Investigation on crystal structure, phase transition behavior, and structural geometries of organic-inorganic hybrid [N(C3H7)4]2ZnBr4

Investigation on crystal structure, phase transition behavior, and structural geometries of organic-inorganic hybrid [N(C3H7)4]2ZnBr4 | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Investigation on crystal structure, phase transition behavior, and structural geometries of organic-inorganic hybrid [N(C 3 H 7 ) 4 ] 2 ZnBr 4 Huiyeong Ju, Ae Ran Lim This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8654223/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Apr, 2026 Read the published version in Scientific Reports → Version 1 posted 12 You are reading this latest preprint version Abstract Organic–inorganic hybrid compounds have attracted significant attention as a versatile class of functional materials owing to their unique structural characteristics and tunable physicochemical properties. In this study, colorless and transparent single crystals of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 were grown from an aqueous solution. Thermal analyses (differential scanning calorimetry, differential thermal analysis), powder X-ray diffraction (XRD), and optical microscopy revealed a phase transition (T C ) at 395 K, followed by decomposition and melting at 529 and 540 K, respectively. From the single-crystal XRD experiment, crystallographic analysis indicates a monoclinic symmetry (space group C2/c), with the unit cell dimensions a =33.1977 Å, b =14.2615 Å, c =15.1130 Å, and β=110.3840°, and remains thermally stable up to approximately 521 K. Solid-state nuclear magnetic resonance (NMR) results further support these findings: the 1 H and 14 N magic angle spinning (MAS) NMR chemical shifts show discontinuous changes near the T C , while the 13 C MAS NMR spectra exhibit variations in peak multiplicity, indicating a reduction in symmetry below the transition point. Moreover, the progressive line narrowing observed in the 1 H, 13 C, and 14 N spectra with increasing temperature reflects enhanced molecular motion, particularly reorientational dynamics associated with the T C . Physical sciences/Chemistry Physical sciences/Materials science Physical sciences/Physics Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Introduction Organic–inorganic hybrid compounds have emerged as a prominent class of functional materials owing to their unique structural characteristics and versatile physicochemical properties. Considerable research efforts have been devoted to this family of compounds, driven by their potential utility in diverse technological applications. 1–7 The intrinsic features of hybrid compounds arise from the synergistic contributions of their organic and inorganic constituents: the organic cations predominantly influence optical responses and structural adaptability, whereas the inorganic metal halide framework dictates thermal robustness and mechanical stability. 8, 9 This complementary interplay renders hybrid compounds highly attractive as next-generation materials. Nevertheless, critical challenges remain, particularly regarding the improvement of long-term stability and the establishment of scalable fabrication processes, both of which are essential for practical implementation. 10 Furthermore, the recent incorporation of ferroelectric behavior into hybrid compound systems has expanded their functional scope, opening new prospects for applications in emerging fields such as flexible and wearable electronics. 11–14 Quaternary ammonium metal halides of the general formula [N(C n H 2 n +1 ) 4 ] 2 MX 4 , where M =Mn, Co, Cu, Zn, Cd; X = Cl, Br; n = 1–3), have been extensively investigated as a distinct subclass of organic–inorganic hybrid materials. 15–60 These compounds are characterized by frameworks in which discrete MX 4 2- anionic units are stabilized by bulky tetra-alkylammonium cations. The interplay between the inorganic complexes and the organic cations gives rise to diverse structural motifs, including layered, chain-like, and molecular crystal architectures, the specific arrangement being strongly dependent on the alkyl-chain length and the choice of metal and halide ions. A notable feature of these materials is the frequent occurrence of order–disorder phase transitions, which originate from the orientational dynamics and positional displacements of the tetra-alkylammonium groups. Importantly, systematic modification of the metal center or halide ligands provides a means of tuning their electronic, magnetic, and optical behaviors. Owing to this combination of structural flexibility and functional versatility, [N(C n H 2 n +1 ) 4 ] 2 MX 4 salts represent a valuable platform for fundamental investigations as well as for potential applications across materials science, coordination chemistry, and soft condensed matter physics. To date, studies on [N(C 3 H 7 ) 4 ] 2 ZnBr 4 ( M =Zn; X =Br) with n =3, 54, 56, 60-62 a member of the A 2 MX 4 family, have been very limited. Among the few existing reports, structural and optical results of [N(C 3 H 7 ) 4 ] 2 M Br 4 ( M =Zn, Co, Cu) crystals were briefly reported by Belka and Sabatini. 61,62 And, Chkoundali et al. 54 investigated the crystal structure, thermal and dielectric properties of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 . They reported that the compound crystallizes in a monoclinic structure with the space group C2/c, with lattice constants a=33.145 Å, b=14.234 Å, c=15.081 Å, β=110.207°, and Z=8. And, two phase transitions were reported at 340 and 393 K under a heating rate of 5℃/min. In addition, the electrical conductivity study induced phase transition were discussed. 56 More recently, the synthesis, spectral, thermal characterization and antioxidant activity were described by Kanagarajan et al. 60 They reported that 390 K obtained by TG (thermogravimetry)/DTG (derivative thermogravimetry) curves corresponds to the melting point rather than a phase transition. Meanwhile, various studies have been conducted on single crystals of [N(C 3 H 7 ) 4 ] 2 M Br 4 ( M =Co, Zn, Cd) where X =Br, 49,54,56,57,59 and these crystals are reported to have slightly different structures compared to those with X =Cl. Although not much research has been done on the [N(C 3 H 7 ) 4 ] 2 ZnBr 4 crystals among the A 2 MX 4 group in the past, it has recently been considered as a material worthy of interest due to its potential applications. In this study, we aim to elucidate the phase transition mechanism of the organic–inorganic hybrid compound [N(C 3 H 7 ) 4 ] 2 ZnBr 4 by correlating its structural, thermal, and dynamic properties. The crystal structure was determined by single-crystal X-ray diffraction (SCXRD) at 300 K to establish the structural framework of the material. The phase transition behavior was systematically investigated using differential scanning calorimetry (DSC), thermogravimetric and differential thermal analysis (TG/DTA), optical microscopy, and powder X-ray diffraction (PXRD). Furthermore, temperature-dependent 1 H, 13 C, and 14 N nuclear magnetic resonance (NMR) chemical shifts and spin–lattice relaxation times (T 1 ) were analyzed to probe the dynamics of the [N(C₃H₇)₄] cations near the phase transition temperature. Through these combined experimental approaches, this work seeks to clarify the role of cation dynamics and energy transfer processes in governing the phase transition and physical properties of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 . Experimental methods Crystal growth High-quality single crystals of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 were grown through the slow evaporation process form supersaturated solutions by dissolving N(C 3 H 7 ) 4 Br (Sigma Aldrich 98 %) and ZnBr 2 (Sigma Aldrich 99 %) in distilled water with molecular weight of 2:1. After the solution was stirred and heated until saturation, single crystals were obtained through slow evaporation over several weeks while maintaining a constant temperature of 300 K. The colorless and transparent single crystals with a hexagonal prismatic morphology were grown. Although these single crystals were stable under ambient conditions, they were stored in a desiccator to prevent moisture-related degradation. Characterization Differential scanning calorimetry (DSC) measurements were carried out on a TA Instruments system (Model 25) at a heating rate of 10℃/min between 200 and 570 K under a continuous flow of dry nitrogen. Temperature-dependent changes in crystal morphology were examined using an optical microscope (Carl Zeiss) equipped with a Linkam THMS 600 heating stage. Thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) were further performed from 300 to 873 K under a nitrogen atmosphere with a heating rate of 10℃/min. 63 Single-crystal X-ray diffraction (SCXRD) measurements were performed at 300 K at the Korea Basic Science Institute (KBSI), Research Center for Materials Analysis, to determine the crystal structure and unit-cell parameters. Data were collected using a Bruker SMART CCD diffractometer equipped with graphite-monochromated Mo-Kα radiation. 63 The SMART APEX3 and SAINT software packages were employed for data acquisition and integration, 64 while absorption corrections were applied using the multiscan method implemented in SADABS. The structure was solved by direct methods and subsequently refined by full-matrix least-squares procedures on F² using the SHELXTL program. 65 Non-hydrogen atoms were refined with anisotropic displacement parameters, and hydrogen atoms were placed in calculated positions based on idealized geometry. In addition, powder X-ray diffraction (PXRD) analysis was conducted using an Expert Pro-MPD X-ray diffractometer (PANalytical) fitted with Cu-Kα radiation. This experimental setup was employed to analyze the crystal structure and phase transition behavior of the samples. In addition, temperature-dependent PXRD measurements were carried out using an Anton Paar HTK 1200N high-temperature stage integrated with the same diffractometer, enabling the evaluation of structural evolution at elevated temperatures. 66 Solid-state NMR measurements for [N(C 3 H 7 ) 4 ] 2 ZnBr 4 were carried out using Bruker Avance NEO spectrometers. The NMR spectra were acquired at the KBSI, Metropolitan Seoul Center, using a 400 MHz instrument, while spin–lattice relaxation times (T 1 ) were determined on a 500 MHz spectrometer at the Laboratory of NMR, NCIRF, Seoul National University. The 1 H MAS NMR experiments were performed at Larmor frequencies of 400.13 and 500.13 MHz, and 13 C MAS NMR spectra were obtained at 100.61 and 125.75 MHz. Chemical shifts for both 1 H and 13 C nuclei were referenced to tetramethylsilane (TMS). The 14 N MAS NMR spectra were measured at a Larmor frequency of 28.90 MHz, with NH 4 NO 3 serving as the external reference. 