- The standard enthalpies of combustion and formation of crystalline cobalt tetrakis(4-metoxyphenyl)porphin complex
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The energy of combustion of cobalt tetrakis(4-metoxyphenyl)porphin was determined in an isothermic-shell liquid calorimeter with a stationary calorimetric bomb. The standard enthalpies of combustion and formation of the complex were calculated, -Δ c
- Tarasov,Volkov,Bazanov,Semeikin
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- Kinetic parameters of the electroreduction of oxygen on a graphitized carbon electrode activated by tetrakis(4-methoxyphenyl)porphyrin and its cobalt complexes
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Electrochemical and electrocatalytic properties of tetrakis(4- methoxyphenyl)porphyrin, tetrakis(4-methoxyphenyl)porphyrinatocobalt(II), and (tetrakis(4-methoxyphenyl)porphyrinato)chlorocobalt(III) are studied using the method of cyclic voltammetry. The redox-potentials of the electrode processes, the potentials of the half-wave and stationary rate constants for electroreduction of molecular oxygen are determined from an analysis of the voltammetric curves. The cobalt complex is found to be characterized by higher electrocatalytic activity than other analyzed compounds.
- Tesakova,Noskov,Bazanov,Berezina,Parfenyuk
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- Spectroscopic characterization, X-ray molecular structures and cyclic voltammetry study of two (piperazine) cobalt(II) meso-arylporphyin complexes. Application as a catalyst for the degradation of 4-nitrophenol
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Two new cobaltous-porphyrin complexes, namely (μ-piperazine)-bis[(meso-tetra(para-methoxyphenyl)porphyrinato)]cobalt(II) and (piperazine)[meso-tetra(para-chlorophenyl)porphyrin]cobalt(II) dichloromethane disolvate, with the formulas [{CoII(TMPP)}2(μ2-pipz)] (complex 1) and [CoII(TClPP)(pipz)]·2CH2Cl2 (complex 2), were used efficiently as catalysts in the degradation of 4-nitrophenol (4-NP) in an aqueous hydrogen peroxide solution. These cobalt(II)-pipz porphyrin complexes were characterized by a variety of spectroscopic methods including infrared, UV–visible, fluorescence, proton nuclear magnetic resonance, electron paramagnetic resonance (EPR) as well as mass spectrometry. A cyclic voltammetry investigation was also carried out on these two Co(II) metalloporphyrins. The EPR results indicate that both complexes 1 and 2 are paramagnetic low-spin (S = 1/2) cobalt(II) porphyrin complexes. Furthermore, the X-ray diffraction crystal structures of 1 and 2 were determined, and the intermolecular interactions were investigated by Hirshfeld surface analysis.
- Al-Ghamdi, Youssef O.,Brahmi, Jihed,Guergueb, Mouhieddinne,Guerineau, Vincent,Loiseau, Frédérique,Molton, Florian,Nasri, Habib,Nasri, Soumaya,Roisnel, Thierry
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- Efficient oxidation of cycloalkanes with simultaneously increased conversion and selectivity using O2 catalyzed by metalloporphyrins and boosted by Zn(AcO)2: A practical strategy to inhibit the formation of aliphatic diacids
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The direct sources of aliphatic acids in cycloalkanes oxidation were investigated, and a strategy to suppress the formation of aliphatic acids was adopted through enhancing the catalytic transformation of oxidation intermediates cycloalkyl hydroperoxides to cycloalkanols by Zn(II) and delaying the emergence of cycloalkanones. Benefitted from the delayed formation of cycloalkanones and suppressed non-selective thermal decomposition of cycloalkyl hydroperoxides, the conversion of cycloalkanes and selectivity towards cycloalkanols and cycloalkanones were increased simultaneously with satisfying tolerance to both of metalloporphyrins and substrates. For cyclohexane, the selectivity towards KA-oil was increased from 80.1% to 96.9% meanwhile the conversion was increased from 3.83 % to 6.53 %, a very competitive conversion level with higher selectivity compared with current industrial process. This protocol is not only a valuable strategy to overcome the problems of low conversion and low selectivity lying in front of current cyclohexane oxidation in industry, but also an important reference to other alkanes oxidation.
- Shen, Hai-Min,Wang, Xiong,Ning, Lei,Guo, A-Bing,Deng, Jin-Hui,She, Yuan-Bin
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- Mechanochemical insertion of cobalt into porphyrinoids using Co2(CO)8as a cobalt source
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Cobalt porphyrinoids find broad use as catalysts or electrode materials. Traditional solution state cobalt insertion reactions into a free base porphyrinoid to generate the corresponding cobalt complex generally require fairly harsh conditions, involving the heating of the reactants in high-boiling solvents for extended period of times. We report here an alternative method of cobalt insertion: A solvent-free (at least for the insertion step) mechanochemical method using a planetary ball mill with Co2(CO)8as a cobalt source. The scope and limits of the reaction were investigated with respect to the porphyrinic substrate susceptible to the reaction conditions, the influences of different grinding aids, and bases added. While the mechanochemical method is, like other metal insertion methods into porphyrinoids, not universally suitable for all substrates tested, it is faster, milder, and greener for several others, when compared to established solution-based methods.
