Kuppens Tom, Herrebout Wouter, van der Veken Benjamin, Bultinck Patrick
Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281-S3, B-9000 Ghent, Belgium.
J Phys Chem A. 2006 Aug 31;110(34):10191-200. doi: 10.1021/jp0608980.
Carboxylic acids are known for their strong intermolecular associations. With chiral carboxylic acids, this behavior can be studied using vibrational circular dichroism (VCD). Tetrahydrofuran-2-carboxylic acid 1, a chiral building block for beta-lactam antibiotics, is studied by emphasizing the effect of the dimerization. Experimental results indicate that for solutions of 1 in CDCl3 and CS2, a complex equilibrium exists between the monomers and dimers. B3LYP/aug-cc-pVTZ calculations are performed on both monomer and dimer structures. To simulate IR and VCD spectra, populations for monomer and dimers were approximated using a semiquantitative model. A good agreement between experimental and simulated spectra is obtained by taking into account both the monomeric and the dimeric structures, weighted using the experimentally determined populations.
羧酸以其强烈的分子间缔合而闻名。对于手性羧酸，可以使用振动圆二色性（VCD）来研究这种行为。β-内酰胺抗生素的手性结构单元四氢呋喃-2-羧酸1，通过强调二聚化的影响进行了研究。实验结果表明，对于1在CDCl3和CS2中的溶液，单体和二聚体之间存在复杂的平衡。对单体和二聚体结构都进行了B3LYP/aug-cc-pVTZ计算。为了模拟红外和VCD光谱，使用半定量模型估算了单体和二聚体的丰度。通过考虑单体和二聚体结构，并使用实验测定的丰度进行加权，实验光谱和模拟光谱之间取得了良好的一致性。