63 Powdered samples were packed into 4 mm CP/MAS rotors and spun at rates of 5, 7, and 10 kHz to suppress spinning sidebands. One-dimensional 1 H and 13 C MAS NMR spectra were collected using a delay time of 10 s, whereas the 14 N NMR spectra was obtained at a delay time of 5 s . And, the 90° pulse lengths for 1 H and 13 C were set to 1.2 μs , and that for 14 N was set to 4 μs . The 1 H and 13 C T 1 values were measured with delay times ranging from 10 ms to 15 s . NMR measurements were carried out in the temperature range of 180 to 420 K. Experimental results and discussion Phase transition temperature and thermodynamic p roperties To accurately determine the phase transition temperatures (T C ) of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 , single-crystal samples were first finely pulverized using a mortar. DSC measurements were then carried out on approximately 6.3 mg of the resulting powder at both heating and cooling rates of 10°C/min. As shown in Fig. 1, three distinct endothermic peaks were detected upon heating, while no corresponding exothermic peak appeared during cooling, indicating that the process is irreversible. The enthalpy associated with the peak at 395 K was determined to be 23.91 kJ/mol. As shown in the inset of Fig. 1, the morphology of the colorless and transparent single crystal remained unchanged at 300 K and 340 K, as well as at 430 K (Fig. 1(a)~(c)), which is above T C . The endothermic peak at 529 K corresponds to the decomposition temperature, as evidenced by the single crystal becoming opaque in the optical microscopy experiment as shown in Fig. 1(d). In contrast, when the temperature reached 550 K, the crystal was observed to melt, in good agreement with the endothermic peak occurring at 540 K. The peaks observed at 529 K and 540 K were determined as the decomposition (T d ) and melting temperatures (T m ), respectively, as confirmed by optical microscopy. This interpretation is further supported by subsequent PXRD analysis. To examine the thermal behavior of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 , TGA and DTA experiments were performed. Following a procedure analogous to that used for the DSC experiments, the sample was finely powdered, 66 and approximately 6.8 mg was subjected to analysis. Thermogravimetric measurements were performed from 300 to 873 K at a constant heating rate of 10°C/min, matching the conditions employed in the DSC study. As illustrated in Fig. 2, the TGA results indicate that the crystal maintains thermal stability up to approximately 521 K, with only a minor mass loss of around 2%. Partial thermal decomposition commenced at this temperature, followed by a pronounced weight loss above the decomposition temperature (T d ) of 521 K. The DTA curve displayed two endothermic peaks, one near 393 K without weight loss and another around 540 K, which are in good agreement with the DSC and optical microscopy results. Two inflection points detected at 547 K and 615 K are attributed to the release of [N(C 3 H 7 ) 4 ] and 2[N(C 3 H 7 ) 4 ], corresponding to ~25 % and 49 % of the initial molecular weight, respectively, and indicates major thermal degradation. At temperatures above 728 K, nearly complete decomposition occurred, with the total weight loss approaching 100 %. Overall, these thermal analyses provide important insights into the thermal stability, phase transitions, and decomposition characteristics of the compound. X-ray diffraction experiment on single-crystal SCXRD analysis was carried out on [N(C 3 H 7 ) 4 ] 2 ZnBr 4 at 300 K. The crystal structure was identified as monoclinic (space group C2/c), characterized by lattice constants a =33.1977 Å, b =14.2615 Å, c =15.1130 Å, together with a β angle of 110.3840°. This result is in good agreement with the previously reported results of Chkoundali et al. 54 The number of formula units per unit cell is Z=8, as summarized in Table 1. Figs. 3(a) and 3(b) depict the monoclinic crystal structure and the colorless, transparent single crystal with a hexagonal prismatic morphology, respectively. The thermal ellipsoids of each atom in [N(C 3 H 7 ) 4 ] 2 ZnBr 4 at 300 K are shown in Fig. 4, and three crystallographically distinct tetra-propylammonium cations within the unit cell, denoted as [N(1)(C 3 H 7 ) 4 ], [N(2)(C 3 H 7 ) 4 ], and [N(3)(C 3 H 7 ) 4 ], are present. The organic–inorganic architecture is composed of the organic cations in combination with isolated ZnBr₄²⁻ anions. Detailed bond-lengths and bond-angles are summarized in Supplementary Information. The Zn–Br distances, which fall in the range of 2.4057–2.4342 Å, indicate a mildly distorted tetrahedral coordination environment around the Zn center. The mean N(1)–C and N(2)–C bond-lengths were determined to be 1.519 and 1.518 Å, respectively, while the N(3)–C bond-lengths are shorter, averaging 1.466 Å. Notably, in N(3), the distance between the N–CH 2 and the middle CH 2 is 1.262 Å, the shortest among the corresponding distances in N(1) and N(2). The C–H bond-lengths in the case of N–CH 2 and middle CH 2 groups are 0.97 Å, and the C-H bond-lengths in the CH 3 group are 0.96 Å. The Br–Zn–Br bond-angles vary between 106.93° and 112.16°, indicating a distorted tetrahedral coordination geometry around the Zn 2+ ion. The complete crystallographic dataset has been deposited with the Cambridge Crystallographic Data Centre (CCDC 2493839). Table 1 . Crystallographic parameters and structure refinement details of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 determined at 300 K. Temperature (K) 300 Weight Color/shape 757.71 White/hexagonal prismatic Chemical formula C 24 H 56 N 2 ZnBr 4 Crystal system Monoclinic Space group C2/c a (Å) 33.1977 (10) b (Å) 14.2615 (4) c (Å) 15.1130 (4) β(°) 110.3840 (10) Z 8 V (Å 3 ) 6707.2 (3) Radiation type Mo-Kα Wavelength (Å) Crystal size (mm 3 ) Thera range Index ranges 0.71073 0.273×0.200×0.093 1.969 to 28.296 -44≤h≤44, -19≤k≤19, -20≤l≤19 Reflections collected 73653 Independent reflections 8310 ( R int =0.0716) Goodness-of-fit on F 2 1.006 Final R indices [I>2 sigma(I)] R 1 =0.0492, wR 2 =0.0924 R indices (all data) R 1 =0.1121, wR 2 =0.1139 The PXRD pattern simulated from the CIF file obtained by SCXRD at 300 K is in good agreement with the experimental PXRD pattern measured from powdered [N(C 3 H 7 ) 4 ] 2 ZnBr 4 , as shown in Fig. 5. In particular, two well-defined diffraction peaks appeared at 2θ values of 9.88° and 10.63°, which were assigned to the (111) and (31 ) crystallographic planes, respectively. Indexing of these reflections was carried out using the Mercury software. 67 The PXRD patterns shown in Fig. 5 were recorded over a 2θ range of 8–50° in the temperature range of 300–550 K. The diffraction patterns obtained below T C (=395 K) remained nearly identical, while a clear change in the PXRD pattern was observed near 400 K, close to T C . This corresponds well with the endothermic peak observed near 395 K in the DSC and DTA analysis. Analysis of the PXRD pattern near 395 K revealed a structural transition, indicating that the material adopts a monoclinic structure below 395 K and transforms into a new phase above T C . Furthermore, the absence of distinct diffraction peaks at 550 K indicates that the sample is in a molten, non-crystalline state. Following heating to 550 K and subsequent cooling to 300 K, the PXRD pattern (labelled 300 K (a)) differed markedly from the initial pattern recorded at 300 K. This observation suggests that the structural transformation is irreversible, in agreement with the DSC results. Based on the combined evidence from DSC, DTA, optical microscopy, and PXRD analyses, the phase transition temperature (T C ) of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 is estimated to be approximately 395 K, the decomposition temperature (T d ) is 529 K, and the melting temperature (T m ) is 540 K. 1 H MAS NMR chemical shifts and spin-lattice relaxation time The 1 H MAS NMR spectra of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 single crystals were measured at a Larmor frequency of 400.13 MHz under a magnetic field of 9.4 T to discuss structural change near T C . Tetramethylsilane (TMS) served as the reference compound for chemical shift calibration. The 1 H MAS NMR spectra were recorded at magic-angle spinning frequencies of 7 and 10 kHz. However, due to instrumental strain caused by the fast spinning rate at high and low temperatures, most experiments were conducted at 7 kHz, and the results are presented in Figs. 6(a) and (b). The signals indicated by cross symbols are attributed to spinning sidebands appearing at approximately ±17.5 ppm relative to the main 1 H resonance, which is consistent with a MAS rate of 7 kHz. 66 A single broad signal as shown in Fig. 6(a) is observed below 390 K, while three peaks as shown in Fig. 6(b) appear above this temperature. At 300 K below T C , a very broad 1 H NMR chemical shift was observed at 1.15 ppm, whereas at 420 K above T C , the spectrum exhibited the very sharp 1 H NMR chemical shift that was resolved into three distinct peaks at 1.12, 1.92, and 3.38 ppm. The three signals can be interpreted as follows; these three peaks correspond to the 1 H NMR peaks of the terminal methyl CH 3 , middle methylene CH 2 , and N–CH 2 in the organic group, respectively. Based on the 1 H MAS NMR spectra in Fig. 6, the temperature-dependent variations in chemical shifts and line widths are illustrated in Fig. 7. The 1 H NMR chemical shift remains nearly constant with temperature; however, above T C it resolves into three distinct peaks corresponding to the terminal CH 3 groups, the middle CH 2 , and the N–CH 2 of the organic [N(C 3 H 7 ) 4 ] cation. Moreover, at 180 K, where a single peak was observed, the line width was very broad at 10.71 ppm, whereas at 400 K, where it split into three peaks, it sharply narrowed to 1.07 ppm. The rapid narrowing of the line width is also attributed to the splitting of the NMR peak into three above T C , and the line widths of the three peaks were nearly similar to each other. These observations demonstrate that the mobility of 1 H increases markedly as the temperature rises. On the other hand, the 1 H NMR spectra of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 single crystals at 300 K were measured at a Larmor frequency of 500.13 MHz under a magnetic field of 11.7 T. The 1 H spin–lattice relaxation time (T 1 ) of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 was evaluated, and the corresponding inversion recovery behavior of the nuclear magnetization was found to follow a single-exponential decay, which can be described by the equation given below. 66, 68, 69 M( t ) = M(0) [1−2exp(− t /T 1 )] (1) Here, M( t ) denotes the longitudinal magnetization after a delay time t following the inversion pulse, M(0) is the equilibrium magnetization. The 1 H NMR experiments were carried out at 300 K with systematically varied delay times. The resulting spectra collected for delay times ranging from 10 ms to 15 s are shown in Fig. 8, and the magnetization recovery traces followed the exponential function described by Eq. (1). The four signals can be interpreted as follows: the peaks at 1.12, 1.92, and 3.38 ppm correspond to the 1 H NMR peaks of terminal CH 3 , middle CH 2 , and N–CH 2 in the organic group, respectively, while the most intense peak at 4.66 ppm corresponds to the 1 H NMR peak of H 2 O. Accordingly, from the slope of the intensity decay curves of the magnetization recovery traces of these peaks, the T 1 was obtained. The T 1 value of the terminal CH 3 in the organic group was found to be approximately 1.95 s , and the T 1 values of 1 H in the middle CH 2 and N–CH 2 groups appeared similar to that of CH 3 . 13 C MAS NMR chemical shifts and spin-lattice relaxation time The 13 C MAS NMR spectra of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 were measured at a resonance frequency of 100.61 MHz under a 9.4 T magnetic field, with TMS serving as an external reference for accurate calibration. For technical reasons, spectra at very low and high temperatures were not recorded at 10 kHz, since such spinning rates could cause excessive mechanical stress on the probe. Instead, the temperature-dependent spectra were obtained at a spinning rate of 7 kHz, as shown in Fig. 9(a). Distinct resonances were detected at approximately 13, 16, and 60 ppm; as a result, the methyl carbons, which ends up with a value of ~10 ppm, and peaks near 14 ppm are the neighbouring methylene carbons. The methylene carbons, which is directly attached to the nitrogen atoms have a higher value of 60 ppm. A magnified view is presented in Fig. 9(a), and detailed temperature-dependent NMR chemical shifts are shown in Fig. 9(b). The 13 C NMR spectrum acquired at 300 K under a spinning rate of 10 kHz is represented inside of Fig. 9(b). The 13 C resonances of the terminal CH 3 and N–CH 2 moieties exhibit noticeable splitting, whereas those corresponding to the middle CH 2 groups remain largely unresolved. These observations indicate that the local environment around the middle CH 2 carbons possesses higher symmetry compared to that surrounding the terminal CH 3 and N–CH 2 carbons. Below T C , each of these three resonances is further resolved into multiple peaks, a phenomenon attributable to the three crystallographically inequivalent cations revealed by SCXRD, reflecting their reduced local symmetry. Above T C , however, these split signals collapse into single resonances, demonstrating that the carbon environments become more symmetric at elevated temperatures. Overall, the chemical shifts show only slight changes with temperature. Nevertheless, the spectral splitting observed for CH 3 , middle CH 2 , and N–CH 2 below T C and its disappearance above T C clearly indicate that the local symmetry around the 13 C nuclei is lower in the low-temperature phase and significantly improves upon passing the transition. Similar to the 1 H NMR spin-lattice relaxation, the 13 C NMR spin-lattice relaxation time at 300 K was measured under an 11.7 T magnetic field at a Larmor frequency of 125.75 MHz. The magnetization recovery traces were recorded by varying the delay time from 10 ms to 15 s , and they were fitted well by a single exponential function. In the organic [N(C 3 H 7 ) 4 ] cations, three types of carbon sites were considered; CH 3 , middle CH 2 , and N–CH 2 . For the CH 3 and N–CH 2 groups, the 13 C NMR signals consisted of multiple overlapping peaks, making it difficult to determine T 1 values. In contrast, the middle CH 2 site showed a single peak, and its 13 C T 1 was determined to be 1.17 s. 14 N MAS NMR chemical shifts The 14 N MAS NMR spectra were acquired at a Larmor frequency of 28.9 MHz under an applied magnetic field strength of 9.4 T, and the temperature-dependent 14 N NMR spectra of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 are shown in the inset of Fig. 10. Although 14 N has a very high natural abundance, it is difficult to obtain NMR peaks due to its low NMR frequency and broad line width. 