Synthesis, Crystal Structures And Properties Of Coordination Polymers Bridged By Cyano And Carboxylic Groups

A series of coordination polymers with definite structure were synthesized by thecoordination reaction of the flexible ligand （4,4’-dithiodipyridine, dpds），the rigidligand (1,^2-bis（4-pyridyl）ethylene, tvp;1,3,5-benzenetricarboxylic acid, BTC),transition metal ions such as Zn（II），Cd（II），Mn（II） and metal salts K₂[M（CN）₄]（M=Ni,Pt, Pd） and KAg（CN）2. The effects of synthesis methods, rigidity of ligands anddifferent metal ions on crystal structures, thermal stability and sorption properties ofcoordination polymers were systematically studied. The contents are as following:1)4,4’-Dithiodipyridine （dpds） as the ligand, two framework compounds with3Dstructure were constructed by the slow diffusion method of big-small vial. Singlecrystal X-ray analysis reveals that the Cd（II） ions in two compounds aresix-coordinated. However, the Cd（II） ions have different coordination environment,leading to the different crystal structures of two compounds. It’s interesting that onlythree cyano groups of Ni（CN）4^2-in Cd-dpds-Ni take part in coordination, while thereare only two cyano groups of Pd（CN）4^2-in Cd-dpds-Pd acting as ligands, which areobviously different from the reported four-coordinated model of Ni（CN）4^2-andPd（CN）4^2-. In addition, dpds acts as a bridging ligand linking Cd（II）, Ni（CN）4^2-andPd（CN）4^2-, resceptively, leading to the formaiton of two stratified structure. Then, thethree-dimensional network structures are formed by the weak interaction force of s-Ï€between the adjacent layers.2)1,^2-Dis（4-pyridyl）ethylene （tvp） as the ligand, three coordination polymers with3D structures were constructed by the slow diffusion method of single tube.Mn-tvp-Ag and Cd-tvp-Ag have the similar interpenetrating3D structures. Analysesof topologies show that structures of the two compounds belong to rutile. Mn-tvp-Niis a classic Hofmann compound with3D structure. Tvp is not only a pillared ligand, but also acts as guests, which are located in the channel of Mn-tvp-Ni by weakinteraction force between tvp and the host. In addition, the high-pressure hydrogenadsorptive behavior of Mn-tvp-Ni was investigated.3)Based on1,3,5-benzenetricarboxylic acid （BTC） and Zn（NO₃）₂, the porousframework compound Zn（BTC）（EtOH）（DMF） was prepared by solvothermal method,which has high thermal stability and evident high-pressure hydrogen adsorptive ability.Its topology structure belongs to rutile.