title: [Electronic structure and energetics of transitions in absorption spectra of hypericin].
abstract: In half-empirical sigma, pi-valent approximation (PM3) the energetics of tautomer transitions of hypericin and nature of electronic transitions in experimental and calculation absorption spectra is investigated. On the basis of quantum-chemical researches results concerning five tautomer condition of hypericin is established that the most stable is its known structure of a quinone I (7,14-dion-1,3,4,6,8,13-hexahydroxydianthrone). Is determined that longwave characteristic bands in hypericin experimental absorption electronic spectra are connected with its electron- and proton-donor, and acceptor properties, and are caused by modifications of its quinone structure by formation of alcohols, cation- and anion-radicals.
authors.affiliation: Grishko National Botanical Garden of NAS of Ukraine, Kyiv. makov@hypericum.kiev.ua
authors.forename: O Iu
authors.initials: OIu
authors.lastname: Makovets'ka
authors.forename: L S
authors.initials: LS
authors.lastname: Dehtiar'ov
authors.forename: A P
authors.initials: AP
authors.lastname: Lebeda
mesh_terms: D000873:Anthracenes; D004583:Electrons; D007536:Isomerism; D015394:Molecular Structure; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000873:Anthracenes; D010569:Perylene; C004965:hypericin