Isopolymolybdate-based inorganic–organic hybrid compounds constructed by multidentate N-donor ligands: syntheses, structures and properties

Abstract

Taking advantage of isopolymolybdate [(NH₄)₆Mo₇O₂₄·4H₂O] as a POM building block with multidentate N-donor molecules (tris[(2-pyridyl)methyl]amine = TPMA, 1-(tetrazo-5-yl)-3-(triazo-1-yl)benzene = 1,3-ttb) as organic ligands, five different inorganic–organic hybrid compounds were synthesized and characterized by single-crystal X-ray diffraction, infrared spectroscopy (IR) and powder X-ray diffraction (PXRD). Compound 1 is a Mo(VI)-based structure in which the TPMA ligand shows a tridentate coordination mode, which bears an uncoordinated pyridyl arm, and can further react with transition metals. Compound 2 exhibits a Cu(II)-based zero-dimensional (0D) structure consisting of the TPMA ligand and [β-Mo₈O₂₆] polyanion. Compounds 3 and 4 have the same molecular formula with slight structural differences; both have the Co(II)-based one-dimensional (1D) chain structure. Compared to the β-Mo₈O₂₆ polyanion in compound 3, the [Mo₈O₂₈]⁸⁻ units condense via sharing two common terminal O atoms to form infinite [Mo₈O₂₆]_n⁴ⁿ⁻ chains in compound 4. Compound 5 is a Cu(II)-based two-dimensional (2D) layer structure consisting of TPMA and 1,3-ttb mixed ligands and [β-Mo₈O₂₆]. In addition, the electrochemical properties and photocatalytic activities for the degradation of two types of organic dyes were explored for several compounds.