69 The 14 N NMR experiments were performed at a spinning speed of 5 kHz, using NH 4 NO 3 as a standard reference. At 300 K, a single peak was observed around 44 ppm, and the sidebands marked as open circles are located at ±173 ppm relative to the 14 N NMR peak under a spinning rate of 5 kHz. Just below the transition temperature (T C ) at 390 K, a signal appeared at 44 ppm, whereas at 400 K, a signal was observed at 47 ppm. Although the changes of the chemical shift near T C were not large with temperature, the 14 N NMR line width was observed to be very broad (~40 ppm) at lower temperatures and narrowed significantly to ~6 ppm as the temperature increased. These results suggest that the chemical shifts observed in the 14 N spectra arise from structural geometric changes in the environment surrounding 14 N, reflecting alterations in the atomic arrangement around the 14 N nuclei. Furthermore, the narrowing of the line width with increasing temperature indicates that the mobility of 14 N becomes significantly faster. Conclusions Colorless and transparent single crystals of [N(C 3 H 7 ) 4 ] 2 ZnBr 4 were grown via an aqueous solution method. Based on DSC, DTA, PXRD, and optical microscopy experiments, a phase transition occurs at 395 K indicating that the process is irreversible, and the decomposition temperature and melting takes place at 529 K and 540 K, respectively. The T C (393 K) and T m (529 K) values determined in this work are slightly shifted relative to the previously reported phase transition temperatures at 340 and 393 K, and exhibit minor differences compared with earlier reports that suggested melting at 393 K. These discrepancies may be attributed to variations in the solvent conditions and crystal growth temperature during the single-crystal growth process. The compound adopts a monoclinic crystal structure with the C2/c space group and remains thermally stable up to approximately 521 K. In addition, the discontinuities in the 1 H and 14 N NMR chemical shifts are observed near the transition temperature (T C ), and the 13 C MAS NMR spectra show pronounced changes in peak multiplicity across this temperature range, implying a reduction in symmetry below T C . The NMR results suggest that the phase transition of this material originates from the orientational dynamics and positional displacements of the [N(C 3 H 7 ) 4 ] groups, consistent with an order–disorder phase transition. Also, these observations indicate that the crystal preserves monoclinic symmetry at temperatures below T C , while transforming into a phase with higher symmetry upon heating. Furthermore, the line widths of 1 H, 13 C, and 14 N NMR spectra were found to decrease with increasing temperature; the temperature dependence of the NMR line width is primarily governed by molecular dynamics. The observed line narrowing with increasing temperature reflects the activation of molecular motions, including reorientational dynamics and phase transitions. Overall, [N(C 3 H 7 ) 4 ] 2 ZnBr 4 is a zero-dimensional organic–inorganic hybrid metal halide composed of isolated [ZnBr 4 ] 2 - tetrahedra separated by bulky organic cations. The compound exhibits good thermal stability and clear local structural dynamics, as confirmed by DSC, DTA, SCXRD, PXRD, and NMR analyses, making it a useful model system for fundamental studies of thermal stability and structure–dynamics relationships in hybrid materials. In addition, the low toxicity and high thermal stability of zinc-based halides highlight their potential for environmentally benign optoelectronic materials. Declarations Acknowledgement This research was supported by the Regional Innovation System & Education (RISE) program through the Jeonbuk RISE Center, funded by the Ministry of Education (MOE) and the Jeonbuk State, Republic of Korea (2025-RISE-13-JJU). Data availability The datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request. CCDC 2493839 contains the supplementary crystallographic data for this paper. Funding This research was supported by the Regional Innovation System & Education (RISE) program through the Jeonbuk RISE Center, funded by the Ministry of Education (MOE) and the Jeonbuk State, Republic of Korea (2025-RISE-13-JJU). Author contributions A.R. Lim performed crystal growth, DSC, TG, and NMR experiments, and wrote the manuscript. H. Ju measured X-ray experiment. Competing interest The author declares no competing interests. 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Phase-transition mechanisms of [N(C 2 H 5 ) 4 ] 2 BCl 4 and [N(CH 3 ) 4 ] 2 BCl 4 (B= 63 Cu and 67 Zn) single crystals studied by proton NMR. Solid State Commun . 147 , 11 (2008). Biskupski, P. & Tylczynski, Z. Structure of TEA 2 ZnCl 4 crystal surfaces studied by AFM, Phase transition 81 , 971 (2008). Ostrowski, A. & Cizman, A. EPR studies of linewidth anomalies at phase transitions in [N(C 2 H 5 ) 4 ] 2 MnCl 4 . Physica B 403 , 3110 (2008). Lim, A. R. Study on ethyl groups with two different orientations in [N(C 2 H 5 ) 4 ] 2 CuBr 4 . J. phys. Chem. Solids 93 , 59 (2016). Lim, A. R. Study of the ferroelastic phase transition in the tetraethylammonium compound [N(C 2 H 5 ) 4 ] 2 ZnBr 4 by magic-angle spinning and static NMR. AIP Advances 6 , 035307 (2016). Lim, A. R., Kim, M. S. & Lim, K.-Y. Nuclear magnetic resonance study of the ferroelastic phase transition of order-disorder type [N(C 2 H 5 ) 4 ] 2 CdCl 4 . Solid State Sciences 58 , 101 (2016). Lim, A. R. & Lim, K.-Y. 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A new eco-friendly and highly emitting Mn-based hybrid perovskite toward high-performance green-converted LEDs. J. Materials Chemicstry C 12 , 286 (2024). Banupriya, K., Revathi, A., Sudha, D., Kirubavathy, S. J. & Umarani, R. Tetrapropylammonium tribromocuprate complex [(C 3 H 7 ) 4 N]CuBr 3 (II) synthesis, thermal and spectral characterization. Materials today: proccdings 45 , 8024 (2021). Moutia, N., Oueslati, A., Gzaiel, M. B. & Khirouni, K. Crystal structure and AC conductivity mechanism of [N(C 3 H 7 ) 4 ] 2 CoCl 4 compound. Physica E 83 , 88 (2016). Chkoundali, S., Hlel, F.& Khemekhem, H. Synthesis, crystal structure, thermal and dielectric properties of tetrapropylammonium tetrabromozincate [N(C 3 H 7 ) 4 ] 2 [ZnBr 4 ] compound. Appl. Phys . A 122 , 1066 (2016). Moutia, N., Gzaiel, M. B., Oueslati, A. & Khirouni, K. Electric characterization and vibrational spectroscopic investigations of order-disorder phase transitions in [N(C 3 H 7 ) 4 ] 2 CoCl 4 compound . J. Mol. 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SMART and SAINT-Plus v6.22, Bruker AXS Inc., Madison, Wisconsin, USA, 2000. Kim, S. H., Shin, D., Ko, Y.-J. & Lim, A. R. Comprehensive study of organic-inorganic hybrid [N(C 2 H 5 ) 4 ] 2 CdBr 4 : crystal structure, phase transitions, and structural geometry, RSC Advances 15 , 34939 (2025). Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. Mercury: visualization and analysis of crystal structures, J. Appl. Crystallogr . 39 , 453 (2006). Koenig, J. L. Spectroscopy of Polymers, Elsevier, New York, 1999. Abragam, A. The Principles of Nuclear Magnetism, Oxford University Press, 1961. Additional Declarations No competing interests reported. Supplementary Files SupplementaryInformation.docx Cite Share Download PDF Status: Published Journal Publication published 04 Apr, 2026 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 05 Feb, 2026 Reviews received at journal 04 Feb, 2026 Reviewers agreed at journal 02 Feb, 2026 Reviews received at journal 02 Feb, 2026 Reviewers agreed at journal 31 Jan, 2026 Reviewers agreed at journal 29 Jan, 2026 Reviewers agreed at journal 29 Jan, 2026 Reviewers invited by journal 28 Jan, 2026 Editor invited by journal 28 Jan, 2026 Editor assigned by journal 24 Jan, 2026 Submission checks completed at journal 24 Jan, 2026 First submitted to journal 20 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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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-8654223","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":583610767,"identity":"6445883b-0451-4d22-9821-eb08214272c1","order_by":0,"name":"Huiyeong Ju","email":"","orcid":"","institution":"Korea Basic Science Institute","correspondingAuthor":false,"prefix":"","firstName":"Huiyeong","middleName":"","lastName":"Ju","suffix":""},{"id":583610768,"identity":"8b30c6c7-1788-4cf5-972d-0ec76b211a9d","order_by":1,"name":"Ae Ran Lim","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA30lEQVRIiWNgGAWjYNCCAgkGfgkwS0KGSC0GEgySMyBaeIAEYwMRWoDoBoRJWAt/e+/DzwUGFtHGt5ufPbpRY8HDIN18/AE+LRJnjhtLzzCQyN1255i5cc4xoMNkjiXid9iNNAZpHpCWGwlm0jlsQC0SOYZ4tcjff8b8G6Rl84z0b9I5/0Ba8j/i1WJwg40NbMsGiRwz6dw2sC34vW94Jo3NGqRlxo2cMuncPgkeNok0wxn4tMgdP8Z8m6eiLrd/Rvo26ZxvdXL8EskPPuDTggnYSFM+CkbBKBgFowAbAACq7EBc1BwEVAAAAABJRU5ErkJggg==","orcid":"","institution":"Jeonju University","correspondingAuthor":true,"prefix":"","firstName":"Ae","middleName":"Ran","lastName":"Lim","suffix":""}],"badges":[],"createdAt":"2026-01-21 02:24:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8654223/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8654223/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-026-45431-2","type":"published","date":"2026-04-04T15:58:35+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":101676711,"identity":"8fe52825-b3fc-4310-8a23-1668c8f6f59c","added_by":"auto","created_at":"2026-02-02 13:41:32","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":216753,"visible":true,"origin":"","legend":"\u003cp\u003eDSC curves of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4 \u003c/sub\u003emeasured at heating and cooling rates of 10°C/min, and the morphology for (a) 300 K, (b) 340 K, (c) 430 K, (d) 530 K, and (e) 550 K of the single crystal.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/227034bedb0a2fc0894d952b.png"},{"id":101676722,"identity":"71661f1e-95ed-412b-a17b-41778860735e","added_by":"auto","created_at":"2026-02-02 13:41:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":80999,"visible":true,"origin":"","legend":"\u003cp\u003eTGA and DTA curves of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4 \u003c/sub\u003emeasured at a heating rate 10°C/min. T\u003csub\u003ed\u003c/sub\u003e is decomposition temperature, T\u003csub\u003eC\u003c/sub\u003e is phase transition temperature, and T\u003csub\u003em\u003c/sub\u003e is melting temperature.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/a4c1f58ed29c569df80741ee.png"},{"id":101676700,"identity":"3123b880-b96f-4780-8d31-c7e3fb867a2e","added_by":"auto","created_at":"2026-02-02 13:41:29","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":320140,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Monoclinic structure of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4 \u003c/sub\u003esingle crystal at 300 K, and (b) morphology of the colorless and transparent single crystal.