dichloromethane (CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e) using hybrid exchange\u0026ndash;correlation functional B3PW91 [\u003cspan additionalcitationids=\"CR25\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. We have employed LANL2DZ base set [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] for all atoms augmented with \u003cem\u003ed\u003c/em\u003e polarization functions on C, N, S, and O, and augmented with \u003cem\u003ef\u003c/em\u003e polarization functions on Pt. The \"relativistic\" HayWat pseudo-potential associated with LANL2DZ basis set was used to describe the inner electron of the Pt. The solvent effects were introduced using the polarizable continuum model PCM [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] implemented in Gaussian [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The low-lying excited states were studied using the TD-DFT method in term of natural transition orbitals (NTOs) [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. All spectra were simulated with gaussian function (FWHM\u0026thinsp;=\u0026thinsp;0.35 eV) using GaussSum GUI application [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. S\u003csub\u003e0\u003c/sub\u003e geometries were used as starting point to optimize the first triplet excited states T\u003csub\u003e1\u003c/sub\u003e of all studied complexes by unrestricted DFT (UB3PW91) in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e with the same basis sets cited above. Frequency calculations were performed to confirm that both S\u003csub\u003e0\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e geometries of all complexes correspond to true minima on the Potential Energy Surface (PES). Phosphorescence wavelengths were calculated according to ΔSCF\u003csup\u003evert\u003c/sup\u003e and ΔSCF\u003csup\u003eadiab\u003c/sup\u003e procedures. 0\u0026ndash;0 wavelengths were calculated taking into account zero-point vibrational energy (ZPVE) corrections. To simulate the phosphorescence spectra, the vibrational structure contributions to the T\u003csub\u003e1\u003c/sub\u003e-S\u003csub\u003e0\u003c/sub\u003e electronic transition were studied using adiabatic Hessian (AH) and adiabatic shift (AS) approaches according to the FC approximation. Emission spectra were plotted using VMS program [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. All calculations were performed by Gaussian 09. We have use Avogadro-1 [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] to get isosurface orbitals and to visualizing geometric structures.\u003c/p\u003e"},{"header":"Results and discussions","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003eGround-state study\u003c/h2\u003e\n \u003cp\u003eGround state geometries (S\u003csub\u003e0\u003c/sub\u003e) of the four complexes were fully optimized in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e using B3PW91 functional. Selected bond lengths and angles are given in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e together with available experimental data (data not available for complex \u003cstrong\u003ePt-3\u003c/strong\u003e). As the crystal structures, all optimized geometry complexes display a distorted square planar geometry around the metal (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). As shown in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, computed bond lengths and bond angles agree with experimental values. For all complexes, Pt\u0026thinsp;\u0026minus;\u0026thinsp;N bond lengths are slightly longer than Pt\u0026thinsp;\u0026minus;\u0026thinsp;C bond lengths. Pt\u0026thinsp;\u0026minus;\u0026thinsp;N\u003csub\u003e1\u003c/sub\u003e and Pt-N\u003csub\u003e2\u003c/sub\u003e bond lengths are closes in each complex, which means that N\u003csub\u003e1\u003c/sub\u003e and N\u003csub\u003e2\u003c/sub\u003e coordinate similarly with Pt. Same conclusion for Pt\u0026thinsp;\u0026minus;\u0026thinsp;C\u003csub\u003e1\u003c/sub\u003e and Pt\u0026thinsp;\u0026minus;\u0026thinsp;C\u003csub\u003e2\u003c/sub\u003e. Replacing methyl with hexyl and/or fluorine atoms with methoxy groups does not affect Pt-ligand bonds lengths.\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eSelected \u003cstrong\u003eo\u003c/strong\u003eptimized and experimental bond lengths (in \u0026Aring;) and bond angles (in \u0026deg;) of the four studied complexes calculated with B3PW91.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePt-1\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePt-2\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePt-3\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePt-4\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\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB3PW91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eExp\u003csup\u003e[23]\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB3PW91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eExp\u003csup\u003e[23]\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB3PW91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB3PW91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eExp\u003csup\u003e[23]\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt \u0026ndash; N\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.079\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.064\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.079\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.068\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.075\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.080\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.057\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt \u0026ndash; N\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.093\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.077\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.093\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.075\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.080\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.075\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.054\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt \u0026ndash; C\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.988\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.995\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.988\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.987\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.989\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.988\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.980\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt \u0026ndash; C\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.987\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.996\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.986\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.988\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.988\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.997\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN\u003csub\u003e1\u003c/sub\u003e \u0026ndash; Pt-N\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e93.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e93.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e92.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e93.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e95.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e95.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e96.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN\u003csub\u003e1\u003c/sub\u003e\u0026ndash; Pt-C\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e80.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e80.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e80.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e80.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e80.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC\u003csub\u003e2\u003c/sub\u003e \u0026ndash; Pt-C\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e104.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e103.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e104.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e103.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e101.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e102.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e102.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC\u003csub\u003e2\u003c/sub\u003e \u0026ndash; Pt-N\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC\u003csub\u003e2\u003c/sub\u003e \u0026ndash; Pt-N\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e167.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e171.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e167.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e168.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e170.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e169.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e171.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC\u003csub\u003e1\u003c/sub\u003e \u0026ndash; Pt-N\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e173.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e173.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e172.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e173.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e174.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e174.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e176.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003eFrontier molecular orbitals (FMOs) of the four complexes were studied using B3PW91 functional. Energy levels, energy gaps and the composition selected FMOs in term of orbital fragments are depicted in Scheme \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. Energy levels of fluorinated complexes (\u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e) are lower than those of \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e containing methoxy groups instead fluorine atoms due to the electron withdrawing character of fluorine atoms. While replacing methyl with hexyl at the linker do not affect the energies and the compositions of FMOs of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e. The five highest occupied orbitals (HOMO \u0026mdash; H-5) of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e are delocalized over pypy ligands and dPt orbitals with different percentages. The proportion of dPt orbitals are dominated only in H-2 orbitals in both \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e. For the complexes \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e, the two highest occupied orbitals HOMO and H-1 are delocalized only over pypy orbitals while the four orbitals H-2, H-3, H-4 and H-5 are contributed with dPt and pypy orbitals. The lowest unoccupied orbitals of the four complexes (Scheme \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e) are delocalized in pypy orbitals without any contribution of dPt orbitals. Replacing methyl with hexyl at the linker don\u0026rsquo;t affect the energy gaps, indeed \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e have very close energy gaps 4.02 and 4.03 eV respectively also \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e have almost same energy gaps (\u0026Delta;E\u0026thinsp;\u0026asymp;\u0026thinsp;3.72 eV). While, the energy gaps of the fluorinated complexes (\u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2)\u003c/strong\u003e are larger than \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e containing dimethoxy-pypy ligands.