Syntheses,Structures And Properties Of Inorganic-Organic Hybrids Based On 4′-hydroxy-2,2′:6′,2′′-terpyridine And Polyoxometalates

Inorganic-organic hybrids have always been favored by researchers due to the dual characteristics of both inorganic and organic components,and are often used in many fields such as catalyses,functional materials,and medicines.When nitrogen-containing ligands with flexible and strong coordination ability（such as terpyridine ligands）are used as organic components,and polyoxometalate with excellent physical and chemical properties are used as inorganic components,the inorganic-organic hybrids with diverse structures and unique properties can be constructed.In this paper,4′-hydroxy-2,2′:6′,2′′-terpyridine（LOH）,polyoxometalates and metal ions were constructed together through solvothermal method to obtain four unreported inorganic-organic hybrids:[Co_2.5（LOH）（LO）₂（H₂O）₂(PW₁₂O₃₉)]·3CH₃CN·2OH（1）,[Zn_1.5（LOH）₃](PMo₁₂O₄₀)·CH₃OH·2H₂O（2）,[Cd_1.5（LOH）₃](PW₁₂O₄₀)·2CH₃OH·1.5H₂O（3）and[Mn（LOH）₂](PW₁₂O₄₀)·2CH₃CN·H₃O（4）.They were characterized by X-ray single crystal diffraction,elemental analysis,thermogravimetric analysis,Infrared spectrum analysis and PXRD.Hybrid 1 exhibits a one-dimensional chain structure,and the adjacent chains further formed supramolecular surfaces and 3D supramolecular structures by H-bonds.Hybrids 2-4 feature monomolecular structures,which are sequentially connected into 1D chain,2D surface and 3D supramolecular structures via H-bonds.Through experimental investigation,It is found that the activated 1 displays a high catalytic activity for the cycloaddition reaction of CO₂ and epoxides,and the hybrid 2 has a significant promotion effect on the oxidative desulfurization reaction of sulfides.Both 1 and 2 can be employed as heterogeneous catalysts owing to excellent catalytic performance,stable structures and the recyclability.The possible catalytic mechanisms for the reactions catalyzed by hybrids 1 and 2are proposed in this paper.In addition,it is found that both 1 and 2 can be used as electrocatalysts to catalyze the reduction of Na Br O₃ and the oxidation of ascorbic acid,through the exploration of the electrochemical performance of them.