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/ec28fa28a35778f5def856db.png"},{"id":101676767,"identity":"22bbcb75-8c4a-421c-abc8-1e471c6653b6","added_by":"auto","created_at":"2026-02-02 13:41:44","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":189728,"visible":true,"origin":"","legend":"\u003cp\u003eThree possible orientations of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2 \u003c/sub\u003ecations and one ZnBr\u003csub\u003e4 \u003c/sub\u003ein the [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e at 300 K.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/84ffb235a2e709f72e3cb266.png"},{"id":101676782,"identity":"99a3bc8b-7676-4e35-8c31-d29487f959d6","added_by":"auto","created_at":"2026-02-02 13:41:47","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":406786,"visible":true,"origin":"","legend":"\u003cp\u003eExperimental powder XRD patterns at 300, 320, 330, 350, 370, 400, 450, and 550 K of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e. Here, 300 K(a) represents the result measured, after heating the sample up to 550 K and then cooling it back down to 300 K. The simulated powder XRD pattern at 300 K is marked as red color.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/94d149d3be875d0fadda11a7.png"},{"id":101676704,"identity":"d5e0914d-4782-4f3e-ac01-93bfcf167103","added_by":"auto","created_at":"2026-02-02 13:41:30","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":182313,"visible":true,"origin":"","legend":"\u003cp\u003e(a) \u003csup\u003e1\u003c/sup\u003eH MAS NMR spectra in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e below T\u003csub\u003eC\u003c/sub\u003e, and (b) \u003csup\u003e1\u003c/sup\u003eH MAS NMR spectra in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e above T\u003csub\u003eC\u003c/sub\u003e. x is the sidebands for the \u003csup\u003e1\u003c/sup\u003eH NMR peak.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/be4e8eb02456ccc2e7794190.png"},{"id":101676723,"identity":"b5125844-c104-44e8-ba06-8bed919866dd","added_by":"auto","created_at":"2026-02-02 13:41:34","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":188977,"visible":true,"origin":"","legend":"\u003cp\u003eNMR chemical shifts and line widths for \u003csup\u003e1\u003c/sup\u003eH in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e as the increasing temperature at a Larmor frequency 400.13 MHz. The three peaks (N-CH\u003csub\u003e2\u003c/sub\u003e, middle CH\u003csub\u003e2\u003c/sub\u003e, and terminal CH\u003csub\u003e3\u003c/sub\u003e) observed above T\u003csub\u003eC\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/c6eb51b388cc61180db5de80.png"},{"id":101676698,"identity":"dea20876-88b9-4a7d-86df-d394fbc4ac42","added_by":"auto","created_at":"2026-02-02 13:41:28","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":98281,"visible":true,"origin":"","legend":"\u003cp\u003eThe inversion recovery traces for \u003csup\u003e1\u003c/sup\u003eH NMR spectrum of N-CH\u003csub\u003e2\u003c/sub\u003e, middle CH\u003csub\u003e2\u003c/sub\u003e, and terminal CH\u003csub\u003e3\u003c/sub\u003e in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e according to delay time ranging from 10 \u003cem\u003ems\u003c/em\u003e to 15 \u003cem\u003es\u003c/em\u003e under a Larmor frequency 500.13 MHz at 300 K.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/96fcbe6083b7b1c93eb8b0d4.png"},{"id":101676727,"identity":"05a6568f-18c0-49ed-be44-0888f8fb7be2","added_by":"auto","created_at":"2026-02-02 13:41:35","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":441422,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Changes of \u003csup\u003e13\u003c/sup\u003eC NMR spectra of N-CH\u003csub\u003e2\u003c/sub\u003e, middle CH\u003csub\u003e2\u003c/sub\u003e, and terminal CH\u003csub\u003e3\u003c/sub\u003e in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e,\u003csub\u003e \u003c/sub\u003eand (b) \u003csup\u003e13\u003c/sup\u003eC NMR chemical shifts of N-CH\u003csub\u003e2\u003c/sub\u003e, middle CH\u003csub\u003e2\u003c/sub\u003e, and terminal CH\u003csub\u003e3\u003c/sub\u003e in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4 \u003c/sub\u003eas the increasing temperature at a Larmor frequency 100.61 MHz (Inset: the \u003csup\u003e13\u003c/sup\u003eC NMR spectrum recorded with the spinning rate of 10 kHz under a Larmor frequency 100.61 MHz at 300 K).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/891923fd79ac748d3c80adf4.png"},{"id":101676784,"identity":"45d3e7bd-9d6f-48d7-8018-74a1f87acefe","added_by":"auto","created_at":"2026-02-02 13:41:47","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":200625,"visible":true,"origin":"","legend":"\u003cp\u003eNMR chemical shifts and line widths for \u003csup\u003e14\u003c/sup\u003eN in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e as the increasing temperature at a Larmor frequency 28.9 MHz (Inset: \u003csup\u003e14\u003c/sup\u003eN NMR spectra as the temperature rises).\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/508d2959ba211e155f76c4fb.png"},{"id":106344854,"identity":"390ea88f-dc99-4420-b401-b80a33b7d969","added_by":"auto","created_at":"2026-04-07 16:17:00","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3656279,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/357efe4a-6e08-47d0-a6d0-cad0f6fe981e.pdf"},{"id":101676761,"identity":"95ac229c-271f-48c7-9291-1fb77c1dc956","added_by":"auto","created_at":"2026-02-02 13:41:42","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":19492,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-8654223/v1/5aa0fdaa3c96405264ea9c81.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eInvestigation on crystal structure, phase transition behavior, and structural geometries of organic-inorganic hybrid [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eOrganic\u0026ndash;inorganic hybrid compounds have emerged as a prominent class of functional materials owing to their unique structural characteristics and versatile physicochemical properties. Considerable research efforts have been devoted to this family of compounds, driven by their potential utility in diverse technological applications.\u003csup\u003e1\u0026ndash;7\u003c/sup\u003e The intrinsic features of hybrid compounds arise from the synergistic contributions of their organic and inorganic constituents: the organic cations predominantly influence optical responses and structural adaptability, whereas the inorganic metal halide framework dictates thermal robustness and mechanical stability.\u003csup\u003e8, 9\u003c/sup\u003e This complementary interplay renders hybrid compounds highly attractive as next-generation materials. Nevertheless, critical challenges remain, particularly regarding the improvement of long-term stability and the establishment of scalable fabrication processes, both of which are essential for practical implementation.\u003csup\u003e10\u003c/sup\u003e Furthermore, the recent incorporation of ferroelectric behavior into hybrid compound systems has expanded their functional scope, opening new prospects for applications in emerging fields such as flexible and wearable electronics.\u003csup\u003e11\u0026ndash;14\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eQuaternary ammonium metal halides of the general formula [N(C\u003cem\u003e\u003csub\u003en\u003c/sub\u003e\u003c/em\u003eH\u003csub\u003e2\u003cem\u003en\u003c/em\u003e+1\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e\u003cem\u003eMX\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e, where \u003cem\u003eM\u003c/em\u003e=Mn, Co, Cu, Zn, Cd; \u003cem\u003eX\u003c/em\u003e = Cl, Br; \u003cem\u003en\u003c/em\u003e = 1\u0026ndash;3), have been extensively investigated as a distinct subclass of organic\u0026ndash;inorganic hybrid materials.\u003csup\u003e15\u0026ndash;60\u003c/sup\u003e These compounds are characterized by frameworks in which discrete\u0026nbsp;\u003cem\u003eMX\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e anionic units are stabilized by bulky tetra-alkylammonium cations. The interplay between the inorganic complexes and the organic cations gives rise to diverse structural motifs, including layered, chain-like, and molecular crystal architectures, the specific arrangement being strongly dependent on the alkyl-chain length and the choice of metal and halide ions. A notable feature of these materials is the frequent occurrence of order\u0026ndash;disorder phase transitions, which originate from the orientational dynamics and positional displacements of the tetra-alkylammonium groups. Importantly, systematic modification of the metal center or halide ligands provides a means of tuning their electronic, magnetic, and optical behaviors. Owing to this combination of structural flexibility and functional versatility, [N(C\u003cem\u003e\u003csub\u003en\u003c/sub\u003e\u003c/em\u003eH\u003csub\u003e2\u003cem\u003en\u003c/em\u003e+1\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e\u003cem\u003eMX\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e salts represent a valuable platform for fundamental investigations as well as for potential applications across materials science, coordination chemistry, and soft condensed matter physics.\u003c/p\u003e\n\u003cp\u003eTo date, studies on [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e (\u003cem\u003eM\u003c/em\u003e=Zn; \u003cem\u003eX\u003c/em\u003e=Br) with \u003cem\u003en\u003c/em\u003e=3,\u003csup\u003e54, 56, 60-62\u003c/sup\u003e a member of the \u003cem\u003eA\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e\u003cem\u003eMX\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e family, have been very limited. Among the few existing reports, structural and optical results of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e\u003cem\u003eM\u003c/em\u003eBr\u003csub\u003e4\u003c/sub\u003e (\u003cem\u003eM\u003c/em\u003e=Zn, Co, Cu) crystals were briefly reported by Belka and Sabatini.\u003csup\u003e61,62\u003c/sup\u003e And, Chkoundali et al.\u003csup\u003e54\u0026nbsp;\u003c/sup\u003einvestigated the crystal structure, thermal and dielectric properties of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e. They reported that the compound crystallizes in a monoclinic structure with the space group C2/c, with lattice constants a=33.145 \u0026Aring;, b=14.234 \u0026Aring;, c=15.081 \u0026Aring;, \u0026beta;=110.207\u0026deg;, and Z=8. And, two phase transitions were reported at 340 and 393 K under a heating rate of 5℃/min. In addition, the electrical conductivity study induced phase transition were discussed.\u003csup\u003e56\u003c/sup\u003e More recently, the synthesis, spectral, thermal characterization and antioxidant activity were described by Kanagarajan et al.\u003csup\u003e60\u003c/sup\u003e They reported that 390 K obtained by TG (thermogravimetry)/DTG (derivative thermogravimetry) curves corresponds to the melting point rather than a phase transition. Meanwhile, various studies have been conducted on single crystals of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e\u003cem\u003eM\u003c/em\u003eBr\u003csub\u003e4\u003c/sub\u003e (\u003cem\u003eM\u003c/em\u003e=Co, Zn, Cd) where \u003cem\u003eX\u003c/em\u003e=Br,\u003csup\u003e49,54,56,57,59\u003c/sup\u003e and these crystals are reported to have slightly different structures compared to those with \u003cem\u003eX\u003c/em\u003e=Cl. Although not much research has been done on the [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e crystals among the \u003cem\u003eA\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e\u003cem\u003eMX\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e group in the past, it has recently been considered as a material worthy of interest due to its potential applications.