title: Supramolecular exciton chirality of carotenoid aggregates.
abstract: The conventional organic chemistry concept of chirality relates to single molecules. This article deals with cases in which exciton chirality is generated by the interaction of associated carotenoids. The handed property responsible for exciton signals in these systems is due to the alignment of neighboring molecules held together by secondary chemical forces. Their mutual positions are characterized by the overlay angle. Experimental manifestation is obtained by spectroscopic studies on carotenoid aggregates. Compared to molecular spectra, both UV/visible and circular dichroism spectroscopic observations reveal modified absorption bands and induced Cotton effects of opposite sign (exciton couplets), respectively. A new term, "supramolecular exciton chirality," is suggested for these phenomena, allowing the detection of weak chemical interactions not readily accessible for experimental studies, although highly important in the mechanism of biological processes.
authors.affiliation: Department of Molecular Pharmacology Institute of Chemistry, CRC, Budapest, Hungary. msimonyi@chemres.hu
authors.forename: Miklós
authors.initials: M
authors.lastname: Simonyi
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bikádi
authors.forename: Ferenc
authors.initials: F
authors.lastname: Zsila
authors.forename: József
authors.initials: J
authors.lastname: Deli
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry*; D002338:Carotenoids / Q000737:chemistry* / Q000302:isolation & purification; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002942:Circular Dichroism; D006801:Humans; D017665:Hydroxyl Radical / Q000737:chemistry; D008968:Molecular Conformation; D011485:Protein Binding; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism
chemical_list: D000975:Antioxidants; D017665:Hydroxyl Radical; D002338:Carotenoids