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Hao J, Nishiyama A, Mori S, Furukawa K, Shimizu S. Oxidation of 5,15-Dioxaporphyrin: Its Generality and Novelty as an Oxaporphyrin Analogue. Angew Chem Int Ed Engl 2023; 62:e202307862. [PMID: 37401745 DOI: 10.1002/anie.202307862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/28/2023] [Accepted: 07/04/2023] [Indexed: 07/05/2023]
Abstract
5,15-Dioxaporphyrin (DOP) is a novel meso-oxaporphyrin analogue and exhibits unique 20π-antiaromaticity, unlike its mother congener of 18π-aromatic 5-oxaporphyrin, commonly known as its cationic iron complex called verdohem, which is a key intermediate of heme catabolism. To reveal its reactivities and properties as an oxaporphyrin analogue, the oxidation of tetra-β-arylated DOP (DOP-Ar4 ) was explored in this study. Stepwise oxidation from the 20π-electron neutral state was achieved, and the corresponding 19π-electron radical cation and 18π-electron dication were characterized. Further oxidation of the 18π-aromatic dication resulted in the formation of a ring-opened dipyrrindione product by hydrolysis. Considering a similar reaction of verdoheme to ring-opened biliverdin in the heme degradation in nature, the current result consolidates the ring-opening reactivity of oxaporphyrinium cation species.
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Affiliation(s)
- Jiping Hao
- Department of Applied Chemistry, Graduate School of Engineering and Center for Molecular Systems (CMS), Kyushu University, Fukuoka, 819-0395, Japan
| | - Akihide Nishiyama
- Department of Applied Chemistry, Graduate School of Engineering and Center for Molecular Systems (CMS), Kyushu University, Fukuoka, 819-0395, Japan
| | - Shigeki Mori
- Advanced Research Support Center (ADRES), Ehime University, Matsuyama, 790-8577, Japan
| | - Ko Furukawa
- Center for Coordination of Research Facilities, Institute for Research Administrator, Niigata University, Niigata, 950-2181, Japan
| | - Soji Shimizu
- Department of Applied Chemistry, Graduate School of Engineering and Center for Molecular Systems (CMS), Kyushu University, Fukuoka, 819-0395, Japan
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2
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Takiguchi A, Kang S, Fukui N, Kim D, Shinokubo H. Dual Emission of a Free‐Base 5‐Oxaporphyrinium Cation from its
cis
‐ and
trans
‐NH Tautomers. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202013542] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Asahi Takiguchi
- Department of Molecular and Macromolecular Chemistry Graduate School of Engineering Nagoya University Furo-chi, Chikusa-ku Nagoya 464-8603 Japan
| | - Seongsoo Kang
- Department of Chemistry and Spectroscopy Laboratory for, Functional π-Electronic Systems Yonsei University Seoul 03722 South Korea
| | - Norihito Fukui
- Department of Molecular and Macromolecular Chemistry Graduate School of Engineering Nagoya University Furo-chi, Chikusa-ku Nagoya 464-8603 Japan
| | - Dongho Kim
- Department of Chemistry and Spectroscopy Laboratory for, Functional π-Electronic Systems Yonsei University Seoul 03722 South Korea
| | - Hiroshi Shinokubo
- Department of Molecular and Macromolecular Chemistry Graduate School of Engineering Nagoya University Furo-chi, Chikusa-ku Nagoya 464-8603 Japan
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3
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Takiguchi A, Kang S, Fukui N, Kim D, Shinokubo H. Dual Emission of a Free‐Base 5‐Oxaporphyrinium Cation from its
cis
‐ and
trans
‐NH Tautomers. Angew Chem Int Ed Engl 2020; 60:2915-2919. [DOI: 10.1002/anie.202013542] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Indexed: 11/10/2022]
Affiliation(s)
- Asahi Takiguchi
- Department of Molecular and Macromolecular Chemistry Graduate School of Engineering Nagoya University Furo-chi, Chikusa-ku Nagoya 464-8603 Japan
| | - Seongsoo Kang
- Department of Chemistry and Spectroscopy Laboratory for, Functional π-Electronic Systems Yonsei University Seoul 03722 South Korea
| | - Norihito Fukui
- Department of Molecular and Macromolecular Chemistry Graduate School of Engineering Nagoya University Furo-chi, Chikusa-ku Nagoya 464-8603 Japan
| | - Dongho Kim
- Department of Chemistry and Spectroscopy Laboratory for, Functional π-Electronic Systems Yonsei University Seoul 03722 South Korea
