Investigation on the organic–inorganic hybrid crystal [NH(2)(CH(3))(2)](2)CuBr(4): structure, phase transition, thermal property, structural geometry, and dynamics

Understanding the physical properties of the organic–inorganic hybrid [NH(2)(CH(3))(2)](2)CuBr(4) is essential to expand its applications. The single [NH(2)(CH(3))(2)](2)CuBr(4) crystals were grown and their comprehensive properties were investigated. The crystals had a monoclinic structure with the space group P2(1)/n and lattice constants of a = 8.8651 (5) Å, b = 11.9938 (6) Å, c = 13.3559 (7) Å, and β = 91.322°. The transition temperature from phase I to phase II was determined to be 388 K. Variations in the (1)H nuclear magnetic resonance chemical shifts of NH(2) and (14)N NMR chemical shifts according to the temperature changes in the cation were attributed to vibrations of NH(2) groups at their localization sites. The (1)H and (13)C spin–lattice relaxation times (T(1ρ)) in phase II changed significantly with temperature, indicating that these values are governed by molecular motion. The T(1ρ) values were much longer in phase I than in phase II, which means energy transfer was difficult. Finally, the activation energies for phases I and II were considered. According to the basic mechanism of [NH(2)(CH(3))(2)](2)CuBr(4) crystals, organic–inorganic materials may have potential applications in various fields.