振动圆二色谱-光衍未来

振动圆二色谱

立即预约

附件下载

设备简介

计算内容：振动圆二色谱 (Vibrational Circular Dichroism)
（1）定义：振动圆二色谱是在红外波长区域测定分子圆二色性的一种方法。极大地扩展了圆二色谱法通过构象搜索、量子化学计算等手段准确预测手性分子的振动圆二色谱图，进而与实测谱图进行比较确定其绝对构型。是有效测定手性分子绝对构型的常规方法。
（2）说明：The predicted VCD spectrum for (S, R_mp) shows a positive band at 1541 cm^-¹ and negative band at 1526 cm^-¹, both of roughly equal magnitudes. Visualization of the vibrations responsible for this bisignate feature reveals a combination of Amide II and C-C stretching of neighboring benzene ring. All three such amide-benzene groups are participating to produce the respective vibrations along the macrocycle. The predicted VCD spectrum for (S, S_mp) shows a triplet of neighboring bands, with large positive at 1513 cm^-¹ and two weak negative bands one on each side. Visualization of the vibrations responsible for 1513 cm^-¹ band reveals it to also be a concerted Amide II and benzene ring C-C stretching vibration but localized to the benzene ring closest to the stereocenter. It is somewhat difficult to draw a definitive conclusion on the AC of 1 based solely on this region of the experimental VCD spectrum. In addition, the commonly used similarity analyses between experimental and theoretical VCD spectra are unreliable when there are only a small number of spectral features for comparison (see ESI). However, there are two experimental VCD bands that have favorable comparisons with those in the predicted spectrum for (S, R_mp), but not in that for (S, S_mp).
文献来源：DOI: 10.1002/chir.23365