| | - Hiroshi Shinokubo
- Department of Molecular and Macromolecular Chemistry Graduate School of Engineering Nagoya University Furo-chi, Chikusa-ku Nagoya 464-8603 Japan
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4
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Kupietz K, Białek MJ, Hassa K, Białońska A, Latos-Grażyński L. Oxygenation of Phenanthriporphyrin and Copper(III) Phenanthriporphyrin: An Efficient Route to Phenanthribilinones. Inorg Chem 2019; 58:12446-12456. [PMID: 31454233 DOI: 10.1021/acs.inorgchem.9b02183] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Photooxidation of copper(III) 5,6-dimethoxyphenathriporphyrin and copper(III) 5,6-dioxophenanthriporphyrin, which contain phenanthrene or dioxophenathrene moieties built into the macrocyclic frameworks, resulted in the regioselective cleavage that afforded organometallic copper(III) complexes of open-chain phenanthribilinone-type acyclic ligands terminated by carbonyl groups. The copper(III) coordinates two carbon atoms of phenantherene (dioxophenanthrene) and two nitrogen atoms of pyrrole and pyrrolone units, preserving the donor sets of the paternal complexes. The primary dioxygen attack is located at the meso carbon atom adjacent to the phenanthrene moiety. Demetalation of copper(III) 21-benzoyl-phenanthribilin-1-one and copper(III) 21-benzoyl-dioxophenanthribilin-1-one yielded mainly two diastereomers [15Z, 20E] and [15Z, 20Z], which differ in the configurations at two Cα-Cmeso double bonds. The regioselectivity of the cleavage, detected in the course of experimental studies, has been substantiated by DFT investigations. The regioselective cleavage of 5,6-dimethoxyphenanthriporphyrin in reaction with basic iron(III) acetate was detected, providing the synthetically efficient methodology to produce 21-benzoyl-dioxophenanthribilin-1-one.
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Affiliation(s)
- Kamil Kupietz
- Department of Chemistry , University of Wrocław , F. Joliot-Curie 14 , 50-383 Wrocław , Poland
| | - Michał J Białek
- Department of Chemistry , University of Wrocław , F. Joliot-Curie 14 , 50-383 Wrocław , Poland
| | - Karolina Hassa
- Department of Chemistry , University of Wrocław , F. Joliot-Curie 14 , 50-383 Wrocław , Poland
| | - Agata Białońska
- Department of Chemistry , University of Wrocław , F. Joliot-Curie 14 , 50-383 Wrocław , Poland
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5
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Gheidi M, Safari N, Zahedi M. Density functional theory studies on the conversion of hydroxyheme to iron-verdoheme in the presence of dioxygen. Dalton Trans 2018; 46:2146-2158. [PMID: 28120965 DOI: 10.1039/c6dt04250c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Detailed insight into the second step of heme degradation by heme oxygenase, oxophlorin to verdoheme and biliverdin, is presented. Density functional theory methods are reported for the conversion of oxophlorin to verdoheme. Since it is currently unclear whether dioxygen binding to iron oxophlorin is followed by a reduction or not, in this work we have focused on the difference in reactivity between [(Im)(O2˙)FeIII(PO˙)] (PO˙ is the oxophlorin dianion radical) and [(Im)(O2˙)FeIII(PO)]- (PO is the oxophlorin trianion). Thus, we have shown that in [(Im)(O2˙)FeIII(PO˙)] and [(Im)(O2˙)FeIII(PO)]-, the mechanisms are stepwise with an initial C-O bond activation to form a ring-structure where the oxophlorin is distorted from planarity. This is followed by homolytic dioxygen bond breaking that directly leads to iron-oxo verdoheme products. The [(Im)(O2˙)FeIII(PO˙)] mechanism proceeds via two-state-reactivity patterns on the adjacent doublet and quartet spin state surfaces, whereas the [(Im)(O2˙)FeIII(PO)]- route shows single-state-reactivity on a triplet spin state surface. In both, the rate determining step is the C-O bond activation, with substantially lower barriers on the [(Im)(O2˙)FeIII(PO˙)] surface of 12.15 kcal mol-1 in the gas phase compared to 22.55 kcal mol-1 for the intermediate-spin of [(Im)(O2˙)FeIII(PO)]-. The complete active space self-consistent-field wave functions with second-order multi-reference perturbation theory were also studied. Finally, the effects of the solvent and the medium on the reaction barriers were tested and shown to be considerable.
