Thermally induced transformation of a Cu₄I₄-based cluster to a Cu₂I₂-based cluster under mild conditions

A reaction of 6,6 '-bis((benzylthio)methyl)-2,2 '-bipyridine (L) with CuI at room temperature led to one Cu4I4-based cluster, which could be thermally transformed to a Cu2I2-based one under mild conditions due to the formation of a Cu-S bond. Along with the structural transformation, remarkable changes in the color and luminescence have been triggered.