Electrochemistry of Corroles in Nonaqueous Media

Fang, Yuanyuan; Ou, Zhongping; Kadish, Karl M.

doi:10.1021/acs.chemrev.6b00546

Cited by 181 publications

(161 citation statements)

References 248 publications

(839 reference statements)

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“…Such an anion effect on the redox potential of Mn corroles was reported by Kadish and co-workers; 22 it has been demonstrated that Mn(III) corroles binding anions, such as Cl − , CN − , OAc − , F − , and OH − , changed their redox potentials with the negative shift of the redox couple of Mn IV/III.22 Thus, Mn(III) corroles binding anionic axial ligands can be oxidized more easily as compared with those without axial ligands.…”

Section: Resultssupporting

confidence: 68%

Dioxygen Activation and O–O Bond Formation Reactions by Manganese Corroles

et al. 2017

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Activation of dioxygen (O2) in enzymatic and biomimetic reactions has been intensively investigated over the past several decades. More recently, O–O bond formation, which is the reverse of the O2-activation reaction, has been the focus of current research. Herein, we report the O2-activation and O–O bond formation reactions by manganese corrole complexes. In the O2-activation reaction, Mn(V)-oxo and Mn(IV)-peroxo intermediates were formed when Mn(III) corroles were exposed to O2 in the presence of base (e.g., OH−) and hydrogen atom (H atom) donor (e.g., THF or cyclic olefins); the O2-activation reaction did not occur in the absence of base and H atom donor. Moreover, formation of the Mn(V)-oxo and Mn(IV)-peroxo species was dependent on the amounts of base present in the reaction solution. The role of the base was proposed to lower the oxidation potential of the Mn(III) corroles, thereby facilitating the binding of O2 and forming a Mn(IV)-superoxo species. The putative Mn(IV)-superoxo species was then converted to the corresponding Mn(IV)-hydroperoxo species by abstracting a H atom from H atom donor, followed by the O–O bond cleavage of the putative Mn(IV)-hydroperoxo species to form a Mn(V)-oxo species. We have also shown that addition of hydroxide ion to the Mn(V)-oxo species afforded the Mn(IV)-peroxo species via O–O bond formation and the resulting Mn(IV)-peroxo species reverted to the Mn(V)-oxo species upon addition of proton, indicating that the O–O bond formation and cleavage reactions between the Mn(V)-oxo and Mn(IV)-peroxo complexes are reversible. The present study reports the first example of using the same manganese complex in both O2-activation and O–O bond formation reactions.

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Section: Resultssupporting

confidence: 68%

Dioxygen Activation and O–O Bond Formation Reactions by Manganese Corroles

et al. 2017

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“…If the two connected tripyrrolic units were noninteracting then similar electrochemical behavior might be seen for the copper tripyrrinone and HexaPyCu 2 1b. However, if the two tripyrrolic units were interacting, one would then observed a splitting of the redox processes as has often been described for molecules with two equivalent and interacting redox centers [48]. This seems to be the case for the reduction of HexaPyCu 2 1b where the first reversible reduction of the copper tripyrrinone at -0.61 V (Fig.…”

Section: Electrochemistrymentioning

confidence: 60%

“…A true thermodynamic HOMO-LUMO gap is based on the difference between the reversible first oxidation and reversible first reduction at the conjugated macrocycle, with the exact values depending upon the type and oxidation state of the central metal ions, the meso and/ or b-substituents of the compound, the planarity of the macrocycle, and the size of the p-system as well as the [48]. The HOMO-LUMO gap (DE 1/2 ) for most "regular" and planar porphyrins averages 2.25 ± 0.05 V where both sets of redox reactions are reversible [49].…”

Section: Electrochemistrymentioning

confidence: 99%

Electrochemistry and spectroelectrochemistry of metallohexaphyrins containing bis-copper or bis-zinc central metal ions