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Affiliation(s)
- Mahin Gheidi
- Department of Chemistry, Faculty of Sciences, Shahid Beheshti University, G. C., Evin, 19839-63113, Tehran, Iran.
| | - Nasser Safari
- Department of Chemistry, Faculty of Sciences, Shahid Beheshti University, G. C., Evin, 19839-63113, Tehran, Iran.
| | - Mansour Zahedi
- Department of Chemistry, Faculty of Sciences, Shahid Beheshti University, G. C., Evin, 19839-63113, Tehran, Iran.
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6
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Abstract
The reactions of iron(III) hydroxyisoporphyrin, chloro[5-(hydroxy)-5,10,15,20-tetrakis(4-methyl)-5,21H-porphinato]iron(III) [Fe(4-Me-HTPI)(Cl)](-), 1 and chloro[5-(hydroxy)-5,10,15,20-tetrakis(4-methoxy-5,21H-porphinato]iron(III) [Fe(4-OMe-HTPI)(Cl)](-), 2 with different O(-), N(-) and S(-) nucleophiles have been performed to understand the reactivity of iron isoporphyrins with nucleophiles. The treatment of iron(III) hydroxy isoporphyrin with alcohols is found to form ring opened 19-benzoyl-1-alkoxy-bilin iron complexes. When alkyl amines were used the formation of ring opened 19-benzoyl-1-alkylamine-bilin iron complexes was observed, but heterocyclic N-nucleophiles such as pyridine and imidazole form benzoyl bilinone iron complexes. No role of oxygen was found in these nucleophilic ring opening reactions. The treatment of a S-nucleophile such as PhSH is found to reduce iron(III)-hydroxyisoporphyrin in the parent iron(III) porphyrin compound. The ring opening products were characterized using electronic and ESI-mass spectroscopy. The mechanism for the formation of ring opening products is based on the formation of a tetrahedral intermediate at the carbon atom near the saturated meso carbon atom similar to the hydrolytic pathway of verdoheme conversion to biliverdin.
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Affiliation(s)
- Jagannath Bhuyan
- Department of Chemistry, North Eastern Regional Institute of Science and Technology, Nirjuli, Arunachal Pradesh-791109, India.
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7
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Kakeya K, Nakagawa A, Mizutani T, Hitomi Y, Kodera M. Synthesis, Reactivity, and Spectroscopic Properties of meso-Triaryl-5-oxaporphyrins. J Org Chem 2012; 77:6510-9. [DOI: 10.1021/jo3010342] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kazuhisa Kakeya
- Department of Molecular Chemistry and Biochemistry,
Faculty of Science and Engineering, and Center for Nanoscience Research, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan
| | - Aya Nakagawa
- Department of Molecular Chemistry and Biochemistry,
Faculty of Science and Engineering, and Center for Nanoscience Research, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan
| | - Tadashi Mizutani
- Department of Molecular Chemistry and Biochemistry,
Faculty of Science and Engineering, and Center for Nanoscience Research, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan
| | - Yutaka Hitomi
- Department of Molecular Chemistry and Biochemistry,
Faculty of Science and Engineering, and Center for Nanoscience Research, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan
| | - Masahito Kodera
- Department of Molecular Chemistry and Biochemistry,
Faculty of Science and Engineering, and Center for Nanoscience Research, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan
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8
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Abstract
The chlorido iron(III) complex of octaethyl-2,2′-bidipyrrin has been transformed to a series of pseudohalide complexes by ligand exchange reactions with azide, cyanate, thiocyanate and selenocyanate anions. All new complexes show the expected N-coordination of the axial ligand to the iron(III) center. In the solid state, all four species display an intermediate spin (S = 3/2) ground state, with a gradual increase of a high spin (S = 5/2) contribution at elevated temperatures for the members with the smallest ligand field strengths, i.e. the cyanato and the azido derivatives. In solution, proton NMR, and in particular IR spectroscopic studies support the interpretation of a high-spin state at ambient temperature throughout the series. The dependency of the spin state on the crystalline or dissolved state thus resembles that found for a similar series of halide derivatives before. In dichloromethane solution, the thiocyanato and selenocyanato complexes are very sensitive to aerial oxidation, forming oxacorrole and thiacorrole complexes as the only isolated products. These complexes show a S = 3/2 spin state in the solid as well as in solution, and their structural analyses prove the expected strong π-binding of the linear pseudohalide ion to the iron(III) central metal.
