Two-step phosphorescent mechanochromism due to intramolecular deformation

A triphosphine-supported Pt2Cu heterotrinuclear complex (1) constrained with 3,6-di-tert-butyl-1,8-diethynyl-9H-carbazole exhibits two-step phosphorescent mechanochromism due to intramolecular deformation. The stepwise phosphorescent mechanochromism following green → yellow → orange-red corresponds exactly to the phosphorescent emission observed in crystal morphs 1·4THF (green), 1·3acetone (yellow), and 1·4CH2Cl2 (orange-red), respectively, with different degrees of intramolecular deformation, as demonstrated by X-ray crystallography.