Electrocatalytic oxygen reduction and evolution reactions are involved in new energy conversion and storage technologies,such as various fuel cells and metal-air batteries and also water splitting devices[1,2].However...Electrocatalytic oxygen reduction and evolution reactions are involved in new energy conversion and storage technologies,such as various fuel cells and metal-air batteries and also water splitting devices[1,2].However,both reactions are very slow in kinetics,and thus catalysts are required[3,4].展开更多
The bis(nitrito-N) cobalt(III) octaethylporphyrin derivative with the formula [K(18-C-6)(NO2)0.5(H2O)0.5]2 [CoIII(OEP)(NO2)2] (1) (OEP = octaethylporphyrin and 18-C-6 is the crown ether18-crown-6) has been synthesized...The bis(nitrito-N) cobalt(III) octaethylporphyrin derivative with the formula [K(18-C-6)(NO2)0.5(H2O)0.5]2 [CoIII(OEP)(NO2)2] (1) (OEP = octaethylporphyrin and 18-C-6 is the crown ether18-crown-6) has been synthesized and characterized by UV-vis, IR and proton NMR spectroscopy which indicate, inter alia, that the cobalt ion presents the oxidation state III. The synthesis utilizes 18-crown-6 to solubilize potassium nitrite in the synthetic procedure. This compound crystallizes in the triclinic system, with the centric space group P-1 and the following unit cell parameters: 11.6724(2) ?, b = 12.5715(2) ?, c = 13.4722(3) ?, α = 101.1290(6)°, β = 106.6498(6)°, γ= 109.1507(6)°, Z = 1 and V = 1696.74(5) ?3. The crystal structure has been solved and refined to R = 0.0499 and R(w) = 0.1319. The X-rays molecular structure of 1 shows that there is a relatively close interaction of both two NO2- axial ligands of the ion complex [CoIII(OEP)(NO2)2]- with the potassium atoms of the two counterions [K(18-C-6) (NO2)0.5(H2O)0.5]0.5+. The title compound exhibits one-dimension polymer-like structure where “monomers” are linked together through strong O(H2O)—H…O(nitrito-O) hydrogen bonds.展开更多
The four cobalt porphyrins [Co (3, 4, 5 MeO TPP) (1) ; Co (TTP) (2) ; Co (4 CI TPP) (3);Co (4 HSO 3 TPP) (4)] were synthesized and considered as two mimic of superoxide dismutaes (SOD) and catalase (CAT). The ...The four cobalt porphyrins [Co (3, 4, 5 MeO TPP) (1) ; Co (TTP) (2) ; Co (4 CI TPP) (3);Co (4 HSO 3 TPP) (4)] were synthesized and considered as two mimic of superoxide dismutaes (SOD) and catalase (CAT). The catalytic efficiency of them on deplete the harmful radical have been proved using riboflavin methionine photoreduction method in the concentration range of 10 6 ～10 5 mol/L. The catalytic efficiency of them at decomposing H 2O 2 has been performed by spectrophotometer. The percentage of decomposing H 2O 2 while the increasing the concentration of the imitating compounds. The lipid peroxidationproduced in liver homogenatcd of mice was determined by spectrophotometer detecting the content of MDA.展开更多
It has been found that phenyl cobalt tetraphenylporphyrin (C_6H_5Cotpp) was formed when cobalt tetraphenylporphyrin (Cotpp) and benzene were introduced into the ion source of mass spectrometer, the mass spectra of Cot...It has been found that phenyl cobalt tetraphenylporphyrin (C_6H_5Cotpp) was formed when cobalt tetraphenylporphyrin (Cotpp) and benzene were introduced into the ion source of mass spectrometer, the mass spectra of Cotpp and C_6H_5Cotpp are discussed.展开更多
The title compound, [N-(2-pyridylmethyl)-(L)-alanine]Co(III) thiocyanate (1) was obtained from the reaction of Co(OOCH3)2·H2O with the tridentate reduced Schiff base ligand, N-(2-pyridylmethyl)-(L)-alanine (L) an...The title compound, [N-(2-pyridylmethyl)-(L)-alanine]Co(III) thiocyanate (1) was obtained from the reaction of Co(OOCH3)2·H2O with the tridentate reduced Schiff base ligand, N-(2-pyridylmethyl)-(L)-alanine (L) and NH4SCN and characterized by elemental analysis, IR, UV-visible, TGA and single- crystal X-ray diffraction. Structural and spectroscopic analyses reveal [Co(L)2)]SCN to be monomeric with Cobalt(III) adopting a pseudo-octahedral geometry, coordinating to two reduce Schiff base ligands. In the crystal lattice, the thiocyanate anion forms an intermolecular SCN···HNamine hydrogen bond, while adjacent monomers are linked by intermolecular Ocarboxyl···HNamine···H-bonds to form a supramolecular network. This work is therefore undertaken in an attempt to construct coordination framework structures of varying properties using the mixed-ligand strategy involving reduced Schiff bases and the thiocyanate ion.展开更多
