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.