Photochemical [2+2] cycloaddition as a tool to study a solid-state structural transformation

The solid-state structural transformation of the hydrogen-bonded 1D coordination polymer [Cd(bpe)(CH3COO)(2)- (H2O)](n), to a ladder-type structure is evident from a photochemical [2 + 2] cycloaddition reaction forming 100% rctt-cyclobutane isomer.