Transition metal catalysts M-N-C（M = Co,Fe,Mn） were synthesized by a template-free method by heating meso-tetraphenyl porphyrins（i.e.CoTPP,FeTPPCl,MnTPPCl） precursors.The catalysts were characterized by N2 adsorpt...Transition metal catalysts M-N-C（M = Co,Fe,Mn） were synthesized by a template-free method by heating meso-tetraphenyl porphyrins（i.e.CoTPP,FeTPPCl,MnTPPCl） precursors.The catalysts were characterized by N2 adsorption-desorption,thermogravimetry,high-resolution transmission electron microscopy,and Raman and X-ray photoelectron spectroscopy.The selective oxidation of ethylbenzene with molecular oxygen under a solvent-free condition was carried out to explore the catalytic performance of the M-N-Cs,which exhibited different catalytic performance.That was ascribed to the difference in M（Co,Fe,Mn） and different graphitization degree forming during the heating process,in which M（Co,Fe,Mn） might have different catalytic activity on the formation of the M-N-C catalyst.All the M-N-C composites had remarkable recyclability in the selective oxidation of ethylbenzene.展开更多
A redox‐neutral avenue to access isoquinolines has been realized by a Co（III）‐catalyzed C–H activa‐tion process. Starting from readily available N‐sulfinyl imine substrates and alkynes, the reaction occurred vi...A redox‐neutral avenue to access isoquinolines has been realized by a Co（III）‐catalyzed C–H activa‐tion process. Starting from readily available N‐sulfinyl imine substrates and alkynes, the reaction occurred via N–S cleavage with broad substrate scope and functional group compatibility in the presence of cost‐effective cobalt catalysts.展开更多
Metal-N_(4)(M-N_(4))macrocyclic complexes are interesting electrocatalysts due to their well-defined structures and rich molecular tuning.Among them,metal phthalocyanines have been widely studied for the carbon dioxid...Metal-N_(4)(M-N_(4))macrocyclic complexes are interesting electrocatalysts due to their well-defined structures and rich molecular tuning.Among them,metal phthalocyanines have been widely studied for the carbon dioxide reduction reaction(CO_(2)RR)in heterogeneous systems and demonstrated good electrocatalytic performance.However,other complexes like metal corroles and metal porphyrins are much less explored,and often show inferior performances.In this study,three cobalt macrocyclic complexes,cobalt phthalocyanine,cobalt meso-tetraphenylporphyrin,and cobalt meso-triphenylcorrole(CoPc,CoTPP and CoTPC)are investigated in heterogeneous electrocatalysis of CO_(2)RR.Although CoPc/carbon nanotube(CNT)hybrid exhibits high electrocatalytic activity,CNT hybridization does not work for CoTPC and CoTPP that hold weak interactions with CNTs.By the drop-dry method with a high molecular loading of 5.4×10^(–7) mol cm^(–2),CoTPC and CoTPP could deliver appreciable electrode activities.Poly(4-vinylpyridine)(PVP)introduction is further demonstrated as a facile method to afford enhanced activities for CoTPP at low molecular loadings through enhancing molecule-substrate interactions.The partial current density of carbon monoxide for CoTPP+CNT/PVP is around 8 times higher than the sample without PVP at–0.67 V versus reversible hydrogen electrode.This work provides solutions to enhance the electrode activities of molecular electrocatalysts with weak substrate interactions in heterogeneous systems.展开更多
