Construction Of Coordination Polymers Based On Carboxylate-containing Ligand

The study of coordination polymers has attracted greatly attention recently, inview of their interesting and varied constructions as well as their potentialapplications in many areas such as optics, magnetism, catalysis, gas adsorption andseparation, etc.In this paper five complexes assembled from5-amino-isophthalic acid,4-amino-3,4-bis(2-pyridyl)-1,2,4-triazole and the transition metal ions were prepared:{[Ni(3-bpt)(aip)(H2O)2]·(H2O)2}n(1),{[Co(3-bpt)(aip)(H2O)2]·(H2O)2}n(2),{[Cu(3-bpt)(aip)(H2O)2]·(H2O)2}n(3),{[Mn(3-bpt)(aip)(H2O)2]·(H2O)2}n(4),{[Zn(3-bpt)(aip)(H2O)2]·(H2O)2}n(5). All complexes have been characterized bysigle-crystal X-ray diffraction, IR, elemental analysis, powder X-ray diffraction.Their thermal stabilities have also been studied.Single-crystal X-ray diffraction analyses indicate that the structures of thesecomplexes are isostructural. H2aip was fully deprotonated (aip2-)to balance the chargeof the complex. The metal ion have a octahedral geometry: which is surrounded by two Natoms from pyridyl of-3-bpt, four O atoms from two coordinated water molecules and two aip2-ligands respectively. The carboxyl group of aip ligands adopting bis(monodentate)bridging motif and pyridine group of cis--3-bpt link the two equivalent metal centersto form a1D undulated chain. Besides,The hydrogen bonds expand1D to3Dconstruction. Beside hydrogen bonding, π–π stacking interactions were found in thecomplex.Many factors such as the structure of the ligands, the metal ions, the ratio ofmetal to ligand, solvent and the pH value of the solution can affect the complexstructures. The polarity of the solvent have an important influence on the synthesis ofthe complexes.The system of methanol and water is the best condition for the crystal growth. Thechange of ions have no effect on the crystal structure.The value of pH is different for differentmetal ions.