Convenient synthesis of copper(i) halide quasi-one-dimensional coordination polymers: their structures and solid-state luminescent properties

The heterogeneous reaction between copper(i) halide and pyridine derivative ligand in a suspension conveniently afforded luminescent copper(i) complexes. The progress of the reaction was confirmed by powder X-ray diffraction (PXRD) and thermogravimetric (TG) measurements. The structure of the obtained complexes was clarified by comparison with the X-ray analysis of a single crystal obtained by the homogeneous reaction in a solution. The reaction was affected by the type of solvent and substituents on the pyridine ligand. The reaction proceeded quantitatively, not depending on copper(i) halide, when ethyl acetate and 3-bromopyridine were used as the solvent and ligand, respectively. X-ray analysis of the single-crystals obtained by the corresponding reaction in solution revealed that the reaction in suspension afforded the same stair-shaped quasi-one-dimensional structure. The obtained copper(i) complex powders displayed luminescence, which was attributed to the halide/metal-to-ligand charge transfer (XMLCT), as elucidated by crystal orbital distribution and principal component of excitation based on density functional theory (DFT) calculations.