52242-06-5Relevant academic research and scientific papers
Reaction of a {Co(NO)}8 complex with superoxide: Formation of a six coordinated [CoII(NO)(O2[rad]–)] species followed by peroxynitrite intermediate
Mazumdar, Rakesh,Mondal, Baishakhi,Saha, Shankhadeep,Samanta, Bapan,Mondal, Biplab
, (2022/01/11)
A nitrosyl complex of cobalt(II) porphyrinate, [Co(F20TPP2?)(NO)], (F20TPPH2 = 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin) having {Co(NO)}8 configuration was synthesized and characterized by means of spectroscopic and structural analyses. Single crystal X-ray structure of the complex revealed the square pyramidal geometry around the cobalt center with a bent nitrosyl group. It reacts with superoxide (O2[rad]–) ion in CH2Cl2 at ?40 °C to result in the corresponding nitrite (NO2?) complex. Involvement of a cobalt(II)-peroxynitrite intermediate is proposed in the course of the reaction. Moreover, spectroscopic studies suggested the formation of a transient six-coordinated [CoII(NO)(O2[rad]–)] species.
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
Shen, Hai-Min,Wang, Xiong,Ning, Lei,Guo, A-Bing,Deng, Jin-Hui,She, Yuan-Bin
, (2020/11/20)
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.
Significantly boosted oxygen electrocatalysis with cooperation between cobalt and iron porphyrins
Lei, Haitao,Zhang, Qingxin,Wang, Yabo,Gao, Yimei,Wang, Yanzhi,Liang, Zuozhong,Zhang, Wei,Cao, Rui
supporting information, p. 5120 - 5123 (2021/04/26)
Developing electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is of great importance. Herein, Co tetrakis(pentafluorophenyl)porphyrin (Co-P) and Fe chloride tetrakis(pentafluorophenyl)porphyrin (Fe-P) were loaded on carbon nanotubes (CNTs) for combining the electrocatalytic advantages of both Co-P and Fe-P. The resultant (Co-P)0.5(Fe-P)0.5@CNT composite displayed significantly boosted activity for the selective four-electron ORR with a half-wave potential of 0.80 Vversusreversible hydrogen electrode (RHE) and for the OER with a potential of 1.65 VversusRHE to obtain 10 mA cm?2current density in 0.1 M KOH. A Zn-air battery assembled from (Co-P)0.5(Fe-P)0.5@CNT exhibited a small charge-discharge voltage gap of 0.74 V at 2 mA cm?2, a high power density of 174.5 mW cm?2and a good rechargeable stability (>120 cycles).
Mechanochemical insertion of cobalt into porphyrinoids using Co2(CO)8as a cobalt source
Damunupola, Dinusha,Chaudhri, Nivedita,Atoyebi, Adewole O.,Brückner, Christian
, p. 3643 - 3652 (2020/07/30)
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.
Efficient and selective oxidation of tertiary benzylic C[sbnd]H bonds with O2 catalyzed by metalloporphyrins under mild and solvent-free conditions
Hu, Meng-Yun,Liu, Lei,Qi, Bei,She, Yuan-Bin,Shen, Hai-Min,Ye, Hong-Liang
, (2020/05/19)
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.
Co-Catalyzed Transannulation of Pyridotriazoles with Isothiocyanates and Xanthate Esters
Zhang, Ziyan,Gevorgyan, Vladimir
supporting information, p. 8500 - 8504 (2020/11/03)
An efficient radical transannulation reaction of pyridotriazoles with isothiocyanates and xanthate esters was developed. This method features conversion of pyridotriazoles into two N-fused heterocyclic aromatic systems-imino-thiazolopyridines and oxo-thia
Design of oxophilic metalloporphyrins: An experimental and DFT study of methanol binding
Olsson, Sandra,Dahlstrand, Christian,Gogoll, Adolf
supporting information, p. 11572 - 11585 (2018/08/28)
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.
Transition metal tetrapentafluorophenyl porphyrin catalyzed hydrogen evolution from acetic acid and water
Zhang, Dong-Xu,Yuan, Hui-Qing,Wang, Hua-Hua,Ali, Atif,Wen, Wei-Hong,Xie, An-Na,Zhan, Shu-Zhong,Liu, Hai-Yang
, p. 773 - 782 (2017/09/25)
The performance of Cu (1), Co (2) and Zn (3) complexes of meso-tetrakis(pentafluorophenyl)porphyrin in the electrocatalyzed evolution of hydrogen has been investigated. In acetic acid media, hydrogen evolution turnover frequency (TOF) values for complexes 1, 2 and 3 were 22.1, 19.8 and 18.1?h?1, respectively, at an overpotential of 942?mV versus Ag/AgNO3. In buffer solution at pH 7.0, the corresponding hydrogen evolution TOF values increased dramatically, to 266, 234, 218?h?1 at a similar overpotential of 878?mV versus SHE. The Faradaic yields of 1, 2, and 3 for sustained proton reduction in catalytic experiments at a glassy carbon electrode over 72?h were 89.7, 90.4 and 91.0%, respectively, with no observable catalyst decomposition.
Porphyrin cobalt(III) "Nitrene radical" reactivity; Hydrogen atom transfer from Ortho-YH substituents to the nitrene moiety of cobalt-bound aryl nitrene intermediates (Y = O, NH)
Goswami, Monalisa,Rebreyend, Christophe,De Bruin, Bas
, (2016/04/20)
In the field of cobalt(II) porphyrin-catalyzed metallo-radical reactions, organic azides have emerged as successful nitrene transfer reagents. In the pursuit of employing ortho-YH substituted (Y = O, NH) aryl azides in Co(II) porphyrin-catalyzed nitrene transfer reactions, unexpected hydrogen atom transfer (HAT) from the OH or NH2 group in the ortho-position to the nitrene moiety of the key radical-intermediate was observed. This leads to formation of reactive ortho-iminoquinonoid (Y = O) and phenylene diimine (Y = NH) species. These intermediates convert to subsequent products in non-catalyzed reactions, as is typical for these free organic compounds. As such, the observed reactions prevent the anticipated cobalt-mediated catalytic radical-type coupling of the nitrene radical intermediates to alkynes or alkenes. Nonetheless, the observed reactions provide valuable insights into the reactivity of transition metal nitrene-radical intermediates, and give access to ortho-iminoquinonoid and phenylene diimine intermediates from ortho-YH substituted aryl azides in a catalytic manner. The latter can be employed as intermediates in one-pot catalytic transformations. From the ortho-hydroxy aryl azide substrates both phenoxizinones and benzoxazines could be synthesized in high yields. From the ortho-amino aryl azide substrates azabenzene compounds were obtained as the main products. Computational studies support these observations, and reveal that HAT from the neighboring OH and NH2 moiety to the nitrene radical moiety has a low energy barrier.
