Single-crystal-to-single-crystal transformation of a two-dimensional coordination polymer through highly selective [2+2] photodimerization of a conjugated dialkene.

A 2D network [Zn4(OH)2(5-NO2-1,3-BDC)2(5-NO2-1,3-HBDC)2(ppene)2]n underwent a highly selective [2+2] photodimerization reaction upon UV irradiation. The coordination polymer retains its single crystallinity after photoreaction.