Dual luminescence in solid CuI(piperazine): hypothesis of an emissive 1-D delocalized excited state

Solid [CuI(piperazine)0.5]∞, characterized by a structure with an infinite double chain of CuI, presents an unexpected dual luminescence. The short copper–copper distances allow the existence of both cluster-centered and 1-D delocalized electronic transitions, as emerged from theoretical calculations. Beyond the more common cluster-centered emission a higher energy band, which differs in lifetime and in temperature dependence, is observed.