Organic-inorganic hybrid [NH(CH)NH]ZnBr crystal: structural characterization, phase transitions, thermal properties, and structural dynamics.

Organic-inorganic hybrid [NH(CH)NH]ZnBr crystals were prepared by slow evaporation; the crystals had a monoclinic structure with space group 2/ and lattice constants = 7.7833 Å, = 14.5312 Å, = 13.2396 Å, = 90.8650°, and = 4. They underwent two phase transitions, at 370 K ( ) and 430 K ( ), 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 H and C chemical shifts were observed near , indicating changing structural environments around H and C. The spin-lattice relaxation time, , increased rapidly near suggesting very large energy transfer, as indicated by a large thermal displacement around the C atoms of the cation. However, the environments of H, N, and C1 located close to NH in the [NH(CH)NH] cation did not influence it significantly, indicating a minor change in the N-H⋯Br hydrogen bond with the coordination geometry of the ZnBr anion. We believe that the information on the physiochemical properties and thermal stability of [NH(CH)NH]ZnBr, as discussed in this study, would be key to exploring its application in stable, environment friendly solar cells.