Mechanochromic and Thermochromic Luminescence of a Copper Iodide Cluster

The mechanochromic and thermochromic luminescence properties of
a molecular copper(I) iodide cluster formulated [Cu4I4(PPh2(CH2CHCH2))4] are reported. Upon mechanical grinding in a mortar, its
solid-state emission properties are drastically modified as well as
its thermochromic behavior. This reversible phenomenon has been attributed
to distortions in the crystal packing leading to modifications of
the intermolecular interactions and thus of the [Cu4I4] cluster core geometry. Notably, modification of the Cu−Cu
interactions seems to be involved in this phenomenon directly affecting
the emissive properties of the cluster.