\u003c/p\u003e\n\u003cp\u003eIn this study, we aim to elucidate the phase transition mechanism of the organic\u0026ndash;inorganic hybrid compound\u0026nbsp;[N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e by correlating its structural, thermal, and dynamic properties. The crystal structure was determined by single-crystal X-ray diffraction (SCXRD) at 300 K to establish the structural framework of the material. The phase transition behavior was systematically investigated using differential scanning calorimetry (DSC), thermogravimetric and differential thermal analysis (TG/DTA), optical microscopy, and powder X-ray diffraction (PXRD). Furthermore, temperature-dependent\u0026nbsp;\u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC, and \u003csup\u003e14\u003c/sup\u003eN nuclear magnetic resonance (NMR)\u0026nbsp;chemical shifts and spin\u0026ndash;lattice relaxation times (T\u003csub\u003e1\u003c/sub\u003e) were analyzed to probe the dynamics of the [N(C₃H₇)₄] cations near the phase transition temperature. Through these combined experimental approaches, this work seeks to clarify the role of cation dynamics and energy transfer processes in governing the phase transition and physical properties of\u0026nbsp;[N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e.\u003c/p\u003e"},{"header":"Experimental methods","content":"\u003cp\u003e\u003cstrong\u003eCrystal growth\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHigh-quality single crystals of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e were grown through the slow evaporation process form supersaturated solutions by dissolving N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003eBr (Sigma Aldrich 98 %) and ZnBr\u003csub\u003e2\u003c/sub\u003e (Sigma Aldrich 99 %) in distilled water with molecular weight of 2:1. After the solution was stirred and heated until saturation, single crystals were obtained through slow evaporation over several weeks while maintaining a constant temperature of 300 K. The colorless and transparent single crystals with a hexagonal prismatic morphology were grown. Although these single crystals were stable under ambient conditions, they were stored in a desiccator to prevent moisture-related degradation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacterization\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDifferential scanning calorimetry (DSC) measurements were carried out on a TA Instruments system (Model 25) at a heating rate of 10℃/min between 200 and 570 K under a continuous flow of dry nitrogen. Temperature-dependent changes in crystal morphology were examined using an optical microscope (Carl Zeiss) equipped with a Linkam THMS 600 heating stage. Thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) were further performed from 300 to 873 K under a nitrogen atmosphere with a heating rate of 10℃/min.\u003csup\u003e63\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSingle-crystal X-ray diffraction (SCXRD) measurements were performed at 300 K at the Korea Basic Science Institute (KBSI), Research Center for Materials Analysis, to determine the crystal structure and unit-cell parameters. Data were collected using a Bruker SMART CCD diffractometer equipped with graphite-monochromated Mo-K\u0026alpha; radiation.\u003csup\u003e63\u003c/sup\u003e The SMART APEX3 and SAINT software packages were employed for data acquisition and integration,\u003csup\u003e64\u003c/sup\u003e while absorption corrections were applied using the multiscan method implemented in SADABS. The structure was solved by direct methods and subsequently refined by full-matrix least-squares procedures on F\u0026sup2; using the SHELXTL program.\u003csup\u003e65\u003c/sup\u003e Non-hydrogen atoms were refined with anisotropic displacement parameters, and hydrogen atoms were placed in calculated positions based on idealized geometry.\u003c/p\u003e\n\u003cp\u003eIn addition, powder X-ray diffraction (PXRD) analysis was conducted using an Expert Pro-MPD X-ray diffractometer (PANalytical) fitted with Cu-K\u0026alpha; radiation.\u0026nbsp;This experimental setup was employed to analyze the crystal structure and phase transition behavior of the samples. In addition, temperature-dependent PXRD measurements were carried out using an Anton Paar HTK 1200N high-temperature stage integrated with the same diffractometer, enabling the evaluation of structural evolution at elevated temperatures.\u003csup\u003e66\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSolid-state NMR measurements for [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e were carried out using Bruker Avance NEO spectrometers. The NMR spectra were acquired at the KBSI, Metropolitan Seoul Center, using a 400 MHz instrument, while spin\u0026ndash;lattice relaxation times (T\u003csub\u003e1\u003c/sub\u003e) were determined on a 500 MHz spectrometer at the Laboratory of NMR, NCIRF, Seoul National University. The \u003csup\u003e1\u003c/sup\u003eH MAS NMR experiments were performed at Larmor frequencies of 400.13 and 500.13 MHz, and \u003csup\u003e13\u003c/sup\u003eC MAS NMR spectra were obtained at 100.61 and 125.75 MHz. Chemical shifts for both \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC nuclei were referenced to tetramethylsilane (TMS). The \u003csup\u003e14\u003c/sup\u003eN MAS NMR spectra were measured at a Larmor frequency of 28.90 MHz, with NH\u003csub\u003e4\u003c/sub\u003eNO\u003csub\u003e3\u003c/sub\u003e serving as the external reference.\u003csup\u003e63\u003c/sup\u003e Powdered samples were packed into 4 mm CP/MAS rotors and spun at rates of 5, 7, and 10 kHz to suppress spinning sidebands. One-dimensional \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC MAS NMR spectra were collected using a delay time of 10 s,\u0026nbsp;whereas the \u003csup\u003e14\u003c/sup\u003eN NMR spectra was obtained at a delay time of 5 \u003cem\u003es\u003c/em\u003e. And, the 90\u0026deg; pulse lengths for \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC were set to 1.2 \u003cem\u003e\u0026mu;s\u003c/em\u003e, and that for \u003csup\u003e14\u003c/sup\u003eN was set to 4 \u003cem\u003e\u0026mu;s\u003c/em\u003e. The \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC T\u003csub\u003e1\u003c/sub\u003e values were measured with delay times ranging from 10 \u003cem\u003ems\u003c/em\u003e to 15 \u003cem\u003es\u003c/em\u003e. NMR measurements were carried out in the temperature range of 180 to 420 K.\u0026nbsp;\u003c/p\u003e"},{"header":"Experimental results and discussion","content":"\u003cp\u003e\u003cstrong\u003ePhase transition temperature\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;and thermodynamic p\u003c/strong\u003e\u003cstrong\u003eroperties\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo accurately determine the phase transition temperatures (T\u003csub\u003eC\u003c/sub\u003e) of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e, single-crystal samples were first finely pulverized using a mortar. DSC measurements were then carried out on approximately 6.3 mg of the resulting powder at both heating and cooling rates of 10\u0026deg;C/min. As shown in Fig. 1,\u0026nbsp;three distinct endothermic peaks were detected upon heating, while no corresponding exothermic peak appeared during cooling, indicating that the process is irreversible. The enthalpy associated with the peak at 395 K was determined to be 23.91 kJ/mol. As shown in the inset of Fig. 1, the morphology of the colorless and transparent single crystal remained unchanged at 300 K and 340 K, as well as at 430 K (Fig. 1(a)~(c)), which is above T\u003csub\u003eC\u003c/sub\u003e. The endothermic peak at 529 K corresponds to the decomposition temperature, as evidenced by the single crystal becoming opaque in the optical microscopy experiment as shown in Fig. 1(d). In contrast, when the temperature reached 550 K, the crystal was observed to melt, in good agreement with the endothermic peak occurring at 540 K. The peaks observed at 529 K and 540 K were determined as the decomposition (T\u003csub\u003ed\u003c/sub\u003e) and melting temperatures (T\u003csub\u003em\u003c/sub\u003e), respectively, as confirmed \u0026nbsp;by optical microscopy. This interpretation is further supported by subsequent PXRD analysis.\u003c/p\u003e\n\u003cp\u003eTo examine the thermal behavior of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e, TGA and DTA experiments were performed. Following a procedure analogous to that used for the DSC experiments, the sample was finely powdered,\u003csup\u003e66\u003c/sup\u003e and approximately 6.8 mg was subjected to analysis. Thermogravimetric measurements were performed from 300 to 873 K at a constant heating rate of 10\u0026deg;C/min, matching the conditions employed in the DSC study. As illustrated in Fig. 2, the TGA results indicate that the crystal maintains thermal stability up to approximately 521 K, with only a minor mass loss of around 2%. Partial thermal decomposition commenced at this temperature, followed by a pronounced weight loss above the decomposition temperature (T\u003csub\u003ed\u003c/sub\u003e) of 521 K. The DTA curve displayed two endothermic peaks, one near 393 K without weight loss and another around 540 K, which are in good agreement with the DSC and optical microscopy results. Two inflection points detected at 547 K and 615 K are attributed to the release of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] and 2[N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e], corresponding to ~25 % and 49 % of the initial molecular weight, respectively, and indicates major thermal degradation. At temperatures above 728 K, nearly complete decomposition occurred, with the total weight loss approaching 100 %. Overall, these thermal analyses provide important insights into the thermal stability, phase transitions, and decomposition characteristics of the compound.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;X-ray diffraction experiment on single-crystal\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSCXRD analysis was carried out on [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e at 300 K. The crystal structure was identified as monoclinic (space group C2/c), characterized by lattice constants \u003cem\u003ea\u003c/em\u003e=33.1977 \u0026Aring;, \u003cem\u003eb\u003c/em\u003e=14.2615 \u0026Aring;, \u003cem\u003ec\u003c/em\u003e=15.1130 \u0026Aring;,\u0026nbsp;together with a \u0026beta; angle of\u0026nbsp;110.3840\u0026deg;. This result is in good agreement with the previously reported results of Chkoundali et al.\u003csup\u003e54\u003c/sup\u003e The number of formula units per unit cell is Z=8, as summarized in Table 1. Figs. 3(a) and 3(b) depict the monoclinic crystal structure and the colorless, transparent single crystal with a hexagonal prismatic morphology, respectively. The thermal ellipsoids of each atom in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e at 300 K are shown in Fig. 4, and three crystallographically distinct tetra-propylammonium cations within the unit cell, denoted as [N(1)(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e],\u0026nbsp;[N(2)(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e],\u0026nbsp;and\u0026nbsp;[N(3)(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e],\u0026nbsp;are present.\u0026nbsp;The organic\u0026ndash;inorganic architecture is composed of the organic cations in combination with isolated\u0026nbsp;ZnBr₄\u0026sup2;⁻\u0026nbsp;anions. Detailed bond-lengths and bond-angles are summarized in Supplementary Information. The Zn\u0026ndash;Br distances, which fall in the range of 2.4057\u0026ndash;2.4342 \u0026Aring;, indicate a mildly distorted tetrahedral coordination environment around the Zn center. The mean N(1)\u0026ndash;C and N(2)\u0026ndash;C bond-lengths were determined to be 1.519 and 1.518 \u0026Aring;, respectively, while the N(3)\u0026ndash;C bond-lengths are shorter, averaging 1.466 \u0026Aring;. Notably, in N(3), the distance between the N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e and the middle CH\u003csub\u003e2\u003c/sub\u003e is 1.262 \u0026Aring;, the shortest among the corresponding distances in N(1) and N(2). The C\u0026ndash;H bond-lengths in the case of N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e and middle CH\u003csub\u003e2\u003c/sub\u003e groups are 0.97 \u0026Aring;, and the C-H bond-lengths in the CH\u003csub\u003e3\u003c/sub\u003e group are 0.96 \u0026Aring;. The Br\u0026ndash;Zn\u0026ndash;Br bond-angles vary between 106.93\u0026deg; and 112.16\u0026deg;, indicating a distorted tetrahedral coordination geometry around the Zn\u003csup\u003e2+\u003c/sup\u003e ion. The complete crystallographic dataset has been deposited with the Cambridge Crystallographic Data Centre (CCDC 2493839).