Sadlej Joanna, Dobrowolski Jan Cz, Rode Joanna E, Jamróz Michał H
Department of Chemistry, Warsaw University, 1 Pasteura Street, 02-093 Warsaw, Poland.
Phys Chem Chem Phys. 2006 Jan 7;8(1):101-13. doi: 10.1039/b509351a. Epub 2005 Nov 16.
This paper presents a discussion of the interaction energies, conformations, vibrational absorption (VA, harmonic and anharmonic) and vibrational circular dichroism (VCD) spectra for conformers of monomeric chiral d(-)-lactic acid and their complexes with water at the DFT(B3LYP)/aug-cc-pVDZ and DFT(B3LYP)/aug-cc-pVTZ levels. A detailed analysis has been performed principally for the two most stable complexes with water, differing by lactic acid conformation. The VCD spectra were found to be sensitive to conformational changes of both free and complexed molecules, and to be especially useful for discriminating between different chiral forms of intermolecular hydrogen bonding complexes. In particular, we show that the VCD modes of an achiral water molecule after complex formation acquire significant rotational strengths whose signs change in line with the geometry of the complex. Using the theoretical prediction, we demonstrate that the VCD technique can be used as a powerful tool for structural investigation of intermolecular interactions of chiral molecules and can yield information complementary to data obtained through other molecular spectroscopy methods.
本文讨论了单体手性d(-)-乳酸构象异构体及其与水形成的配合物在DFT(B3LYP)/aug-cc-pVDZ和DFT(B3LYP)/aug-cc-pVTZ水平下的相互作用能、构象、振动吸收（VA，谐波和非谐波）以及振动圆二色性（VCD）光谱。主要针对两种与水形成的最稳定配合物进行了详细分析，这两种配合物因乳酸构象不同而有所差异。发现VCD光谱对游离分子和配合物分子的构象变化均敏感，并且对于区分分子间氢键配合物的不同手性形式特别有用。特别是，我们表明，形成配合物后，非手性水分子的VCD模式获得了显著的旋转强度，其符号随配合物的几何形状而变化。利用理论预测，我们证明VCD技术可作为研究手性分子间相互作用结构的有力工具，并能提供与通过其他分子光谱方法获得的数据互补的信息。
