The Synthesis And Structural Analysis Of Supramolecular Self-assemblies Based On ?-cyclodextrin And Polyoxometalates

Polyoxometalates(POMs)are all-inorganic metal oxygen clusters compounds with diverse structures and excellent physical and chemical properties.They are very useful in the fields of catalysis,electricity,light,medicine,magnetism,biology,and adsorption.The structure determines the properties,so the design and synthesis of new POMs is a hot research topic.Cyclodextrins(CDs)are organic cyclic molecules that can form supramolecular compounds with POMs in a bottom-up manner under certain conditions.This work mainly studies the self-assembly process of cyclodextrin and POMs as well as POMs precursors.Finally,several examples of organic-inorganic supramolecular compounds with new structures were successfully synthesized.According to the complementarity of the structure of POMs and cyclodextrin,we firstly synthesized two new host-guest compounds with the chemical formulas are K₃(NHC₆H₁₅O₃)₃{[?-P₂W₁₈O₆₂](C₄₈H₈₀O₄₀)}·21H₂O(1)and K(NHC₆H₁₅O₃)₅{[?-P₂W₁₈O₆₂](C₄₈H₈₀O₄₀)₂}·21H₂O(2).They are prepared from?-CD and?-P₂W₁₈ under conventional synthetic conditions.The interactions in 1 and 2 between?-CD and?-P₂W₁₈were studied in solid phase(single crystal X-ray diffraction)and liquid phase(¹H NMR and ³¹P NMR).Compound 1 and 2 are both monoclinic crystal systems,each unit cell contains 4 molecules,the difference between them is that the ratio of the?-CD to?-P₂W₁₈.Then we studied the self-assembly of cyclodextrin with POMs and POMs precursors.Exploring under normal conditions,finally we obtained a novel compound K₆Na₇(NHC₂H₆)₂{[?-P₂W₁₈O₆₂][Fe Mo₆O₂₄](C₄₈H₈₀O₄₀)₂}·32H₂O(3).The compound 3was characterized and analyzed by single crystal XRD,IR,¹H NMR,³¹P NMR,TGA etc.Compound 3 crystallizes in the monoclinic system,each unit cell contains 2molecules.Compound 3 is a new three-component supramolecular compound,in which[Fe Mo₆O₂₄]^9-formed by self-assembly.The synthesis of compound 3 provides ideas and methods for the next step of direct experiments using cyclodextrin and POMs precursors.Finally,the self-assembly of cyclodextrin and POMs precursor was studied under conventional synthetic conditions,and a new type of supramolecular compound Na₁₁{[Mo₆O₁₉][Fe Mo₆O₂₄](C₄₈H₈₀O₄₀)₂}·28H₂O(4)was successfully synthesized.Compound 4 is in triclinic crystal system,a unit cell contains 2 molecules.The successful synthesis of compound 4 shows that it is feasible to directly use cyclodextrin and POMs precursor for self-assembly.Supramolecular compounds based on cyclodextrin and polyoxometalate are still in their infancy.The compound synthesized in this topic not only enriches the structure of polyoxometalate,but also broadens the way for the post-functionalization of POMs.This research laid the foundation for the POMs application in functional materials.