- Ionic multi-component complexes containing TDAE·+ and C60·- radical ions and neutral D1 molecules: D1·TDAE·C60
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New ionic complexes containing TDAE·+ and C60·- radical ions and neutral molecules: (TBPDA)2·TDAE·C60 (1); CTV·TDAE·C60 (2); and CoIITPP·TDAE·C60 (3) (TDAE: tetrakis(dimethylamino)ethylene; TBPDA: N,N,N′,N′-tetrabenzyl-p-phenylenediamine; CTV: cyclotriveratrylene and CoIITPP: tetraphenylporphyrinate cobalt (II)) were obtained as single crystals. The presence of TDAE·+, C60·- and neutral donors in 1-3 was proved by optical absorption spectra in the IR and UV-vis-NIR ranges. In the crystal structure of 1 studied by single crystal X-ray diffraction, TDAE·+ and C60·- are spatially separated by bulky TBPDA molecules. Magnetic susceptibilities of 1 and 2 follow the Curie-Weiss law with the negative Weiss temperatures (-2.3 and -2.0 K) and their magnetic moments decrease below 60 and 15 K, respectively. The EPR signals from 1 and 2 at the same temperatures are split into two components, which shift in the opposite directions to lower and higher fields with the temperature decrease. This phenomenon is explained by the formation of field-induced short-range magnetically ordered clusters. CoIITPP and C60·- form diamagnetic σ-bonded (CoIITPP·C60-) anions in 3 in the 1.9-190 K range. This allows one to observe the EPR signal from the isolated TDAE·+ radical cations (g = 2.0031 and halfwidth = ΔH = 3.22 mT at 4 K). Above 190 K the magnetic moment of 3 increases and the EPR signal is essentially broadened and shifted to a lager g-factor (g = 2.0194, ΔH = 24.2 mT at 290 K). This is attributed to the dissociation of the σ-bonded diamagnetic (CoIITPP·C60-) anions to non-bonded paramagnetic CoIITPP and C60·- components.
- Konarev, Dmitri V.,Neretin, Ivan S.,Saito, Gunzi,Slovokhotov, Yury L.,Otsuka, Akihiro,Lyubovskaya, Rimma N.
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- Concerning the deactivation of cobalt(III)-based porphyrin and salen catalysts in epoxide/CO2 copolymerization
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Functioning as active catalysts for propylene oxide (PO) and carbon dioxide copolymerization, cobalt(III)-based salen and porphyrin complexes have drawn great attention owing to their readily modifiable nature and promising catalytic behavior, such as high selectivity for the copolymer formation and good regioselectivity with respect to the polymer microstructure. Both cobalt(III)-salen and porphyrin catalysts have been found to undergo reduction reactions to their corresponding catalytically inactive cobalt(II) species in the presence of propylene oxide, as evidenced by UV/Vis and NMR spectroscopies and X-ray crystallography (for cobalt(II)-salen). Further investigations on a TPPCoCl (TPP=tetraphenylporphyrin) and NaOMe system reveal that such a catalyst reduction is attributed to the presence of alkoxide anions. Kinetic studies of the redox reaction of TPPCoCl with NaOMe suggests a pseudo-first order in cobalt(III)-porphyrin. The addition of a co-catalyst, namely bis(triphenylphosphine)iminium chloride (PPNCl), into the reaction system of cobalt(III)-salen/porphyrin and PO shows no direct stabilizing effect. However, the results of PO/CO2 copolymerization by cobalt(III)-salen/porphyrin with PPNCl suggest a suppressed catalyst reduction. This phenomenon is explained by a rapid transformation of the alkoxide into the carbonate chain end in the course of the polymer formation, greatly shortening the lifetime of the autoreducible PO-ring-opening intermediates, cobalt(III)-salen/porphyrin alkoxides.
- Xia, Wei,Salmeia, Khalifah A.,Vagin, Sergei I.,Rieger, Bernhard
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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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- Sulfur-mediated synthesis of N-doped carbon supported cobalt catalysts derived from cobalt porphyrin for ethylbenzene oxidation
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Nitrogen-doped carbon supported cobalt catalysts are synthesized by a sulfur-mediated heat treatment. Cobalt(ii) meso-tetraphenyl porphyrin (CoTPP) is used as a nitrogen-rich ligand for Co-Nx precursor complex formation and sublimed sulfur is designed as an external sulfur species. The catalysts have been investigated by techniques such as BET, TEM, HRTEM, SEM, XRD, Raman, FT-IR and XPS. The results reveal that the addition of sublimed sulfur not only changes the physical structure of the catalysts, such as specific surface area and pore volume, but also modifies the chemical properties by doping into the catalysts as well as changing the content of Co-Nx sites. When the mass ratio of adding sublimed sulfur is 0.2, the cobalt catalyst exhibits higher catalytic performance for ethylbenzene oxidation (i.e., 17.3% ethylbenzene conversion and 75.6% selectivity to acetophenone). This is ascribed to more Co-Nx active sites caused by the enhancement of sublimed sulfur. In addition, it could be easily recovered by centrifugation and reused 6 times without any significant loss in activity and selectivity (i.e., 16.3% ethylbenzene conversion and 73.9% selectivity to acetophenone) which may be attributed to the stabilization effect of S on Co-Nx by modifying the electronic density of the carbon matrix.
- Fu, Lingling,Chen, Yuan,Zhao, Sufang,Liu, Zhigang,Zhu, Runliang
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- Olefin oxidation with dioxygen catalyzed by porphyrins and phthalocyanines intercalated in α-zirconium phosphate
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Oxidation of cyclohexene and cis-stilbene with dioxygen in presence of metal phthalocyanines or metal tetraphenylporphyrins complexes intercalated in α-zirconium phosphate and isobutyraldehyde were studied. The degradation of free metal complexes in solution in the reaction media was verified. It was observed that the matrix protects the metal complexes from degradation and the activity of the catalytic system is preserved. Oxidation of cyclohexene with intercalated complexes gave epoxide as the predominant product, while allylic oxidation products were obtained in smaller proportion and the product distributions depended on the identity of the individual metal complexes. Since the addition of a free radical inhibitor stops the reaction, a free radical mechanism should be present. Oxidation of cis-stilbene with intercalated metal complexes gives different ratios of cis- to trans-stilbene oxide and of benzaldehyde which depend on the intercalated metal complex, suggesting that in addition to the free radicals there is another active oxidizing agent.
