Study On Organic Functionalization And Self-assembly Of Anderson Type Polyoxometalate

As a typical class of inorganic compounds,polyoxomethoxylate（POM）has a wide range of applications in the fields of catalysis,electrochemistry and biomedicine due to their rich molecular structures and diverse physicochemical properties.However,as a class of inorganic compounds,it is extremely difficult to modify and modify their molecular structure to achieve control of molecular size,shape and physicochemical properties.Since organic compounds possess the function of easy molecular modification,the organic modification of POM using organic compounds is not only expected to construct new hybrid materials with controllable structure and stable properties,but also can provide useful ideas for the development of new special functional materials.Barbituric acid has attracted our attention due to its good self-assembly properties and ease of modification.In this work,two barbituric acid-POM organic-inorganic hybrids are designed and synthesized,and the supramolecular self-assembly process of the two organic-inorganic hybrids is investigated in depth.The results show that the two hybrids can self-assemble into petal-like and plate-like structures at a volume ratio of 1:3 in methanol/chloroform solvent mixture,respectively.Thus,the supramolecular structures can be adjusted by adjusting the molecular structures and solution components.Furthermore,both barbituric acid-POM hybrids prepared in a methanol/chloroform mixture at a volume ratio of1:3 can be used as effective catalysts for the degradation of the organic dye methylene blue.In addition,the natural product dousterol was selected for the organic modification of the polyoxomethoxylate.First,stigmasterol itself is modified,and the resulting compounds 1 and2 are self-assembled into gels in methanol and dimethyl sulfoxide（DMSO）,respectively.When compounds 1 and 2 form gels in DMSO at a mass concentration of 12 mg/m L,the gel-sol phase transition temperatures(T_gel)are 51 and 46℃,respectively,indicating that the thermal stability of gel formation decreas significantly with the increase of steroidal structural units in the gelators.On this basis,the gel prepared by compound 1 is used as the carrier to study the encapsulation and release of Rhodamine B,methylene blue and adriamycin by UV-vis spectroscopy.The results show that the gel could be used as a drug carrier,and reachs the maximum release value of 84%in water at 240 min.Based on this,compound 1 is used as an organic group to modify Anderson-POM,and the prepared stigmasterol-POM-stigmasterol complex can self-assembly into a stable gel when the acetonitrile/chloroform volume ratio is 6:4.The preparation of stigmasterol-POM hybrid gels can be used as drug carrier,which can provide useful ideas for drug delivery.In this work,by selecting barbiturate and stigmasterol derivatives as organic groups,using covalent bonds to modify polyoxometalate,and explore its self-assembly behavior in solution.This study will not only contribute to our understanding of supramolecular self-assembly behavior,but also deepen our understanding of molecular structures and how solution components affect the microstructure.At the same time,it is expected that the research on organic-inorganic compounds based on POM can promote the development of hybrid materials containing polyoxometalate.