Design And Synthesis Of Metal-carboxylate Coordination Polymers And Their Fluorescent Properties And Applications

The aim of this paper is the synthesis of new coordination polymers on the basis ofcarboxylic ligands (folic acid;2,4-dichloro-5-sulfamoylbenzoic acid;4-chloro-5-sulphamoylbenzoic acid) and main group metal ions or transition metal ions.Eleven new coordination polymers have been obtained via self-assembly reactionsunder hydrothermal conditions. Single crystal X-ray diffraction revealed that thesecompounds possess one dimensional, two dimensional and three dimensional structures,respectively. Their properties have been studied via ICP, XPRD, TG, IR, Fluorescenceand Magnetism measurements. Moreover, the synthetic conditions and laws have alsobeen investigated as well as the intrinsic link between structures and properties of thesecompounds.1. Under similar hydrothermal conditions, by using a new carboxylate ligand withmultifunctional groups, H3sba (2,4-dichloro-5-sulfamoylbenzoic acid) and bpy(4,4′-bipyridine) ligand as well as different transition metals as additives and addingdilute sodium hydroxide solution to adjust the pH, four new coordination polymers wereobtained:Co(bpy)(H2sba)2(H2O)2(1)Cd(bpy)(Hsba)H2O (2)Zn(bpy)(Hsba)(3)[Cu6(bpy)5(H2ssa)6(H2O)2]·5H2O (4)Structural analysis revealed that with addition of different metal ions, numbers ofthe unique components are changed, and the raise of the unique components would bring more complexity of the whole structure system, which are covering fromstructural segments to architectural dimensions. Interestingly, when Cu ions wereintroduced into the present reaction system, a new ligand H4ssa was obtained in situ bythe hydrolysis of chlorine in H3sba. Strong fluorescent properties were observed forcompounds2and3and reinforced them candidates for potential photoactive materials.Magnetic measurements indicated that compound4have ferromagnetic couplingbetween the adjacent metal ions.2. Under similar hydrothermal conditions, a new carboxylate ligand H3L(4-chloro-5-sulphamoylbenzoic acid) was introduced into the synthetic system as wellas the bpy ligand and transition metals. Dilute sodium hydroxide solution or diluteammonia solution was used to adjust the pH, and six new compounds were obtained:Cu(bpy)(H2L)2(5)Co(bpy)(H2L)2(H2O)2(6)Mn(bpy)(H2L)2(H2O)2(7)Ag(bpy)(H2L)(8)Cd(bpy)(HL)(H2O)(9)[Zn(bpy)(HL)]·H2O (10)Structural analysis revealed that compounds5-7exhibit1D linear chain, compound8has1D double chain, compound9possesses2D square-grid sheet and compound10shows3D window-shaped net. Photoluminescent investigation displays that differentmetals induced different luminescent emissions. Weak Co(II)-based yellow, intenseMn(II)-based blue, Ag(I)-based green, Cd(II)-based violet and Zn(II)-based violetluminescence upon irradiation with a standard UV lamp (λex=254nm) at roomtemperature. While the Cu(II)-based compound shows fluorescence quenching.Furthermore, the luminescent quantum yields (QYs) and lifetimes under UV irradiationof6-10as well as the H3L and bpy ligands have been performed. Further investigationrevealed that Cd(II)-and Zn(II)-based violet luminescence compounds9and10showgood photobleaching stability on excitation with UV light.3. Under hydrothermal conditions, one compound has been synthesized based on 22diamine solution adjusting the pH:[Pb(C19H15N7O6)]·4H2O (11)Single crystal X-ray diffraction revealed that this compound exhibits2D layeredstructure. Investigations on fluorescent properties suggested that the fluorescenceintensity of11is significantly enhanced compared with that of pure folic acid. The QYof11also significantly doubles the yield of pure folic acid. The effect of pH on thefluorescence property of11as well as the photostability indicated that11has potentialapplications in a wide range of pH and showed better photobleaching stability. The11showed an excellent staining ability with living4T1cells and were successfully used asfluorescent probes.