title: Facile method for spectroscopic examination of radical ions of hydrophilic carotenoids.
abstract: Hydrophilic carotenoids, unusual members of an intrinsically hydrophobic family, and their radical ions are important reactants. An all-optical method for generating singly charged radical ions of a hydrophilic carotenoid (Car) is described. It relies on photolyzing an aqueous mixture of Car and a photoionizable auxiliary solute (A), and making conditions conducive to the capture, by Car, of the hydrated electron (e(aq)(-)) or the positive hole in A(*)(+) or both. When A is Trolox (TOH), only e(aq)(-) can be captured, since TOH (*)(+) deprotonates too rapidly to be a hole donor; when A is Trolox methyl ether (TOMe), both Car(*)(-) and Car(*)(+) are formed, since TOMe (+) lives long enough to transfer its positive hole to Car; formation of Car(*)(-) is prevented under aerobic conditions.
authors.affiliation: Department of Physics, Norwegian University of Science and Technology (NTNU), N-7491, Trondheim, Norway. razi.naqvi@ntnu.no
authors.forename: K Razi
authors.initials: KR
authors.lastname: Naqvi
authors.forename: Thor Bernt
authors.initials: TB
authors.lastname: Melø
authors.forename: Tamás
authors.initials: T
authors.lastname: Jávorfi
authors.forename: Sergio
authors.initials: S
authors.lastname: González-Pérez
authors.forename: Juan B
authors.initials: JB
authors.lastname: Arellano
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000838:Anions; D002338:Carotenoids / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods; D004563:Electrochemistry / Q000379:methods; D004583:Electrons; D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007477:Ions; D008027:Light; D010777:Photochemistry / Q000379:methods*; D011522:Protons; D012997:Solvents / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods*
chemical_list: D000097:Acetonitriles; D000838:Anions; D005609:Free Radicals; D007477:Ions; D011522:Protons; D012997:Solvents; D002338:Carotenoids; C032159:acetonitrile