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Affiliation(s)
- Martin Bröring
- Institute of Inorganic and Analytical Chemistry, Technical University Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Silke Köhler
- Institute of Inorganic and Analytical Chemistry, Technical University Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Clemens Pietzonka
- Institute of Inorganic and Analytical Chemistry, Technical University Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
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9
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Berlicka A, Latos-Grażyński L, Szterenberg L, Pawlicki M. Photooxidation of Dithiaethyneporphyrin. European J Org Chem 2010. [DOI: 10.1002/ejoc.201000792] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Matsui T, Unno M, Ikeda-Saito M. Heme oxygenase reveals its strategy for catalyzing three successive oxygenation reactions. Acc Chem Res 2010; 43:240-7. [PMID: 19827796 DOI: 10.1021/ar9001685] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Heme oxygenase (HO) is an enzyme that catalyzes the regiospecific conversion of heme to biliverdin IXalpha, CO, and free iron. In mammals, HO has a variety of physiological functions, including heme catabolism, iron homeostasis, antioxidant defense, cellular signaling, and O(2) sensing. The enzyme is also found in plants (producing light-harvesting pigments) and in some pathogenic bacteria, where it acquires iron from the host heme. The HO-catalyzed heme conversion proceeds through three successive oxygenations, a process that has attracted considerable attention because of its reaction mechanism and physiological importance. The HO reaction is unique in that all three O(2) activations are affected by the substrate itself. The first step is the regiospecific self-hydroxylation of the porphyrin alpha-meso carbon atom. The resulting alpha-meso-hydroxyheme reacts in the second step with another O(2) to yield verdoheme and CO. The third O(2) activation, by verdoheme, cleaves its porphyrin macrocycle to release biliverdin and free ferrous iron. In this Account, we provide an overview of our current understanding of the structural and biochemical properties of the complex self-oxidation reactions in HO catalysis. The first meso-hydroxylation is of particular interest because of its distinct contrast with O(2) activation by cytochrome P450. Although most heme enzymes oxidize exogenous substrates by high-valent oxo intermediates, HO was proposed to utilize the Fe-OOH intermediate for the self-hydroxylation. We have succeeded in preparing and characterizing the Fe-OOH species of HO at low temperature, and an analysis of its reaction, together with mutational and crystallographic studies, reveals that protonation of Fe-OOH by a distal water molecule is critical in promoting the unique self-hydroxylation. The second oxygenation is a rapid, spontaneous auto-oxidation of the reactive alpha-meso-hydroxyheme; its mechanism remains elusive, but the HO enzyme has been shown not to play a critical role in it. Until recently, the means of the third O(2) activation had remained unclear as well, but we have recently untangled its mechanistic outline. Reaction analysis of the verdoheme-HO complex strongly suggests the Fe-OOH species as a key intermediate of the ring-opening reaction. This mechanism is very similar to that of the first meso-hydroxylation, including the critical roles of the distal water molecule. A comprehensive study of the three oxygenations of HO highlights the rational design of the enzyme architecture and its catalytic mechanism. Elucidation of the last oxygenation step has enabled a kinetic analysis of the rate-determining step, making it possible to discuss the HO reaction mechanism in relation to its physiological functions.
