Freedman Teresa B, Cao Xiaolin, Luz Zeev, Zimmermann Herbert, Poupko Raphy, Nafie Laurence A
Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA.
Chirality. 2008 May 15;20(5):673-80. doi: 10.1002/chir.20514.
The use of isotopic difference spectra in vibrational optical activity is demonstrated as a supplemental aide in determining the absolute configuration of chiral molecules. It is shown that IR and VCD difference spectra associated with isotopic substitution observed in experimental spectra can be accurately reproduced by density functional theory calculations when the IR and VCD spectra of the original isotopomer are calculated to reasonable accuracy. Results for isotopically substituted nonamethoxy cyclotriveratrylene are presented to illustrate the degree of agreement between measured and calculated IR and VCD difference spectra for several isotopomers of this molecule. These findings highlight the utility of isotoptic substitution as an aide to verifying the determination of absolute configuration using vibrational optical activity.
同位素差异光谱在振动光学活性中的应用被证明是确定手性分子绝对构型的一种辅助手段。结果表明，当原始同位素异构体的红外光谱和振动圆二色光谱（VCD）计算达到合理精度时，实验光谱中观察到的与同位素取代相关的红外和VCD差异光谱可以通过密度泛函理论计算精确再现。给出了同位素取代的九甲氧基环三藜芦烃的结果，以说明该分子几种同位素异构体的实测红外和VCD差异光谱与计算光谱之间的吻合程度。这些发现突出了同位素取代作为一种辅助手段在使用振动光学活性验证绝对构型测定方面的实用性。
