The Constructions And Properties Of Complexes Based On Flexible Bifunctional Nitrogen Heterocyclic-carboxylate Connector

The rational design and construction of new coordination complexes have attracted significant interest due to their intriguing structural diversity and promising applications in catalysis, sorption, sensors, photonics and magnetism areas. In order to get novel complexes, much effort should be devoted not only to investigating the factors that have important effect on the structures of complexes: metal ions, pH value, temperature, solvent, but also to selecting organic ligands. Accordingly, aromatic multicarboxylate ligands are excellent building blocks in the construction of coordination polymers for their outstanding features of flexible coordination fashions, because these building blocks contain nitrogen and oxygen atoms and can coordinate with metal centers in versatile ways, resulting in the formations of various complexes with specific topologies and useful properties.Firstly, we chose4’-[4-methyl-6-(1-methyl-1H-benzimidazoly-l-2-group)-2-n-propyl-1H-benzimidazolylmethyl]-biphenyl-2-carboxylic acid (Hmbbc) as a target ligand. Five2D complexes {Ag2(Hmbbc)2(ClO4)2(H2O)}n (1),{Ag(mbbc)(H2O)}n (2){Cd(mbbc)2}n (3){Ag2(Hmbbc)2(SO3CF3)2}n (4) and {Co(mbbc)2}n (5) based on d10metal centres and the flexible ligand have been synthesized in the EtOH-H2O solvent system.1–5are further extended into3D supra-molecular architectures by hydrogen bonds and π···π interactions. The photoluminescence properties1–4in the solid state have been investigated. With the temperature reduction, the increased lifetimes in millisecond range and the large Stokes shift agree with strong intense phosphorescence emission of1and2. In contrast to Hmbbc,3exhibits weak luminescence emission at room temperature.Secondly, we chose3-(4-(2-(1H-tetrazol-5-yl)phenyl-4-yl)phenyl)-2-ethoxy-3H-benzimidazole-4-carboxylic acid (tppbc) as a target ligand and prepared five novel complexes {Zn2(tppbc)2(Dpy)}n (6),{Cd(tppbc)(py)(H2O)}n (7),{[Pb2(H2O)4(tppbc)2]·(CH3)2NCHO}n (8),{Co(tppbc)(py)(H2O)}n (9) and {Ni(tppbc)(py)(H2O)}n (10). X-ray analysis demonstrates that6is2D layer, while complexes7–10feature1D chains. The results indicate the crystal structures have been also influenced by the the coordination geometries of metal centers and the types of organic ligands.