Absolute Configuration of a Cyclic Dipeptide Reflected in Vibrational Optical Activity: Ab Initio and Experimental Investigation

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• 作者：Xiaojun Li ; Kathrin H. Hopmann ; Jana Hudecov谩 ; Wenche Stensen ; Jana Novotn谩 ; Marie Urbanov谩 ; John-Sigurd Svendsen ; Petr Bou艡 ; Kenneth Ruud
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：March 15, 2012
• 年：2012
• 卷：116
• 期：10
• 页码：2554-2563
• 全文大小：746K
• 年卷期：v.116,no.10(March 15, 2012)
• ISSN：1520-5215

文摘

The ability of Raman optical activity (ROA) and vibrational circular dichroism (VCD) experiments to determine the absolute configuration of chiral molecules with multiple stereogenic centers was explored for four diastereoisomers of a conformationally flexible cyclic dipeptide, cyclo(Arg鈥揟yr(OMe)). The reliability of the interpretation depended on the correct description of the molecular conformation, which was found to be strongly affected by intramolecular interactions. In particular, when dispersion corrections were included in the density functional theory calculations, the simulated spectra matched the experimental observations well. Experimental and theoretical ROA and VCD spectra were well correlated for all the absolute configurations (RS, SR, SS, and RR) of protonated cyclo(Arg鈥揟yr(OMe)). These spectroscopies thus appear useful not only for reliable determination of the absolute configuration and conformation but also in revealing the role of hydrogen bonds and C鈥揌路路路蟺 interactions in the structure stabilization, which can potentially be used when designing enzyme inhibitors and supramolecular architectures.