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003eUV\u0026ndash;vis absorption spectra\u003c/h2\u003e\n \u003cp\u003eSinglet excited states of the four complexes were studied using B3PW91 functional in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e. Absorption spectra were simulated using gaussian band shape with a fixed full width at half-minimum (FWHM) of 0.33 eV (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). Wavelengths, oscillator strengths and character of selected S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003en\u003c/sub\u003e absorptions are reported together with experimental data in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e (\u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e) and Table \u003cspan class=\"InternalRef\"\u003eS1\u003c/span\u003e (\u003cstrong\u003ePt-2\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e). As shown in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e, B3PW91 gives acceptable results compared to the experience and reproduces the main characteristic of the observed spectra. A comparison between \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e spectrum and between \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e spectrum, shows that the replacement of methyl group with hexyl group do not change the shape of both simulated and experimental spectra. While replacing the four fluorine atoms of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e by four methoxy groups to get \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e affects the spectrum shapes. Indeed, \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e spectrum contain multiple bands between 250 and 400 nm unlike \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e spectrum which contain two distinctive bands. The singlet excited states of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e reported in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e are quasi similar with those of \u003cstrong\u003ePt-2\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e respectively. For this reason, we only studied the excited states of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e in terms of NTOs (Tables \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e and S2). S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e1\u003c/sub\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.01) and S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e2\u003c/sub\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.06) absorptions of \u003cstrong\u003ePt-1\u003c/strong\u003e calculated at 370 and 349 nm respectively correspond to single hole-electron transition which occurs principally from dPt to pypy ligand orbitals and to intra-pypy ligands charge transfer. We can assign these absorptions to the weak band observed at 350\u0026ndash;390 nm. The weak band simulated at the region 325\u0026ndash;350 nm is contributed with S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e3\u003c/sub\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.13) and S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e4\u003c/sub\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.11) absorptions calculated at 321 and 314 nm. S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e3\u003c/sub\u003e contains double hole-electron transitions, the first (weight\u0026thinsp;=\u0026thinsp;0.66) correspond to a mixed character MLCT/LLCT while the second (weight\u0026thinsp;=\u0026thinsp;0.33) principally to LLCT transition. S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e4\u003c/sub\u003e absorption contains one hole-transition and corresponds to MLCT/ILCT character. The tow absorptions S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e3\u003c/sub\u003e and S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e4\u003c/sub\u003e can be attributed to the two absorptions observed at 332 and 306 nm respectively. The intense band simulated at ~\u0026thinsp;300 nm is contributed with S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e5\u003c/sub\u003e and S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e6\u003c/sub\u003e absorptions with significant oscillator strengths \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.27 and \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.23 respectively.\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eWavelengths (\u0026lambda;\u003csub\u003ecal\u003c/sub\u003e and \u0026lambda;\u003csub\u003eexp\u003c/sub\u003e), oscillator strengths and the character of selected singlet excited states of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026lambda;\u003csub\u003ecal\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTransition\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026lambda;\u003csub\u003eexp\u003c/sub\u003e\u003csup\u003e[23]\u003c/sup\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCharacter\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\u003ePt-1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e370\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-1\u0026rarr;LUMO (95%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMLCT/LLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e349\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-2\u0026rarr;LUMO (79%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e377\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMLCT/LLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e321\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHOMO\u0026rarr;L\u0026thinsp;+\u0026thinsp;1 (52%)\u003c/p\u003e\n \u003cp\u003eH-3\u0026rarr;LUMO (31%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e332\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMLCT/LLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e314\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-4\u0026rarr;LUMO (78%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e306\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e5\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e285\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH\u0026rarr;L\u0026thinsp;+\u0026thinsp;2 (36%)\u003c/p\u003e\n \u003cp\u003eH-3\u0026rarr;L\u0026thinsp;+\u0026thinsp;1 (31%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLLCT/MLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e6\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e279\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-3\u0026rarr;L\u0026thinsp;+\u0026thinsp;1 (45%)\u003c/p\u003e\n \u003cp\u003eH-2\u0026rarr;L\u0026thinsp;+\u0026thinsp;1 (25%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e273\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLLCT/MLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e7\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-3\u0026rarr;L\u0026thinsp;+\u0026thinsp;3 (46%)\u003c/p\u003e\n \u003cp\u003eH-2\u0026rarr;L\u0026thinsp;+\u0026thinsp;3 (20%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLLCT/MLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePt-3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e405\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHOMO\u0026rarr;LUMO (82%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e421\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMLCT/LLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e356\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-2\u0026rarr;LUMO (61%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e356\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMLCT/LLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e334\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-4\u0026rarr;LUMO (69%)\u003c/p\u003e\n \u003cp\u003eHOMO\u0026rarr;L\u0026thinsp;+\u0026thinsp;1 (20%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMLCT/LLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e309\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-4\u0026rarr;L\u0026thinsp;+\u0026thinsp;1 (15%)\u003c/p\u003e\n \u003cp\u003eHOMO\u0026rarr;L\u0026thinsp;+\u0026thinsp;2 (64%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e5\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e290\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-4\u0026rarr;L\u0026thinsp;+\u0026thinsp;1 (34%)\u003c/p\u003e\n \u003cp\u003eH-1\u0026rarr;L\u0026thinsp;+\u0026thinsp;3 (18%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e295\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLLCT/MLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e6\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e281\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH-4\u0026rarr;L\u0026thinsp;+\u0026thinsp;2 (10%)\u003c/p\u003e\n \u003cp\u003eH-4\u0026rarr;L\u0026thinsp;+\u0026thinsp;3 (11%)\u003c/p\u003e\n \u003cp\u003eH-3\u0026rarr;L\u0026thinsp;+\u0026thinsp;3 (47%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e272\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLLCT/MLCT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003eNTO analyzes show that the two absorptions are composed with two hole-electron transitions, with two different proportions corresponding to MLCT/LLCT characters. The two absorptions are assigned to the most intense band observed experimentally above 270 nm. For \u003cstrong\u003ePt-3\u003c/strong\u003e, S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e1\u003c/sub\u003e absorption computed at 405 nm containing one NTO pair transition correspond to a mixed character MLCT/LLCT and can be assigned to the weak band observed at ~420 nm. The band simulated at 320-350 nm is attributed principally with two absorptions S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e2\u003c/sub\u003e (\u003cem\u003ef\u003c/em\u003e=0.16) and S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e3\u003c/sub\u003e (\u003cem\u003ef\u003c/em\u003e=0.21). NTO analysis show that the two absorptions correspond to transitions from dPt and pypy ligand orbitals to pypy ligand orbitals. The two absorptions are assigned to the band observed at 330-380 nm. The two most intense absorptions S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e4\u003c/sub\u003e (\u003cem\u003ef\u003c/em\u003e=0.22) and S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e5\u0026nbsp;\u003c/sub\u003e(\u003cem\u003ef\u003c/em\u003e=0.39) computed at 309 and 290 nm are assigned to the intense band observed at ~295 nm. S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e4\u003c/sub\u003e and S\u003csub\u003e0\u003c/sub\u003e-S\u003csub\u003e5\u0026nbsp;\u003c/sub\u003econtain two hole-electron transitions, one dominant and the second minority corresponding both to MLCT/LLCT characters (Table 3).\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n \u003ch2\u003eFirst triplet excited state study\u003c/h2\u003e\n \u003cp\u003eThe first triplet excited states T\u003csub\u003e1\u003c/sub\u003e of the studied complexes were optimized in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e using UB3PW91 functional. Frequency calculations were performed to check that T\u003csub\u003e1\u003c/sub\u003e obtained correspond to true global minimum. A comparison between T\u003csub\u003e1\u003c/sub\u003e of the four complexes show that introducing substituents methyl or hexyl at the linker between the two pypy ligands does not change T\u003csub\u003e1\u003c/sub\u003e bond lengths (Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e and S3). While, the substituents on the two pyridine ligands (fluorine or methoxy), cause a slight modification around Pt and on intra-pypy ligand bonds. A comparative study between S\u003csub\u003e0\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e geometries are reported in Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e (\u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e) and in Table S3 (\u003cstrong\u003ePt-2\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e). Only bond lengths with significant |T\u003csub\u003e1\u003c/sub\u003e-S\u003csub\u003e0\u003c/sub\u003e| are reported and classified in descending order. In \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e, Pt-N and Pt-C bonds of one pypy ligand are the most affected bonds around Pt. Indeed, the two pyridines of pypy become closer to Pt through N and C by 0.044 and 0.022\u0026Aring; respectively. Pt-N and Pt-C bond lengths between Pt and the second pypy ligand don\u0026rsquo;t change significantly (~\u0026thinsp;0.003\u0026Aring;) after S\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e1\u003c/sub\u003e transition. For intra-ligand bond lengths, the most affected bonds are located in pyridine rings of one pypy ligand which shows that during T\u003csub\u003e1\u003c/sub\u003e relaxation the electronic redistribution occurs only on this ligand (colored bonds in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). For the methoxy complexes (\u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4)\u003c/strong\u003e, Pt-N and Pt-N reducing by 0.035 and 0.034\u0026Aring; after S\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e1\u003c/sub\u003e transition, are the most affected bonds around the metal. For ligand bond lengths, the most important deformations occur over the two pypy ligands. Visualizations of the singly occupied natural orbital (SONO) pairs of all T1 show that charge density distribution are localized in one pypy ligand for \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e and delocalized over the two pypy ligands for \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e.\u003c/p\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eA comparison between S\u003csub\u003e0\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e geometries of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e complexes. Bond length colors are depicted in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003ePt-1\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003ePt-3\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\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e0\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e|T\u003csub\u003e1\u003c/sub\u003e-S\u003csub\u003e0\u003c/sub\u003e|\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003e0\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e|T\u003csub\u003e1\u003c/sub\u003e-S\u003csub\u003e0\u003c/sub\u003e|\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-N\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.093\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.049\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.044\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-N\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.075\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.040\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.035\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-C\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.987\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.965\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.022\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-N\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.080\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.046\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.034\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-N\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.079\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-C\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.989\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.975\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.014\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-C\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.988\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.991\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-C\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.988\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.976\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.012\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003ered\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.398\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.072\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN-C\u003csub\u003e\u003cem\u003egreen\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.373\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.403\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN-C\u003csub\u003e\u003cem\u003egreen\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.362\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.426\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.064\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN-C\u003csub\u003e\u003cem\u003egreen\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.403\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.028\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003eblue\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.400\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.453\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.053\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003ered\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.463\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.435\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.028\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003eyellow\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.436\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.483\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.047\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003ered\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.463\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.435\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.028\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