title: Salen complexes with bulky substituents as useful tools for biomimetic phenol oxidation research.
abstract: The catalytic properties of bulky water-soluble Co-, Cu-, Fe- and Mn-salen complexes in the oxidation of phenolic lignin model compounds have been studied in aqueous water--dioxane solutions (pH 3--10). Mn catalysts were found to oxidize coniferyl alcohol in a same reaction time as horseradish peroxidase (HRP) enzyme and Mn and Co catalysts showed different regioselectivity suggesting a different substrate to catalyst interaction in the oxidative coupling. When the oxidation of material more relevant to plant polyphenolics was studied, the results indicated that the complexes catalyze one- and two-electron oxidations depending on the bulk of the substrate.
authors.affiliation: University of Helsinki, Department of Chemistry, Laboratory of Organic Chemistry, PO Box 55, FIN-00014 University of Helsinki, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Haikarainen
authors.forename: J
authors.initials: J
authors.lastname: Sipilä
authors.forename: P
authors.initials: P
authors.lastname: Pietikäinen
authors.forename: A
authors.initials: A
authors.lastname: Pajunen
authors.forename: I
authors.initials: I
authors.lastname: Mutikainen
mesh_terms: D001671:Biochemistry / Q000379:methods*; D003035:Cobalt / Q000737:chemistry; D005029:Ethylenediamines / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry; D008031:Lignin / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005029:Ethylenediamines; D007093:Imidazoles; D009942:Organometallic Compounds; D010636:Phenols; D003035:Cobalt; C090577:N,N'-bis(salicylideneamino)ethane-manganese(II); D008031:Lignin; C011452:disalicylaldehyde ethylenediamine; D006735:Horseradish Peroxidase