Scissor-like AuCu Cluster with Phosphorescent Mechanochromism and Thermochromism.

Reaction of [Au(tht)](ClO) (tht = tetrahydrothiophene), [Cu(CHCN)](ClO), 3,6-di--butyl-1,8-diethynyl-9-carbazole (Hdecz), and bis(2-diphenylphosphinophenyl)ether (POP) in the presence of triethylamine (NEt) gave the cluster complex AuCu(decz)(POP) as yellow crystals. As revealed by X-ray crystallography, the AuCu cluster exhibits scissor-like structure sustained by two decz and two POP ligands and stabilized by Au-Cu and Au-Au interactions. The AuCu cluster shows bright yellow to orange photoluminescence upon irradiation at >300 nm, arising from [π (decz)→5d (Au)] LMCT (ligand-to-metal charge transfer) and [π→π* (decz)] IL (intraligand) triplet states as revealed by theoretical and computational studies. When it is mechanically ground, reversible phosphorescence conversion from yellow to red is observed owing to more compact molecular packing and thus stronger intermetallic interaction. Variable-temperature luminescence studies reveal that it displays distinct red-shifts of the emission whether the temperature is elevated or lowered from ambient temperature, suggestive of exceptional thermochromic phosphorescence characteristics.