Theoretical and experimental investigations of the electronic circular dichroism and absorption spectra of bicyclic ketones
Theoretical and experimental investigations of the electronic circular dichroism and absorption spectra of bicyclic ketones
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DOI：
10.1016/s0301-0104(97)00258-9
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发表时间：
1997-12-01
期刊：
影响因子：
2.3
通讯作者：
Peyerimhoff, SD
中科院分区：
文献类型：
--
作者：
Pulm, F;Schramm, J;Peyerimhoff, SD
The absorption and circular dichroism (CD) spectra of the bicyclic ketones norcamphor, camphor and fenchone were measured in the gas phase in the energy range 3.5-8.5 eV (350-145 nm). The experimental results are compared with theoretical density functional calculations combined with a configuration interaction treatment employing extended AO basis sets. This approach gives a quantitative agreement between theory and experiment for the excitation energies and transition moments of four separated bands. On this basis a complete assignment of the excited singlet states involved could be made. In particular, an intense band found in the CD spectra at 7.0-7.5 eV is attributed to contributions from sigma --> pi valence excited states which is a special feature of cyclic ketones. Relative energy shifts, the sign of the CD bands and sign inversions as a function of the methyl group substitution pattern in the three molecules are discussed. A simple model which partitions the bicyclic structures into an inherently chiral cyclopentanone moiety and perturbing substituents is useful in this respect. (C) 1997 Elsevier Science B.V.
