| Polyoxometalates(POMs),including polyoxovanadates(POVs),are a large range of metal-oxygen molecular clusters,representing a large diversity in composition,sizes and shapes.Their versatile nature in terms redox-and photochemistry,medicine and energy generation are garnering increasing attention,and catalysis is still the most important area of application today.Selective oxidation is one of the most important reactions in the production of fine chemicals,which occupies an extremely important position in the chemical industry.Low catalytic efficiency and bad selectivity is the bottleneck of the hydrocarbon catalytic oxidation,which has become a problem for catalytic chemistry and industry.Looking for high activity and selectivity of the catalyst system,as well as the exploring of green,efficient selective oxidation reaction is an effective way to solve the technical problems of selective oxidation.In this paper,combined superior catalytic performance of POM with different characteristics of metal-organic units,the POM-based metal-organic crystalline hybrid materials can be designed and constructed.Through systematically modulating the types of POMs and the structures of metal-organic units,the catalytic performance of these crystalline materials can be improved.Further exploration of the synergistic effect between the structural components,green and efficient POM-based metal-organic crystalline catalyst system can be obtained.Twenty POM-based metal-organic crystalline hybrid materials have been synthesized under hydrothermal conditions.The catalytic activities of these hybrids have been investigated by selective oxidation of cyclooctene.Detailed works are as follows:1.An alkene-bridged thioether was designed and used for its first study within POM hybrid system,and six stable POM-based copper(I)-alkene complex have been isolated.Uncommon bonding interactions between transition metals and unsaturated C=C moieties render the title complexs unprecedented solubility in organic media.Such dramatic transformation is particularly exciting because it provides a new route for nano structured materials.Through a simple and fast solvent-diffusion method with the solution processable precursor of title phase,spherical micro-and nano-particles can be fabricated in a facile,one-step,room-temperature process on a large scale.Six title compounds:[Cu3(bmbe)3(PMo12O40)]·H2O(1)[Cu(bmbe)]{[Cu(bmbe)]2[(PMo12O40)]}(2)[Cu(bmbe)]2{[Cu(bmbe)][(PMo12O40)]}(3)[Cu6(bmbe)6(H20)2(PMoO2O40)2]·5H2O(4)[Cu6(bmbe)4Cl2(SiW12O40)]·H20(5)[Cu4(bmbe)4(DMS)(SiW12O40)](6)2.Non-covalent interactions,including hydrogen bonding and ?-? stacking are important intermolecular forces,they can contribute to self-assembly processes when extended structures are formed from basic building blocks.However,the question on how the complexes are packed in the crystal lattice is not well documented in the structure discussion,and this is of fundamental importance for the further development of supramolecular chemistry and the tuning and prediction of crystal structures.In this work,we aimed to examine the interplay between coordinative and non-covalent interaction bonded self assembly of supramolecular architectures via POM anion control and smart organic ligand design.As such,a tris(tetrazolyl)benzene core was designed and introduced into the POM chemistry,and four POM-encapsulated metal-organic supramolecular complexs have been isolated.For better understanding and utilization of non-covalent interactions,the four title compounds can be regarded as ideal structural models.Four title compounds:[Cu4(tmtb)4][PMo12O40](7)[Cu4(tmtb)4][SMo12O40](8)[Cu4(tmtb)4][SiW12O40](9)[Cu4(tmtb)4][(Mo6O19)2](10)3.Undoubtedly,the structural features would determine the potential functionalities of the eventual materials.For the eventual architectures,differentroles of POMs in the crystal lattice would exhibit distinct physicochemical properties.However,the univeasl one-pot reaction system invariably occured in solution mask a vast and complex range of intricate self-assembly processes,and it is therefore difficult to predict or control the assembly process.Here,a tetrazole-functionalized flexible ligands has been designed and used for the role-control of POMs during the self-assembly processes.With isolation of eight Keggin-type POM-supported hybrid materials,we demonstrate here it is feasible to access the role-control of POMs by rational synthetic strategy.Eight title compounds:[Ni2(bmps)4(H2O)4][SiW12O40]·10H2O(11)[Cue(bmps)2(H2O)3(PMo12O40)]·(OH)-2.5H2O(12)[Cue(bmps)4(H2O)2(SiW12O40)]·5H2O(13)[Cu2(bmps)2(EN)2(SiW12O40)]·3H2O(14)[Cu4(bmps)6][SiW12O40]·2H2O(15)[Ag6(bmps)6(H20)2(PW12O40)2]·H2O(16)[Ag6(bmps)6(PMo12O40)2](17)[Ag3(bmps)3(PMo12O40)]·H2O(18)4.POVs chemistry is developing rapidly today.However,exploratory synthesis of pure all-inorganic crystalline materials based on the self-condensation of hollow POV units is slowly proceeding.In this study,through a tetrazole derivative,we exploit a reduction-condensation strategy to control the size and aggregation of hollow clusters.Such ligand is selected as an efficient reducing agent for the conversion of vanadium centres,and it could also prevent undesired coordinate interactions,allowing the formation of pure inorganic crystalline materials.Through covalent connection of phosphate groups,an all-inorganic open framework has been prepared.It is built from a spherical {V10-type} structure.The semiconductor behavior and electrochemical properties have been studied.Heterogeneous catalytic activity has also been investigated.Title compound:[NH4]9[P4V10O34]1.5·3H2O(19)5.The design and synthesis of POM-based hybrid materials with specific catalytic properties are the core issues of the current catalysis chemistry.From crystal engineering view,the selection of structural components is crucial.In this study,with the use of Ni2+ and small ethylenediamine(EN)molecule,a POV-supported Ni-EN complex has been synthesized.We have observed that,through covalent bonding,the catalytic activity of eventual architecture can be modified and enhanced by structure components.The title complex exhibits excellent catalytic activity for the selective oxidation of cyclooctene with air as a sole oxidant under a mild condition,and it shows relatively high catalytic activity and selectivity of epoxy products in comparison with all of previous hybrid materials.This work provides new promising materials as heterogeneous catalyst in hydrocarbon selective oxidation field.Title compound:[Ni(EN)(H20)3(V34082)]2·4(EN)·33H20(20)... |
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