- Ni?o, Martha E,Giraldo, Sonia A,Páez-Mozo, Edgar A
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- Cobalt-doped porphyrin-based porous organic polymer-modified separator for high-performance lithium-sulfur batteries
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Lithium-sulfur (Li-S) batteries are the most promising next-generation energy storage devices owing to their excellent theoretical specific capacity (1675 mA h g?1) and the abundant availability of sulfur resources at low costs. However, serious shuttle effects and sluggish reaction kinetics obstruct the practical implementation of Li-S batteries. Herein, a functional separator modified with polytetraphenylporphyrin cobalt adsorbed onto multi-walled carbon nanotubes (PTPPCo/MWCNT) was fabricated by a simple vacuum filtration method. Because of the excellent conductivity of the MWCNT as well as the enhanced chemical adsorption and powerful catalytic activity of PTPPCo, the shuttle effect was effectively suppressed and the reaction kinetics were greatly enhanced. Consequently, the Li-S cells with the modified functional separator PTPPCo/MWCNT showed a prominent initial reversible capacity of 1330 mA h g?1at a current density of 0.2C, enhanced rate performance, outstanding cycling stability (with a slight average capacity decay of 0.038% per cycle at 2C for 500 cycles), and excellent anti-self-discharge ability.
- Hu, Shunyou,Yi, Mingjie,Huang, Xiyan,Wu, Dong,Lu, Beibei,Wang, Tiansheng,Li, Na,Zhu, Zhenye,Liu, Xiangli,Zhang, Jiaheng
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- Direct synthesis of a metalloporphyrin complex on a surface
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We demonstrate that well-defined monolayers of a metal complex on a surface can be prepared by direct vapor deposition of the metal atoms on monolayers of the ligand. In particular, ordered monolayers of adsorbed tetraphenylporphyrin (2H-TPP) on a silver surface were exposed to cobalt vapors, resulting in the complexation of the metal by the porphyrin. The formation of the metal complexes was monitored by means of X-ray photoelectron spectroscopy (XPS), which reveals that this metalation reaction leads to a chemical equivalence of all four nitrogen atoms. The described in situ metalation provides a convenient way to produce adsorbed monolayers of more reactive (e.g., air- or solvent-sensitive) or thermally unstable metalloporphyrins that are difficult to evaporate or even to obtain as pure compounds at room temperature. Copyright
- Gottfried, J. Michael,Flechtner, Ken,Kretschmann, Andreas,Lukasczyk, Thomas,Steinrueck, Hans-Peter
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- Dye-sensitizer effects on a Pt/KTa(Zr)O3 catalyst for the photocatalytic splitting of water
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(Figure Presented) Back to the elements: The activity of Pt/K 0.95Ta0.92Zr0.08O3 for the photocatalytic splitting of water into H2 and O2 is greatly improved by dye sensitization (see picture). Among the organic dyes examined, the highest photocatalytic activity is obtained with cyanocobalamin (vitamin B12) as a sensitizer.
- Hagiwara, Hidehisa,Ono, Naoko,Inoue, Takanori,Matsumoto, Hiroshige,Ishihara, Tatsumi
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- SOLVENT EFFECTS ON OPTICAL AND ESR SPECTRA OF ONE-ELECTRON REDUCED SPECIES OF COBALT(III) AND MANGANESE(III) TETRAPHENYLPORPHYRINS PRODUCED BY gamma -RADIOLYSIS AT 77 K.
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One-electron reduction by gamma -ray irradiation of cobalt(III) and manganese(III) tetraphenylporphyrins (ClCo(III)TPP, ClMn(III)TPP, and IMn(III)TPP) in ethanol and MTHF(2-methyltetrahydrofuran) solutions at 77 K results in the reduction of the central m
- Hoshino,Konishi,Imamura
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- Axial Modification of Cobalt Complexes on Heterogeneous Surface with Enhanced Electron Transfer for Carbon Dioxide Reduction
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Efficient electron communication between molecular catalyst and support is critical for heterogeneous molecular electrocatalysis and yet it is often overlooked during the catalyst design. Taking CO2 electro-reduction on tetraphenylporphyrin cobalt (PCo) immobilized onto graphene as an example, we demonstrate that adding a relay molecule improves the interfacial electron communication. While the directly immobilized PCo on graphene exhibits relatively poor electron communications, it is found that diphenyl sulfide serves as an axial ligand for PCo and it improves the redox activity of PCo on the graphene surface to facilitate the generation of [PCo].- active sites for CO2 reduction. Thus, the turnover frequencies of the immobilized Co complexes are increased. Systematic structural analysis indicates that the benzene rings of diphenyl sulfide exhibit strong face-to-face stacking with graphene, which is proposed as an efficient medium to facilitate the interfacial electron communication.
- Huang, Xiang,Wang, Jiong,Wang, Xin,Xi, Shibo,Xu, Hu
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- Novel synthetic method for metalloporphyrins with inorganic metal salts in high-temperature water
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Cobalt, nickel, copper, and oxidovanadium(2+) could be incorporated into nonpolar tetraphenyl porphyrin by using feed materials as metal sulfate, nitrate, and chloride salts and reaction in high-temperature water (423 to 673 K). Yields of metalloporphyrin
- Sato, Takafumi,Ebisawa, Katsutoshi,Ito, Satoshi,Sue, Kiwamu,Itoh, Naotsugu
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- A flexible bis-Co(III) porphyrin cage as a bimetallic catalyst for the conversion of CO2 and epoxides into cyclic carbonates
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A molecular cage consisting of two free-base porphyrins connected by four flexible linkers was metalated with Co(III) to afford in good yield a bimetallic catalyst. The catalytic activity of the bis-Co(III) porphyrin molecular cage (CoCl)2-1 was studied for the formation of cyclic carbonates from CO2 and propylene oxide (PO) or styrene oxide (SO) with pyridine as cocatalyst. Various reaction parameters such as the molar ratio of the catalyst and the co-catalyst, the time of reaction, the temperature and CO2 pressure were investigated. The molecular cage was shown to be a catalyst of high selectivity for the studied reactions and much more efficient to convert the epoxides to the corresponding cyclic carbonates than the monomeric Co(III)Cl meso-tetraphenylporphyrin (CoCl-TPP) model. When quantitative conversion of PO into propylene carbonate (PC) was reached (0.1 mol% catalyst, 1.2 mol% pyridine, 120 °C, 30 bar of CO2) only 23 % of PC was obtained with CoCl-TPP (0.2 mol%). This enhanced catalytic activity is attributed to the synergistic effect of the two metal sites incorporated in the framework of the molecular cage.
- Schoepff, Laetitia,Monnereau, Laure,Durot, Stéphanie,Jenni, Sébastien,Gourlaouen, Christophe,Heitz, Valérie
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- Formation Reaction, Spectroscopy, and Photoelectrochemistry of the Donor–Acceptor Complex (5,10,15,20-Tetraphenyl-21,23H-porphinato)cobalt(II) with Pyridyl-Substituted Fullero[60]pyrrolidine
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Kinetic and thermodynamic parameters of the donor–acceptor self-organization in the system (5,10,15,20-tetraphenyl-21H,23H-porphyrinato)cobalt(II) (CoTPP)–1-methyl-2-(pyridin-4′-yl)-3,4-fullero[60]pyrrolidine (PyC60)–toluene yielding the 1: 2 complex (PyC60)2CoTPP are presented. The chemical structure of the supramolecular triad was elucidated by UV-vis, IR, and (1H, 13C) NMR spectroscopy. The photoelectrochemical characteristics of the Ti|TiO2 electrode modified by the triad and its precursors were determined and the redox behavior of the latter was studied by cyclic voltammetry in dichloromethane.
