title: Femtosecond transient absorption spectroscopic study of a carbonyl-containing carotenoid analogue, 2-(all-trans-retinylidene)-indan-1,3-dione.
abstract: The photophysical properties of a carbonyl-containing carotenoid analogue in an s-cis configuration, relative to the conjugated π system, 2-(all-trans-retinylidene)-indan-1,3-dione (C20Ind), were investigated by femtosecond time-resolved spectroscopy in various solvents. The lifetime of the optically forbidden S(1) state of C20Ind becomes long as solvent polarity increases. This trend is completely opposite to the situation of S(1-ICT) dynamics of carbonyl-containing carotenoids, such as peridinin and fucoxanthin. Excitation energy dependence of the transient absorption measurements shows that the transient absorption spectra in nonpolar solvents were originated from two distinct transient species, while those in polar and protic solvents are due to a single transient species. By referring to the results of MNDO-PSDCI (modified neglect of differential overlap with partial single- and double-configuration interaction) calculations, we conclude: (1) in polar and protic solvents, the S(1) state is generated following excitation up to the S(2) state; (2) in nonpolar solvents, however, both the S(1) and the (1)nπ* states are generated; and (3) C20Ind does not generate the S(1-ICT) state, despite the fact that it has two conjugated carbonyl groups.
authors.affiliation: CREST/JST and Department of Physics, Graduated School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kusumoto
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kosumi
authors.forename: Chiasa
authors.initials: C
authors.lastname: Uragami
authors.forename: Harry A
authors.initials: HA
authors.lastname: Frank
authors.forename: Robert R
authors.initials: RR
authors.lastname: Birge
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cogdell
authors.forename: Hideki
authors.initials: H
authors.lastname: Hashimoto
mesh_terms: D000975:Antioxidants; D002338:Carotenoids / Q000737:chemistry; D008958:Models, Molecular; D012997:Solvents; D013057:Spectrum Analysis / Q000379:methods*; D024341:Xanthophylls
chemical_list: D000975:Antioxidants; D012997:Solvents; D024341:Xanthophylls; C025164:fucoxanthin; C016040:peridinin; D002338:Carotenoids