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Bhunia S, Ghatak A, Dey A. Second Sphere Effects on Oxygen Reduction and Peroxide Activation by Mononuclear Iron Porphyrins and Related Systems. Chem Rev 2022; 122:12370-12426. [PMID: 35404575 DOI: 10.1021/acs.chemrev.1c01021] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Activation and reduction of O2 and H2O2 by synthetic and biosynthetic iron porphyrin models have proved to be a versatile platform for evaluating second-sphere effects deemed important in naturally occurring heme active sites. Advances in synthetic techniques have made it possible to install different functional groups around the porphyrin ligand, recreating artificial analogues of the proximal and distal sites encountered in the heme proteins. Using judicious choices of these substituents, several of the elegant second-sphere effects that are proposed to be important in the reactivity of key heme proteins have been evaluated under controlled environments, adding fundamental insight into the roles played by these weak interactions in nature. This review presents a detailed description of these efforts and how these have not only demystified these second-sphere effects but also how the knowledge obtained resulted in functional mimics of these heme enzymes.
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Affiliation(s)
- Sarmistha Bhunia
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
| | - Arnab Ghatak
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
| | - Abhishek Dey
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
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Li SX, Qiang JW, Liao BL. Structure, magnetism and oxygen reduction reaction in mixed-valent Cu(I)⋯Cu(II) complex supported by benzimidazole derivative. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2021.120356] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Kim H, Rogler PJ, Sharma SK, Schaefer AW, Solomon EI, Karlin KD. Ferric Heme Superoxide Reductive Transformations to Ferric Heme (Hydro)Peroxide Species: Spectroscopic Characterization and Thermodynamic Implications for H‐Atom Transfer (HAT). Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202013791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Hyun Kim
- Chemistry Department Johns Hopkins University Baltimore MD 21218 USA
| | - Patrick J. Rogler
- Chemistry Department Johns Hopkins University Baltimore MD 21218 USA
| | - Savita K. Sharma
- Chemistry Department Johns Hopkins University Baltimore MD 21218 USA
| | | | | | - Kenneth D. Karlin
- Chemistry Department Johns Hopkins University Baltimore MD 21218 USA
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Kim H, Rogler PJ, Sharma SK, Schaefer AW, Solomon EI, Karlin KD. Ferric Heme Superoxide Reductive Transformations to Ferric Heme (Hydro)Peroxide Species: Spectroscopic Characterization and Thermodynamic Implications for H-Atom Transfer (HAT). Angew Chem Int Ed Engl 2021; 60:5907-5912. [PMID: 33348450 PMCID: PMC7920932 DOI: 10.1002/anie.202013791] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Indexed: 01/07/2023]
Abstract
A new end-on low-spin ferric heme peroxide, [(PIm )FeIII -(O22- )]- (PIm -P), and subsequently formed hydroperoxide species, [(PIm )FeIII -(OOH)] (PIm -HP) are generated utilizing the iron-porphyrinate PIm with its tethered axial base imidazolyl group. Measured thermodynamic parameters, the ferric heme superoxide [(PIm )FeIII -(O2⋅- )] (PIm -S) reduction potential (E°') and the PIm -HP pKa value, lead to the finding of the OO-H bond-dissociation free energy (BDFE) of PIm -HP as 69.5 kcal mol-1 using a thermodynamic square scheme and Bordwell relationship. The results are validated by the observed oxidizing ability of PIm -S via hydrogen-atom transfer (HAT) compared to that of the F8 superoxide complex, [(F8 )FeIII -(O2.- )] (S) (F8 =tetrakis(2,6-difluorophenyl)porphyrinate, without an internally appended axial base imidazolyl), as determined from reactivity comparison of superoxide complexes PIm -S and S with the hydroxylamine (O-H) substrates TEMPO-H and ABNO-H.
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Affiliation(s)
- Hyun Kim
- Chemistry Department, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Patrick J Rogler
- Chemistry Department, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Savita K Sharma
- Chemistry Department, Johns Hopkins University, Baltimore, MD, 21218, USA
| | | | - Edward I Solomon
- Chemistry Department, Stanford University, Stanford, CA, 94305, USA
| | - Kenneth D Karlin
- Chemistry Department, Johns Hopkins University, Baltimore, MD, 21218, USA
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Singha A, Mondal A, Nayek A, Dey SG, Dey A. Oxygen Reduction by Iron Porphyrins with Covalently Attached Pendent Phenol and Quinol. J Am Chem Soc 2020; 142:21810-21828. [PMID: 33320658 DOI: 10.1021/jacs.0c10385] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Phenols and quinols participate in both proton transfer and electron transfer processes in nature either in distinct elementary steps or in a concerted fashion. Recent investigations using synthetic heme/Cu models and iron porphyrins have indicated that phenols/quinols can react with both ferric superoxide and ferric peroxide intermediates formed during O2 reduction through a proton coupled electron transfer (PCET) process as well as via hydrogen atom transfer (HAT). Oxygen reduction by iron porphyrins bearing covalently attached pendant phenol and quinol groups is investigated. The data show that both of these can electrochemically reduce O2 selectively by 4e-/4H+ to H2O with very similar rates. However, the mechanism of the reaction, investigated both using heterogeneous electrochemistry and by trapping intermediates in organic solutions, can be either PCET or HAT and is governed by the thermodynamics of these intermediates involved. The results suggest that, while the reduction of the FeIII-O2̇- species to FeIII-OOH proceeds via PCET when a pendant phenol is present, it follows a HAT pathway with a pendant quinol. In the absence of the hydroxyl group the O2 reduction proceeds via an electron transfer followed by proton transfer to the FeIII-O2̇- species. The hydrogen bonding from the pendant phenol group to FeIII-O2̇- and FeIII-OOH species provides a unique advantage to the PCET process by lowering the inner-sphere reorganization energy by limiting the elongation of the O-O bond upon reduction.
