Biomimetic Oxidation Of Chlorophenol Catalyzed By Metal Phthalcocyanine And Its Application In Chlorophenol Detection

The design and preparation of fiber optic sening materials is an important research direction of fiber optic chemical sensors. The performance of fiber optic chemical sensors will be directly determined by the properities of sensing materials. Therefore, it is of great significance to imporve the performance of fiber optic chemical sensors by exploring sensing materials with high performance. Metal phthalocyanine (MPc) is a planar ring-conjugated complex with stable physical and chemical properties. Due to its excellent performance of biomimetic catalysis and good stability, MPcs became the artificial catalysts to replace natural enzymes and were used as the sensing materials of fiber optic chemical sensors. The fiber optic chemical sensors based on MPc catalysis can overcome the shortages of those enzyme sensors such as high cost, poor stability and reproducibility, which exhibiting promising prospect. Consequently, the exploration of MPcs with low cost, high catalysis performance and stability is our research idea. We synthesized the MPcs by using the molecular design method of changing metal ions in the center of Pc ring and introducing the functional groups into Pcs. The best experimental conditions for MPc catalyzed chlorophenol (CP) oxidation were studied for the fast and sensitive detection of CP.In this thesis, the investigations on catalysis of MPcs have been performed in the following aspects. The main conclusion was deduced as following:1. TNFe(II)Pc catalyzed oxidation of four chlorophenol pollutants(1) The synthesis of TNFe(Ⅱ)Pc complexes could be achieved via solid fusion reaction during three hours. The oxidation of four common phenolic compounds which included2-chlorophenol (2-CP),4-chlorophenol (4-CP),2,4-chlorophenol (DCP) and phenol, could be efficiently catalyzed by TNFe(II)Pc in the prescence of4-aminoantipyrine (4-AAP), and the pink quinone imide dyes could be formed rapidly. The fast chromogenic phenomenon could be observed in2-CP and DCP system, and the reaction rate constant reached53.38×10"3and81.13x10-3min-1, respectively.(2) The mechanism experiments testified that the active oxygen species was superoxide anion radical (O2·-) for TNFe(Ⅱ)Pc catalyzed CP oxidation. The coordination of CP-TNFe(Ⅱ)Pc-O2is the key step for catalytic reaction. The quinone imide dyes were the coupling products between p-quinoid radicals and Antipyrine-NH·(radical form of4-AAP).(3) These TNFe(Ⅱ)Pc catalysts could be reused for several times after the simple post-treatment. The catalytic activity of TNFe(Ⅱ)Pc catalyst could be preserved more than90%of the initial activity after three cycling repeated experiments.2. The quantum chemistry study of TNFe(Ⅱ)Pc and Fe(Ⅱ)Pc catalystThe molecular structure of TNFe(Ⅱ)Pc and Fe(Ⅱ)Pc complexes were optimized by using the Density Function Theory (DFT) B3LYP with LanL2DZ and6-31G(d, p) basis sets. The Mulliken atomic charges of TNFe(Ⅱ)Pc and Fe(Ⅱ)Pc were analyzed based on the results of structural optimization calculation. The donor-acceptor molecular hardness (ηda) was estimated to illuminate the difference of catalytic activity of TNFe(Ⅱ)Pc and Fe(Ⅱ)Pc. The results show that the smaller ηDa between TNFe(Ⅱ)Pc and CP contributed to the electron transfer from HOMO of CP to LUMO of TNFe(Ⅱ)Pc, which was in consistent with the experimental results.3. The construction and study of fiber optic2-CP sensor on the basis of aerobic reaction catalyzed by TNFe(Ⅱ)PcThe fiber optic2-CP sensor was constructed based on the principle of TNFe(Ⅱ)Pc catalyzed2-CP oxidation. The tris (2,2'-bipyridyl) ruthenium(Ⅱ) chloride complexes (Ru(Ⅱ)(byp)3Cl2) were immobilized into a cellulose acetate (CA) membrane and used as oxygen-sensitive materials. The results show the good linear relationship between the relative phase delay (△(?)) of sensitive membrane and2-CP concentration in its detection range of1×10-6to7×10-6mol/L and7×10-6to1×10-4mol/L. The detection limit of this sensor was1×10-6mol/L and the response time of this sensor was five minutes. The as-prepared fiber optic2-CP sensor showed good repeatability and long-term stabilization.4. The OCFe(Ⅲ)Pc-CdTe composite system for the measurement of chlorophenol pollutant(1) The catalytic activity of OCFe(Ⅲ)Pc could be greatly enhanced by the addition of tert-butyl hydroperoxide (BuOOH) in the selected chromogenic system of2-CP,1-naphthol and phenol. The chromogenic reaction of2-CP system could be completed just within five minutes under best experimental conditions. PcOCFeⅣ=O and O2·-were possible active species in our catalytic system which resulted in the fast formation of the pink quinone imide dyes. (2) On the basis of the proposed principle of chemical catalysis and fluorescence quenching, the fluorescence probe of CdTe QDs was constructed. A good linear relationship between the fluorescence quenching degree (Po/P) and the concentration of chlorophenol was found in the range from1×10-6to1×10-4mol/L. The detection limit of this fluorescence measurement could achieve to1×10-6mol/L.5. Study of sunlight-assisted Mn(Ⅱ)Pc catalyzed chlorophenol oxidation and its chromogenic reactionUnder the irradiation of sunlight, the chromogenic reaction could be efficiently catalyzed by Mn(Ⅱ)Pc and proceed three to five time faster than that performed in the laboratory room with the reaction temperature of RT and40℃. The mechanism investigation testified that the singlet oxygen CO2) and superoxide anion radical (O2·-) were the active species formed via oxygen in the presence of Mn(Ⅱ)Pc under osunlight irradiation, and thus the oxidation of chlorophenol and its chromogenic reaction could be accelerated.