Edge plane pyrolytic graphite (EPG) electrodes coated with the Co(II)/Pt(II)2 analog of 5,15-bis-(4-pyridyl)-10,20-bis-(3-methoxy-4-hydroxyphenyl)porphyrin undergo an electrochemical-chemical-electrochemical (ECE) rea...Edge plane pyrolytic graphite (EPG) electrodes coated with the Co(II)/Pt(II)2 analog of 5,15-bis-(4-pyridyl)-10,20-bis-(3-methoxy-4-hydroxyphenyl)porphyrin undergo an electrochemical-chemical-electrochemical (ECE) reaction when anodically scanned in 1.0 M sulfuric acid. The new redox couple formed from this anodic conditioning of the coated electrode is dependent on the pH of the solution. Roughened EPG electrodes coated with the Co(II)/Pt(II)2 trimetallic porphyrin show a catalytic shift of 400 mV for the reduction of O2 when compared to the reduction of O2 at a bare EPG electrode. An additional catalytic shift of ca. 150 mV is observed for O2 reduction at an EPG electrode coated with the Co(II)/Pt(II)2 porphyrin which has been oxidized in 1.0 M sulfuric acid. In addition to the added electrocatalysis, a significant percentage of O2 reduced at the oxidized Co(II)/Pt(II)2 EPG electrode is converted to H2O as determined by rotating disk electrode measurements.展开更多
We present a microscopic investigation on the structure-activity relationship of the Co-N4 site in the oxygen reduction reaction(ORR)by electrochemical scanning tunneling microscopy(ECSTM)at the molecular scale.The co...We present a microscopic investigation on the structure-activity relationship of the Co-N4 site in the oxygen reduction reaction(ORR)by electrochemical scanning tunneling microscopy(ECSTM)at the molecular scale.The cobalt porphyrins with various substituents(CoTPPX_(4),X=Cl,H,OCH_(3))that delicately regulate the electronic structure of the active site were investigatedasmodel catalysts.Electrochemical measurements evidenced that the CoTPPCl_(4)exhibits better activity,higher product selectivity for H_(2)O,and lower stability.The CoTPPX_(4)-O_(2)complex with higher contrast can be observed in the STM images and the proportion of the CoTPPCl_(4)-O_(2)is appreciably larger than that of CoTPP-O_(2)and CoTPP(OCH_(3))4-O_(2).Theoretical simulations of the model catalysts and the reaction processes of the ORR reveal the relationship between the electronic structure and the catalytic behavior of the model catalysts.The transformation of the CoTPPX_(4)-O_(2)and CoTPPX_(4)in the electrocatalytic reaction was monitored by in situ ECSTM characterization.The structure-activity relationship clarified by experimental and theoretical investigations in this work should help to guide the rational design and optimization of high-performance catalysts.展开更多
基金the support from the National Natural Science Foundation of China(21773146,22171176 and 22102092)the Fok Ying-Tong Education Foundation for Outstanding Young Teachers in University+2 种基金the Research Funds of Shaanxi Normal Universitythe Fundamental Research Funds for the Central Universitiesthe NRF of Korea(NRF-2021R1A3B1076539 and NRF-2020R1I1A1A01074630)。
文摘Electrocatalytic oxygen reduction and evolution reactions are involved in new energy conversion and storage technologies,such as various fuel cells and metal-air batteries and also water splitting devices[1,2].However,both reactions are very slow in kinetics,and thus catalysts are required[3,4].
文摘The bis(nitrito-N) cobalt(III) octaethylporphyrin derivative with the formula [K(18-C-6)(NO2)0.5(H2O)0.5]2 [CoIII(OEP)(NO2)2] (1) (OEP = octaethylporphyrin and 18-C-6 is the crown ether18-crown-6) has been synthesized and characterized by UV-vis, IR and proton NMR spectroscopy which indicate, inter alia, that the cobalt ion presents the oxidation state III. The synthesis utilizes 18-crown-6 to solubilize potassium nitrite in the synthetic procedure. This compound crystallizes in the triclinic system, with the centric space group P-1 and the following unit cell parameters: 11.6724(2) ?, b = 12.5715(2) ?, c = 13.4722(3) ?, α = 101.1290(6)°, β = 106.6498(6)°, γ= 109.1507(6)°, Z = 1 and V = 1696.74(5) ?3. The crystal structure has been solved and refined to R = 0.0499 and R(w) = 0.1319. The X-rays molecular structure of 1 shows that there is a relatively close interaction of both two NO2- axial ligands of the ion complex [CoIII(OEP)(NO2)2]- with the potassium atoms of the two counterions [K(18-C-6) (NO2)0.5(H2O)0.5]0.5+. The title compound exhibits one-dimension polymer-like structure where “monomers” are linked together through strong O(H2O)—H…O(nitrito-O) hydrogen bonds.
