Syntheses, Crystal Structures And Charactrizations Of Corrdination Polymers Based On N-Heterocyclic Carboxylic Acids

The self-assembly of coordination polymers has been attracted great deal interest.So far, variety of coordination polymers, which comprise of various topologicalarchitectures and interesting properties, have been synthesized and characterized inthe last decades. However, the crystal engineering of coordination polymers withdesired topologies and specific properties still remains a difficult challenge. This isbecause the self-assembly process was affected by various factors, such as the natureof ligands, the coordination geometries of metal ions, metal-to-ligand ratio, thereaction temperature and pH values. Consequently, intelligent choice and design ofligands and controlled reaction conditions are the key steps toward designedmaterials.We used Nicotinic Acid, Iso-Nicotinic Acid , 3-Carboxy-1-carboxymethylpyridinium Hydroxide,1H-Benzotriazole-1-acetic acid,(1H-benzimidazol-2ylthio)acetic acid and Pyridine-2,3,5,6-tetracarboxylate asbridging ligands in the presence of 4,4'-bipyridine to react with transition metal ionsunder suitable reaction conditions, which produced ten new coordination polymers.These compounds were characterized by single crystal X-ray diffraction analysis,powder X-ray diffraction analysis, IR, TGA and fluorescence studies. The results areshown as following:1. The ten coordination polymers are:(1)[Cu₂L₃¹Cl(H₂O)₂]·EtOH.H₂O(1)(2)[Cu₂(OH)L₃²]·MeOH(2)(3)[PbClL³](3)(4)[CdClL³]·0.5H₂O(4)(5)ZnCl(L⁴)(HL⁴)]·H₂O(5)(6)[CuL₂⁴](6)(7)[Cu₂L⁵(H₂O)₃(4,4'-bpy)]·2H₂0(7)(8)[Cu₃(H₂O)₄(HL⁵)₂(4,4'-bpy)₂]·3H₂0(8) (9)[ZnL₂⁵(4,4'-bpy)(H₂O)₆]·5H₂O(9)(10)[Cd₂L⁵(H₂O)₄]·H₂O(10)2.The crystal structures of the ten coordination polymers have beencharacterized by single crystal X-ray diffraction analysis. Compounds 1, 2, 3, 4, 5, 6and 7 are 2D lamellar framework structures, while compounds 8, 9 and 10 are 3Dporous framework networks.3.We have detailed the crystal structures of the ten coordination polymers,including the coordination modes of the bridging ligands, the coordinationenvironments of metal centers and the interactions between the polymeric motifs.4. All of these coordination polymers have been characterized by IR analysis.Compounds 5, 6, 8, 9 and 10 were characterized by TGA analysis. The luminescentproperties of compounds 5 and 6 have been studied, and the relationship with theircrystal structures were investigated.