| As a new porous material,metal-organic frameworks(MOFs)are different from traditional inorganic porous materials(such as zeolite,etc.)and general organic complexes.MOFs have not only the nature of the organic ligands and inorganic metal,but also the feature of uniform porosity,pore size,large surface area,tunable pore surface and interesting topology structures,making it potential application and broad prospects in gas adsorption and separation,biological molecular recognition,selective catalysis.In this paper,four MOF materials with pores have been constructed under solvothermal condition by the reaction of the triangle tricarboxylic acid ligands,4,4',4''-(benzenetri-carbonyltris(azanediyl))tribenzoic acid(H3L1),with Mn2+,Co2+Mg2+and Sr2+salts.{[Mg3(BTCIT)2]}n(1){[Sr3(BTCIT)(OH-)3]}n(2){[Co3(BTCIT)(OH-)3]}n(3){[Mn3(BTCIT)2(DMF)(MeOH)2(H2O)]}n(4)The stability experiments of complexes 1-4 showed that complex 2 is well stable heated to350°C in the air,or in CH3OH of pH=111,or in a usual pure solvent.The adsorption experiments of complex 2 for dyes with different sizes and different charges found that it could selectively adsorb the small-sized positive dyes of Methylene Blue(MB)and Crystal Violet(MV).Based on its selectivity,the separation of MB or MB was successfully achieved respectively from the composite MB&RhB or MB&Orange II.Furthermore,the loaded dye on complex 2 can be released in methanol.For close to practical application,the complex 2 was made into a filter membrane which was documented to realize the rapid adsorption of MB.Catalytic experiments showed that complexes 1-4 had good catalytic effect on the Knoevenagel condensation reaction,maybe due to the potential synergistic effect from porous structure and Lewis base active sites.Due to the excellent stability of the complex 2,its TON value still keeps as high as 1000 in the sixth catalytic cycle.For exploring the pore-sized selectivity of complex 2,malononitrile was replaced by larger-sized Meldrums acid and no catalysis was found.Therefore,it could be concluded that complex 2 has the size selectivity to substrate for the catalysis of Knoevenagel condensation reaction.The yield of cycloaddition reaction of carbon dioxide with epoxy compound can reach up to95%under normal pressure conditions,with complex 2 as a catalyst and tetrabutylammonium bromide(TBAB)as a cocatalyst.Due to the good stability of complex 2 in a strong alkaline environment,the morpholine is used to capture the carbon dioxide in the air to carry out a cycloaddition reaction of epoxy compounds,and the yield can also reach 99%.In this paper,Zn4-TC4A-SO2,formed by the reaction of Zn(II)with Sulfonylcalix[4]arene(H4TC4A-SO2),is used as a precursor to further react respectively with the tricarboxylate acid of benzene-1,3,5-tricarboxylic acid(H3L2),1,3,5-trip(4-Carboxyphenyl)benzene(H3L3)and N,N,N-tris(4-methylenebenzoic acid)(H3L4)to construct three discrete metal-organic cages 5-7.{[Zn24(TC4A-SO2)6(BTC)8(H2O)6]}n(5){[Zn24(TC4A-SO2)6(TCB)8(H2O)6]}n(6){[Zn24(TC4A-SO2)6(TMB)8(H2O)6]}n(7)Dye extraction experiment of complex 5 was processed due to its good solubility in chloroform.It was found that 5 could selectively extract positively charged dyes,which may be attributed to many uncoordinated oxygen atoms on the Sulfonylcalix[4]arene those induce the vertexes of cage being the feature of partial negative charge.In addition,complex 5 does not exhibit size selectivity due to its large cavity size. |
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