In Situ Preparation, Structure, Photoluminescence and Theoretical Study of an Unusual Bismuth Complex

Abstract

A novel bismuth photoluminescent material, (N,N′-dimethyl-2,2′-bipy)₂(Bi₂Cl₁₀)·2H₂O (1) (bipy = bipyridine), with the N,N′-dimethyl-2,2′-bipy²⁺ moiety obtained in situ, has been synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction. Compound 1 is characterized by an isolated structure, consisting of N,N′-dimethyl-2,2′-bipy²⁺ cations, Bi₂Cl₁₀^4– anions and lattice water molecules. Photoluminescence experiments with solid-state samples discover that compound 1 exhibits a strong emission in the green region. Time-dependent density functional theory (TDDFT) calculation reveals that the essence of the photoluminescence of 1 can be assigned to the combination of the metal-to-ligand charge transfer (MLCT) (from the HOMO of the bismuth ion to the LUMO of the N,N′-dimethyl-2,2′-bipy²⁺ moiety) and the ligand-to-ligand charge transfer (LLCT) (from the HOMO of the chloride ions to the LUMO of the N,N′-dimethyl-2,2′-bipy²⁺ moiety).