Synthesis And Biologically Inspired Catalytic Activity Of Benzimidazole Derivatives Copper Complexes

In recent years,iron-porphrin and iron-phthalocyanine complexes have been used as the model compounds of iron-porphrin-containing oxidase,such as P-450.The model compounds have been used as catalysis in the treatment of dyes pollutants with environmentally friendly oxidants,such as hydrogen peroxide.More attentions have been paid to this.The copper-containing oxidase,such as laccase,has been used in the dye removal.The activity center is Cu atom and the coordination atoms from histidine and other ligands with the Cu atom in the copper-containing oxidase.Benzimidazole derivatives have the similar structure of histidine（His）and cysteine（Cys）.In this thesis,benzimidazole derivatives copper complexes were designed and synthesized,which could be used as the model compounds of copper-containing oxidase in dyes degradation.The study would be very important to solve the pollution problems of dyes wastewater.The experiments and results are as follows:（1）Benzimidazole derivatives and their copper complexes were synthesized and characterized by 1HNMR spectra,IR spectra and element analysis.Found that the molar ratio of the ligand and Cu²⁺ was 1:1 in CuL^d and 2:1 in CuL^c,the probable structure of the series of CuL^d and CuL^c were deduced.（2）The degradation of Methyl Orange,Rhodamine B,Acid Blue 9,Methyl Violet Alizarin Red and Azo B0115 in aqueous solution were investigated with CuL^d or CuL^c as catalysis in presence of n（H₂O₂）:n（dye）:（complex）=1000:1:0.08.Found that CuL^d or CuL^c have novel catalytic activities in the degradation of Methyl Orange,Rhodamine B,Acid Blue 9,Methyl Violet and Alizarin Red without Azo B0115.And found that CuL^d or CuL^c have poor catalytic activities in the degradation of Azo B0115 for –NO₂ and –Br in the Azo B0115 structure.（3）The effects of pH and H₂O₂ on the catalytic activities were investigated.The optimum experimental conditions were n（H₂O₂）:n（dye）:n（complex）=200:1:0.08,pH=9.0.（4）The effects of salts were investigated in the optimum experimental conditions.Found that Cl^-、SO₄²-、NO₃^-、Br-and NO₂^-are easier to combine with hydroxyl radical,which results in lower removal rate.（5）The effects of the substituting group in the ligand on the catalytic activities were investigated.Found that electron-withdrawing group of ligand could be of benefit to the catalytic activity.The catalytic activity with electron-withdrawing group would be better than the catalytic activity with electron-donating group.（6）The stability of CuL^d and CuL^c was investigated in presence of HCl,Na OH and pH=9.0 buffer.The catalyst CuL^d and CuL^c are stable in the presence of the buffer,they have been repeatedly used up to 5 cycle runs without loss in activity.The catalytic activity disappeared in the presence of HCl,but resumed while the base added.The catalytic activity disappeared in the presence of Na OH,but not resumed while the acid added.（7）The degradation of Methyl Orange,Rhodamine B and Alizarin Red solution were investigated by UV-Vis spectra and COD methods.The results show that the removal of dyes was not only decolorization,but also degradation.（8）The products of degradation were investigated by LC-MS and HPLC.Found that there exists maleic acid in final products,and complex of CuL^d or CuL^c with the dye in middle products.The degradation mechanism and the catalytic mechanism were deduced..（9）The Michaelis-Menten constant was established by Graph Pad Prism 5.The Km values of the complexes CuL^d4 and CuL^c4 as mimetic enzyme in degradation of Methyl Orange and Rhodamine B were in 10^-210^-5 mol/L,which show that the mimics CuL^d4 and CuL^c4 has natural enzyme activity.