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e.\u0026nbsp;Crystallographic parameters and structure refinement details of\u0026nbsp;[N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e determined at 300 K.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"359\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eTemperature (K)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e300\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eWeight\u003c/p\u003e\n \u003cp\u003eColor/shape\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e757.71\u003c/p\u003e\n \u003cp\u003eWhite/hexagonal prismatic\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eChemical formula\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003eC\u003csub\u003e24\u003c/sub\u003eH\u003csub\u003e56\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eCrystal system\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003eMonoclinic\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eSpace group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003eC2/c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003e\u003cem\u003ea\u003c/em\u003e (\u0026Aring;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e33.1977 (10)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003e\u003cem\u003eb\u003c/em\u003e (\u0026Aring;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e14.2615 (4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003e\u003cem\u003ec\u003c/em\u003e (\u0026Aring;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e15.1130 (4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003e\u0026beta;(\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e110.3840 (10)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eZ\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eV (\u0026Aring;\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e6707.2 (3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eRadiation type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003eMo-K\u0026alpha;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eWavelength (\u0026Aring;)\u003c/p\u003e\n \u003cp\u003eCrystal size (mm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003cp\u003eThera range\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eIndex ranges\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e0.71073\u003c/p\u003e\n \u003cp\u003e0.273\u0026times;0.200\u0026times;0.093\u003c/p\u003e\n \u003cp\u003e1.969 to 28.296\u003c/p\u003e\n \u003cp\u003e-44\u0026le;h\u0026le;44, -19\u0026le;k\u0026le;19, -20\u0026le;l\u0026le;19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eReflections collected\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e73653\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eIndependent reflections\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e8310 (\u003cem\u003eR\u003c/em\u003e\u003csub\u003eint\u003c/sub\u003e=0.0716)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eGoodness-of-fit on \u003cem\u003eF\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e1.006\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eFinal \u003cem\u003eR\u0026nbsp;\u003c/em\u003eindices [I\u0026gt;2 sigma(I)]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e=0.0492, \u003cem\u003ewR\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e=0.0924\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003eR indices (all data)\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 174px;\"\u003e\n \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e=0.1121, \u003cem\u003ewR\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e=0.1139\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe PXRD pattern simulated from the CIF file obtained by SCXRD at 300 K is in good agreement with the experimental PXRD pattern measured \u0026nbsp;from powdered \u0026nbsp;[N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e, \u0026nbsp;as shown in \u0026nbsp;Fig. 5. In particular, two well-defined diffraction peaks appeared at 2\u0026theta; values of 9.88\u0026deg; and 10.63\u0026deg;, which were assigned to the (111) and (31 ) crystallographic planes, respectively. Indexing of these reflections was carried out using the Mercury software.\u003csup\u003e67\u003c/sup\u003e The PXRD patterns shown in Fig. 5 were recorded over a 2\u0026theta; range of 8\u0026ndash;50\u0026deg; in the temperature range of 300\u0026ndash;550 K. The diffraction patterns obtained below T\u003csub\u003eC\u003c/sub\u003e (=395 K) remained nearly identical, while a clear change in the PXRD pattern was observed near 400 K, close to T\u003csub\u003eC\u003c/sub\u003e. This corresponds well with the endothermic peak observed near 395 K in the DSC and DTA analysis. Analysis of the PXRD pattern near 395 K revealed a structural transition, indicating that the material adopts a monoclinic structure below 395 K and transforms into a new phase above T\u003csub\u003eC\u003c/sub\u003e. Furthermore, the absence of distinct diffraction peaks at 550 K indicates that the sample is in a molten, non-crystalline state. Following heating to 550 K and subsequent cooling to 300 K, the PXRD pattern (labelled 300 K (a)) differed markedly from the initial pattern recorded at 300 K. This observation suggests that the structural transformation is irreversible, in agreement with the DSC results.\u0026nbsp;Based on the combined evidence from DSC, DTA, optical microscopy, and PXRD analyses, the phase transition temperature (T\u003csub\u003eC\u003c/sub\u003e) of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e is estimated to be approximately 395 K, the decomposition temperature (T\u003csub\u003ed\u003c/sub\u003e) is 529 K, and the melting temperature (T\u003csub\u003em\u003c/sub\u003e) is 540 K.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003e1\u003c/sup\u003e\u003c/strong\u003e\u003cstrong\u003eH MAS NMR chemical shifts and spin-lattice relaxation time\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe \u003csup\u003e1\u003c/sup\u003eH MAS NMR spectra of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e single crystals were measured at a Larmor frequency of 400.13 MHz under a magnetic field of 9.4 T to discuss structural change near T\u003csub\u003eC\u003c/sub\u003e. Tetramethylsilane (TMS) served as the reference compound for chemical shift calibration. The \u003csup\u003e1\u003c/sup\u003eH MAS NMR spectra were recorded at magic-angle spinning frequencies of 7 and 10 kHz. However, due to instrumental strain caused by the fast spinning rate at high and low temperatures, most experiments were conducted at 7 kHz, and the results are presented in Figs. 6(a) and (b). The signals indicated by cross symbols are attributed to spinning sidebands appearing at approximately \u0026plusmn;17.5 ppm relative to the main \u003csup\u003e1\u003c/sup\u003eH resonance, which is consistent with a MAS rate of 7 kHz.\u003csup\u003e66\u003c/sup\u003e A single broad signal as shown in Fig. 6(a) is observed below 390 K, while three peaks as shown in Fig. 6(b) appear above this temperature. At 300 K below T\u003csub\u003eC\u003c/sub\u003e, a very broad \u003csup\u003e1\u003c/sup\u003eH NMR chemical shift was observed at 1.15 ppm, whereas at 420 K above T\u003csub\u003eC\u003c/sub\u003e, the spectrum exhibited the very sharp \u003csup\u003e1\u003c/sup\u003eH NMR chemical shift that was resolved into three distinct peaks at 1.12, 1.92, and 3.38 ppm. The three signals can be interpreted as follows; these three peaks correspond to the \u003csup\u003e1\u003c/sup\u003eH NMR peaks of the terminal methyl CH\u003csub\u003e3\u003c/sub\u003e, middle methylene CH\u003csub\u003e2\u003c/sub\u003e, and N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e in the organic group, respectively.\u003c/p\u003e\n\u003cp\u003eBased on the \u003csup\u003e1\u003c/sup\u003eH MAS NMR spectra in Fig. 6, the temperature-dependent variations in chemical shifts and line widths are illustrated in Fig. 7. The \u003csup\u003e1\u003c/sup\u003eH NMR chemical shift remains nearly constant with temperature; however, above T\u003csub\u003eC\u003c/sub\u003e it resolves into three distinct peaks corresponding to the terminal CH\u003csub\u003e3\u003c/sub\u003e groups, the middle CH\u003csub\u003e2\u003c/sub\u003e, and the N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e of the organic [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] cation. Moreover, at 180 K, where a single\u0026nbsp;\u003c/p\u003e\n\u003cp\u003epeak was observed, the line width was very broad at 10.71 ppm, whereas at 400 K, where it split into three peaks, it sharply narrowed to 1.07 ppm. The rapid narrowing of the line width is also attributed to the splitting of the NMR peak into three above T\u003csub\u003eC\u003c/sub\u003e, and the line widths of the three peaks were nearly similar to each other. These observations demonstrate that the mobility of \u003csup\u003e1\u003c/sup\u003eH increases markedly as the temperature rises.\u003c/p\u003e\n\u003cp\u003eOn the other hand, the \u003csup\u003e1\u003c/sup\u003eH NMR spectra of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e single crystals at 300 K were measured at a Larmor frequency of 500.13 MHz under a magnetic field of 11.7 T. The \u003csup\u003e1\u003c/sup\u003eH spin\u0026ndash;lattice relaxation time (T\u003csub\u003e1\u003c/sub\u003e) of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e was evaluated, and the corresponding inversion recovery behavior of the nuclear magnetization was found to follow a single-exponential decay, which can be described by the equation given below.\u003csup\u003e66, 68, 69\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eM(\u003cem\u003et\u003c/em\u003e) = M(0) [1\u0026minus;2exp(\u0026minus;\u003cem\u003et\u003c/em\u003e/T\u003csub\u003e1\u003c/sub\u003e)] \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;(1) \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHere, M(\u003cem\u003et\u003c/em\u003e) denotes the longitudinal magnetization after a delay time\u003cem\u003e\u0026nbsp;t\u003c/em\u003e following the inversion pulse, M(0) is the equilibrium magnetization. The \u003csup\u003e1\u003c/sup\u003eH NMR experiments were carried out at 300 K with systematically varied delay times. The resulting spectra collected for delay times ranging from 10 ms to 15 s are shown\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ein Fig. 8, and the magnetization recovery traces followed the exponential function described by Eq. (1). The four signals can be interpreted as follows: \u0026nbsp;the peaks at 1.12, 1.92, and 3.38 ppm correspond to the \u003csup\u003e1\u003c/sup\u003eH NMR peaks of terminal CH\u003csub\u003e3\u003c/sub\u003e, middle CH\u003csub\u003e2\u003c/sub\u003e, and N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e in the organic group, respectively, while the most intense peak at 4.66 ppm corresponds to the \u003csup\u003e1\u003c/sup\u003eH NMR peak of H\u003csub\u003e2\u003c/sub\u003eO. Accordingly, from the slope of the intensity decay curves of the magnetization recovery traces of these \u0026nbsp;peaks, the \u0026nbsp;T\u003csub\u003e1\u003c/sub\u003e was obtained. \u0026nbsp;The T\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e\n\u003cp\u003evalue of the terminal CH\u003csub\u003e3\u003c/sub\u003e in the organic group was found to be approximately 1.95 \u003cem\u003es\u003c/em\u003e, and the T\u003csub\u003e1\u003c/sub\u003e values of \u003csup\u003e1\u003c/sup\u003eH in the middle CH\u003csub\u003e2\u003c/sub\u003e and N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e groups appeared similar to that of CH\u003csub\u003e3\u003c/sub\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003e13\u003c/sup\u003e\u003c/strong\u003e\u003cstrong\u003eC MAS NMR chemical shifts and spin-lattice relaxation time\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe \u003csup\u003e13\u003c/sup\u003eC MAS NMR spectra of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e were measured at a resonance frequency of 100.61 MHz under a 9.4 T magnetic field, with TMS serving as an external reference for accurate calibration. For technical reasons, spectra at very low and high temperatures were not recorded at 10 kHz, since such spinning rates could cause excessive mechanical stress on the probe. Instead, the temperature-dependent spectra were obtained at a spinning rate of 7 kHz, as shown in Fig. 9(a). Distinct resonances were detected at approximately 13, 16, and 60 ppm; as a result, the methyl carbons, which ends up with a value of ~10 ppm, and peaks near 14 ppm are the neighbouring methylene carbons. The methylene carbons, which is directly attached to the nitrogen atoms have a higher value of 60 ppm. A magnified view is presented in Fig. 9(a), and detailed temperature-dependent NMR chemical shifts are shown in Fig. 9(b). The \u003csup\u003e13\u003c/sup\u003eC NMR spectrum acquired at 300 K under a spinning rate of 10 kHz is represented inside of Fig. 9(b). The \u003csup\u003e13\u003c/sup\u003eC resonances of the terminal CH\u003csub\u003e3\u003c/sub\u003e and N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e moieties exhibit noticeable splitting, whereas those corresponding to the middle CH\u003csub\u003e2\u003c/sub\u003e groups remain largely unresolved. These observations indicate that the local environment \u0026nbsp; around \u0026nbsp; \u0026nbsp;the \u0026nbsp; middle \u0026nbsp;CH\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e carbons \u0026nbsp;possesses \u0026nbsp;higher symmetry compared to that surrounding the terminal CH\u003csub\u003e3\u003c/sub\u003e and N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e carbons. Below T\u003csub\u003eC\u003c/sub\u003e, each of these three resonances is further resolved into multiple peaks, a phenomenon attributable to the three crystallographically inequivalent cations revealed by SCXRD, reflecting their reduced local symmetry. Above T\u003csub\u003eC\u003c/sub\u003e, however, these split signals collapse into single resonances, demonstrating that the carbon environments become more symmetric at elevated temperatures. Overall, the chemical shifts show only slight changes with temperature. Nevertheless, the spectral splitting observed for CH\u003csub\u003e3\u003c/sub\u003e, middle CH\u003csub\u003e2\u003c/sub\u003e, and N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e below T\u003csub\u003eC\u003c/sub\u003e and its disappearance above T\u003csub\u003eC\u003c/sub\u003e clearly indicate that the local symmetry around the \u003csup\u003e13\u003c/sup\u003eC nuclei is lower in the low-temperature phase and significantly improves upon passing the transition.\u003c/p\u003e\n\u003cp\u003eSimilar to the \u003csup\u003e1\u003c/sup\u003eH NMR spin-lattice relaxation, the \u003csup\u003e13\u003c/sup\u003eC NMR spin-lattice relaxation time at 300 K was measured \u0026nbsp;under an \u0026nbsp;11.7 T \u0026nbsp;magnetic \u0026nbsp;field at \u0026nbsp;a \u0026nbsp;Larmor \u0026nbsp;frequency of \u0026nbsp;125.75 MHz. \u0026nbsp;The \u0026nbsp;magnetization\u0026nbsp;\u003c/p\u003e\n\u003cp\u003erecovery traces were recorded by varying the delay time from 10 \u003cem\u003ems\u003c/em\u003e to 15 \u003cem\u003es\u003c/em\u003e, and they were fitted well by a single exponential function. In the organic [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] cations, three types of carbon sites were considered; CH\u003csub\u003e3\u003c/sub\u003e, middle CH\u003csub\u003e2\u003c/sub\u003e, and N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e. For the CH\u003csub\u003e3\u003c/sub\u003e and N\u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e groups, the \u003csup\u003e13\u003c/sup\u003eC NMR signals consisted of multiple overlapping peaks, making it difficult to determine T\u003csub\u003e1\u003c/sub\u003e values. In contrast, the middle CH\u003csub\u003e2\u003c/sub\u003e site showed a single peak, and its \u003csup\u003e13\u003c/sup\u003eC T\u003csub\u003e1\u003c/sub\u003e was determined to be 1.17 s.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003e14\u003c/sup\u003e\u003c/strong\u003e\u003cstrong\u003eN MAS NMR chemical shifts\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe \u003csup\u003e14\u003c/sup\u003eN MAS NMR spectra were acquired at a Larmor frequency of 28.9 MHz under an applied magnetic field strength of 9.4 T, and the temperature-dependent \u003csup\u003e14\u003c/sup\u003eN NMR spectra of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e are shown in the inset of Fig. 10. Although \u003csup\u003e14\u003c/sup\u003eN has a very high natural abundance, it is difficult to obtain NMR peaks due to its low NMR frequency and broad line width.\u003csup\u003e69\u003c/sup\u003e The \u003csup\u003e14\u003c/sup\u003eN NMR experiments were performed at a spinning speed of 5 kHz, using NH\u003csub\u003e4\u003c/sub\u003eNO\u003csub\u003e3\u003c/sub\u003e as a standard reference. At 300 K, a single peak was observed around 44 ppm, and the sidebands marked as open circles are located at \u0026plusmn;173 ppm relative to the \u003csup\u003e14\u003c/sup\u003eN NMR peak under a spinning rate of 5 kHz. Just below the transition temperature (T\u003csub\u003eC\u003c/sub\u003e) at 390 K, a signal appeared at 44 ppm, whereas at 400 K, a signal was observed at 47 ppm. Although the changes of the chemical shift near T\u003csub\u003eC\u003c/sub\u003e were not large with temperature, the \u003csup\u003e14\u003c/sup\u003eN NMR line width was observed to be very broad (~40 ppm) at lower temperatures and narrowed significantly to ~6 ppm as the temperature increased. These results suggest that the chemical shifts observed in the \u003csup\u003e14\u003c/sup\u003eN spectra arise from structural geometric changes in the environment surrounding \u003csup\u003e14\u003c/sup\u003eN, reflecting alterations in the atomic arrangement around the \u003csup\u003e14\u003c/sup\u003eN nuclei. Furthermore, the narrowing of the line width with increasing temperature indicates that the mobility of \u003csup\u003e14\u003c/sup\u003eN becomes significantly faster.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eColorless and transparent single crystals of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e were grown via an aqueous solution method. Based on DSC, DTA, PXRD, and optical microscopy experiments, a phase transition occurs at 395 K indicating that the process is irreversible, and the decomposition temperature and melting takes place at 529 K and 540 K, respectively. The T\u003csub\u003eC\u003c/sub\u003e (393 K) and T\u003csub\u003em\u003c/sub\u003e (529 K) values determined in this work are slightly shifted relative to the previously reported phase transition temperatures at 340 and 393 K, and exhibit minor differences compared with earlier reports that suggested melting at 393 K. These discrepancies may be attributed to variations in the solvent conditions and crystal growth temperature during the single-crystal growth process. The compound adopts a monoclinic crystal structure with the C2/c space group and remains thermally stable up to approximately 521 K. In addition, the discontinuities in the \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003eH and \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003eN NMR chemical shifts are observed near the transition temperature (T\u003csub\u003eC\u003c/sub\u003e), and the \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003eC MAS NMR spectra show pronounced changes in peak multiplicity across this temperature range, implying a reduction in symmetry below T\u003csub\u003eC\u003c/sub\u003e. The NMR results suggest that the phase transition of this material originates from the orientational dynamics and positional displacements of the [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] groups, consistent with an order\u0026ndash;disorder phase transition. Also, these observations indicate that the crystal preserves monoclinic symmetry at temperatures below T\u003csub\u003eC\u003c/sub\u003e, while transforming into a phase with higher symmetry upon heating. Furthermore, the line widths of \u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC, and \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003eN NMR spectra were found to decrease with increasing temperature; the temperature dependence of the NMR line width is primarily governed by molecular dynamics. The observed line narrowing with increasing temperature reflects the activation of molecular motions, including reorientational dynamics and phase transitions.\u003c/p\u003e \u003cp\u003eOverall, [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e is a zero-dimensional organic\u0026ndash;inorganic hybrid metal halide composed of isolated [ZnBr\u003csub\u003e4\u003c/sub\u003e]\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e-\u003c/sup\u003e tetrahedra separated by bulky organic cations. The compound exhibits good thermal stability and clear local structural dynamics, as confirmed by DSC, DTA, SCXRD, PXRD, and NMR analyses, making it a useful model system for fundamental studies of thermal stability and structure\u0026ndash;dynamics relationships in hybrid materials. In addition, the low toxicity and high thermal stability of zinc-based halides highlight their potential for environmentally benign optoelectronic materials.\u003c/p\u003e "},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis research was supported by the Regional Innovation System \u0026amp; Education (RISE) program through the Jeonbuk RISE Center, funded by the Ministry of Education (MOE) and the Jeonbuk State, Republic of Korea (2025-RISE-13-JJU).\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request. CCDC 2493839 contains the supplementary crystallographic data for this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis research was supported by the Regional Innovation System \u0026amp; Education (RISE) program through the Jeonbuk RISE Center, funded by the Ministry of Education (MOE) and the Jeonbuk State, Republic of Korea (2025-RISE-13-JJU).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA.R. Lim performed crystal growth, DSC, TG, and NMR experiments, and wrote the manuscript. H. Ju measured X-ray experiment.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe author declares no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorrespondence\u003c/strong\u003e and requests for materials should be addressed to A.R. Lim.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGao, Y.-F., Zhang, T., Zhang, W.-Y., Ye, Q. \u0026amp; Fu, D.-W. Great advance in high \u003cem\u003eT\u003c/em\u003e\u003cem\u003e\u003csub\u003ec\u003c/sub\u003e\u003c/em\u003e for hybrid photoelectric-switch bulk/film coupled with dielectric and blue-white light, \u003cem\u003eJ. Mater. Chem\u003c/em\u003e. C \u003cstrong\u003e7\u003c/strong\u003e, 9840 (2019). \u003c/li\u003e\n\u003cli\u003eAbdel-Aal, S. K., Abdel-Rahman, A. S., Gamal, W. 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Crystallographic characteristics and phase transitions in the [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eCdBr\u003csub\u003e4\u003c/sub\u003e crystal in the low-temperature range. \u003cem\u003ePhys. Solid State\u003c/em\u003e \u003cstrong\u003e49\u003c/strong\u003e, 1973 (2007).\u003c/li\u003e\n\u003cli\u003eDekola, T. I., Sheleg, A. U. \u0026amp; Tekhanovich, N. P. Heat capacity of the [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eCdBr\u003csub\u003e4\u003c/sub\u003e crystal in the temperature range 80-300 K. \u003cem\u003ePhys. Solid State\u003c/em\u003e \u003cstrong\u003e49\u003c/strong\u003e, 1766 (2007).\u003c/li\u003e\n\u003cli\u003eLim, A. R. \u0026amp; Lim, K.-Y. Phase-transition mechanisms of [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eBCl\u003csub\u003e4\u003c/sub\u003e and [N(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eBCl\u003csub\u003e4\u003c/sub\u003e (B=\u003csup\u003e63\u003c/sup\u003eCu and \u003csup\u003e67\u003c/sup\u003eZn) single crystals studied by proton NMR. \u003cem\u003eSolid State Commun\u003c/em\u003e. \u003cstrong\u003e147\u003c/strong\u003e, 11 (2008).