- Bichan,Ovchenkova,Mozgova,Kudryakova,Lomova
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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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- A biomimetic photoelectrocatalyst of Co-porphyrin combined with a g-C3N4 nanosheet based on π-π Supramolecular interaction for high-efficiency CO2 reduction in water medium
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Aiming at high-efficiency biomimetic CO2 photoelectrochemical conversion, a photoelectrocatalyst with excellent CO2 catalytic activity was designed and prepared by immobilizing CoTPP (cobalt meso-tetraphenylporphyrin) onto g-C3N4 conveniently via self-assembly based on π-π supramolecular interaction. The quasi 3-D structure of CoTPP showed a suitable hole with a size of 3.8 ? × 9.6 ? which favoured CO2 adsorption. The pores formed by the π-π stacking of CoTPP and g-C3N4 also provided additional space for CO2 adsorption, which was confirmed by the appearance of a desorption peak at 250 °C in the temperature programmed desorption measurement for CoTPP/g-C3N4. As a normal efficient homogeneous catalyst in organic media, CoTPP commendably maintained outstanding CO2 photoelectrocatalytic activity in heterogeneous aqueous solution, even at a low overpotential of -0.6 V (vs. normal hydrogen electrode, NHE). Under 8 h PEC CO2 reduction, formic acid generation on CoTPP/g-C3N4 reached 154.4 μmol with a TON of 137 and high selectivity of nearly 100% in liquid products. The formation of CoTPP-COO- and CoTPP-COOH intermediates by the Co(ii) active site and CO2 was investigated by in situ UV-vis and Raman spectra. Moreover, an isotopic labelling experiment indicated that water supplied abundant protons for the production of formic acid.
- Liu, Jibo,Shi, Huijie,Shen, Qi,Guo, Chenyan,Zhao, Guohua
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- Co(II)-porphyrin-decorated carbon nanotubes as catalysts for oxygen reduction reactions: An approach for fuel cell improvement
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The development of high-performance and cost-effective catalysts for the oxygen reduction reaction (ORR) is essential for the advancement of fuel cells. In this work, three different functionalized cobalt porphyrins, meso-tetraphenylporphyrinatocobalt(ii) (CoTPP), meso-tetrakis(4′-hydroxyphenyl)porphyrinatocobalt(ii) (CoTHPP) and meso-tetrakis(4′-carboxy-phenyl)porphyrinatocobalt(ii) (CoTCPP), are prepared. These porphyrins are immobilized non-covalently on multiwalled carbon nanotubes (MWCNTs) and used for the ORR in 0.1 M HClO4, 0.1 M phosphate buffer solution (pH 7.0) and 0.1 M KOH media. The composite materials are characterized by using spectroscopic and electrochemical techniques and their oxygen reduction efficiencies are compared in different media. Kinetic interpretations and hydrodynamic voltammetry (in three media) studies demonstrated that the MWCNT-CoTPP, MWCNT-CoTHPP and MWCNT-CoTCPP composite materials exhibit significant efficiency with decreased overpotential, considerable methanol tolerance and long term operational stability (up to 3000 cycles) for the ORR similar to commercially available platinum carbon (Pt-C) catalysts. These results reveal that the new MWCNT-cobalt porphyrin composite materials can be a potential alternative to the expensive Pt-C catalysts or other commercial cathode materials in fuel cells.
- Sonkar, Piyush Kumar,Prakash, Kamal,Yadav, Mamta,Ganesan, Vellaichamy,Sankar, Muniappan,Gupta, Rupali,Yadav, Dharmendra Kumar
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- A Br-regulated transition metal active-site anchoring and exposure strategy in biomass-derived carbon nanosheets for obtaining robust ORR/HER electrocatalysts at all pH values
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A novel Br-regulated "Transition Metal Active-site Anchoring and Exposure" (TMAAE) strategy is reported, for the first time, to fabricate a hierarchical porous Co/N-doped bio-carbon bifunctional electrocatalyst (CoTBrPP?bio-C) for an all-pH ORR and HER by using a simple one-pot co-pyrolysis over a mushroom (MR) template with adsorbed Br-substituted porphyrinato cobalt (CoTBrPP). Introduction of CoTBrPP onto the MR template not only leads to a larger specific area of 604 m2 g-1 in CoTBrPP?bio-C relative to that of CoTPP?bio-C (CoTPP = Br-free CoTBrPP), 98 m2 g-1, but more importantly also regulates the oriented distribution of pores precisely which promotes effective exposure of multiple active sites depending on the departure of Br-species attached to the Co-N4 macrocycle periphery. Impressively, CoTBrPP?bio-C with a Co loading down to 0.77 at% exhibits higher all-pH ORR and HER performance compared to CoTPP?bio-C with a Co loading of 3.5 at%. An efficient TMAAE makes CoTBrPP?bio-C possess higher onset and half-wave potentials of 0.93 and 0.85 V for the ORR, and a smaller Tafel slope of 80 mV dec-1 for the HER in an alkaline medium. CoTBrPP?bio-C also had a superior all-pH long-term stability and outstanding methanol tolerance, surpassing commercial Pt/C and most non-precious-metal catalysts reported to date. Furthermore, Zn-air batteries assembled with CoTBrPP?bio-C exhibited a higher peak power density of 100 mW cm-2 and excellent durability than Pt/C.
- Lv, Xuehui,Chen, Yanli,Wu, Yanling,Wang, Haoyuan,Wang, Xinlong,Wei, Chuangyu,Xiao, Zuoxu,Yang, Guangwu,Jiang, Jianzhuang
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- Saddle-shaped macrocycle distortion and symmetry decrease in cobalt (II) meso-tetraphenylporphyrin: Structure of a dichloromethane solvate and DFT calculations
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Many studies about porphyrins have emerged in recent years, including studies using porphyrins as building blocks for supramolecular assemblies. Understanding new solid state forms of porphyrins and the elucidation of their structures can have remarkable benefits for nanoscience and synthetic biology. In this study, a new pseudopolymorph of cobalt (II) meso-tetraphenylporphyrin, (CoTPP), was synthesized in a known one-pot reaction, rather than using many-step conventional methods, was isolated and was characterized for the first time by low-temperature single crystal X-ray diffraction. It is a nonstoichiometric solvate assembled into dichloromethane channels. The most striking feature of this structure is the conformation adopted by the porphyrin macrocycle. In contrast to the non-solvated form of CoTPP that exhibits a ruffled core distortion and crystallizes in the tetragonal space group I-42d, this solvated form has been crystallized in the triclinic space group Piˉ and shows a distinct saddle-shaped macrocycle distortion. In the triclinic form, the conformation of one of the four phenyl rings is remarkably different from the others. A potential energy surface scan of the torsional angles around the bonds between this phenyl moiety and the macrocycle of CoTPP in both the non-solvated and the solvate forms demonstrates that the saddle-shaped macrocycle distortion depends on the unusual phenyl conformation. The distortion is responsible for the symmetry decrease in the channel solvate form, causing a loss of the 4-fold rotoinversion axis observed in the non-solvated tetragonal phase, which has identical phenyl conformations.
