Synthesis, Structure And Properties Of Complexes Based On 3-carboxy-1-(3'-carboxybenzyl)-2-pyridine Oxid

Coordination polymers are one-dimensional,two-dimensional and three-dimensional infinite chain networks formed by metal ions or metal clusters connected with bridged organic ligands.The synthesis of the first coordination polymer,Prussian blue,dates back to the 18th century.However,it is only in the past20 years that research activity in the field of CPs has grown rapidly.This is due not only to the simple synthetic routes for the manufacture of these materials and the X-ray crystallography techniques commonly available to ordinary researchers,but also to a wide range of promising applications ranging from gas storage,separation and catalysis to magnetism,conductivity,luminescence,sensing and drug delivery.The unique properties of metal ions,the reversible binding of strong M-L bonds and the potential for designing the required topologies also attract researchers for these CPs.Therefore,CPs is a very important and developing field in crystal engineering.Using modular methods based on a variety of organic ligands and metal ions or clusters,many potential network structures can be designed,which have the functions of giving required properties such as porosity,surface area and luminescence.Obviously,research in this field still needs to make further progress in controlling the performance of different applications.In this work,a series of coordination polymers were synthesized by hydrothermal method from dicarboxylic acid（3-carboxyl-1-（3-carboxybenzyl）-2-pyridine oxide）ligands,nitrogen-containing ligands and metal ions.They are respectively[Zn（L）（H₂O）₂]_n（1）,[Zn（L）（2,2’-bpy）（H₂O）]_n（2）,[Zn（L）（4,4’-bpy）_0.5]_n（3）,[Cd（L）（2,2’-bpy）]_n（4）,[Cd（L）（phen）（H₂O）]_n（5）,[Co（L）（H₂O）₂]_n（6）,[Co（L）（2,2’-bpy）（H₂O）]_n（7）,[Co（L）（4,4’-bpy）_0.5]_n（8）,[Mn₂（L）₂（2H₂O）]_n（9）,[Mn（L）（2,2’-bpy）（H₂O）]_n（10）,[Mn（L）（phen）（H₂O）]_n（11）,[Cu（L）（H₂O）]_n（12）,[Cu（L）（phen）（H₂O）]·2H₂O（13）,{[Cu（L）（bis）_0.5]·H₂O}_n（14）,{[Cu（L）（biim-4）_0.5（H₂O）]·1.5H₂O}_n（15）,[Mg（L）（2H₂O）]_n（16）and{[Ca₂（L）₂（H₂O）₂]·2H₂O}_n（17）.The structures of the coordination polymers were determined by X-ray single crystal diffraction and characterized by elemental analysis,infrared spectroscopy,UV diffuse reflectance spectra,thermogravimetric analysis and powder X-ray diffraction.Compounds 1,4,6and 16 show an 1D double-stranded structure,which contain a metal ring structure.Compounds 2,5,7,10 and 11 display an one-dimensional single-chain structure,and then the adjacent one-dimensional chains further expand the 3D supramolecular structure through weak interaction hydrogen bonds orπ-πstacking interaction.Compounds 3 and 8 directly formed a 3D organic skeleton,and the linear ligand4,4’-bpy can effectively improve the structure size.In compounds 3 and 8,a 2D layer constructed by L^2-and metal ions is further connected to 4,4’-bpy to form a 3D skeleton.Compound 9 is a two-dimensional planar structure containing metal oxygen clusters.Compound 13 show a 0D structure and forms an 1D supramolecular chain through intermolecular hydrogen bonds.Compound 17 shows an 1D ring structure.In this paper,the fluorescence properties of compounds 1-5 were analyzed,the UV-visible absorption spectrum and structure of compounds 6-15 were analyzed in detail,and the luminescent properties of compound 16-17 were explored.