Construction And Catalytic Properties Of Supramolecular Host-Guest Complexes Containing Keggin Polyoxometalate

Supramolecules are structural units with a certain stability and unique properties formed by multiple molecules through non-covalent interactions（such as hydrogen bonding,van der Waals forces,and ionic equivalence）.Host-guest chemistry is a science that studies molecular recognition and non-covalent bonding.Polyoxometalate（POMs）is a large anion family of metal oxide base clusters with large closed threedimensional structure formed by condensation of Ⅴ and Ⅵ group transition metals（generally Mo,W,V）in the highest oxidation state.Due to the fact that the central metal atoms have many oxidation valence states and the multi-acid main body has good thermal stability,Catalysts with polyoxometalate as guest have good catalytic potential in both electrocatalysis and organic catalysis.This paper constructs supramolecular catalysts（including electrocatalysts and organic catalysts）with simple Keggin-type polyoxometalates as basic guest components and crown ether,cyclodextrin,and column aromatics as supramolecular main components respectively.The main research contents are as follows:In the first part,K⁺ was used to bridge crown ether 18-crown-6,and polyoxometalate[SiMo₁₂O₄₀]and crown ether were synthesized at low temperature to obtain hybrid complexes of crown ether and SiMo₁₂O₄₀:[K(H₂₄C₁₂O₆]₃[K(H₂₄C₁₂O₆（CH₃CN）][SiMo₁₂O₄₀],then the complex was characterized and analyzed,and the electrocatalytic hydrogen evolution performance was tested.The overpotential and Tafel slope of the 1/CP electrode of the complex were verified and the long-term stability was determined in the acidic medium.The innovation of synthesizing a supramolecular polyoxometalate hybrid electrocatalyst with an excellent electrocatalytic performance by a simple synthesis method was realized.In the second part,novel spiral supramolecular crystals {（NH₄）₁₅K[βCD)₄(SiMo₁₂O₄₀)₄]-2H₂O} P and {（NH4）₄[（β-CD）(SiMo₁₂O₄₀)]·2H₂O} M were obtained by co-crystallization of Keggin-type polyoxometalates and β-CD The chiral separation effect of several racemes was studied,and it was found that these two chiral catalysts could achieve very good results in the chiral separation experiment of phenylalanine racemes.A relatively ideal peak curve of chiral reaction was obtained to characterize the circular dichroic CD spectrum,and the strength of all of them reached about 25 mA cm^-2.The innovation of applying a supramolecular multi-acid host-guest self-assembly catalyst to a chiral field has been realized and made a breakthrough.In the third part,the subsequent structure characterization,analysis,and electrocatalytic hydrogen evolution performance of the catalyst prepared by supramolecular self-assembly of water-soluble aminoized column aromatic[5]hydrocarbons and Keggin-type polyoxometalate PW12O40 were conducted,the overpotential,long-term stability and Tafel slope of the 1/CP electrode of the complex was verified in the acidic medium.The innovation of synthesizing supramolecular polyoxometalate hybrid electrocatalyst with excellent electrocatalytic performance using a new generation of supramolecular column aromatics has been realized.