Self-assembly And Catalysis Performance Of Organic-inorganic Hybrid Materials Based On Metal Clusters

Hybrid materials chemistry is significantly impacting the development of modern society.It represents an inherent cross-cutting field of science research and bridges together numerous different communities.Taking advantages of various sizes and special physical properties,metal cluster has become an excellent inorganic building block for constructing the organic-inorganic hybrid materials.The hybrid materials with different size scales and colorful functional applications can be bottom-up synthesized from basic molecular precursor and inorganic metal cluster units.Self-assembly has gradually become one of the main methods to construct various structures of hybrid materials.In the process of self-assembly,the researches of the interaction and contributions of various weak forces have become one of the most basic problems in this field.Furthermore,rationally utilizing the mechanism of self-assembly,directional design hybrid molecular with special self-assembly properties,and functional applications,such as catalytic organic reactions,become the development direction of the organic-inorganic hybrid materials.In this paper,three hotspots hybrid materials based on metal clusters have been selected as models for studying the further self-assembly and catalytic properties from homogeneous to heterogeneous systems.Nano-scaled organic metal cluster hybrids exist as macroions in homogeneous solution,and the published studies of their spontaneous self-assembly solution behaviors are still limited.Moreover,the main difficulty is that the combination of organic and inorganic properties makes the interactions in solution system more complex.Furthermore,using catalytic olefin peroxidation as the functional guidance,synthesis new hybrid materials with self-assembly mechanism or appling typical hybrid materials for catalyzing new peroxy reactions are one of the direction of this paper.However,it's hard to remain the stability of peroxy group in the process of catalytic,at the same time to achieve economic,green,and high selective catalytic performance.The first part of this work applys the predesigned trinuclear zinc organic cluster Zn3QDB3(NO3)4(Zn-QDB)as one of the hybrid models.Zn-QDB was observed to self-assemble into a hollow,spherical,single-layered "blackberry"-type structure.The self-assembly behaviors of the Zn-QDB are significantly influenced by additional small ions.Specifically,the cations exhibit strong co-ion effects on the interaction between cationic macrocycles which are different from the previously reported co-ion effects of simple anions on anionic polyoxometalates.This unusual phenomenon is due to the unique cation-?interaction between small cations and electron-rich cavity of Zn-QDB.The variation of hydrodynamic radius(Rh)of assemblies with the changes of solution ionic strength and the type of cations reveals the competition between counterion-mediated attraction and cation-?interaction during the self-assembly process.Furthermore,the cooperativity of cation-?interaction and ?-? stacking play a vital role in enhancing the stability of the supramolecular structure.After understanding the self-assembly properties of hybrid materials,the second part of this paper focoused on the synthesis of new polyoxometelate-organic hybrid molecule PQ1 by lacunary polyoxometelate anion and organic ammonium cation via covalent bond guiding by catalysis functional requirements.Electrostatic attraction,covalent interaction,hydrogen bond,and hydrophilic-hydrophobic interaction are involved in the same molecule,and coorpratively drive PQ1 to self-assembly into a uniform nanoparticles.The assmblies of PQ1 were applied for catalyzing the reaction of synthesize a-hydroxy peroxide compounds.A one pot synthesis a-hydroxy peroxy product reaction was achieved by the hybrid catalysis system.Furthermore,the strong restraining force of covalent bond makes organic cation closer to polyoxometelate anion,leading to a stronger corporative catalytic effect,thus resulting higher reaction selectivity.Finally,a novel and practical peroxy-trifluoromethylation of olefins was achieved in one pot reaction under the catalysis of heterogeneous hybrid framework material Cu3(BTC)2 with binuclear copper cluster.The binuclear copper cluster of Cu3(BTC)2 is crucial to the reaction.As active catalysis site,the copper cluster uniformly located on the site of framework and were responsible for dual activation of Togni reagent and TBHP for the electrophilic trifluoromethylation initiated pathway.Compared with the homogeneous copper salts,the heterogeneous Cu3(BTC)2 showed a superior catalytic activity and intrinsic shape-selectivity for this reaction.Furthermore,a ionic-type mechanism was proposed and the derivatives with carbonyl or hydroxyl groups were obtained.