Analysis of the Structure, Thermal, and Molecular Dynamics of Organic–Inorganic Hybrid Crystal at Phases IV, III, II, and I: [NH(2)(CH(3))(2)](2)CdBr(4)

[Image: see text] A comprehensive understanding of the physicochemical properties of organic–inorganic hybrids is essential for their solid-state lighting applications. Therefore, a single crystal of [NH(2)(CH(3))(2)](2)CdBr(4) was grown; the crystal structure was monoclinic, and the phase transition temperatures for the four phases IV, III, II, and I were 383 K (T(C1)), 417 K (T(C2)), and 427 K (T(C3)). Furthermore, the chemical shifts caused by the local field around (1)H, (13)C, (14)N, and (113)Cd changed continuously with temperature, especially near T(C1), indicating that the local environment changes with temperature. Owing to the large change in (113)Cd chemical shifts, the coordination geometry of Br around Cd in the CdBr(4) tetrahedra changes near T(C1). Therefore, it is proposed that Br plays a significant role in the N–H···Br hydrogen bond. Finally, the spin-lattice relaxation time T(1ρ), representing the energy transfer around the (1)H and (13)C atoms of the cation, changed significantly with temperature. The activation energies obtained from the T(1ρ) results were two times larger at high temperatures than at low temperatures. This study provides an understanding of the fundamental properties of organic–inorganic hybrid compounds to broaden their applications.