Self-assembly of four new extended architectures based on reduced polyoxometalate clusters and cadmium complexes

Four new [P4Mo6] cluster-based extended structures containing cadmium complexes, [Cd3(4,4′-Hbpy)2(4,4′-bpy)2(H2O)8][Cd(H2PO4)2(HPO4)4(PO4)2(MoO2)12(OH)6]·7H2O 1, (4,4′-Hbpy)2[Cd(4,4′-bpy)3(H2O)3][Cd(4,4′-bpy)(H2O)]2[Cd(H2PO4)2(HPO4)4 (PO4)2(MoO2)12(OH)6]·H2O 2, [Cd4(phen)2(H2O)4][Cd(phen)(H2O)]2[Cd(HPO4)4 (HPO4)4(MoO2)12(OH)6]·5H2O 3 and [Cd4(2,2′-bpy)2(H2O)4][Cd(2,2′-bpy)(H2O)]2 [Cd(HPO4)4(HPO4)4(MoO2)12(OH)6]·3H2O 4 (4,4′-bpy=4,4′-bpyridine, phen=1,10-phenanthroline, 2,2′-bpy=2,2′-bpyridine), have been synthesized and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The structure of compound 1 is constructed from the Cd[P4Mo6]2 dimers linked by [Cd3(4,4′-Hbpy)2(4,4′-bpy)2(H2O)8] subunits to generate a plane layer. Compound 2 consists of the positive 2D sheets that constructed from Cd[P4Mo6]2 dimers linked by [Cd(4,4′-bpy)(H2O)] complexes, then the 2D sheets are further linked up together to form a 3D supramolecular framework via extensive hydrogen-bonding interactions among the [P4Mo6] clusters, free 4,4′-bpy molecules, dissociated [Cd(4,4′-bpy)3(H2O)3]2+ complexes and water molecules. Compounds 3 and 4 show new 2D layered structure, with Cd[P4Mo6]2 building blocks connected by tetra-nuclear [Cd4{(phen)2/(2,2′-bpy)2}(H2O)4] clusters and [Cd(phen/2,2′-bpy)(H2O)] complexes. The fluorescent activities of compounds 3 and 4 are reported.