Synthesis Of Two-types Of Tungstates With Strandberg And Keggin Structures By Controllable Assembly Of Phosphonic Acid,Inorganic Oxyacid/Oxysalt

Strandberg-type polyoxometalate with organophosphorus center can be synthesized through the assembly of phosphonic acid and simple inorganic oxyacid/oxysalt.So far,some organophosphomolybdates with Strandberg-type have been reported.As far as we know,only one Strandberg-type organophosphotungstate,i.e.a simple charge transfer salt,has been reported.Which means that it is difficult to get such organophosphotungstates.Using phenylphosphonic acid,simple tungstate and transition metal compounds as the starting materials,two types of polyoxometalates(POMs)were self-assembled by controlling the reaction conditions,such as pH,the molar ratio and the feeding order of raw materials,etc.These obtained POMs were fully characterized,taking the synthesis of cyclohexanone ethylene ketal as a model reaction,and their acid catalytic performances were evaluated.1.Using phenylphosphonic acid,simple tungstate,copper(?)compounds and 4,4'-bipy as starting materials,a Strandberg-type organophosphotungstate-Cu(?)-bipy coordination polymer,{[(Cu(H2O)(?-bipy))2(C6H5PO3)2W5O15]}n(bipy=4,4 '-bipyridyl)(1),was successfully assembled under hydrothermal conditions at pH=2-3.Compound 1 represents the first example of a transition metal complex modified organophosphotungstate cluster with Strandberg structure.2.Using the same raw materials.a hollow Keggin isopolytungstate coordination polymer{[Cu(bipy)2((?-bipy)Cu(bipy))2(H2W12O40)]·12H2O}n(2)was assembled successfully under different material ratio and pH.3.Utilizing the same hydrothermal synthetic method as above,copper(?)was used in place of cobalt(?),and 2,2'-H2biim replace 4,4'-bipy,a isopolytungstate {H2W12}-Co(?)H2biim complex,[Co(H2biim)3]2H2[H2W12O40]·3H2O(H2biim=2,2 '-H2biim)(3)was obtained.In addition,another isopolytungstate(H4biim)3(H2Wi2O40)·7H2O(4)was self-assembled using a routine synthetic method.4.These compounds were characterized by single-crystal X-ray diffraction,XRPD diffraction,IR spectroscopy,TG-DTA analysis.Compounds 1-4 were used as acid-catalysts in the synthesis of cyclohexanone ethylene ketal,and their catalytic activities were discussed,and fluorescence properties of compound 1 was preliminary studied.