Preparation, Characterization And Applications Of The Coordination Polymers Based On Bis(Imidazole) And Multicarboxylate Ligands

Organic ligands play an important role in coordination polymers frameworks. Designing and selecting appropriate ligands and metal ions, as well as controlling the reaction conditions to assemble coordination polymers with novel structure and specific functions are the main contents of coordination polymers synthesis.In this thesis, twenty new coordination polymers, namely [Ni(BDC)(bix)(H2O)](1),[Co(BDC)(bix)(H2O)](2),[Ni(NDC)(bix)(H2O)](3),[Co(NDC)(bix)(H2O)](4),[Ni(TDC)(bix)(H2O)]·H2O(5),[Cd(TDC)(bix)(H2O)](6),[Cd3(BTC)2(bix)2]·H2O(7),[Zn2(biim-4)2(TDC)2]·2.5H2O(8),[Cd2(TDC)2(biim-4)2(H2O)2](9),[Cd(NDC)(biim-4)]·0.5H2O(10),[Ni(NDC)(biim-4)(H2O)](11),[Co(NDC)(biim-4)]·0.25H2O(12),[Zn2(ADP)2(bib)2](13),[Cu(ADP)(bib)(H2O)2](14),[Zn(OBA)(bib)]·2H2O(15),[Ni(OBA)(bib)](16),[Cd3(BTC)2(bib)2](17),[Zn2(BTC)2(bib)(H2O)]·H2O(18),[Co(BDC)(bib)](19) and [Co(NDC)(bib)]·H2O(20)(bix=1,4-bis(imidazol-1-ylmethyl) benzene; biim-4=1,4-bis(1-imidazolyl) butyric alkyl; bib=1,4-bis(1-imidazolyl)benzene; H2BDC=1,4-benzenedicarboxylic acid; H2NDC=1,4-naphthalene dicarboxylic acid; H2TDC=thiophene-2,5-dicarboxylic acid; H2ADP=adipic acid; H2OBA=4,4’-oxybis(benzoate); H3BTC=1,3,5-benzenetri carboxylic acid) were synthesized under hydrothermal conditions. The as-prepared coordination polymers were characterized by elemental analysis, IR spectra, X-ray single crystal diffraction, the thermostabilities and luminescent properties have also been studied.The photocatalytic activities of the coordination polymers1,3,5,8,9and10were evaluated. The results showed that the coordination polymers exhibit good photocatalytic activities for the degradation of methyl organic under UV light irradiation, the kinetic data can be fitted by the pseudo-first-order rate equation. The order of catalytic activities is consistent with the order of the band gap according to solid UV-visible absorption spectrum and the energy gap worked out through the molecular model calculated by the time-dependent density functional theory (TD-DFT). It is also found that in coordination polymers3and10,·OH radicals were active species in the photocatalytic decomposition of MO dyes. Moreover, the recycling experimental results demonstrated that coordination polymers3and10possess good photocatalytic stability and reusability for photodegradation of MO.Coordination polymers14and19modified glassy carbon electrodes were prepared by simple dip-coating method. The cyclic voltammetry tests revealed that the modified electrodes exhibit good electrochemical activities and have effective electrocatalytic activities toward H2O2oxidation in alkaline solution. The coordination polymers14and19modified electrodes can be used for H2O2detection in alkaline solution with high sensitivity and the determination limits were6.8×10-8mol/L and3.6×10-5mol/L, respectively.The catalytic performance of the as-prepared nine transition metal coordination polymers with Ni2+and Co2+ions was investigated through the epoxidation of cyclohexene with molecular oxygen as the oxidant and isobutyraldehyde as the reductant. The conversion rates of substrate were above97.1%for Co2+coordination polymers after2h at room temperature, while for Ni2+coordination polymers, conversion rates exceeded97.9%when the reaction time was4hours. The selectivities for cyclohexene epoxide of the nine coordination polymers were all larger than84.1%. The catalytic activity showed no appreciable decrease when polymers5and19were tested in several consecutive reaction cycles.