Coordination Assembly Based On Pyridine Derivatives And Dicarboyxlic Acid Ligands: Syntheses,structures And Properties

Coordination polymer is a kind of crystalline metal-organic hybrid compound self-assembled from metal ion and organic ligands,and it has the unlimited extensions of one-dimensional or multi-dimensional periodic networks.Great efforts have been expended on crystal engineering of coordination polymers because of their potential values in optics,adsorption,separation and so on.For a long time,people are dedicated to the design and synthesis of novel coordination polymer and exploreed the rule of synthesis.In the last few decades,pyridine and its derivatives and rigid aromatic carboxylic acid ligands have been widely used to construct coordination polymers as they can constitute coordination polymer which often has new structure and unique characteristics with the transition metal.First,pyridine derivatives have abundant chemical properties and good biological activities and rigid aromatic carboxylic acid ligands have a stable structure which make the structure more predictable in the self-assembly process.Then,both pyridine derivatives and rigid aromatic carboxylic acid ligands have strong ability of coordination and flexible co-ordination mode.In addition,they can form the non-covalent bonding interactions,such as hydrogen bonding,?-? stacking,in the coordination polymer.In this work,two pyridine derivatives 1,3-bis[2-?4'-pyridyl?ethenyl]benzene?1,3-BPEB?and 4-[2-?4-imidazole?styryl]pyridine?ISPE?,which have mostly not been explored so far,were choosed to react with transition metal salt and rigid aromatic carboxylic acid ligands by solvent thermal method.Nine coordination polymer crystals were synthesized through self-assembly.We determined their crystal structures and carried out preliminary studies on their structures,thermal stability and fluorescence properties,which provides the reference to investigate the coordinations and explore their potential applications.The main research contents of this paper are shown below:1.Three coordination polymers [Zn?1,3-BPEB??1,4-BDC?]_n?1?,[Zn₂?1,3-BPEB??4,4'-BPDC?₂·DMF]_n?2?and [Zn?1,3-BPEB??4,4'-STDC?]_n?3?have been prepared by solvothermal reaction of 1,3-BPEB ligands,transition metal salt Zn?NO₃?₂·6H₂O and three rigid aromatic dicarboxylic acid?1,4-BDC,4,4'-BPDC,4,4'-STDC?.We determined their crystal structures by X-ray single crystal diffraction.Complex 1 and 2 have 3-D structure obtained by interpenetration of two-dimensional network in the vertical direction.Complex 3 has a fivefold interpenetrating 3-D coordination framework.It can be seen that the dicarboxylic acids has important influence on the fluorescence properties of the coordination polymer from fluorescence analysis.2.Three coordination polymers complexes [Cd3?1,3-BPEB?₃?1,4-BDC?₃·2H₂O]_n?4?,[Cd₂?1,3-BPEB?₂?4,4'-BPDC?₂]_n?5?and [Cd2?1,3-BPEB?₂?4,4'-STDC?₂]_n?6?have been prepared by the solvothermal reaction of 1,3-BPEB ligands,transition metal salt Cd?NO₃?₂·4H₂O and three rigid aromatic dicarboxylic acid?1,4-BDC,4,4'-BPDC,4,4'-STDC?in the same molar ratio and the reaction conditions.We determined their crystal structures by X-ray single crystal diffraction.Complex 4 has three-dimensional network structure.Complex 5 shows a 2-D triple interpenetrating layered structure.Complex 6 has a fivefold interpenetrating 3-D coordination framework.It can be seen that the length of the dicarboxylic acids has important influence on the structure of the coordination polymer.Complexes 4-6 have good thermal stability and fluorescence properties.3.Three coordination polymers [Cd₂?ISPE?₂?1,3-BDC?₂·DMF]_n?7?,[Cd?ISPE??4,4'-BPDC?]_n?8?and [Cd?ISPE?₂?4,4'-STDC?·2H₂O]_n?9?have been prepared by solvothermal reaction of ISPE ligands,transition metal salt and three rigid aromatic dicarboxylic acid?1,3-BDC,4,4'-BPDC,4,4'-STDC?.We determined their crystal structures by X-ray single crystal diffraction.Complex 7 has a 2-D layered structure,complex 8 has sixfold interpenetrating 3-D diamantane structure,complex 9 has 3-D structure formed by stacking of 1-D chains through hydrogen bonds and intermolecular forces.Complexes 7-9 also have good fluorescence properties.