title: Concerted dismutation of chlorite ion: water-soluble iron-porphyrins as first generation model complexes for chlorite dismutase.
abstract: Three iron-5,10,15,20-tetraarylporphyrins (Fe(Por-Ar4), Ar = 2,3,5,6-tetrafluro-N,N,N-trimethylanilinium (1), N,N,N-trimethylanilinium (2), and p-sulfonatophenyl (3)) have been investigated as catalysts for the dismutation of chlorite (ClO2-). Degradation of ClO2- by these catalysts occurs by two concurrent pathways. One leads to formation of chlorate (ClO3-) and chloride (Cl-), which is determined to be catalyzed by O=FeIV(Por) (Compound II) based on stopped-flow absorption spectroscopy, competition with 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonicacid), 18O-labeling studies, and kinetics. The second pathway is a concerted dismutation of chlorite to dioxygen (O2) and chloride. On the basis of isotope labeling studies using a residual gas analyzer, the mechanism is determined to be formation of O=FeIV(Por)*+ (Compound I) from oxygen atom transfer, and subsequent rebound with the resulting hypochlorite ion (ClO-) to give dioxygen and chloride. While the chlorate production pathway is dominant for catalysts 2 and 3, the O2-producing pathway is significant for catalyst 1. In addition to chlorite dismutation, complex 1 catalyzes hypochlorite disproportionation to chloride and dioxygen quantitatively.
authors.affiliation: Brown Laboratory, Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Zdilla
authors.forename: Amanda Q
authors.initials: AQ
authors.lastname: Lee
authors.forename: Mahdi M
authors.initials: MM
authors.lastname: Abu-Omar
mesh_terms: D000042:Absorption; D040761:Biomimetic Materials; D002384:Catalysis; D002704:Chlorates / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002852:Chromatography, Ion Exchange; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D013058:Mass Spectrometry; D008665:Metalloporphyrins / Q000737:chemistry* / Q000378:metabolism; D008956:Models, Chemical; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D010100:Oxygen / Q000737:chemistry; D010103:Oxygen Isotopes / Q000737:chemistry; D012995:Solubility; D013194:Staining and Labeling; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D002704:Chlorates; D002712:Chlorides; D008665:Metalloporphyrins; D016877:Oxidants; D010103:Oxygen Isotopes; D014874:Water Pollutants, Chemical; D014867:Water; D007501:Iron; D010088:Oxidoreductases; C402794:chlorite dismutase; D010100:Oxygen; C001599:chlorite