| Polyoxometalates are a class of clusters with significant structural characteristics formed by the connection of pre-transition metal ions through oxygen atoms,and the frame elements usually contain some high-valence pre-transition metal ions,such as Mo（VI）,W（VI）,V（V）,Nb（V）and Ta（V）.As a research hot spot in the field of inorganic chemistry,polyoxometalates have been receiving extensive attention.Transition metals and organic ligand-modified polyoxometalates can form rich spatial structures and functions.At the same time,adjusting the conditions in the reaction,such as temperature,p H,the type of raw materials,or using different reaction methods,such as hydrothermal method,atmospheric pressure heating,room temperature volatilization,microwave method,etc,which have a great impact on the products.The diversity of composition and the richness of structure make polyoxometalates can be used in many fields,including photocatalysis,thermocatalysis,electrocatalysis,electrochemical sensing,electrochemical energy storage,etc.Coordination compounds are coordination compounds formed by a certain number of ions or molecules（called ligands）which give lone-pairs or multiple unlocalized electrons,and vacancy atoms or ions（collectively referred to as central atoms）which can accept lone-pairs or multiple unlocalized electrons,with a certain composition and spatial configuration.The study of coordination compounds with certain functions is a hot topic in inorganic chemistry.Herein,six polyoxoniobates and four complexes were synthesized,and the structure and composition of crystals were determined through a series of characterizations.The results of the catalytic oxidation of styrene reaction and the electro-catalytic hydrogen evolution properties of compounds were explored.In order to further explore the role of polyoxoniobates in catalysis,coordination compounds as catalysts were used to catalyze the oxidation of styrene.The work is as follows:1.Synthesis of four transition metal-copper complex-modified{Nb24}high-nuclear isopolyoxoniobates by hydrothermal synthesis of room temperature crystallization,and several{Nb24}have different substructures,among which compound 1 and 4have similar structures.The catalytic oxidation of styrene by compound 1 and 4 was mainly explored.H3[Cu（en）2]24.5[Cu（en）2（H2O）]6(KNb24O72H7)4·272H2O（1）[Cu（en）2]13.5[K1.5Nb24O72H9]2·50H2O（2）[Cu（en）2]6[KNb24O72]·44H2O（3）[Cu（en）2]31[K0.5Nb24O72H8]4·229H2O（4）2.Two cases of keggin-type heteropolyoxoniobate were successfully synthesized by hydrothermal method,compounds 5 and 6 were synthesized for the first time,compound 5 had a planar structure similar to a circle,and compound 6 was a neatly arranged rectangular spatial structure.The catalytic oxidation of styrene by compounds 5 and 6 showed that compound 6 had higher conversion rate and styrene oxide selectivity.The electrocatalytic hydrogen evolution performance of compounds5 and 6 showed that compound 5 had a lower overpotential and a smaller Tafel slope value,and the electrochemical impedance value of compound 5 was lower.[Cu（2,2-bpy）（μ3-O）2（μ4-O）]6[PNb12Na O39]·20H2O（5）[Cu（en Me）2[KCu4（en Me）8][VNb12O40（VO）4.25K]（6）3.Four transition metal complexes were synthesized by hydrothermal analysis,of which compounds 8 and 10 were synthesized for the first time,compounds 7 and 10were bilayer planar structures,and compounds 8 and 9 were three-dimensional structures.The catalytic oxidation of styrene by compounds 7 and 9 showed high conversion of compounds 7 and 9,the conversion rate of compound 9 was slightly higher than that of compound 7,and the selective compounds 7 and 9 showed high selectivity for benzaldehyde.The electrocatalytic hydrogen evolution reaction of compounds 7 and 10 showed that compound 10 had better stability and electrochemical impedance.[Cu（2,2-bpy）（μ2-O）（μ3-O）Cl0.5]4Cl2·6H2O（7）[Zn（2,2-bpy）（OH）2]（8）[Cu（4,4-bpy）Cl]4（9）[Cu（5-OH-2,2-bpy）]4（10）... |
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