Sytheses And Properties Of Organically Modified Anderson Type Polyoxometalate Complexes

Polyoxometalates (POMs) are an important class of discrete anionic inorganicmetal-oxide clusters coupled with diverse structures, interesting electrical and opticalproperties, thermal stability, redox activitities and acid-base properties, as well asapplications in areas of light, electricity, magnetic, catalysis, chiral and medicine. Thedesign and synthesis of novel structure and nature of the organic-inorganic hybridcompound are the relentless pursuit of the POM chemical workers. By modulating theacid hetero atoms, the coordinating atoms, anti-ionic and the water of crystallization, wecan change the acid acidity, thermal stability and oxidation-reduction, etc., thus achievinga structure that is similar to the organic compound, namely, the modification of POMs.And through the modification of POMs, not only can enrich the POM structures, and theobtained after the modification of the POM derivatives are also available as a potentialsecondary construction units, and can further be used to construct higher-dimensionalmolecular framework.At present, organic-inorganic synthetic route, namely, the introduction of organicacid groups into the inorganic parts, is an effective way for POMs synthesis. Bycovalently modifying POMs with functional organic group, the basic structure andproperties of POMs are not changed, and may also be combined with the organic part andthe inorganic part by the synergistic interaction producing some novel properties, thus itis widely used in the modification of different kinds of POMs, for example, Anderson-,Dawson-, Lindquist-and Keggin-type POMs. But the methods for organic covalentlymodifying Anderson-type POMs especially aroused our attention, one hand may bebecause of its simple method of modifying, by which it can be very easily modified onmany different functional organic groups; on the other hand may be due to itssymmetrical structure, advantageously its research in the area of self-assembled. Thepreviously reported about covalently modifying Anderson-type POMs, from thedesigning and synthesizing simple Anderson-type POMs complexes to the self-assembly of the Anderson-type polyoxometalate complexes, both of them are completed in theorganic solvent; Meanwhile, most of the synthesized organic modified Anderson-typePOMs are symmetrically modification, but the synthetic methods are the same as themodified method with the symmetric modification Anderson-type POMs, only throughthe regulation of the ratio of the organic, inorganic part, thus bringing the difficulty forpurification and low yield. Therefore, in order to further enrich the the POM structuresand properties and expand the synthesis method of POMs, the development of simple,efficient synthetic methods becomes very important. We choose the method of Triscovalent modification Anderson-type POMs and got azobenzene symmetrically graftedAnderson-type POMs, and through the cation-ion exchange method, we have succeededtransferring it into aqueous solution, as well as we further investigated the host-guestinteraction between the hybrid complexes and cyclodextrin in aqueous solution. Second,on the basis of symmetrical covalent modification of the Anderson-type POMs, wedevelop a simple and efficient synthesis method of asymmetric covalent modification ofthe Anderson-type POMs and further to study the affect of different conditions of theircrystallization.Firstly, we synthesized azobenzene symmetrically grafted Anderson-type POMcomplexe with good water solubility. In order to transfer the organically covalentlymodification of the Anderson-type POM to aqueous solution and investigate theproperties in aqueous solution, and combine the host-guest recognition interactionbetween azobenzene and cyclodextrin in aqueous solution, as well as thephotoisomerization phenomenon of azobenzene, thus, we chose the method of Triscovalently modification of Anderson-type POMs and got azobenzene withphotoisomerization property symmetrically grafted Anderson-type POM complexe, andfurther by simple cation exchange method replaced the counter ions of the complex withsodiumions, obtained a water-soluble azobenzene symmetrically modified Anderson-typePOM complexe. Meanwhile, we investigated the host-guest recognition interaction inaqueous solution with cyclodextrin, and further identified the host-guest recognitioninteraction by controlling the azobenzene photoisomerization phenomenon. We foundthat when azobenzene was in trans form, it can form a host-guest inclusion complexeswith cyclodextrin, and when irradiated it with UV light, the azobenzene group transferredto cis form, which can not form host-guest inclusion complexees with cyclodextrin inaqueous solution. Therefore, we successfully realized the interaction of recognition and decomposition between azobenzene and cyclodextrin by controlling thephotoisomerization phenonmenon of azobenzene.Secondly, we designed and synthesized organically single-side functionalizedAnderson-type POMs. First mixed different Tris derivatives with the B-type Andersontype POMs in aqueous solution, and then by cation exchange method replaced thecounter ions to the tetrabutylammonium salt, so through a two-step synthetic method inthe aqueous solution, we had successfully obtained five kinds of organically single-sidefunctionalized Anderson-type POM complexes. We also found that the stability of thesingle-side functionalized Anderson-type POM complexes had a relationship with its endof the modifying group, and the crystal growth is also greatly affected by different pHconditions. Meanwhile, the carboxyl group functionalized Anderson-type POMs complexalso influenced by the salt ions in solution, in the presence of silver nitrate can not getfunctionalized Anderson-type POMs complex. Thus, by a simple two-step syntheticmethod in aqueous solutions we can successfully prepare the different functional groupsfunctionalized Anderson-type POM complexees.In short, in this thesis we mainly focus on the Anderson-type POMs, firstly througha simple ion exchange method, we successfully transferred the organically symmetricallymodified Anderson-type POMs into the aqueous solution, and further investigated thehost-guest recognition interaction in aqueous solution with cyclodextrin, realized therecognition and decomposition between azobenzene and cyclodextrin by controlling thephotoisomerization phenonmenon of azobenzene. Secondly, by using of the convenientand efficient synthetic method we obtained the single crystal structures of organicallysingle-side functionalized Anderson-type POM complexes, and further investigated thecrystallization under different conditions, for building a functional organically modifiedAnderson-type POM complexes provides a platform, greatly enriched the structures andan area of application of the polyoxometalate.