Study On Synthesis And Properties Of Metal-Organic Frameworks Based On New Rigid Nitrogen-Containing Ligands

With the rapid development of science and technology,metal-organic framework materials（MOFs）have become one of the research hotspots in the field of materials science due to their structural diversity and excellent functional properties.The materials have high porosity,adjustable pore structure,large specific surface area and excellent chemical stability.In this paper,we choose three rigid nitrogen-containing ligands as the building units to obtain a series of novel MOFs.1.Synthesis and properties of an anionic MOF based on bis（4-benzylimidazol-ylphenyl）sulfone.By the mixed-ligand strategy,a unique microporous anionic MOF,namely[Zn₂（btb）₂（bbis）]（Me₂NH₂）₂·6DMF（1）has been synthesized and structurally characterized[bbis=bis（4-benzylimidazol-ylphenyl）sulfone and H₃btb=4,4’,4’’-benzene-1,3,5-triyltribenzoic acid].This compound exhibits a 4-fold interpenetrated anionic framework with ins topology.The existence of Me₂NH₂⁺in pores makes it possible to encapsulate lanthanide ions through the cation exchange method.The study on the potential of Eu³⁺@1 and Tb³⁺@1 as the fluorescence probes for organic small molecule was evaluated.Meanwhile,the adsorption behavior of 1 towards organic dyes was investigated,revealing rapid and selective separation of methylene blue.2.Synthesis and properties of cationic MOFs based on tris(4-（1H-imidazol-1-yl）phosphine oxide ligand.The following two cationic MOFs,namely[Cd（tipo）（HCOO）（H₂O）]·NO₃·DMF（2）and[Ni₂（tipo）₂（bpedc）（H₂O）₄]·2NO₃·2DMF（3）(tipo=tris（4-（1H-imidazol-1-yl）phosphin-e oxide and H₂bpedc=4,4’-stilbenedicaroxylic acid）have been synthesized and structurally characterized.These compounds exhibit rapid and selective separation of methyl orange.Meanwhile,they can also been developed as the potential adsorbent material for the efficient removal of Cr₂O₇^2-from aqueous solutions.3.Synthesis and properties of MOFs based on 9,9-diethyl-2,7-bisimidazolylfluorene ligandBased on a fluorene-based bisimidazole ligand and polycarboxylic acids,six coordination polymers,namely[Cd₂（bpdc）₂（bief）₂]·xsolvent（4）,[Cd（sdc）（bief）]（5）,[Cd（odc）（bief）]·H₂O（6）,[Cd₂（1,4-ndc）₂（bief）₂]·H₂O（7）,[Cd₂（1,4-ndc）₂（bief）₂]·3H₂O（8）and[Cd（tdc）（bief）（H₂O）]（9）（bief=9,9-diethyl-2,7-bisimidazolylfluorene,1,4-H₂ndc=na-phthalene-1,4-dicarboxylicacid,H₂sdc=4,4’-sulfonyldibenzoicacid,H₂odc=4,4’-oxybisbenzoic acid,H₂tdc=thiophene-2,5-dicarboxyl acid,and H₂bpdc=biphenyl-4,4’-dicarboxylic acid）.Compound 4 exhibits a 2-fold interpenetrated sql net.Compound 5 and 6 present the 2D→3D parallel polycatenation of sql net.Compound 7features a 2D→3D parallel polycatenation of binodal 4,6L56 net.Compound 8 exhibits an eight-connected tsi framework.Compound 9 exhibits an eight-connected bcu framework.Their thermal stabilities and photochemical properties have also been studied.