- Damunupola, Dinusha,Chaudhri, Nivedita,Atoyebi, Adewole O.,Brückner, Christian
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p. 3643 - 3652
(2020/07/30)
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- Selective Solvent-Free and Additive-Free Oxidation of Primary Benzylic C–H Bonds with O2 Catalyzed by the Combination of Metalloporphyrin with N-Hydroxyphthalimide
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Abstract: A protocol for solvent-free and additive-free oxidation of primary benzylic C–H bonds with O2 was presented through adjusting the combination of metalloporphyrins and NHPI as binary catalysts to overcome the deficiencies encountered in current oxidation systems. The effects of reaction temperature, porphyrin structure, central metal, catalyst loading and O2 pressure were investigated systematically. For the optimized combination of T(2-OCH3)PPCo and NHPI, all the primary benzylic C–H bonds could be functionalized efficiently and selectively at 120 °C and 1.0?MPa O2 with aromatic acids as the primary products. The selectivity towards aromatic acids could reach up to 70–95% in the conversion of more than 30% for most of the substrates possessing primary benzylic C–H bonds in the metalloporphyrin loading of 0.012% (mol/mol). And the superior performance of T(2-OCH3)PPCo among the metalloporphyrins investigated was mainly attributed to its high efficiency in charge transfer and fewer positive charges around central metal Co (II) which favored the adduction of O2 to cobalt (II) forming the high-valence metal-oxo complex followed by the production of phthalimide N-oxyl radical (PINO) and the initiation of the catalytic oxidation cycle. This work would provide not only an efficient protocol in utilization of hydrocarbons containing primary benzylic C–H bonds, but also a significant reference in the construction of more efficient C–H bonds oxidation systems. Graphic Abstract: The solvent-free and additive-free oxidation of primary benzylic C–H bonds with O2 was presented through adjusting the combination of metalloporphyrins and NHPI as binary catalysts, and the highest selectivity towards aromatic acid reached up to 95.1% with the conversion of 88.5% in the optimized combination of T(2-OCH3)PPCo and NHPI.[Figure not available: see fulltext.].
- Shen, Hai-Min,Qi, Bei,Hu, Meng-Yun,Liu, Lei,Ye, Hong-Liang,She, Yuan-Bin
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p. 3096 - 3111
(2020/04/29)
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- A preparing method of p-nitroacetophenone
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A preparing method of p-nitroacetophenone is disclosed. The method includes reacting p-nitroethylbenzene, as a raw material, in an autoclave at 110-150 DGE C for 3-7 h under the function of a metalloporphyrin catalyst shown as a formula 1 or a formula 2 in an oxygen atmosphere having a pressure of 0.8-2 MPa under a condition of no solvent; and subjecting an obtained reaction liquid mixture to after-treatment to obtain the target product that is p-nitroacetophenone. The method includes reaction in the sealed autoclave, thus greatly reducing volatilization loss of the raw material, and avoidingemission of reaction waste gas so as to avoid environment pollution therefrom. The bionic metalloporphyrin catalyst which is naturally degradable is adopted as an auxiliary catalyst, is low in dosage,and can increase product selectivity. Consumption of an organic solvent and purification of the target product are avoided, thus reducing the cost.
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Paragraph 0057-0059
(2019/01/07)
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- Electrochemical hydrogen evolution by cobalt (II) porphyrins: Effects of ligand modification on catalytic activity, efficiency and overpotential
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Electrochemical H2 evolution of a series of cobalt(II) porphyrins with electron-withdrawing (EW) and electron-donating (ED) substituents at the para positions of the meso-phenyl rings has been investigated in DMSO using acetic acid as a proton source. Our study showed that the nature of substituents significantly influences catalytic activity, efficiency, and the potential at which catalysis occurs. Faradaic efficiencies (FE) ranging from 44 to 99%, turnover numbers (TONs) from 1.5 to 104 (~11 h electrolysis), turnover frequencies (TOFs) from 0.23 to 9.1 h?1, and onset overpotentials from 25 to 445 mV were obtained by tuning the porphyrinic substituents. Cobalt porphyrins with -SO3H, -COOH, or -NH2 groups as the substituents showed high activity and efficiency with more positive onset potentials as compared to the parent [Co(TPP)]. Supports also from the low hydrogen generation activities for complexes with -COOMe, -OMe and -OH groups as the substituents suggest that the acidity of the meso-phenyl substituent plays a key role in enhancing the hydrogen evolution activities during the catalytic processes.