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Affiliation(s)
- Toshitaka Matsui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Masaki Unno
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Masao Ikeda-Saito
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
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11
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Bröring M, Köhler S, Link S, Burghaus O, Pietzonka C, Kelm H, Krüger HJ. Iron Chelates of 2,2′-Bidipyrrin: Stable Analogues of the Labile Iron Bilins. Chemistry 2008; 14:4006-16. [DOI: 10.1002/chem.200701919] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Pacholska‐Dudziak E, Latos‐Grażyński L. NMR Studies of Paramagnetic Metallocarbaporphyrinoids. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200700078] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ewa Pacholska‐Dudziak
- Department of Chemistry, University of Wrocław, 14 F. Joliot‐Curie St., Wrocław 50 383, Poland
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13
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Wood TE, Thompson A. Advances in the chemistry of dipyrrins and their complexes. Chem Rev 2007; 107:1831-61. [PMID: 17430001 DOI: 10.1021/cr050052c] [Citation(s) in RCA: 501] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tabitha E Wood
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, Canada
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14
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Bröring M, Link S, Brandt CD, Tejero EC. Helical Transition-Metal Complexes of Constrained 2,2′-Bidipyrrins. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200600986] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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15
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d’Alessandro N, Tonucci L, Morvillo A, Dragani L, Deo MD, Bressan M. Thermal stability and photostability of water solutions of sulfophthalocyanines of Ru(II), Cu(II), Ni(II), Fe(III) and Co(II). J Organomet Chem 2005. [DOI: 10.1016/j.jorganchem.2005.01.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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16
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Rachlewicz K, Wang SL, Peng CH, Hung CH, Latos-Grazyński L. Remarkable paramagnetically shifted (1)H and (2)H NMR spectra of iron(II) complexes of 2-aza-21-carbaporphyrin: an evidence for agostic interaction. Inorg Chem 2004; 42:7348-50. [PMID: 14606821 DOI: 10.1021/ic034886u] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Iron(II) 2-aza-21-carbaporphyrins have been characterized by paramagnetically shifted (1)H and (2)H NMR spectra. The high-spin iron(II) complex (HCTPPH)Fe(II)Br displays the beta-H resonances which reflect the combination sigma and pi routes of spin density delocalization. The uniquely large isotropic shift of the inner H(21) hydrogen (812 ppm, 298 K) indicates an Fe(II)-[C(21)-H] agostic interaction.
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Affiliation(s)
- Krystyna Rachlewicz
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie Street, Wrocław 50 383, Poland
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17
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Szterenberg L, Latos-Grazyński L, Wojaczyński J. Metallobiliverdin radicals--DFT studies. Chemphyschem 2003; 4:691-8. [PMID: 12901300 DOI: 10.1002/cphc.200200611] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Several aspects of the molecular and electronic structure of biliverdin derivatives have been studied using density functional theory (DFT). The calculations have been performed for complexes of trianion (BvO2)3- and dianion [BvO(OH)]2-, derived from two tautomeric forms of biliverdin, BvO2H3 and [BvO(OH)]H2, with redox innocent metal ions: lithium(I), zinc(II), and gallium(III). One-electron-oxidized and reduced forms of each complex (cation and anion radicals) have been also considered. The molecular structures of all species investigated are characterized by a helical arrangement of tetrapyrrolic ligands with the metal ion lying in the plane formed by the two central pyrrole rings. The spin density distribution in four types of metallobiliverdin radicals--[(BvO2.)Mn+]n-2,[[BvO(OH).]Mn+]n-1 (cation radicals),[(BvO2.)Mn+]n-4,[[BvO(OH).]Mn+]n-3 (anion radicals)--has been investigated. In general, the absolute values of spin density on meso carbon atoms were larger than for the beta-carbon atoms. Sign alteration of spin density has been found for meso positions, and also for the beta-carbon atoms of at least two pyrrole rings. The calculated spin density maps accounted for the essential NMR spectroscopic features of iron biliverdin derivatives, including the considerable isotropic shifts detected for the meso resonances and shift alteration at the meso and beta-positions.
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Affiliation(s)
- Ludmiła Szterenberg
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie St., 50-383 Wrocław, Poland
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18
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Kalish H, Lee HM, Olmstead MM, Latos-Grazyński L, Rath SP, Balch AL. Heme cleavage with remarkable ease: paramagnetic intermediates formed by aerobic oxidation of a meso-amino-substituted iron porphyrin. J Am Chem Soc 2003; 125:4674-5. [PMID: 12696862 DOI: 10.1021/ja021253q] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hemes must be oxidatively stable to carry out their functions as biological oxidants, but introduction of a single amino group at a meso position of octaethylheme renders it extremely sensitive to ring opening by dioxygen. Exposure of a red pyridine (py) solution of diamagnetic (py)(2)Fe(II)(H(2)N-OEP) (1) (H(2)N-OEP is the dianion of meso-amino-octaethylporphyrin) to air results in the immediate formation of a green intermediate which is subsequently converted into a second species that has been crystallized and characterized by X-ray diffraction. This process is distinct from coupled oxidation, a model for biological heme cleavage, because it does not require a sacrificial reducing agent to initiate the process.
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Affiliation(s)
- Heather Kalish
- Department of Chemistry, University of California - Davis, One Shields Avenue, Davis, California 95616, USA
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