- De Melo, Cristiane Cabral,Moreira, Wania Da Concei??o,Martins, Tássia Joi,Cordeiro, Márcia Regina,Ellena, Javier,Guimar?es, Freddy Fernandes,Martins, Felipe Terra
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- Regarding Initial Ring Opening of Propylene Oxide in its Copolymerization with CO2 Catalyzed by a Cobalt(III) Porphyrin Complex
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Cobalt(III) tetraphenylporphyrin chloride (TPPCoCl) was experimentally proved to be an active catalyst for poly(propylene carbonate) production. It was chosen as a model catalyst in the present work to investigate the initiation step of propylene oxide (PO)/CO2 copolymerization, which is supposed to be the ring opening of the epoxide. Ring-opening intermediates (1-7) were detected by using 1HNMR spectroscopy. A first-order reaction in TPPCoCl was determined. A combination of monometallic and bimetallic ring-opening pathways is proposed according to kinetics experiments. Addition of onium salts (e.g., bis(triphenylphosphine)iminium chloride, PPNCl) efficiently promoted the PO ring-opening rate. The existence of axial ligand exchange in the cobalt porphyrin complex in the presence of onium salts was suggested by analyzing collected 1HNMR spectra. Monometallic or bimetallic? Ring-opening intermediates of propylene oxide (PO) catalyzed by a cobalt(III) porphyrin complex were identified by using 1HNMR spectroscopy. The generated metal alkoxides underwent hydrolysis in the presence of trace amounts of water. A combined bimetallic and monometallic ring-opening pathway was suggested from the kinetics results. Addition of onium salts accelerated the PO ring opening. Ligand exchange on the cobalt center in the presence of onium salts was also detected.
- Xia, Wei,Vagin, Sergei I.,Rieger, Bernhard
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- Selective nitrogen reduction to ammonia on iron porphyrin-based single-site metal-organic frameworks
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Constructing efficient catalysts for N2reduction into value added ammonia under ambient conditions is a considerable challenge. Herein, well-defined single-site metal-organic frameworks (MOFs, M-TCPP; M = Fe, Co, or Zn) were constructed and evaluated as electrocatalysts for N2reduction. The prepared Fe-TCPP exhibited prominent performance with a high NH3yield of 44.77 μg h?1mgcat.?1and a faradaic efficiency of 16.23%, superior to that of all the reported molecular and MOF catalysts. The superior performance was ascribed to the highly effective N2activation at the Fe site, and benefited from the overall reaction thermodynamics advantage in the key reaction step of *NNH formation. This study gives an understanding of the intrinsic activity of well-defined catalysts in the electrocatalytic N2reduction, and provides atomic-level insights into the rational design and engineering of highly active catalysts for artificial N2fixation.
- Cong, Meiyu,Chen, Xuyang,Xia, Kai,Ding, Xin,Zhang, Linlin,Jin, Yu,Gao, Yan,Zhang, Lixue
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supporting information
p. 4673 - 4678
(2021/03/09)
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- Reaction, structure and spectroscopic properties of bis(cyano) cobalt(III) porphyrin complexes
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Cyanocobalamin and analogues have drawn much attention for the promising applications in photovoltaic and photocatalytic systems. In this study, two low spin bis(cyano) cobalt(III) porphyrin complexes [K(222)][CoIII(TPP)(CN)2] and [K(222)][CoIII(TMP)(CN)2] (222 = 4,7,13,16,21,24-hexaoxo-1,10-diazabicyclo[8.8.8]hexacosane, TPP = meso-tetraphenylporphyrin dianion, TMP = meso-tetramesitylporphyrin dianion), which were isolated from the reactions between [CoII(Porph)] (Porph = Porphyrin) and [K(222)(CN)], are characterized by a single crystal X-ray diffraction, FT-IR and UV-vis spectroscopies. Combined UV-vis and electron paramagnetic resonance (EPR) investigations have been conducted to understand the reaction mechanisms. The work gives new insights into the reactivities and spectroscopic properties of cyano cobalt macrocyclic complexes.
- Zhao, Jianping,He, Mingrui,Yao, Zhen,Cao, Hongli,Yuan, Yiwen,Bian, Yongzhong,Li, Jianfeng
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p. 825 - 834
(2021/06/18)
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- Co(II)-porphyrin complexes with nitrogen monoxide and imidazole: synthesis, optimized structures, electrochemical behavior and photochemical stability
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UV-vis and 1H-NMR spectroscopy were applied to study axial coordination of imidazole (L1) and nitrogen monoxide (L2) with CoII-porphyrins (CoIIP) containing halogen substituents in the pyrrole and meso-phenyl positions of
- Kaigorodova, Elena Yu.,Mamardashvili, Galina M.,Simonova, Olga R.,Chizhova, Nataliya V.,Mamardashvili, Nugzar Zh.
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p. 2443 - 2462
(2021/11/10)
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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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- Single-atom metal-N4site molecular electrocatalysts for ambient nitrogen reduction
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Electrochemical N2reduction to NH3is an emerging energy technology, attracting much attention due to its features of mild reaction conditions and being non-polluting. In this work, we demonstrate that a well-defined cobalt tetraphenylporphyrin (CoTPP) molecule as a model catalyst exhibits good electrocatalytic nitrogen reduction activity in 0.1 M HCl electrolyte with an ammonia yield of 15.18 ± 0.78 μg h-1mg-1cat.calculated by the indophenol blue method and a Faraday efficiency (FE) of 11.43 ± 0.74%. The catalyst also has satisfactory electrolytic stability and recycling test reusability. The activity displayed by the porphyrin molecular catalysts is attributed to the full exposure of the metal-N4sites. To trace the source of ammonia, an isotope labeling experiment (15N2as the feed gas) is used to calculate the ammonia yieldvia1H nuclear magnetic resonance (NMR), which is close to that of the indophenol blue method. In addition, we replace the central metal to prepare CuTPP and MnTPP, and they also show electrocatalytic nitrogen reduction reaction (NRR) ability. This work proves the feasibility and versatility of using metalloporphyrin molecules as model electrocatalysts for NRR and offers a new strategy for the further development of molecular NRR catalysts.
