Analysis of the Structure, Thermal, and Molecular Dynamics of Organic-Inorganic Hybrid Crystal at Phases IV, III, II, and I: [NH2(CH3)2]2CdBr4.

Abstract

A comprehensive understanding of the physicochemical properties of organic-inorganic hybrids is essential for their solid-state lighting applications. Therefore, a single crystal of [NH2(CH3)2]2CdBr4 was grown; the crystal structure was monoclinic, and the phase transition temperatures for the four phases IV, III, II, and I were 383 K (TC1), 417 K (TC2), and 427 K (TC3). Furthermore, the chemical shifts caused by the local field around 1H, 13C, 14N, and 113Cd changed continuously with temperature, especially near TC1, indicating that the local environment changes with temperature. Owing to the large change in 113Cd chemical shifts, the coordination geometry of Br around Cd in the CdBr4 tetrahedra changes near TC1. Therefore, it is proposed that Br plays a significant role in the N-H···Br hydrogen bond. Finally, the spin-lattice relaxation time T1ρ, representing the energy transfer around the 1H and 13C atoms of the cation, changed significantly with temperature. The activation energies obtained from the T1ρ 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.