Study On The Catalytic Oxidation And Electrocatalytic Hydrogen Evolution Of Corrole Manganese Complexes

The problems of environmental pollution and the energy crisis are becoming increasingly serious on a global scale.Therefore,people pay more attention to developing methods of activating molecular oxygen（O₂）to participate in catalytic oxidation and electrocatalytic hydrogen evolution under mild conditions.In this context,the catalytic reaction of biological enzymes has attracted the attention of researchers.For example,the P450 enzyme and porphyrin oxygenase can efficiently activate O₂ to participate in the reaction at room temperature,and hydrogenases（iron-iron hydrogenase and iron-nickel hydrogenase）can generate hydrogen（H₂）from water.However,the high molecular weight of biological enzyme and its instability under aerobic conditions limit their application in artificial systems.In order to overcome these limitations,researchers have extensively explored the application of other catalysts,among which metalloporphyrin is widely used in the study of cytochrome P450biomimetic catalysis.Corrole is a tetrapyrrole macrocyclic compound with a structure similar to porphyrin and has an 18-πconjugated electronic structure.Three hydrogen atoms in the ring are lost to form trianions,which can stabilize higher valence metal ions compared with dihydroanions in the porphyrin ring.In addition,factors such as substituent of corrole ring,axial coordination anion of central metal and non-redox active metal cation can regulate the catalytic performance of metallocorroles.Therefore,metallocorrole complexes have wide application prospects in catalytic chemistry,biochemistry,coordination chemistry and photochemistry.Among metallocorroles,corrole manganese complexes have attracted extensive attention in catalytic reactions due to central metal manganese is rich in the earth,non-toxic and wide range of oxidation states（II～V,VII）.In the catalytic oxidation of metallocorrole complexes,the common oxygen sources are organic oxidizers such as tert-butyl hydrogen peroxide,iodobenzoyl benzene and m-chloroperoxybenzoic acid is usually used as the oxygen source,but there are few reports on the system that uses green molecular oxygen or hydrogen peroxide as the oxygen source.In addition,the electrochemical characterization of non-precious metal manganese corrole complexes has been widely studied,but the study of its electrocatalytic hydrogen evolution performance has not been reported so far.Based on this,a series of corrole manganese complexes with different push-pull electronic groups were prepared and their catalytic activities in catalytic oxidation and electrocatalytic hydrogen evolution were studied.It is the first time to explore that sodium nitrite（Na NO₂）as oxygen source and cocatalyst to activate O₂ in the air to participate in the oxidation of styrene catalyzed by corrole manganese complexes,the electrocatalytic hydrogen evolution reaction of corrole manganese complexes,the influence of cation and anion（axial coordination anion and non-redox active metal cation）on the catalytic oxidation and electrocatalytic hydrogen evolution reaction of corrole manganese complexes.The main research contents are as follows:（1）A series of freebase corroles with different push-pull electronic effects were synthesized,such as 5,10,15-tris（pentafluorophenyl）corrole(F₁₅C),5,15-bis（pentafluorophenyl）-10-phenyl corrole(F₁₀C)and 5,15-bis（phenyl）-10-pentafluorophenyl corrole（F₅C）.The freebase corrole and their metal complexes were characterized by UV-vis spectrum,fourier transforms infrared spectrum,nuclear magnetic resonance spectrum（hydrogen,fluorine and carbon spectrum）,high-resolutionon mass spectrometry and X-ray photoelectron spectroscopy.The participation of sodium nitrite in the oxidation of styrene catalyzed by the corrole manganese complex was explored for the first time.The effects of time,temperature and oxidant content on the catalytic system were investigated,and its mechanism was explored.The experimental results show that the oxidation of styrene catalyzed by corrole manganese complex with Na NO₂ can produce benzaldehyde with high efficiency and high selectivity,the F₁₅C-Mn complex with the most electron-withdrawing groups has the strongest catalytic activity.In the reaction,Na NO₂ acts as oxidant and cocatalyst,activates molecular oxygen in the air to participate in the reaction;The corrole manganese complex involves not only the conventional oxidation mechanism of styrene catalyzed by Mn^V（O）intermediate but also the hydrolysis pathway of the oxime.（2）The influence of introducing a series of axially coordinated anionic additives（tetrabutylammonium fluoride,tetrabutylammonium bromide,tetrabutylammonium nitrate and tetrabutylammonium hydroxide）and non-redox active cationic additives（calcium triflate,sodium triflate,magnesium triflate,zinc triflate and aluminum triflate）on the oxidation of styrene catalyzed by F₁₅C-Mn complex was explored.The results show that the introduction of anion and cation can promote the oxidation of styrene to benzaldehyde catalyzed by corrole manganese/sodium nitrite system and its mechanism is explored.（3）Corrole manganese complexes(F₁₅C-Mn,F₁₀C-Mn,F₅C-Mn and F₀C-Mn)were used as catalysts for electrocatalytic hydrogen evolution for the first time,and their electrocatalytic hydrogen evolution performance in the organic phase mixed-phase was studied,as well as their effects on electrocatalytic hydrogen evolution performance in the organic phase when acetic acid,trifluoroacetic acid or p-toluenesulfonic acid were used as proton sources respectively.Through cyclic voltammetry and controlled potential electrolysis experiments,it was found that the order of electrocatalytic activity of corrole manganese complexes with different substituent effects in the organic phase and mixed-phase was F₁₅C-Mn>F₁₀C-Mn>F₅C-Mn>F₀C-Mn.When three acids are used as proton sources in the organic phase,the stronger the acidity the of proton source,the higher the electrocatalytic activity the of corrole manganese complex.It can be seen that the proton source and the substituents on the corrole ring have great influence on the electrocatalytic hydrogen evolution performance of the carbofuran complex,and the electron-withdrawing effect of strong acid and the substituents on the corrole ring can improve the electrocatalytic hydrogen evolution activity of the corrole complex.（4）Further explored the influence of introducing axial coordination anionic additive（tetrabutylammonium fluoride）and non-redox active cationic additive（calcium triflate）on the electrocatalytic hydrogen evolution performance of corrole manganese complex.The results show that the introduction of cation and anion can improve the electrocatalytic hydrogen evolution performance of corrole manganese complexes and its mechanism is explored.