- Sun, Sai,Yang, Xiaoxuan,Li, Siqi,Chen, Xinyu,Li, Ke,Lv, Jiaqi,Wang, Wenwen,Cheng, Dongming,Wang, Yong-Hui,Zang, Hong-Ying
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p. 2589 - 2596
(2021/04/22)
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- Efficient oxidation of cumene to cumene hydroperoxide with ambient O2 catalyzed by metalloporphyrins
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A novel and efficient protocol for oxidation of cumene to cumene hydroperoxide was presented using ambient O2 catalyzed by very simple metalloporphyrins. The selectivity toward cumene hydroperoxide reached 98.3% in the cumene conversion of 28.1% with T(4-COOH)PPCu as a catalyst at 80°C. The origin of the higher performance of T(4-COOH)PPCu was mainly ascribed to the low catalytic performance of copper(II) in the cumene hydroperoxide decomposition, and the ability of T(4-COOH)PP in stabilizing cumene hydroperoxide through hydrogen-bond interactions between them. Compared with current industrial processes and academic research in oxidation of cumene to cumene hydroperoxide with O2, the main superiorities of this protocol were the high selectivity, high conversion, simple catalysts, solvent-free, additive-free and mild conditions which made this work an appealing reference for the industrial oxidation of cumene to cumene hydroperoxide, as well as the oxidative functionalization of other C-H bonds in various hydrocarbons. 2021 World Scientific Publishing Company.
- Shen, Hai M.,Ye, Hong L.,Wang, Qin,Hu, Meng Y.,Liu, Lei,She, Yuan B.
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p. 314 - 322
(2021/04/09)
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- Method for synthesizing tetraaryl cobalt porphyrin through synchronous cyclization and metallization
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The invention discloses a method for synthesizing tetraaryl cobalt porphyrin through synchronous cyclization and metallization. Under the catalysis of anhydrous aluminum trichloride, aromatic aldehyde, pyrrole and cobalt salt are subjected to cyclization and metallization reactions synchronously in a DMF solvent and a nitrogen atmosphere to generate the tetraaryl cobalt porphyrin. The reaction process comprises the following steps: sequentially adding anhydrous aluminum trichloride, aryl aldehyde, pyrrole and cobalt salt into DMF while stirring, stopping reaction after heating reflux reactionfor a certain time, cooling, standing overnight near 273K, and carrying out suction filtration to obtain cobalt porphyrin crystals. According to the method, the aromatic aldehyde, the pyrrole and thecobalt salt are directly used as raw materials, porphin is not needed, strongly corrosive organic acid is not used as a solvent, high-purity tetraaryl cobalt porphyrin is obtained at a high yield under the condition that a complex separation means is not needed, and industrial production is easy to achieve.
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Paragraph 0030; 0031
(2020/09/08)
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- Noncovalent immobilization of Co(ii)porphyrin through axial coordination as an enhanced electrocatalyst on carbon electrodes for oxygen reduction and evolution
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Catalysis of fuel-producing reactions can be transferred from homogeneous solution to a surface via attachment of the molecular catalyst. A pyrene-pyridine hybrid (Py-Py) was used as an axial ligand to bridge Co(ii)tetraphenylporphyrin which was finally immobilized on carbon nanotubes via noncovalent interactions and further deposited on glassy carbon. This noncovalent immobilization of Co(ii)porphyrin through axial coordination provides significantly enhanced electrochemically catalyzed oxygen reduction and oxygen evolution, illustrating a new insight into understanding surface catalysis.
- Attatsi, Isaac Kwaku,Zhu, Weihua,Liang, Xu
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supporting information
p. 4340 - 4345
(2020/03/26)
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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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- In situ synthesis of highly dispersed Co-N-C catalysts with carbon-coated sandwich structures based on defect anchoring
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Highly dispersed Co-N-C catalysts were successfully prepared via a defect strategy to anchor metal atoms with a carbon coating. The catalysts showed remarkable catalytic performance under mild conditions (a yield of 97.0% for ethylbenzene oxidation). Meanwhile, BET, TEM, XRD, Raman spectroscopy and XPS studies were employed to investigate the as-prepared catalysts. The results revealed that the unique structure was conducive to producing more defects in carbon, increasing the number of active sites and enhancing the dispersion of cobalt. The outstanding catalytic performance of the catalysts was attributed to the synergy effect of the special structure and the Co-N, pyridine nitrogen and graphite nitrogen species.
- Li, Suisheng,Zhang, Lushuang,Jie, Shanshan,Liu, Zhigang
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p. 5404 - 5409
(2020/04/17)
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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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- Efficient and selective oxidation of tertiary benzylic C[sbnd]H bonds with O2 catalyzed by metalloporphyrins under mild and solvent-free conditions
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The direct and efficient oxidation of tertiary benzylic C[sbnd]H bonds to alcohols with O2 was accomplished in the presence of metalloporphyrins as catalysts under solvent-free and additive-free conditions. Based on effective inhibition on the unselective autoxidation and deep oxidation, systematical investigation on the effects of porphyrin ligands and metal centers, and apparent kinetics study, the oxidation system employing porphyrin manganese(II) (T(2,3,6-triCl)PPMn) with bulkier substituents as catalyst, was regarded as the most promising and efficient one. For the typical substrate, the conversion of cumene could reach up to 57.6% with the selectivity of 70.5% toward alcohol, both of them being higher than the current documents under similar conditions. The superiority of T(2,3,6-triCl)PPMn was mainly attributed to its bulkier substituent groups preventing metalloporphyrins from oxidative degradation, its planar structure favoring the interaction between central metal with reactants, and the high efficiency of Mn(II) in the catalytic transformation of hydroperoxides to alcohols.
- Hu, Meng-Yun,Liu, Lei,Qi, Bei,She, Yuan-Bin,Shen, Hai-Min,Ye, Hong-Liang
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- Method and device for preparing metalloporphyrin compound
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The invention discloses a method and a device for preparing a metalloporphyrin compound. The method comprises the following steps: using a porphyrin and a transition metal acetic acid aqueous salt ora chloride aqueous salt as raw materials, performing a reflux reaction on a metallization reaction device, and using thin layer chromatography (TLC) or UV-Vis spectroscopy (UV-Vis) to monitor the reaction process until porphyrin is completely reacted, distilling off a solvent from the reaction product and washing with water and recrystallizing to obtain the product. due to a higher conjugated structure, the single metalloporphyrin polymer shows better electrocatalytic activity of an oxygen reduction reaction, can catalyze oxygen reduction reaction in acidic, basic or neutral electrolytes, andhas good stability and methanol resistance. The large-scale synthesis method of metalloporphyrin has good social and economic benefits, high yield, low production cost and easy separation of products.
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Paragraph 0047; 0048; 0049; 0050
(2019/05/08)
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- Chlorotrifluoromethylation of Terminal Olefins by Atom Transfer-Type Radical Reaction Catalyzed by Cobalt Complexes
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A cobalt porphyrin-catalyzed chlorotrifluoromethylation reaction of olefins is described. The use of CF3SO2Cl as the CF3 radical source and a cobalt catalyst enabled the selective addition of CF3 radicals under thermal conditions. Various functional groups such as esters and Ar–X moieties, which can be reactive with low valent transition metal catalysts, were well-tolerated in this catalytic process. A highly functionalized alkaloid derivative was also tolerated as a substrate. As a demonstration of the bio-inspired catalytic system, catalytic usage of vitamin B12, which is the commercially available form of the natural cobalt porphyrinoid, was employed, and diastereoselective chlorotrifluoromethylation of the alkaloid molecule was achieved.