003eorange\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.402\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.437\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.035\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003eblue\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.415\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.441\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.026\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003eblack\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.396\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.428\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.032\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003eblue\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.416\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.442\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.026\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN-C\u003csub\u003e\u003cem\u003epurple\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.319\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.293\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.026\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003eyellow\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.434\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.453\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.019\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN-C\u003csub\u003e\u003cem\u003ebrown\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.321\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.346\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003eyellow\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.434\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.452\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.018\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003e\u003cem\u003epink\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.392\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.369\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC-C\u003csub\u003epink\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.391\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.408\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.017\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003ePhosphorescence properties\u003c/h2\u003e\n \u003cp\u003ePhosphorescence spectra of the four studied complexes were modelled using AH method and superposed with experimental spectra for comparison (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). Normal modes with frequencies low than 150 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were cleared to get sufficient spectrum progressions (\u0026gt;\u0026thinsp;95% for all complexes). Simulated phosphorescence wavelengths of most intense band of all spectra are given in Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e together with experimental data. Simulated phosphorescence spectra of the four complexes reproduce nicely the experimental ones. Introducing the substituent hexyl with methyl at the linker doesn\u0026rsquo;t change the shape of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e spectra. While replacing fluorine atoms with methoxy groups red shifts the phosphoresce spectra of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e. Normal modes involved in the vibronic structure are reported in Table \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e. For \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e, the most intense band simulated at 470 nm is not contributed by 0\u0026ndash;0 transition but with the modes 118 and 115 for \u003cstrong\u003ePt-1\u003c/strong\u003e and with 153 and 150 for \u003cstrong\u003ePt-2\u003c/strong\u003e, which have intense stick near to 470 nm. All these modes correspond to in-plane vibrations localized in one pypy ligand assigned to the breathing of the pypy rings and to C-H bending, and are assigned to the intense band observed in \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e spectra. The shoulder simulated at ~\u0026thinsp;500 nm is contributed by the modes |118\u003csup\u003e2\u003c/sup\u003e〉 and |118\u003csup\u003e1\u003c/sup\u003e|115\u003csup\u003e1\u003c/sup\u003e〉 for \u003cstrong\u003ePt-1\u003c/strong\u003e and by the modes |153\u003csup\u003e2\u003c/sup\u003e〉 and |153\u003csup\u003e1\u003c/sup\u003e|150\u003csup\u003e1\u003c/sup\u003e〉 for \u003cstrong\u003ePt-2\u003c/strong\u003e. Noting that |\u003cem\u003en\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e〉 corresponds to the case where the vibration mode \u003cem\u003en\u003c/em\u003e is at v\u0026thinsp;=\u0026thinsp;2 and |\u003cem\u003en\u003c/em\u003e\u003csup\u003e1\u003c/sup\u003e|\u003cem\u003em\u003c/em\u003e\u003csup\u003e1\u003c/sup\u003e〉 is a combination of the vibration mode \u003cem\u003en\u003c/em\u003e at v\u0026thinsp;=\u0026thinsp;1 with the vibration mode \u003cem\u003em\u003c/em\u003e at v\u0026thinsp;=\u0026thinsp;1. These vibration modes can be assigned to the weak band observed at 495 nm (\u003cstrong\u003ePt-1\u003c/strong\u003e) and 500 nm (\u003cstrong\u003ePt-2\u003c/strong\u003e). The bands simulated at 442 nm (\u003cstrong\u003ePt-1\u003c/strong\u003e) and 444 nm (\u003cstrong\u003ePt-2\u003c/strong\u003e) which have not been recorded experimentally, are contributed with 0\u0026ndash;0 transition and the mode 28 (\u003cstrong\u003ePt-1\u003c/strong\u003e) and 36 (\u003cstrong\u003ePt-2\u003c/strong\u003e). For the methoxy complexes, the intense band simulated at 486 nm (\u003cstrong\u003ePt-3\u003c/strong\u003e) and at 484 nm (\u003cstrong\u003ePt-4\u003c/strong\u003e) are contributed principally with 0\u0026ndash;0 transition. Additional modes near to 0\u0026ndash;0 transition with non-negligible intensity contribute to this intense band, in particular modes 41 (\u003cstrong\u003ePt-3\u003c/strong\u003e) and 72 (\u003cstrong\u003ePt-4\u003c/strong\u003e) assigned mainly to in-plane vibrations of pypy fragment. The shoulder in 500\u0026ndash;550 nm region of \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e spectra can be assigned to the vibrational signatures of two modes (87, 156) and (124, 135) in \u003cstrong\u003ePt-3\u003c/strong\u003e and \u003cstrong\u003ePt-4\u003c/strong\u003e spectra respectively (Table \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\n \u003ctable id=\"Tab5\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComputed and experimental phosphorescence wavelengths of the studied complexes.