Phosphorescent mechanochromism through the contraction of Ag12Cu2 clusters in tetradecanuclear copper–silver acetylide complexes

Abstract

Tetraphosphine-supported tetradecanuclear Ag₁₂Cu₂ acetylide cluster complexes were prepared and characterized by X-ray crystallography. They show reversible phosphorescent mechanochromism with striking emission colour change from yellow to orange-red. As demonstrated by the drastic phosphorescent emission red-shifts of the Ag₁₂Cu₂ cluster complexes in a dilute PMMA (polymethyl methacrylate) blend upon mechanical grinding, the mechanochromism is ascribed to the contraction within the Ag₁₂Cu₂ cluster and the enhanced intramolecular Cu–Ag and Ag–Ag contacts. A mechanism of phosphorescent mechanochromism through metal intra-cluster contraction is thus proposed.