| Developed rapidly in recent years,metal-organic frameworks(MOFs)as a new kind of porous functional materials,has shown outstanding performance in many fields such as adsorption,catalysis,sensing,magnetism and drug releasing.Because of the inorganic-organic hybridization,the various coordination modes of inorganic and organic building blocks could lead to the varied structures of MOFs,then the complexity of structures give the possibility of various properties for MOFs materials.Up to now,many synthetic strategies have been explored for the design and construction of MOFs with different characteristics.Molecular building blocks(MBBs)approach is one of the most important among them,and mixed molecular building blocks strategy is the promotion and extension for it.In this thesis,the mixed molecular building blocks strategy is used to design and synthesize new MOFs materials from different views like inorganic or organic building blocks and supermolecular building layers,and then explore their application properties on gas adsorption and separation,CO2 conversion and iodine adsorption and release.This thesis mainly includes the following three aspects:(1)The configuration of metal clusters is more complex than that of mononuclear metal ion,and using different metal clusters-MBBs in the synthesis of MOFs materials can enrich the topological structure types of them.Therefore,based on mixed different metal-MBBs strategy,multiple Cu-MBBs were obtained using Cu I as the metal source and connected with organic ligands of various coordination types,then three novel Cu-MOFs materials based on CuxIy clusters were successfully synthesized,[(Cu4I4)8(Cu8I6)(Dabco)8Cu12(pybz)24DMF12]·2NO3·17DMF(compound1),[(Cu4I4)Cu(pybz)2(Dabco)1.5]·10H2O·2DMF(compound 2)and[(Cu2I2)Cu2(pybz)2(Tzna)2]·solvent(compound 3).Compound 1 contains three kinds of Cu-MBBs,the rare Cu8I6 clusters,classical Cu4I4 clusters and Cu-paddlewheel MBBs.However,the pore size of compound 1 is too tiny for gas molecules to pass through.Compound 2 consists of two building blocks,Cu4I4 clusters and Cu-paddlewheel MBBs.One-dimensional straight channels about 6.8?×9.8?could be observed in the structure of compound 2,and it exhibits high BET surface area and good ability for gas adsorption and separation.Compound3 possesses Cu2I2 clusters and Cu-paddlewheel MBBs,and the framework is not stable enough for carrying gas adsorption test due to the Cu2I2exist.All three compounds display a good capacity of iodine adsorption and release.Through the successful preparation of compounds 1-3 with different topological structures,the effective regulation of MBBs with different configurations and types from the same metal source is realized,which provides a references for the preparation of MOFs with novel structures.(2)Although the coordination configurations of organic ligands are not as intricate as metal clusters,there are many kinds of organic ligands and they are easy to be modified.Functional design of organic building blocks is a useful way to obtain MOFs materials with specific properties,and the mixing of organic building blocks with different properties can prepare MOFs materials with multi-functional sites.Therefore,based on mixed organic-MBBs strategy,three new MOFs materials were successfully constructed by coordinating the triangular and linear ligands with polynuclear metal clusters,[Co3(?2-OH)(bpydc)(Htpim)2]·3NO3·4Me OH·5DMA(compound 4),[Ni3(?2-OH)(bpydc)(Htpim)2]·solvent(compound 5)and[Co3(?2-OH)(?3-OH)(pybz)3(Htpim)]·NO3·DMF·3CH3OH(compound 6).Compound 4 and 5 are formed by triangular N-donor ligands,linear carboxylate-based ligands and binuclear Co/Ni-clusters.By equipping the open metal sites(OMSs)on the N-sites of the carboxylate-based ligand,OMSs has been introducing into the frameworks.Both the two compounds show the CO2 capture and conversion capacity,among which compound 4 is with high conversion rate and mild reaction conditions for its better activation.Simultaneously,they also exhibit excellent gas adsorption and separation performance.Triangular N-donor ligands and linear pyridine carboxylate-based ligands are connected with asymmetric trinuclear Co-clusters,constructing the framework structure of compound 6.There are tetrahedral cavities in the channels of the compound,which could enhance the interaction with the C2H6 molecules and the framework.Besides,no OMSs could be observed in this structure,thus compound 6 has no selectivity for C2H4 molecules.Therefore,compound 6 demonstrates an interesting C2H6-selective C2H6/C2H4separation performance.Although compounds 4 and 6 are respectively obtained by mixing the N-contained triangular ligand with linear ligands of different coordination sites and both the two are Co-MOFs materials,they exhibit different properties in applications.This indicates that the structures and properties of MOFs materials can be effectively regulated by changing the organic building blocks.(3)Using the highly connected molecular building blocks or supermolecular building blocks has been proved to be an effective method for the design and assembly of MOFs materials.The supermolecular building layer(SBLs)approach,as a further step in this study direction,could provide the detailed information about the structures of two-dimensional layers,and allow the modulation of the third direction.Therefore,based on SBLs strategy,triangular carboxylate-based ligands and binuclear Cu-paddlewheel MBBs were selected to assembly SBLs,and the linkers with coordinated sites were used to support the layers,then two MOFs materials of triply interpenetrated frameworks were successfully obtained,[Cu2BTB2/3(Imna)2]·3DMF(compound 7)and[Cu2(NH2-BTB)2/3(Imna)2]·solvent(compound 8).Compound 7 and 8 are both based on hcb topology SBLs and display a structure of tfz topology.There are independent but interconnected hexagonal prismatic cages between the two interpenetrated frameworks,each cage is high about 3.8?,and the distance between the opposite sides is about 14.4?.Compound 8 is a functionalized structure gained by replacing the triangular carboxylate-based ligands in compound 7with a-NH2 modified one,and both two compounds possess good gas adsorption and separation properties.Different from the conventional regulation that applied on the supporting ligands,the-NH2 functional groups are successfully modified into the cages by introducing-NH2 modified ligands into the SBLs of compound 8.Compared with compound 7,the Xe/Kr and C2H2/CH4 separation performance of compound 8 is significantly improved.This functional design provides a reference for the preparation of MOFs materials with gas separation properties. |
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