Department of Chemistry, Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577, Japan.
Phys Chem Chem Phys. 2020 Apr 15;22(15):7671-7679. doi: 10.1039/d0cp00713g.
Vibrational circular dichroism (VCD) spectroscopy is an extension of circular dichroism spectroscopy into the infrared and near-infrared regions where vibrational transitions occur in the ground electronic state of a molecule. The method offers the advantage of studying the chiroptical properties of a wide range of molecules in non-crystalline states. However, because of the smallness of the signals, one measurement requires several hours to yield reliable results. Accordingly, its targets were limited to a stable molecule in a solution. To overcome this difficulty, our group applied the VCD method to supramolecular systems. The work was launched based on the finding that the VCD signal remarkably enhances when low-molecular mass gelators form gels. By analysing a number of well-resolved VCD peaks, the detailed conformation of a component molecule was deduced. This provided a clue to elucidating the molecular organization in supramolecular architectures. Our final goal was to clarify the route from microscopic molecular chirality to supramolecular chirality. For this purpose, a time-step VCD measurement method was developed for the in situ monitoring of the progress of chirality amplification.
振动圆二色性（VCD）光谱学是圆二色性光谱学在红外和近红外区域的扩展，其中分子的基态电子跃迁发生在振动跃迁中。该方法具有研究非晶态下各种分子的手性光学性质的优势。然而，由于信号较小，一次测量需要几个小时才能得出可靠的结果。因此，它的目标仅限于溶液中的稳定分子。为了克服这一困难，我们小组将 VCD 方法应用于超分子体系。这项工作是基于这样一个发现而展开的，即当低分子量凝胶剂形成凝胶时，VCD 信号显著增强。通过分析多个分辨率良好的 VCD 峰，可以推断出组成分子的详细构象。这为阐明超分子结构中的分子组织提供了线索。我们的最终目标是阐明从微观分子手性到超分子手性的途径。为此，开发了一种时间步长 VCD 测量方法，用于实时监测手性放大的进展。
