Studies On The Properties Of Porous Coordination Polymers Based On Triazole Ligands

Coordination polymers（PCPs） consist of node（metal cations or metal clusters） and linker（organic ligands）. A variety of the structures and coordination modes lead to the structural diversity of PCPs in the self-assembling process. PCPs would have wide applications on gas adsorption and separation, luminescence, catalysis and molecular recognition due to the distinctive characteristics such as intriguing structures, high porosity and controllable pore size. So the research of PCPs has become the advancing spot of material science. In this paper, the triazole ligands were used to constructe PCPs with transition-metal ions. The adsorption properties, molecular recognition and photocatalytic properties have been studied systematically.（1） We have designed and synthesized two organic ligands 3-（2-pyrazinyl）-5-（4-pyridyl）-1,2,4-triazole（Hppt） and 3-（2-pyrazinyl）-5-（4-（pyridyl）phenyl）-1,2,4-triazole（Hpptpz） based on pyrazine-2-carboxylic acid. The triazole ligands have various coordination modes, in addition, the introduction of auxiliary ligands enrich the structural diversity.（2） Two 3D compounds [Co（ppt）₂]·guest（1） and{[Cu₅（ppt）5]·H₂O}n（2） were obtained under hydrothermal conditions in the self-assembling system based on Hppt and cobalt（II）, copper（II）. The adsorption properties of the two compounds have been studied as well. When introducing the straight-chain ligands 9-fluorene-2,7-dicarboxylic acid（H₂fdc） and 9Hcarbzaole-3,6- dicarboxylic acid（H₂cdc） into the reaction system, {[Zn₂（ppt）₂（fdc）（H₂O）₂]·2DMF}n（3） and{[Zn₂（ppt）₂（cdc）（H₂O）₂]·2DMA}n（4） were obtained. Compound（3） shows 7-fold interpenetrated 3D structure. It exhibits strong luminescence at room temperature in solid-state. Luminescent property study shows that（3） can be used as a fluorescent sensor for nitrobenzene（NB）. Compound（4） shows 2D layered structure.（3） By using Hppt and Hpptpz we successfully synthesized two 0D compounds [Co₂（ppt）₄(H₃PMo₁₂O₄₀)（H₂O）₄]·4H₂O（5） and [Cu（pptpz）₂(H₂PMo₁₂O₄0)]·4H₂O（6） with the support of molybdenum phosphate oxide cluster. By detail analysis of the results of photocatalytic experiments, we find that compound（6） shows high photocatalytic activities towards methyl blue dye pollutants, in addition, the catalysts can be reused several times without significantly efficiency decay.