- Maeda, Kazuki,Kurahashi, Takuya,Matsubara, Seijiro
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p. 4613 - 4616
(2019/07/18)
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- Bicontinuous mesoporous Co, N co-doped carbon catalysts with high catalytic performance for ethylbenzene oxidation
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A series of bicontinuous mesoporous Co, N co-doped carbon catalysts (Co-N-C), which have large pore sizes and high specific surface areas with remarkable catalytic activity, were prepared through a method using KIT-6 silica as a hard template, and cobalt porphyrin and sucrose as precursors. And morphological and structural characterizations were performed using N2 adsorption-desorption isotherm, XRD, Raman, TEM and XPS techniques. The results showed that the ethylbenzene oxidation with TBHP as an oxidant over the bicontinuous mesoporous Co, N co-doped carbon catalysts achieved 93% of ethylbenzene conversion with about 99% of selectivity to acetophenone. The superior catalytic performance of the catalysts was attributed to the synergistic effect of factors such as high surface area and well-dispersed metal active sites.
- Zhang, Lushuang,Jie, Shanshan,Liu, Zhigang
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supporting information
p. 7275 - 7281
(2019/05/24)
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- Cobalt(II)-based Metalloradical Activation of 2-(Diazomethyl)pyridines for Radical Transannulation and Cyclopropanation
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A new catalytic method for the denitrogenative transannulation/cyclopropanation of in-situ-generated 2-(diazomethyl)pyridines is described using a cobalt-catalyzed radical-activation mechanism. The method takes advantage of the inherent properties of a CoIII-carbene radical intermediate and is the first report of denitrogenative transannulation/cyclopropanation by a radical-activation mechanism, which is supported by various control experiments. The synthetic benefits of the metalloradical approach are showcased with a short total synthesis of (±)-monomorine.
- Roy, Satyajit,Das, Sandip Kumar,Chattopadhyay, Buddhadeb
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supporting information
p. 2238 - 2243
(2018/02/19)
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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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- Design of oxophilic metalloporphyrins: An experimental and DFT study of methanol binding
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By systematic measurements we have evaluated a series of tetraphenyl metalloporphyrins and halogenated tetraphenyl metalloporphyrin derivatives for binding to ligands with oxygen containing functional groups, using methanol, acetic acid and acetone as examples. Experimental binding constants identified three metalloporphyrins with good binding to all three ligands: MgTPFPP, MgTPPBr8 and ZnTPPBr8 as well as a range of porphyrins binding to select ligands. Based on these results the optimal porphyrins can be selected for the desired binding interactions. We also show how to use DFT calculations to evaluate the potential binding between a metalloporphyrin and a ligand, which is deduced from free energies of binding ΔG, charge transfer ΔQ, and change of metal spin state. Computations on unsubstituted porphyrins in lieu of tetraphenyl porphyrin systems yield reliable predictions of binding interactions with good correlation to the corresponding experimental data. The calculations have also yielded interesting insights into the effect of halogenation in the β-position on the binding to ligands with oxygen containing functional groups.
- Olsson, Sandra,Dahlstrand, Christian,Gogoll, Adolf
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supporting information
p. 11572 - 11585
(2018/08/28)
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- Influence of the Coordination Surrounding of Co(II)- and Co(III)-Tetraphenylporphyrins on Their Destruction Processes in the Presence of Organic Peroxides
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The interaction of Co(II)- and Co(III)-5,10,15,20-tetraphenylporphyrins with tert-butylhydroxyperoxide and di-tert-butylhydroxyperoxide in benzene at 298 K were studied by spectrophotometry and 1H NMR spectroscopy. Kinetic parameters of the des
- Mamardashvili,Simonova,Chizhova,Mamardashvili, N. Zh.
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p. 1154 - 1163
(2018/08/16)
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- Cobalt Tetrabutano- and Tetrabenzotetraarylporphyrin Complexes: Effect of Substituents on the Electrochemical Properties and Catalytic Activity of Oxygen Reduction Reactions
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Three series of cobalt tetraarylporphyrins were synthesized and characterized by electrochemistry and spectroelectrochemistry. The investigated compounds have the general formula (TpYPP)Co, butano(TpYPP)CoII, and benzo(TpYPP)CoII, where TpYPP represents the dianion of the meso-substituted porphyrin, Y is a CH3, H, or Cl substituent on the para position of the four phenyl rings, and butano and benzo are respectively the β- and β′-substituted groups on the four pyrrole rings of the compound. Each porphyrin undergoes one or two reductions depending upon the meso substituent and solvent utilized. Two irreversible reductions are observed for (TpYPP)CoII and butano(TpYPP)CoII in CH2Cl2 containing 0.1 M tetra-n-butylammonium perchlorate; the first leads to the formation of a highly reactive cobalt(I) porphyrin, which can then rapidly react with a solvent to give a CoIIICH2Cl as the product. Only one reversible reduction is seen for benzo(TpYPP)CoII under the same solution conditions, and the one-electron-reduction product is assigned as a cobalt(II) porphyrin π-anion radical. Three oxidations can be observed for each examined compound in CH2Cl2. The first oxidation is metal-centered for the (TpYPP)Co and benzo(TpYPP)CoII derivatives, leading to generation of a cobalt(III) porphyrin with an intact π-ring system, but this redox process is ring-centered in the case of butano(TpYPP)CoII and gives a CoII π-cation radical product. Each porphyrin was also examined as a catalyst for oxygen reduction reactions (ORRs) when adsorbed on a graphite electrode in 1.0 M HClO4. The number of electrons transferred (n) during ORRs is 2.0 for the butano(TpYPP)CoII derivatives, consistent with only H2O2 being produced as a product for the reaction with O2. However, the reduction of O2 using the cobalt benzoporphyrins as catalysts gave n values between 2.6 and 3.1 under the same solution conditions, thus producing a mixture of H2O and H2O2 as the reduction product. This result indicates that the β and β′ substituents have a significant effect on the catalytic properties of the cobalt porphyrins for ORRs in acid media.
- Ye, Lina,Fang, Yuanyuan,Ou, Zhongping,Xue, Songlin,Kadish, Karl M.
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p. 13613 - 13626
(2017/11/15)
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- The effect of chemical modification of the macrocycle on the complex formation between porphyrins and metal salts in organic solvents
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The complex formation of β-octaethylporphyrin, β-octaethyl-meso-monophenylporphyrin, β-octaethyl-meso-tetraphenylporphyrin, meso-diphenylporphyrin, meso-triphenylporphyrin, and meso-tetraphenylporphyrin with Zn(II), Cu(II), Co(II), and Mn(II) acetates and chlorides in dimethylformamide, dimethylsulfoxide, pyridine, acetic acid, and a chloroform–methanol 1 : 1 mixture has been studied by means of spectrophotometry. The observed regulations are in line with the concept of chemical reactivity of the N–H bonds in porphyrins of different complexity.
