Synthesis,Stuctures And Properties Of Transition Metal Coordination Polymers Based On Bispyridine Methylidene Cyclohexanone Ligands

Coordination polymers are the complexes with highly regular infinite network structure formed by metal ions and inorganic/organic ligands through Coordination bonds.The porous coordination polymers formed by metal ions or metal clusters with organic ligands are called Metal-organic Frameworks（MOFs）.As a new kind of molecular crystal material,it can crystallize into one,two or three dimensional network structure.Based on the research of structure-function correlation,it is found that coordination polymers has great potential application value in many fields,such as light,electricity,magnetism,gas adsorption and separation,catalysis and so on.In this paper,twelve transition metal coordination polymers were successfully synthesized by two base ligands 2,6-bis（4-pyridyl methylidene）cyclohexanone（BPCH）and 2,6-bis（3-pyridyl methylidene）cyclohexanone（BPMC）with different aromatic carboxylic acids under mixed-ligand synthetic strategy.And their structures and properties are also characterized and explored,the main contents are as follows:（1）The ligand BPCH was synthesized by a simple condensation of aldehydes and ketones.Then,selected three rigid aromatic acid ligands terephthalic acid（H₂TP）,isophthalic acid（H₂IP）and trimesic acid（H₃TMA）,seven coordination polymers were successfully synthesized by solvothermal method.The structure characterization of MOFs reveals that MOFs 1,2 and 3 all showed three-dimensional structures,while MOFs 4-7 showed isoreticular two-dimensional structures.In addition,MOFs all exhibit good fluorescence quenching effect on Fe³⁺.Then,the conductivity of MOF 2was investigated.Result displays that the proton conductivity of MOF 2 was4.10×10^-6 S cm^-1 at condition of 60℃and 98%RH.In the exploration of organic dye adsorption,it was found that MOFs showed a certain adsorption performance for methyl orange dye.（2）The ligand BPMC,similar to the ligand BPCH,was synthesized under the same reaction route of condensation of aldehydes and ketones.The only difference between them was the position of pyridine.Five coordination polymers were synthesized by solvothermal method under the same conditions with three rigid acids ligands,H₂TP,H₂IP and 5-methyl-isophthalic acid（H₂MP）.Structure characterization showed that MOFs 8,9 and 11 were identical to the two-dimensional structures of MOFs 4-7,while MOFs 10 and 12 were different from the previously synthesized structures.In terms of properties,MOFs 9,10 and 11 all have a good fluorescence quenching sensing effect on Fe³⁺.After further investigation of the fluorescence of MOF 10,it is found that it has a good anti-interference effect on other metal ions,and has a certain cycling performance.In addition,the proton conductivity of MOFs 9 and10 are 7.00×10^-7 S cm^-1 and 1.53×10^-7 S cm^-1 at 60℃and 98%RH,respectively.MOFs 8,9,10 and 11 also have a certain adsorption effect on organic dye methyl orange.