| As an emerging class of porous materials,metal-organic frameworks?MOFs?have received great attention from academia and industry during the last few decades,which is mainly attributed to their low density of the framework,exceptionally high surface area as well as tunable pores size.These advantages of MOFs materials make them exhibit excellent performance in many fields,such as gas storage and separation,fluorescence sensing,catalysis,magnetism,and have become a new research hotspot in the field of chemistry and materials science.Although,MOFs perform excellently in various applications,most of these results are believed to be conceptual.Because the poor stability of MOFs derived from the reversible nature of coordination bonds is commonly regarded as the major drawback for their practical applications in most research fields.A remarkable step forward to this end was the discovery of Zr-MOFs.Because Zr-MOFs materials not only have the advantages of the MOFs materials,they also have exceptional thermal and chemical stability,which can make it be applied in many appilcations.In previous work,people often select linear linkers to synthesize Zr-MOFs,but it is difficult to construct Zr-MOFs with novel structure.The V-shaped ligands have more coordination models and spatial adaptabilities which may make a contribution to constructing Zr-MOFs with novel framework and diverse pore structure.Moreover,the bending torsion of V-type carboxylic acid ligands is good which is easy to construct some flexible MOFs materials.Inspired by above,by using the modulator synthesis method and solvothermal synthesis strategy,seven Zr-MOFs with exceptional thermal and chemical stability and two Zn-MOFs with breathing behavior have been successfully constructed and structurally characterized,respectively.Based on the structural characteristics,the molecules adsorption and separation,fluorescence sensing and CO2 conversion properties were investigated.The results mainly include the following three aspects:?1?By using the modulator synthesis method,four stable Zr?Hf?-MOFs?compounds 1-4?,which is constructed by the V shaped ligand,has been successfully constructed and structurally characterized.Among them,compound 1 is isoreticular with compound 2,but the metal sources of two materials are different,so the properties of compound 1 were only tested.Compound 1 which exhibits an interpenetrated 3D framework is constructed by the V-shaped ligand and Zr6 cluster.Meanwhile,there exist double walls in the framework of compound 1,which make it possess extraordinary thermal and chemical stability.Although the BET surface area of compound 1 is lower than majority of Zr-MOFs,its CO2 uptake values are impressive which can rank first among the reported Zr-MOFs.Benifitting from its extraordinary stability,the fluorescent sensing property of compound 1 to detect a series of nitro explosives were explored in aqueous.Compound 1 exhibits high sensitivity and selectivity for detecting TNP in aqueous phase and the Ksv value can reach up to 2.3×105 M-1,which surpass many reported MOFs materials.Compound 3 is constructed by the V-shaped ligand and 10-connected Zr6 cluster.Benefitting from the Zr6 cluster metal chain in the framework,compound 3 exhibits excellent chemical stability in both acidic and alkaline aqueous solutions.Interestingly,compound 3 possesses dual functionalities which exhibits not only commendable trapping capacity and adsorption rate,but also high detecting sensitivity and selectivity for Cr2O72-in aqueous phase.The framework of compound 4 is similar to compound 3.However,due to the lack of pillar ligands,compound 4 is a 2D layered framework.?2?With the help of modulator synthesis method,a mesoporous Zr-based metal-organic framework?compound 5?,has been successfully constructed.Compound 5 having reo topology is constructed by the bent ligands with Lewis basic sites and 8-connected Zr6 clusters.It not only possesses two types of mesoporous cages,but also displays excellent chemical stability in acid and base aqueous phase.Benefiting from the Br?nsted and Lewis acid sites,Lewis basic sites,excellent chemical stability and the mesoporous cages incorporated in the framework,compound 5 can be regarded as a remarkably efficient heterogeneous MOFs catalyst which exhibits excellent catalytic efficiency for CO2 conversion.By the means of ligand functionalization,we successfully prepared two Lewis base modified Zr-MOFs materials,compounds 6 and 7 which are isoreticular with compound 3.Among them,compound 7 has more Lewis base sites.Due to the presence of modified functional groups,the BET surface areas of compounds 6 and 7were lower than that of compound 3,but their isosteric heat?Qst?of CO2 adsorption was significantly increased.Meanwhile,the catalytic performance of CO2 conversion is also enhanced.?3?Using the solvothermal synthesis method,we successfully prepared a doubly interpenetrated Zn-MOF material?compound 8?.It is constructed by the V-shaped ligand and classical Zn4O cluster and exhibiting pcu topology.Although,the structure of compound 8 is dense,it exhibits an interesting breathing behavior upon N2 and CO2adsorption.Furthermore,by adopting direct synthesis method,two isomorphic compounds 8'and 8''have been obtained by partial substituting Zn with different amount of Co into 8 framework,in which the content of Co in compounds 8''is higher than 8'.The gas adsorption study of Co-doped materials reveals that the gate opening effect can be modulated by introducing different contents of Co2+into the framework of compound 8.To investigate the effect of functional groups on breathing behaviour of compound 8,we successfully constructed compound 9,which is isostructural with compound 8,with a methyl functionalized H2DCPB ligand.Due to the introducing of-CH3 functional group,the structure of compound 9 is more dense and the interpenetration degree of compound 9 is closer than that of compound 8.Therefore,compound 9 exhibits a completely different breathing behavior than that of compound8.In summary,we successfully constructed 7 stable Zr?Hf?-MOFs by using the modulator synthesis method.Bennifitting from the stable of Zr-MOFs,their applications for moleculars adsorption and separation,fluorescence sensing and CO2conversion were investigated by combining the experimental and theoretical simulation.On the other hand,we also construct two breathing MOFs and investigate the effect of metal ions and functional groups on their breathing behaviour. |
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