- Maltceva,Mamardashvili, N. Zh.
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p. 1175 - 1183
(2017/08/08)
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- Catalytic Aerobic Oxidation of Biomass-based Furfural into Maleic Acid in Aqueous Phase with Metalloporphyrin Catalysts
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Catalytic oxidation of renewable furfural into valuable maleic acid in aqueous solutions using metalloporphyrin catalysts was investigated for the first time. The synthesized catalysts were characterized by FT-IR, UV–vis, 1H NMR, elemental analysis, and TGA. The catalysts varied in metal active sites and functional groups, which had different effects on their catalytic activity. Furthermore, the effects of temperatures, reaction time, catalyst loading, and oxygen pressure were studied in detail. Maleic acid could be achieved in 44% yield by using FeT(p-Cl)PPCl as catalyst under optimal conditions. Finally, FeT(p-Cl)PPCl could be reused in five consecutive runs without a significant loss of activity.
- Huang, Yi,Wu, Chunyan,Yuan, Wenwen,Xia, Yongmei,Liu, Xiang,Yang, Huamei,Wang, Haijun
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p. 786 - 794
(2017/07/24)
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- Nitrogen-doped carbon cobalt grafted on graphitic carbon nitride catalysts with enhanced catalytic performance for ethylbenzene oxidation
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Nitrogen-doped carbon cobalt (Co-N-C) grafted on graphitic carbon nitride (g-C3N4) catalysts (Co-N-C/g-C3N4) were synthesized via pyrolysis of cobalt(II) 5,10,15,20-tetraphenylporphyrin (CoTPP) immobilized on graphitic carbon nitride in N2 atmosphere. These catalysts were characterized by techniques such as UV-vis, FT-IR, TG-DTA, XRD, SEM, TEM, HRTEM, BET and XPS. The catalytic performance of Co-N-C/g-C3N4 for selective oxidation of ethylbenzene has been investigated. As a result, when the mass ratio of CoTPP to g-C3N4 is 20%, the conversion of ethylbenzene over Co-N-C/g-C3N4 is 28.0%, nearly 2.3 and 1.9 times than those over pure g-C3N4 and Co-N-C, respectively. Moreover, better stability is also performed after 6 runs (i.e., 20.3% conversion of ethylbenzene and 71.1% of selectivity to acetophenone). The results show that the superior catalytic activity and stability maybe attributed to the Co-Nx active site and the synergistic effect between Co-N-C and g-C3N4.
- Lin, Xiu,Zhao, Sufang,Chen, Yuan,Fu, Lingling,Zhu, Runliang,Liu, Zhigang
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- Preparation of CoNC catalysts: Via heating a mixture of cobaltporphyrin and casein for ethylbenzene oxidation
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Biomass-derived cobalt-coordinated N-doped carbon (CoNC) for C-H bond oxidation is synthesized by a facile procedure based on pyrolysis of cobaltporphyrin with natural, amino acid-rich biomass casein as a supplementary nitrogen source. The catalysts are characterized by techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The obtained CoNC catalyst has a high metal content and dispersion and shows superior catalytic performance in C-H bond oxidation with molecular oxygen as oxidant under solvent-free conditions. This is attributed to the promotion of the Co-Nx moiety originating from cobaltporphyrin. Moreover, the catalyst shows remarkable stability and can be recycled several times without losing its activity.
- Yang, Congqiang,Chen, Yuan,Zhao, Sufang,Zhu, Runliang,Liu, Zhigang
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p. 75707 - 75714
(2016/08/24)
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- Synthesis of Co-N-C immobilized on carbon nanotubes for ethylbenzene oxidation
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The catalysts, namely noble-metal-free Co-N-C immobilized carbon nanotubes (CNTs), are synthesized via heating nitrogen-rich cobalt tetraphenyl porphyrin (CoTPP) supported on CNTs in N2 atmosphere. The obtained catalysts have been characterized by BET, Raman, XRD, TEM, HRTEM and XPS. It is found that the synergistic effect between carrier and active sites plays an important role in the catalytic performance of Co-N-C/CNTs for ethylbenzene oxidation. When the mass ratio of CoTPP to CNTs is 0.15, the catalyst exhibits the highest catalytic performance for ethylbenzene oxidation (i.e. 19.9% for ethylbenzene conversion, 72.9% selectivity of acetophenone). It can be attributed to the well-dispersed Co-N-C species and the enhanced interaction chances between substrate and active sites with the introduction of CNTs.
- Qiu, Yuyuan,Yang, Congqiang,Huo, Jia,Liu, Zhigang
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p. 276 - 282
(2016/09/14)
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- Porphyrine type compound having a metal complex manufacturing method
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[Problem] To provide a clean and efficient method for producing a metal complex of a compound that has a porphyrin skeleton, which does not use an organic solvent at all during the synthesis and is capable of easily separating a metal complex in a solid state from an aqueous solution of a metal salt after the reaction, and which places extremely little burden on the environment. [Solution] The above-described problem is solved by a method for producing a metal complex of a compound that has a porphyrin skeleton, wherein a compound having a porphyrin skeleton and a metal salt are caused to react with each other in water at a reaction temperature of 200-450°C (inclusive). It is preferable that tetraphenylporphyrin and a metal salt are caused to react with each other in water at a reaction temperature of 300-400°C (inclusive).
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Paragraph 0068
(2016/12/26)
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- Synthesis, chemical stability, and electrocatalytic properties of zinc(II) and cobalt(II) complexes of N-methyltetraphenylporphine
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Distortion of flat ligand structure in metal complexes of porphyrins caused by N-methyl substitution considerably decreases the kinetic stability of these compounds in DMSO-HOAc proton-releasing medium ((AcO)Zn(N-Me)TPP (Ib) II(N-Me)TPP (Ia) IITPP (IIa)) and their resistance to thermal destruction in crystal state {(AcO)CoII(N-Me)TPP (Ia) 2TPP (II) IITPP (IIa) ZnTPP (IIb)}, however, exerts a positive effect on the electrocatalytic activity of the compounds in the electroreduction of molecular oxygen, which changes in the following order: II I IIa Ib ? Ia. It was proved by thermogravimetry and electron spectroscopy that N-substituted metal complexes with Zn(II) and Co(II), in contrast to the corresponding ligands, undergo dealkylation to form metal porphyrins (MP) when heated above 200°C under both an inert and air oxygen atmosphere.
