14172-90-8Relevant articles and documents
Ionic multi-component complexes containing TDAE·+ and C60·- radical ions and neutral D1 molecules: D1·TDAE·C60
Konarev, Dmitri V.,Neretin, Ivan S.,Saito, Gunzi,Slovokhotov, Yury L.,Otsuka, Akihiro,Lyubovskaya, Rimma N.
, p. 3886 - 3891 (2003)
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.
Concerning the deactivation of cobalt(III)-based porphyrin and salen catalysts in epoxide/CO2 copolymerization
Xia, Wei,Salmeia, Khalifah A.,Vagin, Sergei I.,Rieger, Bernhard
, p. 4384 - 4390 (2015)
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.
Synthesis of 5,10,15,20-tetrakisphenylporphins on a carbon support for the cathodic reduction of oxygen in fuel cells
Kirschenmann,Woehrle
, p. 1403 - 1406 (1988)
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.
Sulfur-mediated synthesis of N-doped carbon supported cobalt catalysts derived from cobalt porphyrin for ethylbenzene oxidation
Fu, Lingling,Chen, Yuan,Zhao, Sufang,Liu, Zhigang,Zhu, Runliang
, p. 19482 - 19491 (2016)
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.
Olefin oxidation with dioxygen catalyzed by porphyrins and phthalocyanines intercalated in α-zirconium phosphate
Ni?o, Martha E,Giraldo, Sonia A,Páez-Mozo, Edgar A
, p. 139 - 151 (2001)
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.
Cobalt-doped porphyrin-based porous organic polymer-modified separator for high-performance lithium-sulfur batteries
Hu, Shunyou,Yi, Mingjie,Huang, Xiyan,Wu, Dong,Lu, Beibei,Wang, Tiansheng,Li, Na,Zhu, Zhenye,Liu, Xiangli,Zhang, Jiaheng
, p. 2792 - 2805 (2021)
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.
Direct synthesis of a metalloporphyrin complex on a surface
Gottfried, J. Michael,Flechtner, Ken,Kretschmann, Andreas,Lukasczyk, Thomas,Steinrueck, Hans-Peter
, p. 5644 - 5645 (2006)
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
Dye-sensitizer effects on a Pt/KTa(Zr)O3 catalyst for the photocatalytic splitting of water
Hagiwara, Hidehisa,Ono, Naoko,Inoue, Takanori,Matsumoto, Hiroshige,Ishihara, Tatsumi
, p. 1420 - 1422 (2006)
(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.
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.
Hoshino,Konishi,Imamura
, p. 1713 - 1717 (1984)
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
Axial Modification of Cobalt Complexes on Heterogeneous Surface with Enhanced Electron Transfer for Carbon Dioxide Reduction
Huang, Xiang,Wang, Jiong,Wang, Xin,Xi, Shibo,Xu, Hu
, p. 19162 - 19167 (2020)
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.
