| Polyoxometalates(POMs)are an important class of multinuclear complexes with special physical and chemical properties in inorganic chemistry.The properties of POMs can be adjusted through the modification of organic groups.Its functional compounds with organic molecules have a wide range of applications in catalysis,biomedicine,light,electricity,magnetism and so on.At present,the use of nucleophilicity of oxygen atoms on polyoxometalates reacting with electrophilic organic molecules is an effective strategy for synthesizing such functional materials.Boronic acids are an important class of boron-containing organic compounds,which have a wide range of applications in organic synthesis,biomedicine and so on.Their structure can be described as one hydroxyl group of orthoboric acid replaced by an aromatic hydrocarbon or an aliphatic hydrocarbon.POMs modified by boronic acid has not been reported yet.In this thesis,we firstly studied the reaction of Dawson-type Nb/W mixed-addendun POM with 3-PyB(OH)2(3-pyridineboronic acid),and successfully synthesized a series of novel boronic acid-Ln-POM complexes(1-3).3-PyB(OH)2 exhibits rich coordination modes.As bidentate or tridentate ligands,it can either coordinate with Ln? or covalently link with POMs.It is found in this study that pH is critical to controlling the coordination mode of boric acid and the formation of the bridge between B-O-Ln and B-O-Nb.Compared with Ln-POM without boric acid,the fluorescence lifetime of compound 3 is longer due to the coordination of boric acid with the Eu? center.H4{Er3[3-PyB(OH)3]4(H2O)12P2W15Nb3O62}·19H2O(1)H3{[Er2(H2O)113-PyB(OH)2][P2W15Nb3O62]}·25H2O(2)H3{[Eu2(H2O)113-PyB(OH)2][P2W15Nb3O62]}·25H2O(3)Secondly,by the reaction of Well-Dawson type Nb/W mixed-addendum POM and 4-PyB(OH)2(4-pyridineboronic acid),a novel chain-like compound(4)which is composed of alternately connected POM dimers and novel boronic acid dimers via Nb-O-B brigdes has been synthesized.The boronic acid dimer which is composed of two 4-PyB(OH)2 linked by a B-O-B bridge has not been reported previously.The existence of pyridine boronic acid,protons and water molecules in 4 render it has potential to be a proton conductor.Alternating-current(AC)impedance measurements reveal that 4 has a conductivity of 2.91 × 10-2 S cm-1 under 343 K and 85%RH.NaH15[(P2W15Nb3O62)2(4-PyBOH)2(4-PyBOH)2(O)]·52H2O(4)Thirdly,in addition to the Well-Dawson type POM,we also explored the reactions of Keggin type POMs with 4-PyB(OH)2.A series of POM-boronic acid supermolecules were obtained(5-8).In these compounds 4-PyB(OH)2 transform into trimer our tetramer,and these boronic acid oligomers interact with POMs through weak forces(?-? stacking,hydrogen bonding,etc.).It is found that the different charges of POMs resulted in the different boronic acid oligomers and the different structures of the finally supermolecules.H4[(4-PyB)3(OH)3(O)2][PMo12O40]·4H2O(5)H6[(4-PyB)3(OH)3(O)2]2[SiW12O40]·11H2O(6)H7[(4-PyB)3(OH)3(O)2][(4-PyB)3(O)3(OH)][BW12O40]·7H2O(7)H6[(4-PyBO)4(OH)][PMo10V2O40]·6H2O(8)... |
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