title: Spectrophotometric investigation on the kinetics of oxidation of adrenaline by dioxygen of μ-dioxytetrakis(histidinato)-dicobalt(II) complex.
abstract: The cobalt(II)histidine complex binds molecular oxygen reversibly to form an oxygen adduct complex, μ-dioxytetrakis-(histidinato)dicobalt(II). The molecular oxygen can be released from the oxygenated complex by heating it or by passing N2, He or Ar gas through its solution. μ-Dioxytetrakis-(histidinato)dicobalt(II) complex oxidizes adrenaline into leucoadrenochrome at 25°C while at higher temperature (>40°C) adrenochrome with λmax at 490nm is formed. The rate of formation of leucoadrenochrome was found to be independent of [bis(histidinato)cobalt(II)]. The rate of reaction for the formation of leucoadrenochrome and adrenochrome increased with the increase in [adrenaline] at its lower concentration but become independent at higher concentration. Similarly, the rate of formation of both leucoadrenochrome and adrenochrome was linearly dependent upon [NaOH]. The values of activation parameters i.e. ΔEa, ΔH(‡) and ΔS(‡) for the formation of leucoadrenochrome are reported.
authors.affiliation: Surfactant Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia. Electronic address: drrafiquee@yahoo.com.
authors.forename: M Z A
authors.initials: MZ
authors.lastname: Rafiquee
authors.affiliation: Advanced Materials Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Masoom R
authors.initials: MR
authors.lastname: Siddiqui
authors.affiliation: Surfactant Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Mohd Sajid
authors.initials: MS
authors.lastname: Ali
authors.affiliation: Surfactant Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Hamad A
authors.initials: HA
authors.lastname: Al-Lohedan
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D004837:Epinephrine / Q000737:chemistry*; D006639:Histidine / Q000031:analogs & derivatives*; D007700:Kinetics; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D016877:Oxidants; D003035:Cobalt; D006639:Histidine; D010100:Oxygen; D004837:Epinephrine
keywords: Adrenaline; Cobalt(II)histidine; Dioxygen; Oxidation; Oxygen carrier