title: Nitrous-acid-mediated synthesis of iron-nitrosyl-porphyrin: pH-dependent release of nitric oxide.
abstract: Two iron-nitrosyl-porphyrins, nitrosyl[meso-tetrakis(3,4,5-trimethoxyphenylporphyrin]iron(II) acetic acid solvate (3) and nitrosyl[meso-tetrakis(4-methoxyphenylporphyrin]iron(II) CH(2)Cl(2) solvate (4), were synthesized in quantitative yield by using a modified procedure with nitrous acid, followed by oxygen-atom abstraction by triphenylphosphine under an argon atmosphere. These nitrosyl porphyrins are in the {FeNO}(7) class. Under an argon atmosphere, these compounds are relatively stable over a broad range of pH values (4-8) but, under aerobic conditions, they release nitric oxide faster at high pH values than that at low pH values. The generated nitric-oxide-free iron(III)-porphyrin can be re-nitrosylated by using nitrous acid and triphenylphosphine. The rapid release of NO from these Fe(II) complexes at high pH values seems to be similar to that in nitrophorin, a nitric-oxide-transport protein, which formally possesses Fe(III). However, because the release of NO occurs from ferrous-nitrosyl-porphyrin under aerobic conditions, these compounds are more closely related to nitrobindin, a recently discovered heme protein.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, UP, India.
authors.forename: Jagannath
authors.initials: J
authors.lastname: Bhuyan
authors.forename: Sabyasachi
authors.initials: S
authors.lastname: Sarkar
mesh_terms: D001128:Argon / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D008665:Metalloporphyrins / Q000737:chemistry*; D008968:Molecular Conformation; D009569:Nitric Oxide / Q000737:chemistry*; D009608:Nitrous Acid / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry
chemical_list: D056831:Coordination Complexes; D008665:Metalloporphyrins; D009943:Organophosphorus Compounds; C578646:nitrosyl(meso-tetrakis(3,4,5-trimethoxyphenylporphyrin))iron(II); C578647:nitrosyl(meso-tetrakis(4-methoxyphenylporphyrin))iron(II); C035807:ferroporphyrin; C061896:triphenylphosphine; D009569:Nitric Oxide; D001128:Argon; D009608:Nitrous Acid