Syntheses And Characterization Of Coordination Polymers From New Bisimidazole Ligands By The Mixed-Ligand Strategy

Over the past few decades,coordination polymers have increased much attention owing to their intriguing structural diversity and potential applications in catalysis,gas sorption/separation,luminescence,magnetism,and so on.However,it is difficult to synthesize entangled motifs with tailored structures and properties,because crystallization is a very complicated process,and the temperature,pH value,solvents and counter anions,can impose unpredictable impact on the final architectures.In this work,we designed and synthesized a series of bisimidazole ligands and constructed 16novel coordination polymers by the mixed-ligand strategy.Meanwhile,their thermal stability,optical properties and adsorption behaviors to organic dyes have been studied.The main results are as follows:1.Based on a flexible bisimidazole ligand 1-(4-（4-（1H-imidazol-1-yl）benzyloxy）phenyl（ibpi）as the building unit to construct novel CPs,we have synthesized eight new coordination polymers,namely[Cd（cba）（ibpi）]（1）,[Cd（sdc）（ibpi）]·H₂O（2）,[Cd₂（bpdc）₂（ibpi）₂]（3）,[Ni₂（sdc）₂（ibpi）₂（H₂O）₂]·H₂O（4）,[Cd₂（tdc）₂（ibpi）]·H₂O（5）,[Cd（Hbtc）（ibpi）]（6）and[Co₂（tdc）₂（ibpi）₂·H₂O]·2H₂O（7）.Compound 1 exhibits a 2-fold parallel interpenetration of sql networks.Compound2 presents a 3-fold parallel interpenetration of sql networks.Compound 3 features a parallel polycatenation of 3-fold interpenetrated sql networks.Compound 4 shows a unique type of inclined interpenetration of sql networks.Compound 5 displays a 3-fold interpenetration of pcu network.Compound 6 exhibits a uninodal self-catenating mab network.Compound 7 shows an 8-connected self-catenating framework of 8T10topology with the point symbol(4²⁰·6⁸).The thermal stabilities and photochemical properties of compounds 1,2,3,5 and 6 have also been studied.2.Wedesignedandsynthesizedanewbisimidazoleligand bis(4-（2’-ethylimidazol-ylphenyl）sulfone（L）as the building unit to construct entangled MOFs.Three linear dicarboxylic acids with different length were also introduced.Successfully,we reported here three entangled MOFs,namely[Zn₂（cba）₂L₂]·2H₂O（8）,[Zn₂（bpdc）₂L₂]·11H₂O（9）and[Zn₄（sda）₄L₂]·14DMF（10）.Compound 8 shows a 4-fold interpenetration of dia net.Compound 9 presents an unusual 1D→3D polycatenane by the 4-fold interpenetration of 1D tubular net.Compound 10 exhibits a 3-fold interpenetration of pcu net.They have good luminescent properties and thermal stability.3.We designed and synthesized a new rigid bisimidazole ligand,2,6-bis（imidazole-1-yl）naphthalene（2,6-bin）as the building unit to construct new MOFs.Successfully,we have synthesized six new MOFs by the mixed-ligand strategy,namely[Cd₂（odc）₂（2,6-bin）₂]·（CH₃）₂NH（11）,[Cd₂（tdc）₂（2,6-bin）₂（H₂O）₂]（12）,[Cd₂（bzdc）₂（2,6-bin）₂]·4DMF（13）,[Cd₂（hfdc）₂（2,6-bin）₂]·H₂O（14）,[Cd₃（tpo）₂（2,6-bin）₃（H₂O）₄]·2DMF·2H₂O（15）and[Zn₃（btb）₂（2,6-bin）]·8DMF（16）.Comound 11 exhibts a three-fold interpenetration of 4T25 network.Compound 12presents a five-fold interpenetration of dia network.Compound 13 displays a 2D→2D three-fold inerpenetration of sql layers.Compound 14 features a 2D→3D parallel polycatenation of sql layers.Compound 15 exhibits an unusual 3,4,6-connected self-catenated network of 3,4,6T206 topology.Compound 16 shows a rare 3,8-connected self-catenated network of 3,8T72 topology.These compounds have been characterized by elemental analysis,thermogravimetric analysis（TGA）and X-ray crystallography.Meanwhile,their adsorption behaviors to organic dyes have been studied.Almost all of these compounds exhibit selective adsorption to anionic methyl orange.