Syntheses, Structures And Properties Of Coordination Polymers Constructed From N-donor Containning Dicarboxylate Ligands

In the past decades, the design and synthesis of coordination polymer hasabstracted more and more attention. These materials are constructed by secondarybuilding units (SBUs) with organic linkers, using strong bonds to create opencrystalline frameworks with permanent porosity. So these materials can widely usedin various research fields, such as luminescence, ion-exchange, gas adsorption andseparation, magnetism and catalysis. Although thousands of coordination polymershave been synthesized but the design and synthesis of a desired functionalcoordination polymer is still a great challenge.There are many factors can affect the growth and final structures of coordinationpolymer, such as reaction solvent, temperature, pH, counterions and organic ligands.The rational selectivity and design of organic ligands can achieve desired functionalpolymers. According to the flexibility of organic ligands, organic ligands can bedivided into three categories: rigid, semi-rigid and flexible ligands. People mostlytend to choose the organic ligand molecules containing O-donor atoms are widelyused to construct novel coordination polymers, due to they have versatile coordinationmodes to satisfy the geometric coordination requirement of metal centers. Recently,as functional metal centers, In(III) ions attract more and more attention because oftheir special chemical characteristics arising from their variable coordinationgeometries and coordination numbers. In contrast to divalent transition metalions,In(III) ion has the ability to adopt MO6, MO7, or even MO8coordinationmodes, while the increased valence charge of In(III) ion may also show someinfluence on the resulting structures. Transition metal complexes and clusters alsohave been studied for decades, mostly because of the unique role in bothphysical and biological research and applications.In this paper, we choose dicarboxylate ligands containing N-donor atoms:2,6-H2pdc and5-(4-pyridyl)-isophthalic acid ligands and In, Zn, Cu as metalcenters to prepare novel corrdination polymers. Four new coordination polymers havebeen successfully prepared and they show good performance in luminescence,catalysis and gas adsorption and separation. The main research results are listed asfollows:1. Using the robust dicarboxylate ligand2,6-H2pdc with InCl3, a novelcoordination polymer, InCl(2,6-pdc)(H2O)(1) was firstly prepared undersolvothermal conditions. it features a two dimensional (2D) network with therhombic windows constructed from novel [In2O6(H2O)2Cl2(2,6-pdc)2] dimericbuilding units and2,6-pdc2-ligands. Then,4,4’-bipy ligand as the secondbuilding block was introduced into the synthetic syntem and finally a newcoordination polymer In2Cl4(2,6-pdc)(4,4’-bipy)2(2) was synthesized undersolvothermal conditions, which possesses a2D layer structure accomplished byconnecting the wavy chains to the distorted4,4’-bipy ligands. The difference inthe structures of1and2show chlorine atoms and organic ligands havepredominant influence on frameworks of final product. In addition,non-classical hydrogen-bond (C–H---Cl) interactions also play an importantrole in the formation of supramolecular architectures, for instance, to link2Dentities to3D frameworks. These new In(III) CPs show intense fluorescenceemission with long lifetimes in the solid state at room temperature.2. We respectively choose the flexible5-(4-pyridyl)-isophthalic acid with ZnSO4and CuSO4to prepare two novel coordination polymers Zn (L) CH3CH2OH (3)and Cu (L)(4) under solvothermal conditions. In compound3, two carboxylategroups of the L2-ligand bridging two Zn atoms to build a second building unit(SBU)[Zn2O8] which can be further linked to form a layered network. Incompound4, two carboxylate groups of the L2-ligand have two coordinationmodes, one bidentately bridging two Cu atoms to create a paddlewheel SBUand the other chelating one Cu atom. The SBUs links the carboxylate of the L2-ligands to form an3D quartz structure framework. Compound3exhibit goodluminescence properties and show excellent catalytic activities in Strecker reaction. Compound4displays good gas adsorption.