\u003c/li\u003e\n\u003cli\u003eBiskupski, P. \u0026amp; Tylczynski, Z. Structure of TEA\u003csub\u003e2\u003c/sub\u003eZnCl\u003csub\u003e4\u003c/sub\u003e crystal surfaces studied by AFM, \u003cem\u003ePhase transition\u003c/em\u003e \u003cstrong\u003e81\u003c/strong\u003e, 971 (2008).\u003c/li\u003e\n\u003cli\u003eOstrowski, A. \u0026amp; Cizman, A. EPR studies of linewidth anomalies at phase transitions in [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eMnCl\u003csub\u003e4\u003c/sub\u003e. \u003cem\u003ePhysica\u003c/em\u003e B \u003cstrong\u003e403\u003c/strong\u003e, 3110 (2008).\u003c/li\u003e\n\u003cli\u003eLim, A. R. Study on ethyl groups with two different orientations in [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eCuBr\u003csub\u003e4\u003c/sub\u003e. \u003cem\u003eJ. phys. Chem. Solids\u003c/em\u003e \u003cstrong\u003e93\u003c/strong\u003e, 59 (2016).\u003c/li\u003e\n\u003cli\u003eLim, A. R. Study of the ferroelastic phase transition in the tetraethylammonium compound [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e by magic-angle spinning and static NMR. \u003cem\u003eAIP Advances\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, 035307 (2016).\u003c/li\u003e\n\u003cli\u003eLim, A. R., Kim, M. S. \u0026amp; Lim, K.-Y. Nuclear magnetic resonance study of the ferroelastic phase transition of order-disorder type [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eCdCl\u003csub\u003e4\u003c/sub\u003e. \u003cem\u003eSolid State Sciences\u003c/em\u003e \u003cstrong\u003e58\u003c/strong\u003e, 101 (2016).\u003c/li\u003e\n\u003cli\u003eLim, A. R. \u0026amp; Lim, K.-Y. Structural changes near phase transition temperatures for the [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] groups in hydrated [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eCuCl\u003csub\u003e4\u003c/sub\u003e∙\u003cem\u003ex\u003c/em\u003eH\u003csub\u003e2\u003c/sub\u003eO. \u003cem\u003eJ. Therm. Anal. Calorim.\u003c/em\u003e \u003cstrong\u003e130\u003c/strong\u003e, 879 (2017).\u003c/li\u003e\n\u003cli\u003eBechir, M. B. \u0026amp; Rhaiem, A. B. Synthesis, Thermal Analysis, Optical, Electric Properties and Conduction Mechanism of Hybrid Halogenometallates: [N(C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eCoCl\u003csub\u003e4\u003c/sub\u003e, \u003cem\u003eJ. Phys. Soc. 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Physica E \u003cstrong\u003e83\u003c/strong\u003e, 405 (2016).\u003c/li\u003e\n\u003cli\u003eAbdelhadi, A. B., Gutierrez, M., Cohen, B., Lezama, L., Lachkar, M. \u0026amp; Douhal, A. A new eco-friendly and highly emitting Mn-based hybrid perovskite toward high-performance green-converted LEDs. \u003cem\u003eJ. Materials Chemicstry\u003c/em\u003e C \u003cstrong\u003e12\u003c/strong\u003e, 286 (2024).\u003c/li\u003e\n\u003cli\u003eBanupriya, K., Revathi, A., Sudha, D., Kirubavathy, S. J. \u0026amp; Umarani, R. Tetrapropylammonium tribromocuprate complex [(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003eN]CuBr\u003csub\u003e3\u003c/sub\u003e(II) synthesis, thermal and spectral characterization. \u003cem\u003eMaterials today: proccdings\u003c/em\u003e \u003cstrong\u003e45\u003c/strong\u003e, 8024 (2021).\u003c/li\u003e\n\u003cli\u003eMoutia, N., Oueslati, A., Gzaiel, M. B. \u0026amp; Khirouni, K. Crystal structure and AC conductivity mechanism of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eCoCl\u003csub\u003e4\u003c/sub\u003e compound. \u003cem\u003ePhysica\u003c/em\u003e E \u003cstrong\u003e83\u003c/strong\u003e, 88 (2016).\u003c/li\u003e\n\u003cli\u003eChkoundali, S., Hlel, F.\u0026amp; Khemekhem, H. Synthesis, crystal structure, thermal and dielectric properties of tetrapropylammonium tetrabromozincate [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e[ZnBr\u003csub\u003e4\u003c/sub\u003e] compound. \u003cem\u003eAppl. Phys\u003c/em\u003e. A \u003cstrong\u003e122\u003c/strong\u003e, 1066 (2016).\u003c/li\u003e\n\u003cli\u003eMoutia, N., Gzaiel, M. B., Oueslati, A. \u0026amp; Khirouni, K. Electric characterization and vibrational spectroscopic investigations of order-disorder phase transitions in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eCoCl\u003csub\u003e4\u003c/sub\u003e compound\u003cem\u003e. J. Mol. Structure\u003c/em\u003e \u003cstrong\u003e1134\u003c/strong\u003e, 697 (2017).\u003c/li\u003e\n\u003cli\u003eChkoundali, S. \u0026amp; Aydi, A. Electrical conductivity and vibrational studies induced phase transition in [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eZnBr\u003csub\u003e4\u003c/sub\u003e. \u003cem\u003eJ. Advanced Dielectrics\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 2150005 (2021).\u003c/li\u003e\n\u003cli\u003eKhalfa, M., Oueslati, A., Khirouni, K., Gargouri, M., Rousseau, A., Lhoste, J., Bardeau, J.-F. \u0026amp; Corbel, G. Synthesis, structural and electrical characterization of a new organic inorganic bromide: [(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003eN]\u003csub\u003e2\u003c/sub\u003eCoBr\u003csub\u003e4\u003c/sub\u003e. \u003cem\u003eRSC Advances\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, 2798 (2022).\u003c/li\u003e\n\u003cli\u003eTaktak, O., Souissi, H., Elhamdi, I., Oueslati, A., Kammoun, S., Gargouri, M. \u0026amp; Dhahri, E. Optical investigations and theoretical simulation of organic-inorganic hybrid: TPA-CoCl\u003csub\u003e4\u003c/sub\u003e. \u003cem\u003eOptical Materials\u003c/em\u003e \u003cstrong\u003e150\u003c/strong\u003e, 115251 (2024).\u003c/li\u003e\n\u003cli\u003eKhalfa, M., Oueslati, A., Khirouni, M., Gargouri, M., Auguste, S., Bardeau, J.-F. \u0026amp; Corbel, G. 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Structural and optical investigations of [N(C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003eMeBr\u003csub\u003e4\u003c/sub\u003e (Me=Zn, Co, Cu) crystals. Proc. SPIE, Photonics Applications in Astronomy, Communcations, Industry, and High-Energy Physics Experiments. \u003cstrong\u003e7124\u003c/strong\u003e, 712403 (2008).\u003c/li\u003e\n\u003cli\u003eSabatini, A. \u0026amp; Sacconi, L. Far-Infrared spectra of some tetrahalo metal complexes. Contribution from the instituto di chimica e inorganica, Universita\u0026rsquo; di Firenze, Firenze, Italy, 1964.\u003c/li\u003e\n\u003cli\u003ePark, H. \u0026amp; Lim, A. R. Phase transition of (CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003eCHNH\u003csub\u003e3\u003c/sub\u003eCuCl\u003csub\u003e3\u003c/sub\u003e: crystal growth, crystal structure, coordination geometry, and molecular motion, \u003cem\u003eMater. 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Crystallogr\u003c/em\u003e. \u003cstrong\u003e39\u003c/strong\u003e, 453 (2006).\u003c/li\u003e\n\u003cli\u003eKoenig, J. L. Spectroscopy of Polymers, Elsevier, New York, 1999. \u003c/li\u003e\n\u003cli\u003eAbragam, A. The Principles of Nuclear Magnetism, Oxford University Press, 1961.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8654223/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8654223/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eOrganic–inorganic hybrid compounds have attracted significant attention as a versatile class of functional materials owing to their unique structural characteristics and tunable physicochemical properties. In this study, colorless and transparent single crystals of [N(C\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e7\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e)\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e]\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eZnBr\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e were grown from an aqueous solution. Thermal analyses (differential scanning calorimetry, differential thermal analysis), powder X-ray diffraction (XRD), and optical microscopy revealed a phase transition (T\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003eC\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e) at 395 K, followed by decomposition and melting at 529 and 540 K, respectively. From the single-crystal XRD experiment, crystallographic analysis indicates a monoclinic symmetry (space group C2/c), with the unit cell dimensions \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003ea\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e=33.1977 Å, \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eb\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e=14.2615 Å, \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003ec\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e=15.1130 Å, and β=110.3840°, and remains thermally stable up to approximately 521 K. Solid-state nuclear magnetic resonance (NMR) results further support these findings: the \u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003eH and \u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e14\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003eN magic angle spinning (MAS) NMR chemical shifts show discontinuous changes near the T\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003eC\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e, while the \u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e13\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003eC MAS NMR spectra exhibit variations in peak multiplicity, indicating a reduction in symmetry below the transition point. Moreover, the progressive line narrowing observed in the \u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003eH, \u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e13\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003eC, and \u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e14\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003eN spectra with increasing temperature reflects enhanced molecular motion, particularly reorientational dynamics associated with the T\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003eC\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","manuscriptTitle":"Investigation on crystal structure, phase transition behavior, and structural geometries of organic-inorganic hybrid [N(C3H7)4]2ZnBr4","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-02 13:41:02","doi":"10.21203/rs.3.rs-8654223/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-05T14:56:56+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-04T11:14:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"300085748814907476008655479480374366008","date":"2026-02-02T09:19:33+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-02T08:23:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"71541839950908494582069455298167707106","date":"2026-01-31T18:52:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"338530743874721155664850837558014568904","date":"2026-01-29T06:03:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"70528538007604213709809373085376994997","date":"2026-01-29T05:04:32+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-29T03:12:55+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-01-28T16:16:29+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-24T07:20:16+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-24T07:19:29+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-01-21T02:12:11+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b03729b3-978f-4c06-b5df-01a2b1f6bf12","owner":[],"postedDate":"February 2nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":62165057,"name":"Physical sciences/Chemistry"},{"id":62165058,"name":"Physical sciences/Materials science"},{"id":62165059,"name":"Physical sciences/Physics"}],"tags":[],"updatedAt":"2026-04-07T16:13:53+00:00","versionOfRecord":{"articleIdentity":"rs-8654223","link":"https://doi.org/10.1038/s41598-026-45431-2","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2026-04-04 15:58:35","publishedOnDateReadable":"April 4th, 2026"},"versionCreatedAt":"2026-02-02 13:41:02","video":"","vorDoi":"10.1038/s41598-026-45431-2","vorDoiUrl":"https://doi.org/10.1038/s41598-026-45431-2","workflowStages":[]},"version":"v1","identity":"rs-8654223","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8654223","identity":"rs-8654223","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}