A photoactive porous metal-organic complex: Synthesis, crystal morphology and the influence of photocycloaddition on fluorescence properties and adsorption behavior

A photoactive porous metal-organic complex has been constructed based on an olefin-containing pyridinium derivative, 1-(3-carboxybenzyl)-4-[2-(4-pyridyl)-vinyl]-pyridinium chloride (m-HBCbpe·Cl). The double bond in the BCbpe ligand has been successfully aligned in a photoactive orientation through cation-π interactions, thus enabling the complex to undergo a photochemical [2 + 2] cycloaddition reaction in 100% yield upon UV-light irradiation. Sudden cracking of the crystal can be observed during this process. Interestingly, photocycloaddition not only induces fluorescence switching from no luminescence to strong yellow luminescence emission under UV light, but also triggers a structural change which has a significant impact on CO₂ adsorption.