Four polyoxometalate-based semiconductive coordination polymers: Syntheses, structures, photoluminescent and photocatalytic properties

•The N-donor ligands were multidentate.•Compounds 1–4 contain polyoxometalate anions.•The conductivities of the compounds have been investigated.•The photoluminescent properties of the compounds have been studied.•The photocatalytic properties of the compounds have been studied.

Four polyoxometalate-based semiconductive coordination polymers, namely, [Cd3(2,3′-Htmbpt)2(2,3′-tmbpt)4(γ-Mo8O26)(β-Mo8O26)(H2O)4]·5H2O (1), [Co(2,3′-Htmbpt)2(β-Mo8O26)]·4H2O (2), [Ag(2,3′-Htmbpt)2(β-Mo8O26)]·H3O·4H2O (3), and [Cu(2,3′-tmbpt)(β-Mo8O26)]·H2O (4) (2,3′-tmbpt = 1-((1H-1,2,4-triazol-1-yl)methyl)-3-(3-pyridyl)-5-(2-pyridyl)-1,2,4-triazole) have been synthesized under hydrothermal conditions. Their structures have been characterized by single-crystal X-ray diffraction analyses, infrared spectra (IR), elemental analyses and powder X-ray diffraction (PXRD) analyses. Polymer 1 has a 3D (4,6)-connected framework with (5·64·8)(4·52·62·7)(42·54·66·7·82) topology. In polymer 2, the [β-Mo8O26]4− anions connect the Co(II) ions to form a chain, which is decorated by the 2,3′-Htmbpt ligands. The chains are extended by the hydrogen bonding interactions to generate a 3D supramolecular framework. Polymer 3 displays a discrete structure, which is linked by the hydrogen bonding interactions to form a chain. The chains span in two different directions, yielding a plywood-like structure. In polymer 4, the [β-Mo8O26]4− anions connect the Cu(II) ions to furnish a layer, which is further coordinated by the 2,3′-Htmbpt ligands. The layers are linked by the hydrogen bonding interactions to form a 3D supramolecular framework. The optical band gaps of 1–4 reveal that they are potential semiconductive materials. The luminescent spectra of polymers 1 and 3 indicate that they emit blue luminescence at room temperature. The photocatalytic investigation indicates that polymers 1–3 can promote the decomposition of methylene blue solution, while polymer 4 inhibits the decomposition process.

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