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Affiliation(s)
- Asmita Singha
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
| | - Arnab Mondal
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
| | - Abhijit Nayek
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
| | - Somdatta Ghosh Dey
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
| | - Abhishek Dey
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
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Kim H, Rogler PJ, Sharma SK, Schaefer AW, Solomon EI, Karlin KD. Heme-Fe III Superoxide, Peroxide and Hydroperoxide Thermodynamic Relationships: Fe III-O 2•- Complex H-Atom Abstraction Reactivity. J Am Chem Soc 2020; 142:3104-3116. [PMID: 31913628 PMCID: PMC7034651 DOI: 10.1021/jacs.9b12571] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Establishing redox and thermodynamic relationships between metal-ion-bound O2 and its reduced (and protonated) derivatives is critically important for a full understanding of (bio)chemical processes involving dioxygen processing. Here, a ferric heme peroxide complex, [(F8)FeIII-(O22-)]- (P) (F8 = tetrakis(2,6-difluorophenyl)porphyrinate), and a superoxide complex, [(F8)FeIII-(O2•-)] (S), are shown to be redox interconvertible. Using Cr(η-C6H6)2, an equilibrium state where S and P are present is established in tetrahydrofuran (THF) at -80 °C, allowing determination of the reduction potential of S as -1.17 V vs Fc+/0. P could be protonated with 2,6-lutidinium triflate, yielding the low-spin ferric hydroperoxide species, [(F8)FeIII-(OOH)] (HP). Partial conversion of HP back to P using a derivatized phosphazene base gave a P/HP equilibrium mixture, leading to the determination of pKa = 28.8 for HP (THF, -80 °C). With the measured reduction potential and pKa, the O-H bond dissociation free energy (BDFE) of hydroperoxide species HP was calculated to be 73.5 kcal/mol, employing the thermodynamic square scheme and Bordwell relationship. This calculated O-H BDFE of HP, in fact, lines up with an experimental demonstration of the oxidizing ability of S via hydrogen atom transfer (HAT) from TEMPO-H (2,2,6,6-tetramethylpiperdine-N-hydroxide, BDFE = 66.5 kcal/mol in THF), forming the hydroperoxide species HP and TEMPO radical. Kinetic studies carried out with TEMPO-H(D) reveal second-order behavior, kH = 0.5, kD = 0.08 M-1 s-1 (THF, -80 °C); thus, the hydrogen/deuterium kinetic isotope effect (KIE) = 6, consistent with H-atom abstraction by S being the rate-determining step. This appears to be the first case where experimentally derived thermodynamics lead to a ferric heme hydroperoxide OO-H BDFE determination, that FeIII-OOH species being formed via HAT reactivity of the partner ferric heme superoxide complex.
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Affiliation(s)
- Hyun Kim
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Patrick J Rogler
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Savita K Sharma
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Andrew W Schaefer
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Edward I Solomon
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Kenneth D Karlin
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
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Zhao R, Guo J, Zhang C, Lu Y, Dagnaw WM, Wang ZX. DFT Mechanistic Insight into the Dioxygenase-like Reactivity of a Co III-peroxo Complex: O–O Bond Cleavage via a [1,3]-Sigmatropic Rearrangement-like Mechanism. Inorg Chem 2020; 59:2051-2061. [DOI: 10.1021/acs.inorgchem.9b03470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ruihua Zhao
- School of Chemical Sciences, University of Chinese Academy of Sciences, Jia #19, Yuquan Road, Beijing 100039, China
| | - Jiandong Guo
- School of Chemical Sciences, University of Chinese Academy of Sciences, Jia #19, Yuquan Road, Beijing 100039, China
| | - Chaoshen Zhang
- School of Chemical Sciences, University of Chinese Academy of Sciences, Jia #19, Yuquan Road, Beijing 100039, China
| | - Yu Lu
- School of Chemical Sciences, University of Chinese Academy of Sciences, Jia #19, Yuquan Road, Beijing 100039, China
| | - Wasihun Menberu Dagnaw
- School of Chemical Sciences, University of Chinese Academy of Sciences, Jia #19, Yuquan Road, Beijing 100039, China
| | - Zhi-Xiang Wang
- School of Chemical Sciences, University of Chinese Academy of Sciences, Jia #19, Yuquan Road, Beijing 100039, China
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