| MOFs are ordered three-dimensional frameworks formed by a type of metal ion or metal cluster unit connected by an organic ligand with coordinate bonds.Due to the variety of choices of metal ions,organic ligands and coordination networks,MOFs have a rich structural variability.With the continuous promotion of many researchers at home and abroad,MOFs have shown unique performance in energy gas storage,selective adsorption and separation,conduction,catalysis,biomedicine,sensing,molecular recognition,magnetism,etc.To the hot spot of coordination chemistry and crystal engineering research,and to become the cross-disciplinary frontier of chemistry,physics,materials and biology.Based on structural design,the research on the structure and structure-activity relationship of functionally oriented MOFs such as holes,magnetism and light has been the focus of this field.Based on the widely studied polycarboxylic acid ligands and polynitrogen ligands,this paper mainly explores the synthesis of carboxylic acid ligands containing N and S heterocycles,and studies the coordination of such ligands with transition metal ions.The assembly rules are used to realize the directional construction of MOFs with certain physicochemical properties such as gas adsorption,iodine loading,magnetism and fluorescence,and reveal the relevant structure-activity relationship.The purpose of this paper is to construct multifunctional MOFs with a certain pore,magnetic,optical,iodine loading and the like.Ligands containing lone pairs of electrons show good properties in these respects.Most of the commonly used ligands are carboxylic acid ligands and polynitrogen ligands.Although the carboxylic acid ligands have strong coordination ability,the coordination mode is difficult to control,and the coordination mode of the multi-nitrogen ligand is simple and easy to control,but the coordination ability is weak.Therefore,we have selected N,S heterocyclic-carboxylic acid ligands for the construction of MOFs.The N heterocyclic-carboxylic acid ligand 4-?4-pyridyl?benzoic acid?Hpybz?was synthesized by Suzuki reaction design.Hpybz and custom ligand2-?pyridin-4-yl?-1H-benzo[d]imidazol-5-carboxylic acid?Hpbca?were used to constructthree-dimensionalMOFs[Cd?pybz?2]·4DMF?1?and[Cd?pbca?2]·1.5DMF·2CH3OH?2?with Cd2+,respectively.Compounds 1 and 2were studied for adsorption,fluorescence and iodine absorption.Compound 1 has N2 adsorption and blue fluorescence;Compound 2 is a multifunctional material with CO2 selective adsorption,efficient capture of iodine vapor and blue fluorescence upon excitation by ultraviolet light.The S heterocyclic-carboxylic acid ligand 4,4'-?benzo[c][1,2,5]thiadiazole-4,7-diyl?dibenzoic acid was synthesized by Suzuki reaction and Heckreactiondesign.H2bdda)and3,3'-?benzo[c][1,2,5]thiadiazole-4,7-substituted?-diacrylic acid?H2btda?.Based on H2bdda,H2btda and ligand thiophene-2,5-dicarboxylic acid?H2tdc?,Zn2+,Co2+,Cd2+and Pb2+were reacted under solvothermal conditions to construct 12 novel MOFs compounds 3-14.Compound[Zn3?tdc?3?DMF?3]·3DMF?3?,[Co3?tdc?3?DMF?3]·4DMF?4?,[Zn3?tdc?3?DMF?3]·3DMF?5?and[Cd3?tdc?3?DMA?3?H2O?]·3DMA·H2O?10?is a porous structure with a pore ratio of about 27 to 57%,and has the adsorptivity of N2 and CO2.The iodine loading test showed that compounds 3,4,and 10 had good iodine loading capacity,and the maximum adsorption amounts to iodine vapor were 0.75,0.32,and 0.24 g·g-1,respectively.Compound[Co3?tdc?3?DMF?3]·2DMF?6?,[Co3?tdc?3?DMF?3]·4DMF?8?,[Co?tdc??DMF?]·4DMF?9?and[NH2?CH3?2]2·[Fe?SO4?4]?14?has antiferro-magnetic properties.The compounds[Pb?bdda??DMF?]?13?have solid state fluorescence. |
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