Dynamic motions of organic cation in organic–inorganic hybrid 1,4-butanediammonium tetrabromocuprate (II) crystal by solid-state nuclear magnetic resonance spectroscopy

Abstract

The organic–inorganic hybrid perovskite [NH3(CH2)4NH3]CuBr4 is an important material for light-emitting and photovoltaic devices. In the present study, the thermal behavior, physicochemical properties, and structural geometries were investigated. Thermogravimetric analysis revealed thermal stability of the compound up to ∼490 K. Moreover, changes were observed in the nuclear magnetic resonance chemical shifts for 1H and 14N in the NH3 group bonded at both ends of the organic chain and for 13C in the CH2-b close to the NH3, which were related to the changes in the N–H•••Br hydrogen bonds. The molecular dynamics were analyzed in terms of the spin–lattice relaxation time T1ρ. The 13C T1ρ value for CH2-b was smaller than that of CH2-a because CH2-b was close to the NH3 group of the organic chain and formed an N–H•••Br hydrogen bond of the CuBr4 inorganic chain. Furthermore, the T1ρ value was smaller when 1H and 13C were located near the paramagnetic Cu2+ ion than when they were far away from the Cu2+ ion. Thus, [NH3(CH2)4NH3]CuBr4 crystal has good applicability because the T1ρ value is nearly constant with temperature.