A crystalline zinc(ii) complex showing hollow hexagonal tubular morphology evolution, selective dye absorption and unique response to UV irradiation.

A protonated mononuclear complex [Zn(Hbpvp)Cl3] (1) is assembled by solvothermal reaction of Zn(NO3)2·6H2O with 3,5-bis-(2-(pyridin-4-yl)vinyl)pyridine (bpvp) in DMF/H2O with a few drops of concentrated HCl added. Hydrogen-bonded zigzag chains of 1 crystallize over time to form large-size hollow hexagonal tubular crystals whose evolution from irregular crystal seeds is monitored by SEM and PXRD. Upon UV light irradiation, single crystals of 1 undergo a stereoselective [2+2] photocycloaddition while its Methyl Blue-coated crystals keep intact.