Synthesis And Properties Of Lanthanide/Transition Metal-Modified Keggin-type Germanotungstates

Polyoxometalates(POMs),as an important family about anionic oxide clusters of the early transition metals,have been regarded as a unique class of inorganic molecules with nano-sized dimensions,a variety of configurations,the surface with rich oxygen atoms,high stability and an unmatched range of physical and chemical properties.Therefore,the interest in the design and synthesis of lanthanide/transition metal-modified germanotungstates with polyoxometalates as inorganic building blocks is extensively increasing,which have potential applications in a wide range of fields such as catalysis,medicine,molecular magnetism,photochemistry,electrochemistry and material science.In this paper,12 new lanthanide/transition metal modified Keggin-type germanotungstates 1-12 were synthesized with lacunary Keggin-type germaniumtungsten as starting materials and characterized by IR,UV spectroscopy,XRPD and single-crystal X-ray diffraction analysis.The magnetic,electrochemical,luminescent and photocatalytic properties of the related products were investigated.The text has been divided into three chapters,which were introduced as follows:1.Three transition metal-modified germaniumtungsten compounds 1-3 have been synthesized under room temperature condition.H10K4[Cu(H2O)5]2[Cu(H2O)2(GeW9O34)2](1)H]4[Mn9(GeW9O34)2(GeW6026)(H20)4](2)H10[K16(H2O)28[Co2(H2O)(GeW8.25Co0.75O36)]2](3)Singel-crystal X-ray diffraction analysis reveals that the structures of 1-3 exhibit new transition metal-modified germaniumtungsten structuers constructed by the coordination interaction between lacunary Keggin-type germaniumtungstens and transition metal ions.The Eg of compounds 1-3 is 3.42?2.80 and 2.76 eV,respectively.Compounds 1-2 represent dominant antiferromagnetic coupling interactions;In addition,compounds 1-2 exhibit good electrocatalytic activity toward the reduction of NaNI2 and H2O2.2.Five Keggin-type(GeW12O40)4--based metal-organic frameworks 4-8 were synthesized with K8-xNaxGeW11O39 nH2O,Ln3+/Zn2+,organic ligand 4,4'-bipyridyl nitroxide(dpdo)as starting materials under hydrothermal condition.{H(GeW12O40)[Sm(dpdo)4.5(H2O)4]·5H2O}n(4){H(GeW12O40)[Eu(dpdo)4(H20)3]}n(5){H(GeW12O40)[Gd(dpdo)4.5(H20)4]·5H2O}n(6){H(GeW12O40)[Tb(dpdo)4(H20)3]}n(7){(GeW12O40)[Zn2(dpdo)4(H20)2]·8H2O}n(8)Compounds 4,6 and 8 are basically isostructural and feature a 3D supramolecular framework decorated with Keggin-type polyanion clusters based on one-dimension polymeric chains.The compounds 5 and 7 formed a two-dimensional framework decorated with Keggin-type polyanion clusters.The energy bands of compounds 4-8 imply that they are broadband semiconductor material.Compounds 4-8 exhibited good electrocatalytic activity toward the reduction of NaNO2 and H2O2.The results showed that compounds 4-8 have good adsorption properties for rhodamine B and good photocatalytic activity for methylene blue.In particular,the catalytic activity of compound 8 to methylene blue was 97%.3.Four germaniumtungsten-polyoxometalate-based 3d-4f heterometallic compounds 9-12 have been synthesized under hydrothermal condition by the reaction of the divacant polyoxometalate[?-GeW10O40]8-,organic chelate ligand 1,2-dap,Ln3+(Sm3+?Eu3+?Gd3+?hb3+)and Cu2+.{[Cu(dap)(H2O)3][SmCu3(dap)3(OH)3(H20)(GeW11O39)]}2·13H2O(9){[Cu(dap)(H2O)3][EuCu3(dap)3(OH)3(H20)(GeW11O39)1}2·13H2O(10){[Cu(dap)(H2O)3][GdCu3(dap)3(OH)3(H20)(GeW11O39)]}2·13H2O(11){[Cu(dap)(H2O)3][TbCu3(dap)3(OH)3(H20)(GeW11O39)]}2·13H20(12)Compounds 9-12 are Keggin-type 3d-4f heterometallic incorporated polyoxotungstate The magnetic properties of compounds 9-12 have been studied,indicating antiferromagnetic coupling interactions.The compounds 9-12 exhibit excellent photocatalytic activity for the degradation of methylene blue under visible light irradiation.