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePt-1\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePt-2\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePt-3\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePt-4\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eExp\u003csup\u003e[23]\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eExp\u003csup\u003e[23]\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eExp\u003csup\u003e[23]\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eExp\u003csup\u003e[23]\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lambda;/nm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e498/470/442\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e495/466\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e500/473/444\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e500/466\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e510/486\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e515/494\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e510/484\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e515/490\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCIE(x,y)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e(0.17,0.22)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e(0.15,0.26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e(0.17,0.24)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e(0.17,0.29)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e(0.17,0.47)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e(0.16,0.46)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e(0.17,0.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e(0.20,0.47)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cp\u003ePhosphorescence colors of the four complexes were studied according to CIE-1931 color system. Color-calculator program was used to generate the CIE (x,y) coordinates from simulated (FC/AH) spectra and also from digitized experimental spectra for comparison (Table \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e). As depicted in the CIE chromaticity diagram (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e), simulated and experimental (x,y) coordinates are located in the same color region of the horseshoes. Which mean that AH/FC method reproduces nicely the observed phosphorescence colors of all complexes. The fluorinated complexes \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-2\u003c/strong\u003e exhibit light bright blue color while the two methoxy complexes \u003cstrong\u003ePt-2\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e exhibit light spring green color. Replacing methyl with hexyl group does not significantly change the CIE (x,y) coordinates of \u003cstrong\u003ePt-1\u003c/strong\u003e and \u003cstrong\u003ePt-3\u003c/strong\u003e and therefore don\u0026rsquo;t affects the their phosphoresce colors.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn this study, the geometrical, optical, and phosphorescence properties of the four complexes were investigated using the B3PW91 and TD-B3PW91 methods. The computed bond lengths and bond angles align with experimental data. Analysis of S\u003csub\u003e0\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e for all complexes indicates that the introduction of methyl or hexyl substituents in the linker, as well as the replacement of fluorine atoms with methoxy groups, does not lead to significant modifications in S\u003csub\u003e0\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e bond lengths. Furthermore, the electronic relaxation of T\u003csub\u003e1\u003c/sub\u003e occurs principally on one pypy ligand for fluorinated complexes and over the two pypy ligands for methoxy complexes. B3PW91 provides acceptable results compared to experimental data and reproduces the main characteristics of both absorption and phosphorescence spectra. The substituents on the linker do not affect the spectra, while the replacement of fluorine atoms with methoxy groups on the pyridine ligands modifies the shape of the UV-vis spectra and induces a red shift in the phosphorescence spectra. NTO analyses show that the most intense absorptions, simulated in the 250\u0026ndash;300 nm region, correspond to MLCT/LLCT character. Normal modes near to the 0\u0026ndash;0 transition involved in the vibronic structure were identified and analyzed. The fluorinated complexes exhibit light bright blue color while the methoxy complexes display light spring green color. Moreover, replacing the two methyl groups with two hexyl groups doesn't affect the phosphorescent colors.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflict of interest statement\u003c/h2\u003e \u003cp\u003eOn behalf of all authors, the corresponding author states that there is no conflict of interest.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthor contributionsHM : Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Resources, Software, Visualization, Writing \u0026ndash; original draft. HB and DH : Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing \u0026ndash; original draft, Writing \u0026ndash; review \u0026amp; editing. MB and FYC : Conceptualization, Data curation, Formal analysis, Methodology, Resources, Software, Validation, Visualization. AG : Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing \u0026ndash; review \u0026amp; editing.