National Changhua University of Education Institutional Repository : Item 987654321/10091
English  |  正體中文  |  简体中文  |  全文笔数/总笔数 : 6491/11663
造访人次 : 23817130      在线人数 : 94
RC Version 3.2 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
搜寻范围 进阶搜寻


题名: Cis-Trans Isomerizations of β-Carotene and Lycopene: A Theoretical Study
作者: Guo, Wen-Hsin;Tu, Cheng-Yi;Hu, Ching-Han
贡献者: 化學系
日期: 2008-09
上传时间: 2012-05-03T06:18:06Z
出版者: American Chemical Society
摘要: The all-trans to mono-cis isomerizations of polyenes and two C40H56 carotenes, β-carotene and lycopene, at the ground singlet (S0) and triplet (T1) states are studied by means of quantum chemistry computations. At the S0 state of polyenes containing n acetylene units (Pn), we find that the energy barrier of the central CC rotation decreases with n. In contrast, however, at the T1 state, the rotational barrier increases with n. For the C40H56 carotenes, the rotational barriers of lycopene are lower than those of their β-carotene counterparts. This difference renders the rotational rates of lycopene to be 1−2 orders of magnitude higher than those of β-carotene at room temperature. For both these carotenes, the barrier is lowest for the rotation toward the 13-cis isomer. The relative abundances are in the following order: all-trans > 9-cis > 13-cis > 15-cis. Although the 5-cis isomer of lycopene has the lowest energy among the cis isomers, its formation from the all-trans form is restricted, owing to a very large rotational barrier. The possible physiological implications of this study are discussed.
關聯: J. Phys. Chem. B, 112(38): 12158-12167
显示于类别:[化學系] 期刊論文


档案 大小格式浏览次数



DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - 回馈