Reversible photoluminescence switch: A stair-step Cu4I4 coordination polymer based on a dithioether ligand

A two-dimensional network stair-step Cu4I4 coordination polymer (1) based on 1,4-bis((methylthio)propanoyl)piperazine was prepared. No emission was observed from 1 (off state), while a heated sample (2) of 1 emitted a strong green light (on state). Conversion between 1 and 2 was reversible upon removal of acetonitrile or exposure of 2 to acetonitrile.