Photocrystallographic analysis of [AuCl(PPh3)2] for elucidation of the crystal packing effect on the photophysical properties

Abstract

A metal–ligand bond shortening of [AuCl(PPh₃)₂] by photoexcitation was analyzed by the photocrystallographic method in the unsolvated crystal. The gradual structural change of photoexcited and ground-state molecules with cooling explains the temperature dependence of the emission spectrum and the excited-state lifetime. Actually, on cooling, the ground-state molecular structure approached the excited-state structure. As a result, the HOMO–LUMO gap of [AuCl(PPh₃)₂] became narrower and a red shift of the absorption and emission bands were observed. Below 180 K, inhibition of the bond shortening was observed due to the intermolecular interactions, which was confirmed by the temperature dependence of the photoexcited phase cell volume, the integrated emission intensity, and the excited-state lifetime measurement.