Simultaneous Luminescent Thermochromism, Vapochromism, Solvatochromism, and Mechanochromism in a C3-Symmetric Cubane [Cu4I4P4] Cluster without Cu–Cu Interaction

A chiral C3-symmetric cubane cluster, [Cu4I4(TMP)4], with enough long Cu-Cu distances to eliminate the presence of Cu-Cu interaction has been synthesized and characterized, which shows simultaneous luminescent thermochromism, solvatochromism, vapochromism, and mechanochromism and is a multiply stimuli-responsive chromic luminescent material. This complex could partly transform into a yellow-emissive bicapped cubane cluster, [Cu6I6(TMP)4(MeCN)2], in acetonitrile (MeCN) vapor and solution, which provides some insight into vapochromism and solvatiochromism. This work challenges and makes us reconsider the conventional viewpoint that Cu-Cu interaction is involved in thermochromism and mechanochromism of copper complexes.