| Metal-organic frameworks?MOFs?are formed by central metal or clusters and organic linkers via coordination bonds.They not only have diverse structures but also attract great attention in potential applications such as gas storage,separation and sensing,et al.Due to their high porosity,large surface area and strong chemical,thermal and water stability,MOFs made up of high-valent metal cations(Cr3+,Fe3+ or Zr4+)and carboxylic acid ligands are widely used in gas adsorption and sensing,etc.In this paper,four kinds of MOFs are obtained by introducing different anionic groups into Cr-SXU-1 materials which were characterized by powder X-ray diffraction?PXRD?,infrared spectra?KBr pellet?,physical gas sorption,thermogravimetric analysis and then investigated as separators for C2H2 and C2H4.By using the same ligand,we further synthesized three Zr-MOFs polymophs by tuning the modulators and investigated their structures and properties in selective gas adsorption and fluorescence sensing.?1?We obtained a cation MOFs by alkylation of the pyridinium nitrogen in the ligand through post modification of Cr-SXU-1.After anion exchange,NO3-and Si F62-can be introduced into the modified Cr-SXU-1.By controlling the proportions of the two anions,four different functionalized Cr-SXU-1 materials are obtained.The adsorption properties for C2H2 and C2H4 at 273 K of these materials were studied.IAST calculations showed that the adsorption selectivity of C2H2/C2H4 could be improved after modification,especially for the double anions functionalized samples.When the ratio of NO3-to SiF62-was tuning to 3:7,the performance of the adsorption selectivity of C2H2 over C2H4 was the best among these samples.?2?Three kinds of Zr-MOFs polymorphs,Zr-SXU-1,Zr-SXU-2 and Zr-SXU-3,were successfully synthesized by using tetracarboxylic acid ligand PBPTTBA and metal zirconium salts through tuning the types and concentrations of modulators.The results show that all these three Zr-MOFs have 3-D structures with high specific surface areas,high thermal and chemical stability.The adsorption properties of Zr-MOFs for C2H2,C2H4,CO2 and CH4 at 273 K were studied.The data of single component gas adsorption showed that these Zr-MOFs had different adsorption capacities for C2H2,C2H4,CO2 and CH4.The IAST results proved that they all had high adsorption selectivity for C2H2/CH4?v: v,50:50?,of which the selectivity of Zr-SXU-2 has the highest selectivity of 14.5 among these three samples.The fluorescence of these Zr-MOFs can be quenched by Fe3+,implying that they can potentially detect Fe3+ions in water. |
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