文摘The four cobalt porphyrins [Co (3, 4, 5 MeO TPP) (1) ; Co (TTP) (2) ; Co (4 CI TPP) (3);Co (4 HSO 3 TPP) (4)] were synthesized and considered as two mimic of superoxide dismutaes (SOD) and catalase (CAT). The catalytic efficiency of them on deplete the harmful radical have been proved using riboflavin methionine photoreduction method in the concentration range of 10 6 ～10 5 mol/L. The catalytic efficiency of them at decomposing H 2O 2 has been performed by spectrophotometer. The percentage of decomposing H 2O 2 while the increasing the concentration of the imitating compounds. The lipid peroxidationproduced in liver homogenatcd of mice was determined by spectrophotometer detecting the content of MDA.
文摘It has been found that phenyl cobalt tetraphenylporphyrin (C_6H_5Cotpp) was formed when cobalt tetraphenylporphyrin (Cotpp) and benzene were introduced into the ion source of mass spectrometer, the mass spectra of Cotpp and C_6H_5Cotpp are discussed.
文摘The title compound, [N-(2-pyridylmethyl)-(L)-alanine]Co(III) thiocyanate (1) was obtained from the reaction of Co(OOCH3)2·H2O with the tridentate reduced Schiff base ligand, N-(2-pyridylmethyl)-(L)-alanine (L) and NH4SCN and characterized by elemental analysis, IR, UV-visible, TGA and single- crystal X-ray diffraction. Structural and spectroscopic analyses reveal [Co(L)2)]SCN to be monomeric with Cobalt(III) adopting a pseudo-octahedral geometry, coordinating to two reduce Schiff base ligands. In the crystal lattice, the thiocyanate anion forms an intermolecular SCN···HNamine hydrogen bond, while adjacent monomers are linked by intermolecular Ocarboxyl···HNamine···H-bonds to form a supramolecular network. This work is therefore undertaken in an attempt to construct coordination framework structures of varying properties using the mixed-ligand strategy involving reduced Schiff bases and the thiocyanate ion.
基金supported by the National Natural Science Foundation of China (21103045, 1210040, 1103312)State Key Laboratory of Heavy Oil at China University of Petroleum (SKCHOP201504)Key Laboratory of Mineralogy and Metallogeny of the Chinese Academy of Sciences at Guangzhou Institute of Geochemistry(KLMM20150103)~~
文摘Transition metal catalysts M-N-C（M = Co,Fe,Mn） were synthesized by a template-free method by heating meso-tetraphenyl porphyrins（i.e.CoTPP,FeTPPCl,MnTPPCl） precursors.The catalysts were characterized by N2 adsorption-desorption,thermogravimetry,high-resolution transmission electron microscopy,and Raman and X-ray photoelectron spectroscopy.The selective oxidation of ethylbenzene with molecular oxygen under a solvent-free condition was carried out to explore the catalytic performance of the M-N-Cs,which exhibited different catalytic performance.That was ascribed to the difference in M（Co,Fe,Mn） and different graphitization degree forming during the heating process,in which M（Co,Fe,Mn） might have different catalytic activity on the formation of the M-N-C catalyst.All the M-N-C composites had remarkable recyclability in the selective oxidation of ethylbenzene.
基金supported by the Dalian Institute of Chemical Physics,Chinese Academy of Sciencesthe National Natural Science Foundation of China (21272231)~~
文摘A redox‐neutral avenue to access isoquinolines has been realized by a Co（III）‐catalyzed C–H activa‐tion process. Starting from readily available N‐sulfinyl imine substrates and alkynes, the reaction occurred via N–S cleavage with broad substrate scope and functional group compatibility in the presence of cost‐effective cobalt catalysts.
