title: Ultra-low temperature oxidation of 5,6-dihydroxyindole: a novel approach to study synthetic melanogenesis.
abstract: The detailed structure of melanin remains elusive due to the complexity and insolubility of the pigment. Herein we describe a novel oxidation of 5,6-dihydroxyindole (DHI) as a means to characterize soluble intermediates formed prior to oligomerization. The approach entails the use of a biomimetic copper-peroxo oxidant, at ultra-low temperature (-78 degrees C). DHI oxidized by [LCuII(O2)CuIIL]B(C6F5)4 (L=2,6,10-trimethyl-2,6,10-triazaundecane) under argon produces the one electron oxidation product, semiquinone radical, which is spectroscopically observed at -78 degrees C. MS analysis of the reaction mixture reveals the DHI dimer as well as other extensively oxidized DHI units.
authors.affiliation: Department of Chemistry, Duke University, Durham, NC, USA.
authors.forename: Lanying Q
authors.initials: LQ
authors.lastname: Hatcher
authors.forename: John D
authors.initials: JD
authors.lastname: Simon
mesh_terms: D032701:Biomimetics; D002384:Catalysis; D003080:Cold Temperature; D003300:Copper / Q000737:chemistry; D007211:Indoles / Q000737:chemistry*; D013058:Mass Spectrometry; D008543:Melanins / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D010084:Oxidation-Reduction; D013057:Spectrum Analysis / Q000295:instrumentation; D013696:Temperature
chemical_list: D007211:Indoles; D008543:Melanins; D009942:Organometallic Compounds; C041877:eumelanin; D003300:Copper; C033871:5,6-dihydroxyindole