Photodimerization of an olefin-containing pyridinium-based metal–organic complex and isomerization of its cyclobutane product upon recrystallization

A photoactive olefin-containing pyridinium-based metal-organic complex underwent solid-state [2 + 2] photocycloaddition reaction in 100% yield, which has been monitored by ¹H NMR, PXRD, IR and Raman spectroscopy. The breakage of the Cd–Cl bond and the coordination bonds between the ligands and Cd(II) ion occurred during the photocycloaddition reaction, leading to the cycloaddition product becoming more soluble in aqueous solution, and the cyclobutane molecule underwent isomerization into an unusual rcct-isomer by recrystallization.