Chen

Ren

et al. 2017

J. Porphyrins Phthalocyanines

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ABSTRACT:Two meso-substituted bis-metallohexaphyrins were synthesized and characterized as to their electrochemical and spectroelectrochemical properties in nonaqueous media. The examined compounds are represented as HexaPyM 2 , where HexaPy represents an expanded macrocycle containing six pyrroles and M = Cu(II) or Zn(II). Each hexaphyrin undergoes four reversible one-electron reductions and two irreversible oxidations in PhCN or CH 2 Cl 2 containing 0.1 M tetrabutylammonium perchlorate. The HexaPyCu 2 is much easier to reduce than the corresponding Cu porphyrin with the same meso-substituents and it is also easier to reduce than a structurally related Cu(II) tripyrrinone. 4-, respectively. The neutral HexaPyCu 2 and HexaPyZn 2 also exhibit two oxidations, both of which are irreversible at a scan rate of 0.10 V/s. The peak separation between the first one-electron addition and the first electron abstraction of HexaPyM 2 ranges from 1.46 to 1.72 V. These non-thermodynamic HOMO-LUMO gaps are similar to the range of HOMO-LUMO gaps for previously characterized sapphyrins which contain five pyrrole ring in the macrocycle. KEYWORDS

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“…[59][60][61] The pentapyrroles previously examined in our laboratory,w ere shown to undergot wo reversible one-electron reductions and two reversible one-electron oxidations, [60] with an averageH OMO-LUMO gap of (1.34 AE 0.04) Vi nC H 2 Cl 2 .H owever,a sd escribed in the currentm anuscript, the reversibility is dependentu pont he solvent and the type of substituent on the meso-aryl groups. [63,64] Corroles are easily protonated and deprotonated in nonaqueous media [63][64][65][66] and this is also the case for sapphyrins, which can lose one pyrrole nitrogen proton or gain two pyrrole protons in non-aqueous media under the same solution conditions. [63,64] Corroles are easily protonated and deprotonated in nonaqueous media [63][64][65][66] and this is also the case for sapphyrins, which can lose one pyrrole nitrogen proton or gain two pyrrole protons in non-aqueous media under the same solution conditions.…”

Section: Introductionmentioning

confidence: 94%

Synthesis, Characterization, and Electrochemistry of Open‐Chain Pentapyrroles and Sapphyrins with Highly Electron‐Withdrawing meso‐Tetraaryl Substituents

Shan

Desbois

Blondeau-Pâtissier

et al. 2017

Chemistry A European J

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A series of open-chain pentapyrroles and sapphyrins with highly electron-withdrawing substituents (i.e., CN, CF , or CO Me) on the meso-phenyl rings was synthesized and characterized as to the spectral properties, protonation reactions, and electrochemistry in non-aqueous media. The investigated compounds are represented as (Ar) PPyH and (Ar) SapH where PPy and Sap correspond to the tri-anion of the open-chain pentapyrrole and sapphyrin, respectively, and Ar=p-CNPh, p-CF Ph, or p-CO MePh. UV/Vis and H NMR spectroscopy as well as mass spectrometry data are given for the confirmation of the structures for the newly synthesized compounds. An X-ray structure for one of the pentapyrroles, that is, (p-CF Ph) PPyH (2), is also presented. The protonation processes were examined by UV/Vis absorption spectroscopy during the titration of the compounds with trifluoroacetic acid (TFA) in CH Cl . Equilibrium constants for the protonation reactions were calculated by using both the Hill equation and the mole ratio method. The protonation-initiated conversion of pentapyrroles to sapphyrins upon oxidation was also investigated. Cyclic voltammetry was used to measure the redox potentials in CH Cl , PhCN, and/or pyridine (Py). Electrochemical properties, protonation constants, and chemical reactions of the six compounds in the two series were then analyzed as a function of the solvent properties and the type of the electron-withdrawing groups on the meso-phenyl rings.

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Electrochemistry of Corroles in Nonaqueous Media

Cited by 181 publications

References 248 publications

Dioxygen Activation and O–O Bond Formation Reactions by Manganese Corroles

Dioxygen Activation and O–O Bond Formation Reactions by Manganese Corroles

Electrochemistry and spectroelectrochemistry of metallohexaphyrins containing bis-copper or bis-zinc central metal ions

Synthesis, Characterization, and Electrochemistry of Open‐Chain Pentapyrroles and Sapphyrins with Highly Electron‐Withdrawing meso‐Tetraaryl Substituents

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