Organic-inorganic hybrid [NH3(CH2)6NH3]ZnBr4 crystal: structural characterization, phase transitions, thermal properties, and structural dynamics.

Organic-inorganic hybrid [NH3(CH2)6NH3]ZnBr4 crystals were prepared by slow evaporation; the crystals had a monoclinic structure with space group P21/c and lattice constants a = 7.7833 Å, b = 14.5312 Å, c = 13.2396 Å, ß = 90.8650°, and Z = 4. They underwent two phase transitions, at 370 K (T C1) and 430 K (T C2), as confirmed by powder X-ray diffraction patterns at various temperatures; the crystals were stable up to 600 K. The nuclear magnetic resonance spectra, obtained using the magic-angle spinning method, demonstrated changes in the 1H and 13C chemical shifts were observed near T C1, indicating changing structural environments around 1H and 13C. The spin-lattice relaxation time, T 1ρ, increased rapidly near T C1 suggesting very large energy transfer, as indicated by a large thermal displacement around the 13C atoms of the cation. However, the environments of 1H, 14N, and C1 located close to NH3 in the [NH3(CH2)6NH3] cation did not influence it significantly, indicating a minor change in the N-H⋯Br hydrogen bond with the coordination geometry of the ZnBr4 anion. We believe that the information on the physiochemical properties and thermal stability of [NH3(CH2)6NH3]ZnBr4, as discussed in this study, would be key to exploring its application in stable, environment friendly solar cells.