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Titolo:
Complexation and proton dissociation behavior of 7-hydroxy-4-methylcoumarin and related compounds in the presence of beta-cyclodextrin
Autore:
Hoshiyama, M; Kubo, K; Igarashi, T; Sakurai, T;
Indirizzi:
Kanagawa Univ, Fac Engn, Dept Appl Chem, Kanagawa Ku, Yokohama, Kanagawa 2218686, Japan Kanagawa Univ Yokohama Kanagawa Japan 2218686 ma, Kanagawa 2218686, Japan Kyushu Univ 86, Inst Adv Mat Study, Kasuga, Fukuoka 8160811, Japan Kyushu Univ 86 Kasuga Fukuoka Japan 8160811 asuga, Fukuoka 8160811, Japan
Titolo Testata:
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
fascicolo: 3, volume: 138, anno: 2001,
pagine: 227 - 233
SICI:
1010-6030(20010131)138:3<227:CAPDBO>2.0.ZU;2-V
Fonte:
ISI
Lingua:
ENG
Soggetto:
INDUCED CIRCULAR-DICHROISM; EXCITED SINGLET-STATE; NAPHTHALENE DERIVATIVES; 4-METHYLUMBELLIFERONE; 7-HYDROXYCOUMARIN; COUMARINS;
Keywords:
7-hydroxycoumarin derivatives; beta-cyclodextrin; proton dissociation; substituent effects; pH effects;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: Sakurai, T Kanagawa Univ, Fac Engn, Dept Appl Chem, Kanagawa Ku, Yokohama,Kanagawa 2218686, Japan Kanagawa Univ Yokohama Kanagawa Japan 2218686 a 2218686, Japan
Citazione:
M. Hoshiyama et al., "Complexation and proton dissociation behavior of 7-hydroxy-4-methylcoumarin and related compounds in the presence of beta-cyclodextrin", J PHOTOCH A, 138(3), 2001, pp. 227-233

Abstract

The pH effects on the 1:1 complexation behavior of beta -cyclodextrin (beta -CDx) with the title compounds have been investigated by measuring ultraviolet (UV) absorption, circular dichroism (CD), fluorescence and H-1 nuclear magnetic resonance (NMR) spectra and fluorescence lifetimes of the beta -CDx inclusion complexes formed. Steric effects of substituent attached at the four position of a guest molecule on the stability of the inclusion complex as well as on the induced CD spectral intensity demonstrated that the guest is included into the beta -CDx cavity so as to locate this substituentaround the rim of the cavity at low and even at high pH (where a tautomer anion is exclusively produced). The H-1 NMR data were consistent with the intracavity immersion of a given guest molecule from the secondary hydroxy group side and, additionally, substantiated the structure of the beta -CDx inclusion complex generated at low pH. Through an analysis of the pH-dependent UV absorption and fluorescence spectra of 7-hydroxycoumarine derivatives, it was found that the proton dissociation abilities of these guests undergo negligible effects of the beta -CDx inclusion in both the ground-state and the excited singlet-state. This finding strongly suggested that both thequinoid-type carbonyl and oxide groups in the tautomer anion guest are exposed to the bulk aqueous phase to interact with the surrounding water molecules. (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/07/20 alle ore 20:43:03