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThis work is part of \u003cem\u003eProjets de Recherche Formation-Universitaire\u003c/em\u003e (PRFU, MESRS, Algeria) supported by the directorate general for scientific research and technological development (DGRSDT, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e\u003ca href=\"http://www.dgrsdt.dz\" target=\"_blank\"\u003ewww.dgrsdt.dz\u003c/a\u003e\u003c/span\u003e\u003cspan address=\"http://www.dgrsdt.dz\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) and the thematic research agency in science and technology (ATRST, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e\u003ca href=\"http://www.dgrsdt.dz\" target=\"_blank\"\u003ewww.atrst.dz\u003c/a\u003e\u003c/span\u003e\u003cspan address=\"http://www.atrst.dz\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). PRFU code: B00L01UN200120230005. All the authors thank DGRSDT.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eYu, T.; Zhang, C.; Zhao, Y.; Guo, S.; Liu, P.; Li, W.; Fan, D. Synthesis, Crystal Structure and Photoluminescence of a Cyclometalated Iridium(III) Coumarin Complex. \u003cem\u003eJ. Fluoresc. \u003c/em\u003e\u003cstrong\u003e2013\u003c/strong\u003e, \u003cem\u003e23\u003c/em\u003e (4), 777-783. DOI: 10.1007/s10895-013-1214-x.\u003c/li\u003e\n\u003cli\u003eLatouche, C.; Skouteris, D.; Palazzetti, F.; Barone, V. TD-DFT Benchmark on Inorganic Pt(II) and Ir(III) Complexes. \u003cem\u003eJ. Chem. Theory Comput. \u003c/em\u003e\u003cstrong\u003e2015\u003c/strong\u003e, \u003cem\u003e11\u003c/em\u003e (7), 3281-3289. DOI: 10.1021/acs.jctc.5b00257.\u003c/li\u003e\n\u003cli\u003eSchira, R.; Latouche, C. 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DOI: 10.1186/1758-2946-4-17.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 3 and 6 are available in the Supplementary Files section.\u003c/p\u003e"},{"header":"Schemes","content":"\u003cp\u003eScheme 1 is available in the Supplementary Files section\u003c/p\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":"theoretical-chemistry-accounts","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"tcac","sideBox":"Learn more about [Theoretical Chemistry Accounts](http://link.springer.com/journal/214)","snPcode":"214","submissionUrl":"https://submission.nature.com/new-submission/214/3","title":"Theoretical Chemistry Accounts","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"TD-DFT, platinum, complexes, absorption, phosphorescence","lastPublishedDoi":"10.21203/rs.3.rs-3921913/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3921913/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this work, the geometrical, optical, and phosphorescence properties of four complexes with general formula [dRpypy―C(OCH3)R\u0026prime;―dRpypy]Pt, with \u003cb\u003ePt-1\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;F, R\u0026prime;=methyl), \u003cb\u003ePt-2\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;F, R\u0026prime;=hexyl), \u003cb\u003ePt-3\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;methoxy, R\u0026prime;=methyl) and \u003cb\u003ePt-4\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;methoxy, R\u0026prime;=hexyl) were studied using the B3PW91 and TD-B3PW91 methods. The effect of the double substitution R and R\u0026prime; on the electronic properties of the four complexes has been investigated. Replacing the two fluorine atoms with the two methoxy groups modifies the shape of the UV-vis spectra and red shift the phosphorescence spectra, while the substituents on the linker R\u0026prime; do not induces changes in both spectra. Normal modes involved in the vibronic structure were identified and analyzed using adiabatic Hessian approaches according to the Franck-Condon approximation. The computed phosphorescence wavelengths agree with the observed ones and indicate that the fluorinated complexes exhibit a bright light blue color, while the methoxy complexes display a light spring green color.\u003c/p\u003e","manuscriptTitle":"Theoretical investigation on phosphorescent platinum complexes based on two tetradentate bipyridine ligands","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-06 06:02:31","doi":"10.21203/rs.3.rs-3921913/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-02-04T11:22:56+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-02-04T11:21:14+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-02-03T13:00:22+00:00","index":"","fulltext":""},{"type":"submitted","content":"Theoretical Chemistry Accounts","date":"2024-02-02T18:54:04+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"theoretical-chemistry-accounts","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"tcac","sideBox":"Learn more about [Theoretical Chemistry Accounts](http://link.springer.com/journal/214)","snPcode":"214","submissionUrl":"https://submission.nature.com/new-submission/214/3","title":"Theoretical Chemistry Accounts","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"fc51a973-857c-4133-98a2-9fa5c5d1bae5","owner":[],"postedDate":"February 6th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-04-01T15:04:38+00:00","versionOfRecord":{"articleIdentity":"rs-3921913","link":"https://doi.org/10.1007/s00214-024-03107-y","journal":{"identity":"theoretical-chemistry-accounts","isVorOnly":false,"title":"Theoretical Chemistry Accounts"},"publishedOn":"2024-03-25 15:01:06","publishedOnDateReadable":"March 25th, 2024"},"versionCreatedAt":"2024-02-06 06:02:31","video":"","vorDoi":"10.1007/s00214-024-03107-y","vorDoiUrl":"https://doi.org/10.1007/s00214-024-03107-y","workflowStages":[]},"version":"v1","identity":"rs-3921913","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3921913","identity":"rs-3921913","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}