A new paratungstate-A-based organic–inorganic hybrid compound: Synthesis,structure and photocatalytic property of [Co(en)3]2[H2W7O24]·8H2O

A new paratungstate-A-based organic–inorganic hybrid compound with the chemical formula of Co(en)₃]₂H₂W₇O₂₄]·8H₂O (en = ethylenediamine) (1) has been hydrothermally synthesized and structurally characterized by the elemental analysis, IR, TG, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space group P2₁/c with a = 17.216(3) Å, b = 14.986(3) Å, c = 23.088(8) Å, β = 128.151(2)°, V = 4684.2 Å³, Z = 1, R₁ = 0.0484, and wR₂ = 0.1087. The structure of 1 consists of the H₂W₇O₂₄]⁴⁻ building blocks and Co(en)₃]²⁺ metal-organic cationic moieties, which are packed together via the electrostatic forces and extensive hydrogen-bonding interactions to form a three-dimensional supramolecular framework. Interestingly, compound 1 represents the first structurally-defined hybrid compound based on the metastable paratungstate-A polyoxoanions and metal–organic units. The degradation of Rhodamine-B (RhB) under UV irradiation with 1 as the heterogeneous photocatalyst has been investigated, showing a good photocatalytic property of 1 for RhB degradation.