文摘Metal-N_(4)(M-N_(4))macrocyclic complexes are interesting electrocatalysts due to their well-defined structures and rich molecular tuning.Among them,metal phthalocyanines have been widely studied for the carbon dioxide reduction reaction(CO_(2)RR)in heterogeneous systems and demonstrated good electrocatalytic performance.However,other complexes like metal corroles and metal porphyrins are much less explored,and often show inferior performances.In this study,three cobalt macrocyclic complexes,cobalt phthalocyanine,cobalt meso-tetraphenylporphyrin,and cobalt meso-triphenylcorrole(CoPc,CoTPP and CoTPC)are investigated in heterogeneous electrocatalysis of CO_(2)RR.Although CoPc/carbon nanotube(CNT)hybrid exhibits high electrocatalytic activity,CNT hybridization does not work for CoTPC and CoTPP that hold weak interactions with CNTs.By the drop-dry method with a high molecular loading of 5.4×10^(–7) mol cm^(–2),CoTPC and CoTPP could deliver appreciable electrode activities.Poly(4-vinylpyridine)(PVP)introduction is further demonstrated as a facile method to afford enhanced activities for CoTPP at low molecular loadings through enhancing molecule-substrate interactions.The partial current density of carbon monoxide for CoTPP+CNT/PVP is around 8 times higher than the sample without PVP at–0.67 V versus reversible hydrogen electrode.This work provides solutions to enhance the electrode activities of molecular electrocatalysts with weak substrate interactions in heterogeneous systems.
文摘Edge plane pyrolytic graphite (EPG) electrodes coated with the Co(II)/Pt(II)2 analog of 5,15-bis-(4-pyridyl)-10,20-bis-(3-methoxy-4-hydroxyphenyl)porphyrin undergo an electrochemical-chemical-electrochemical (ECE) reaction when anodically scanned in 1.0 M sulfuric acid. The new redox couple formed from this anodic conditioning of the coated electrode is dependent on the pH of the solution. Roughened EPG electrodes coated with the Co(II)/Pt(II)2 trimetallic porphyrin show a catalytic shift of 400 mV for the reduction of O2 when compared to the reduction of O2 at a bare EPG electrode. An additional catalytic shift of ca. 150 mV is observed for O2 reduction at an EPG electrode coated with the Co(II)/Pt(II)2 porphyrin which has been oxidized in 1.0 M sulfuric acid. In addition to the added electrocatalysis, a significant percentage of O2 reduced at the oxidized Co(II)/Pt(II)2 EPG electrode is converted to H2O as determined by rotating disk electrode measurements.
基金supported by the National Key R&D Program of China(grant no.2021YFA1501002)the National Natural Science Foundation of China(grant nos.22132007,21972147,21725306)+1 种基金the Key Research Program of the Chinese Academy of Sciences(grant no.XDPB01)the National Postdoctoral Program for Innovative Talents(grant no.BX20220307)of the Chinese Postdoctoral Science Foundation.
文摘We present a microscopic investigation on the structure-activity relationship of the Co-N4 site in the oxygen reduction reaction(ORR)by electrochemical scanning tunneling microscopy(ECSTM)at the molecular scale.The cobalt porphyrins with various substituents(CoTPPX_(4),X=Cl,H,OCH_(3))that delicately regulate the electronic structure of the active site were investigatedasmodel catalysts.Electrochemical measurements evidenced that the CoTPPCl_(4)exhibits better activity,higher product selectivity for H_(2)O,and lower stability.The CoTPPX_(4)-O_(2)complex with higher contrast can be observed in the STM images and the proportion of the CoTPPCl_(4)-O_(2)is appreciably larger than that of CoTPP-O_(2)and CoTPP(OCH_(3))4-O_(2).Theoretical simulations of the model catalysts and the reaction processes of the ORR reveal the relationship between the electronic structure and the catalytic behavior of the model catalysts.The transformation of the CoTPPX_(4)-O_(2)and CoTPPX_(4)in the electrocatalytic reaction was monitored by in situ ECSTM characterization.The structure-activity relationship clarified by experimental and theoretical investigations in this work should help to guide the rational design and optimization of high-performance catalysts.
