Efficient and robust photocatalysts based on {PW} modified by an Ag complex

Two novel Wells-Dawson polyoxometalate-based compounds, (H 2 bimb) 2 [{Ag 1.5 (bimb) 1.5 }(P 2 W 18 O 62 )] ( 1 ), (H 2 bimb) 2 [Ag(bimb)] 0.5 [Ag(eim) 2 ] 0.5 [P 2 W 18 O 62 ]·H 3 O ( 2 ) (bimb = 1,4-bis(imidazole-l-yl)butane, eim = ethyl(imidazole)), have been synthesized under hydrothermal conditions and characterized by IR, thermogravimetric, XRD and single-crystal X-ray diffraction analyses. In compound 1 , two "U"-type bimb ligands are connected together via π interactions of Ag-C to form a ring unit. The ring unit alternately links with the "Z"-type bimb via an Ag-N bond to form an infinite Z-shaped {Ag 4 (bimb) 3 } n chain. The adjacent two {P 2 W 18 } clusters bonded to two Ag1 ions on two adjacent Z-shaped chains to form an inorganic dimer linker, which further joins the Z-shaped chains together, resulting in unique organic-inorganic alternating 2-D layers. Adjacent 2D layers are further aggregated together via Ag-O bonds between the Dawson cluster and the Z-type chain on different layers to yield a 3-D network with a new topology {10 3 } 2 {10}{4·10 2 } 4 {4 2 ·10 4 } 2 . In compound 2 , the eim ligand was synthesized in situ from bimb, which acts as a small molecular ligand to alter the structure and adjust the catalytic activity of compound 2 . Each Ag2 connects with the bimb ligand to form a linear {Ag(bimb)} chain. Adjacent chains are bonded together via the bimb ligand to generate a supermolecule 2-D layer, in which a Dawson dimer cluster as a guest molecule is embedded in both sides of the layer through supermolecule interactions. Such 2-D layers are further supported by Ag(eim) 2 units leading to 3D supermolecule nets. In addition, the compounds exhibit excellent electrocatalytic behavior and better photocatalytic degradation capability for typical dyes than other Wells-Dawson POMs. Ag + and the flexible ligand bimb were introduced into Dawson phosphomolybdate systems as linkage units to induce two fascinating 3-D inorganic-organic networks, which exhibit excellent electro- and photo-catalytic behavior.