A new organic–inorganic hybrid compound based on lanthanide-organic chain and Keggin-type polyoxometalate

The reaction between a double-betaine-containing ligand and DyH[PMo11VO40]·nH2O led to a new polyoxometalate-based lanthanide-organic hybrid compound with the molecular formula [Dy(HL)(L)1.5(H2O)3][PMo11VO40]·8H2O (1) (L = 1,4-bis(pyridinil-4-carboxylato)-l,4-dimethylbenzene). Compound 1 was characterized by elemental analyses, TG, IR, XPS and the single-crystal X-ray diffraction. Compound 1 possesses a cationic 1D polymeric chain [Dy(HL)(L)1.5(H2O)3]n4n+ with cyclic-, chain- and semi-cyclic-like fragments, corresponding to three different configurations of the double-betaine-containing ligand. These 1D chains are connected together by the H-bonds and π–π interactions to form a 3D supramolecular framework, encapsulating the vanadium-substituted Keggin-type polyoxoanions [PMo11VO40]4−and the solvent molecules. This composite compound displays electrocatalytic activities towards the reduction of nitrite and the luminescent property.