- Beyene, Belete B.,Mane, Sandeep B.,Hung, Chen-Hsiung
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p. H481 - H487
(2018/07/06)
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- Thermodynamic and reactivity studies of a tin corrole-cobalt porphyrin heterobimetallic complex
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A heterobimetallic complex, (TPFC)Sn-Co(TAP) (TPFC = 5,10,15-tris(pentafluorophenyl)corrole, TAP = 5,10,15,20-tetrakis(p-methoxyphenyl)porphyrin), was synthesized. The complex featured a Sn-Co bond with a bond dissociation enthalpy (BDE) of 30.2 ± 0.9 kcal mol-1 and a bond dissociation Gibbs free energy (BDFE) of 21.0 ± 0.2 kcal mol-1, which underwent homolysis to produce the (TPFC)Sn radical and (TAP)CoII under either heat or visible light irradiation. The novel tin radical (TPFC)Sn, being the first four-coordinate tin radical observed at room temperature, was studied spectroscopically and computationally. (TPFC)Sn-Co(TAP) promoted the oligomerization of aryl alkynes to give the insertion products (TPFC)Sn-(CHC(Ar))n-Co(TAP) (n = 1, 2, or 3) as well as 1,3,5-triarylbenzenes. Mechanistic studies revealed a radical chain mechanism involving the (TPFC)Sn radical as the key intermediate.
- Wang, Zikuan,Yao, Zhengmin,Lyu, Zeyu,Xiong, Qinsi,Wang, Bingwu,Fu, Xuefeng
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p. 4999 - 5007
(2018/06/12)
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- Synthesis and spectral properties of cobalt(II) and cobalt(III) tetraarylporphyrinates
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Reactions of 5,10,15,20-tetraphenylporphin, 5,10,15,20-tetra(4′- methoxyphenyl)porphyrin, and 5,10,15,20-tetra(4′-chlorophenyl)porphyrin with cobalt(II) acetate in dimethylformamide were studied by spectrophotometry. The corresponding cobalt(II) porphyrin
- Chizhova,Kumeev,Mamardashvili, N. Zh.
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p. 740 - 743
(2013/07/26)
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- Cobaltoporphyrin-catalyzed CO2/epoxide copolymerization: Selectivity control by molecular design
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A series of cobalt(III) chloride porphyrin complexes of the general formula 5,10,15,20-tetra(p-alkoxy)phenylporphyrin cobalt chloride (4b-e) and the related 5,10,15,20-tetra(p-nitro)phenylporphyrin cobalt chloride (4f) are presented and their reactivity toward propylene oxide (PO)/CO2 coupling/copolymerization is explored. While the nitro-substituted complex (4f), in conjunction with an onium salt, shows moderate activity toward cyclization, the 4b-e/onium systems show superior copolymerization activity in comparison to tetraphenylporphyrin Co(III) chloride (4a) with high selectivity and conversion to poly(propylene carbonate) (PPC). A comprehensive copolymerization behavior study of the alkoxy-substituted porphyrin complexes 4b-e in terms of reaction temperature and CO2 pressure is presented. Complexes bearing longer alkoxy-substituents demonstrate the highest polymerization activity and molecular weights, however all substituted catalyst systems display a reduced tolerance to increased temperature with respect to PPC formation. Studies of the resulting polymer microstructures show excellent head-to-tail epoxide incorporation and near perfectly alternating poly(carbonate) character at lower polymerization temperatures.
- Anderson, Carly E.,Vagin, Sergei I.,Xia, Wei,Jin, Hanpeng,Rieger, Bernhard
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p. 6840 - 6849,10
(2020/08/24)
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- Optimized synthesis of tetrakis(4-methoxyphenyl)porphin-Co(II)
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Detailed kinetic investigation of Rothemund synthesis of porphyrins was conducted in different solvents. A one-pot synthesis of tetrakis(4- methoxyphenyl)porphin-Co(II) from pyrrole, anisic aldehyde, and cobalt acetate was developed that gave 35% isolated yield. Chlorobenzene was found to be the best solvent for the reaction. The synthesis can be done with either propionic or chloroacetic acid as catalyst with about the same yield. Cobalt prevents the synthesis of the porphyrin, so it has to be added in the reaction mixture only after the synthesis of the free porphyrin is finished. Optimum time is 2-2.5h at a temperature of 130C. Lower temperatures reduce the yield. Potentially, these dependencies can be applied to synthesis of other analogous porphyrins. Copyright Taylor & Francis Group, LLC.
- Gridnev, Alexei A.,Nikiforov, Gregorii A.
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experimental part
p. 1679 - 1689
(2009/10/02)
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- Synthesis of 5,10,15,20-tetrakisphenylporphins on a carbon support for the cathodic reduction of oxygen in fuel cells
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Several substituted Fe- and Co-containing tetraphenylporphins I were loaded on carbon either by adsorption from acetone or by in situ synthesis on the carbon support. The porphin/carbon combinations were pyrolyzed at 800°C. The electrocatalytic activities in the reduction of dioxygen were investigated in alkaline (KOH) and acid (H2SO4) solutions using porous Teflon-bonded carbon electrodes impregnated with the catalysts. At 700 mV high current densities of 75 mA/cm2 in acid solution and up to 90 mA/cm2 in alkaline solution were obtained.
- Kirschenmann,Woehrle
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p. 1403 - 1406
(2007/10/02)
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