- Berezin,Txao, Vu Thi,Azorina,Shukhto,Guseinov,Berezina
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p. 1267 - 1274
(2015/10/12)
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- Biomimetic Nitration of Phenols Using Metalloporphyrins/H2O2/NO2 -
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An efficient metalloporphyrins/H2O2/NO2 - nitration of phenols has been developed. The total yield of nitrophenol could reach up to 55.1 %, which is about 4 and sixfold higher than that of horse radish peroxidase catalysis and peroxynitrite nitration, respectively. Furthermore, the nitration system attained an enhanced regioselectivity of 1.0 o/p ratio, and exhibited a good substrate scope of monophenols. This protocol is environmentally friendly compared with HNO3/H2SO4 nitration, and stable, inexpensive and organic solvent tolerant compared with enzyme catalytic nitration and peroxynitrite nitration reaction. Graphical Abstract: [Figure not available: see fulltext.]
- Sun, Weizhi,Liu, Yaojie,Zhang, Haibo,Xian, Mo,Liu, Huizhou
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p. 1991 - 1999
(2015/12/24)
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- Cobalt catalysts embedded in N-doped carbon derived from cobalt porphyrin via a one-pot method for ethylbenzene oxidation
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Abstract A template-free method was employed to synthesize cobalt catalysts embedded in N-doped carbon (Co-N-C) through heating cobalt(II) meso-tetraphenyl porphyrin (CoTPP) precursor at different temperature (600°C, 700°C, 800°C). These catalysts were characterized by techniques such as BET, TG-DTA, TEM, STEM, XRD, Raman and XPS. The selective oxidation of ethylbenzene under solvent-free condition with molecular oxygen was carried out to explore the catalytic performance of Co-N-C. 13.4% conversion of ethylbenzene with 73.3% selectivity to acetophenone was achieved over Co-N-C and the catalytic performance of the catalyst was similar to the fresh even after six runs (i.e., 12.5% of ethylbenzene conversion and 72.2% of selectivity to acetophenone). The results show that the stable catalytic performance of the catalysts may be attributed to the stable N-doped graphitic carbon, the stability of carbon-encapsulated Co nanoparticles and the synergistic effect between N-C structure and cobalt oxide.
- Fu, Lingling,Chen, Yuan,Liu, Zhigang
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- One-pot synthesis of cobalt-coordinated N-doped carbon catalysts via co-synthesis of ionic liquids and cobalt porphyrins
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Cobalt-coordinated N-doped carbon (CoNC) was fabricated by heating cobalt porphyrins and ionic liquids. The prepared catalysts displayed superior catalytic capacity for the direct oxidation of ethylbenzene, and unprecedented stability was obtained even after six runs with a similar catalytic performance.
- Chen, Yuan,Fu, Lingling,Liu, Zhigang
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supporting information
p. 16637 - 16640
(2015/11/25)
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- A convenient, high-yielding, chromatography-free method for the insertion of transition metal acetates into porphyrins
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Presented is a quick and efficient method for the insertion of first-row transition metal acetates into 5,10,15,20-tetraphenyl porphyrin, utilizing Soxhlet extraction for the removal of the acetic acid by-product. High yields (>90%) and purity are achieved without requiring chromatographic purification. Basic Mn(III) and Fe(III) acetate may be used, as well as hydrated Co(II), Ni(II), and Cu(II) acetates as starting materials. In the case of Fe, an initial mixture of Fe(TPP)OAc and [Fe(TPP)]2O is formed, which can be quantitatively converted to Fe(TPP)OAc by treatment with acetic acid. The crystal structure of Fe(TPP)OAc is reported, and spectral data for all compounds is presented, including a correction of the literature UV- Vis data for Fe(TPP)OAc. Attempted metalation with basic Cr(III) acetate yielded a mixture of Cr(TPP)OAc and the oxo-bridged dimer. The latter cannot be converted to the desired acetate. No reaction occurred with vanadyl or titanyl acetate under the conditions used.
- Yao, Shu A.,Hansen, Christopher B.,Berry, John F.
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- Oxidative cleavage of isoeugenol to vanillin under molecular oxygen catalysed by cobalt porphyrin intercalated into lithium taeniolite clay
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Three types of Co-porphyrin complexes differing in their porphyrin-ring substituents and nonionic or cationic structure were intercalated into lithium taeniolite (LiTN) using a simple cation exchange method. All the intercalated catalysts displayed expanded clearance spaces (in the range of 0.30-0.51 nm) compared with that of the parent LiTN (0.24 nm). The catalysts were applied for the oxidative cleavage of isoeugenol to vanillin with molecular oxygen as the sole oxidant, and the reaction proceeded effectively under mild reaction conditions. The highest vanillin selectivity of 72% was obtained with CoTPyP/TN, which had the widest clearance space among the three Co-porphyrin catalysts. These intercalated catalysts showed high stability during oxidation, enabling their recycling for at least three runs.
- Adilina, Indri Badria,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
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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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- Cobalt(III) porphyrin catalyzed aza-Diels-Alder reaction
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An efficient protocol for the aza-Diels-Alder reaction of electron-deficient 1,3-dienes with unactivated imines in the presence of a cationic cobalt(III) porphyrin complex was developed. The transformation proceeded smoothly to afford the desired piperidi
- Wakabayashi, Ryota,Kurahashi, Takuya,Matsubara, Seijiro
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supporting information
p. 4794 - 4797
(2013/01/15)
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- Metal porphyrin/phenyltrimethylammonium tribromide: High efficient catalysts for coupling reaction of CO2 and epoxides
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Novel and high efficient catalysts of metal porphyrin (M(TPP)X, M = Co, Fe, Ru, Mn; X = Cl-, Br-, OAc-, OTs-, Cl3CCO2-)/phenyltrimethylammonium tribromide (PTAT) were developed t
- Jin, Lili,Jing, Huanwang,Chang, Tao,Bu, Xiuli,Wang, Li,Liu, Zhongli
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p. 262 - 266
(2008/10/09)
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- Coordination of nitrogen-containing ligands by Co complexes with tetra-and dodeca-substituted porphyrins
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Capabilities of complexes with tetraphenylporphyrin, the derivative of tetrapyridiniumporphyrin, and with β-octabromine-meso-tetraphenylporphyrin to coordinate additional nitrogen-containing ligands are compared. The equilibrium constants of addition of e
- Guseva,Pukhovskaya,Semeikin,Golubchikov
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p. 116 - 119
(2008/10/09)
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- Coordination of nitrogen(II) oxide by metal prophyrins
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The equilibrium constants have been determined for the extra coordination of nitrogen(II) oxide and its metabolite formed in biochemical reactions (the nitrite ion) by cobalt complexes of porphyrins with various structures in ethanolic and aqueous solutions with near-physiological pHs. The far higher values of the thermodynamic stability constants of (NO)CoP nitrosyl complexes compared to those for nitrite complexes argue for a considerable covalence of the Co-NO bond. Nauka/Interperiodica 2007.
- Pukhovskaya,Guseva,Semeikin,Golubchikov
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p. 293 - 296
(2008/10/09)
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