EFFECT OF BETA-CYCLODEXTRIN ON THE EXCITED-STATE PROPERTIES OF 3-SUBSTITUTED INDOLE-DERIVATIVES

Citation
Cn. Sanrame et al., EFFECT OF BETA-CYCLODEXTRIN ON THE EXCITED-STATE PROPERTIES OF 3-SUBSTITUTED INDOLE-DERIVATIVES, Journal of physical chemistry, 100(20), 1996, pp. 8151-8156
Citations number
47
Categorie Soggetti
Chemistry Physical
ISSN journal
00223654
Volume
100
Issue
20
Year of publication
1996
Pages
8151 - 8156
Database
ISI
SICI code
0022-3654(1996)100:20<8151:EOBOTE>2.0.ZU;2-N
Abstract
The effect of beta-cyclodextrin on the absorption and fluorescence spe ctra of 3-R-indoles (R = CH3 or (CH2)(n)-COOH with n = 1, 2 and 3) was studied. The inclusion in beta-cyclodextrin barely changed the UV spe ctra, while significant variations were produced in the emission spect ra, particularly regarding the fluorescence quantum yields. These chan ges, which are pH dependent, allow the determination of the associatio n equilibrium constants (k(Assoc)) under different sets of conditions. For the derivatives with R = (CH2)(n)COOH, the k(Assoc) at pH = 2 inc reased linearly with the number of CH2 groups. The changes in fluoresc ence quantum yield are higher for the neutral than for the ionized com pounds due to greater changes in the nonradiative rates of the neutral species when it is un-ionized.