A Systematic Research on the Synthesis, Structures, and Application in Photocatalysis of Cluster-Based Coordination Complexes

To search for effective photocatalysts in the field of cluster-based coordination complexes, we synthesized {[Cd 2 (dcpp)(beb) 2 (H 2 O)]·H 2 O} n ( 1 ), [Cd 2 (dcpp)(bmb)(H 2 O) 2 ] n ( 2 ), {[Cd 2 (dcpp)(2,2′-bipy)(H 2 O) 2 ]·2H 2 O} n ( 3 ), and {[Cd 2 (dcpp)(4,4′-bipy) 0.5 (H 2 O) 3 ]·H 2 O} n ( 4 ) by utilizing a butterfly-shaped multidentate carboxylic acid (4,5-di(4′-carboxylphenyl)phthalic acid) (H 4 dcpp)) and N-donor ligands (1,4-bis(2-ethylbenzimidazol-1-ylmethyl) benzene (beb), 1,4-bis(2-methylbenzimidazol-1-ylmethyl) benzene (bmb), 2,2′-bipyridine (2,2′-bipy), 4,4′-bipyridine (4,4′-bipy)). Complexes 1 – 4 are constructed based on different SBUs. Complexes 1 and 2 possess three-dimensional (3D) pillar-layered frameworks based on noncluster-type SBUs and dinuclear Cd 2 clusters units, respectively. Complex 3 is a 3D porous structure building on Cd 4 clusters SBUs. Complex 4 is constructed from rare infinite botryoid-like Cd cluster chains and exhibits a 3D complicated framework. The research on optical energy gaps of complexes 1 – 4 indicates that these complexes are potential semiconductive materials. Moreover, complexes 1 – 4 are applied to catalyze the reaction of photocatalytic degradation of methylene orange (MO) under high-pressure mercury lamp irradiation. Excitingly, they exhibit good photocatalytic properties in the presence of H 2 O 2, and the degradation rates for 1 – 4 increase from 43% (without photocatalyst) to 97, 78, 85, and 67%, respectively, after 100 min of irradiation. The photoluminescent properties of complexes 1 – 4 were also studied.