LIGHT-SCATTERING-STUDIES ON THE CRYSTALLIZATION TRANSITION OF NATIVE AND PER-2,6-DIMETHYLATED BETA-CYCLODEXTRINS

Citation
P. Umbach et al., LIGHT-SCATTERING-STUDIES ON THE CRYSTALLIZATION TRANSITION OF NATIVE AND PER-2,6-DIMETHYLATED BETA-CYCLODEXTRINS, Journal of the American Chemical Society, 118(39), 1996, pp. 9314-9319
Citations number
24
Categorie Soggetti
Chemistry
ISSN journal
00027863
Volume
118
Issue
39
Year of publication
1996
Pages
9314 - 9319
Database
ISI
SICI code
0002-7863(1996)118:39<9314:LOTCTO>2.0.ZU;2-4
Abstract
The initial crystallization phase of native and dimethylated beta-cycl odextrins (beta-CD) was investigated with small-angle static light sca ttering. Following simple considerations, one can obtain the crystalli zation exponent, predicted by the Avrami theory, from temperature quen ching experiments. We found that a single-step mechanism, in accordanc e with the classical theory, holds for the crystal formation of native beta-cyclodextrin. The crystal formation mechanism of the heptakis (2 ,6)-di-O-methyl)-beta-CD is more complex, and involves a fast and a sl ow process. The exponents determined for each process indicate that cr ystallization starts with the formation of spherical clusters which ag gregate further to form rod-shaped macrocrystals, in accordance with m icroscopic observations. In either case the determined exponents depen d on the initial cyclodextrin concentration.