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Temperaturabhängiger Circulardichroismus von (3S, 3′R)- und (3S, 3′ S)-Adonixanthin

✍ Scribed by Klaus Noack

Publisher
John Wiley and Sons
Year
1981
Tongue
German
Weight
204 KB
Volume
64
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

The temperature dependent CD. spectra of (3__S__, 3′R)‐ and (3__S__, 3′S)‐adonixanthin are compared with those of (3__R__, 3′R)‐zeaxanthin (1) and (3__S__, 3′S)‐astaxanthin (2). The room temperature spectra of 1 and 2 are quite similar. On cooling to −180° the CD. of 1 simply intensifies, the CD. of 2 changes sign and becomes also very intense. The room‐temperature CD. of (3__S__, 3′R)‐adonixanthin (3) resembles closely those of 1 and 2 at room temperature. On cooling, however, it becomes weak and changes strongly its shape. With (3__S__, 3′S)‐adonixanthin (4) it is the low‐temperature spectrum which resembles that of 2 at low temperature, whereas the room‐temperature spectrum is weak and quite different in shape. These observations can be explained with temperature dependent equilibria where the end groups are twisted out of the plain of the chain thereby conferring chirality to the conjugated system.

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