The Synthesis And Biomimetic Catalytic Application Of Hemin Derivatised Porphyrin Metal Complexes

Metallo-porphyrins are important classes of conjugated organic metal complexes, which could mimic the active site of many important enzymes and displayed broad appli-cation prospects in a variety of biomimetic catalyzed fields. However, most investigation results for metalloporphyrin biomimetic catalyzed applications are obtained based on the use of totally synthesized tetraaryl porphyrins and their derivatives. There were few resear-ches concerning the biomimetic catalysis application of natural metallo-porphyrins and their derivatives. Hemin derivatives can be prepared in high yield from the red blood pigment heme, which is available in almost any desired amount from slaughterhouse wastes. The close relationship to the naturally hemin makes it great significance to design and develop hemin derivatives with high biomimetic catalytic activities.In this thesis, hemin was chose as starting material. Protoporphyrin, protoporphyrin dimethyl ester, metalloprotoporphyrin dimethyl ester and metallomesoporphyrin dimethyl ester were synthesized from hemin through demetalation reaction, esterification reaction, metal complexation reaction and self-catalyzed hydrogenation reaction; Mesoporphyrin and mesoporphyrin dimethyl ester were synthesized by a "one-step" demetalation-hydro-genation reaction and an esterification reaction; Hematoporphyrin and hematoporphyrin dimethyl ester were prepared from hemin by a "one-pot" reaction of demetalation, Mar-kovnikov addition and nucleophilic substitution reaction and an ultrasound irradiated esterification reaction; Hematoporphyrin diether diesters were prepared from hemin throu-gh a "one-pot" reaction of demetalation, Markovnikov addition and ultrasound promoted esterification-etherification reaction; Iso-hematoporphyrin was synthesized from the anti-Markovnikov addition of protoporphyrin dimethyl ester; L-cystine dimethyl ester was chemically introduced into the edge of deuteroporphyrin or mesoporphyrin by the conden-sation of deuteroporphyrin or mesoporphyrin with cystine dimethyl ester dihydrochloride. The metal complexes of hemin derivatives were synthesized from the metal complexation reaction between hemin derivatives and metal salts. The optimum reaction condations were obtained by optimizing the experimental conditions, and the structures of productions were confirmed by1H NMR, IR, MS and UV-vis.A series of3,8-substituted hemin derivatives were used as the catalysts for the catalyzed oxidation of cyclohexane by air. The effects of metal ions and substituents on the catalytic activities of3,8-substituted hemin derivatives were investigated. The mechanism of this reaction was preliminarily studied. The results showed that3,8-substituted hemin derivatives could smoothly catalyze the oxidation of cyclohexane. For example, in the oxidation of cyclohexane catalyzed by Co(II)-mesoporphyrin dimethyl ester, the conver-sion and the total selectivity of cyclohexanol and cyclohenone reached to16.9%and84.2%, respectively; The catalytic activities were influenced by the electron effects and steric effects of substituents and the thermal stability of catalysts; The with-drawing-elec-tron substituents can improve the catalytic activities of hemin derivatives and the activity decreased with the increasing of the size of substituents; The active intermediates of hemin derivatives in this reaction is high-valence metal hemin derivatives radicals.Based on the great enhancement of Mn(III)-or Co(II)-deuteroporphyrin catalyzed chemiluminescence of luminol, a sensitive and high selective flow-injection chemilumine-scence (FI-CL) method for the determination of phenol and diethylstilbestrol was exploited. The optimum experimental conditions and the possible mechanism were investigated. The results showed that the optimum experimental conditions for the detection of phenol is: CNaOH,0.1mol·L-1; CLuminoL,8.0×10-8mol·L-1; CMn(â…¢)DP,3.0×10-6g-mL-1; CH2O2,6.0×10-5mol·L-1; the flow rate of phenol, Mn(III) deuteroporphyrin and NaOH,2.5mL·min-1; the flow rate of luminol and H2O2,2.0mL-min-1. The optimum experimental conditions for the detection of phenol is:CH2O2,6.0×10-5mol·L-1; CNaOH,0.4mol·L-1; Cluminol,8.0×10-7g-mL-1; CCo(â…¡)DP,6.0×10-6g·mL-1; the flow rate of diethylstilbestrol, Co(II)-deuteropor-phyrin and NaOH,3.0mL-min-4; the flow rate of luminol and H2O2,2.5mL-min-1. Under the selected optimized experimental conditions, the relative CL intensity was linear with phenol in the range of4.0×10-9to4.0×10-7g·mL-1and linear with diethylstilbestrol in the range of6.0×10-10-1.0×10-8g·mL-1and1.0×10-8-1.0×10-7g·mL-1. The detection limit (3σ) for phenol and diethylstilbestrol were6.3×10-10g-mL-1and3.83×10-10g·mL-1, respectively. Because of the high catalytic ability of metallo-deuteroporphyrins, the developed methods were more sensitivity, simplicity and stability than other methods.Through the covalent band of S-Au, cystine dimethyl ester cobalt(II) deuteropor-phyrin or cystine dimethyl ester cobalt(II) mesoporphyrin were self-assembled to gold electrodes. The modified electrodes were characterized by IR and X-ray photoelectron spectroscopy spectra and confirmed electrochemically by cyclic voltammogram. Based on the catalytic ability of hemin derivatives, the assembled electrodes were used in electro-catalyzed reduction of dissolved oxygen and H2O2. The investigation results showed that cystine dimethyl ester cobalt(â…¡) deuteroporphyrin or cystine dimethyl ester cobalt(II) mesoporphyrin could oriently and stably assembled onto the surface of gold electrodes and showed good electrocatalytic ability to the reduction of dissolved oxygen and H2O2. Catalyzed by cystine dimethyl ester cobalt(II) deuteroporphyrin self-assembled gold electrode, dissolved oxygen could be reduced by a4electrons reaction to H2O. Cystine dimethyl ester cobalt(II) mesoporphyrin self-assembled gold electrode showed excellent activity for electrocatalyzed reduction of H2O2and the differential pulse voltammogram peak current of the modified electrode displayed a linear increase with the increased concentration of H2O2from1.96â'‹1.0-3μmol·cm-3to0.314μmol·cm-3with the detection limit of8.75×10-4μmol·cm-3.