Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom.
Anal Chem. 2021 Apr 6;93(13):5403-5411. doi: 10.1021/acs.analchem.0c04651. Epub 2021 Mar 26.
Precise optical rotation measurements play an important role in the analysis of chiral molecules in various fields, especially in biological chemistry and pharmacology. In this paper, we demonstrate a new variant of continuous-wave cavity-enhanced polarimetry for detecting the optical activity of two enantiomers of a chiral molecule at 730 nm. It is based on a signal-reversing technique for which the chiral specific rotation is directly determined by the cavity ring-down signal from two counter-propagating beams in a bow-tie cavity. In particular, we ensure reproducible excitation of both modes by broadening the linewidth of a diode laser source by application of a radio frequency perturbation to its injection current. The performance of the polarimeter is demonstrated for the specific rotation of (+)- and (-)-α-pinene in different environments, including the pure vapor, open air, and the liquid phase; the detection precision ranges between 10 and 10 degrees per cavity pass depending on the environment. The apparatus is a robust and practical tool for quantifying chirality and can be developed for the entire visible and near-infrared spectral regions.
精确的旋光测量在各个领域，特别是生物化学和药理学中分析手性分子起着重要作用。在本文中，我们展示了一种新的连续波腔增强偏振测量方法，用于在 730nm 处检测手性分子的两种对映体的旋光活性。它基于一种信号反转技术，其中手性比旋光度可以通过蝴蝶结腔中两个反向传播光束的腔衰减信号直接确定。特别地，我们通过对注入电流施加射频微扰来展宽二极管激光源的线宽，从而确保两种模式的可重复性激发。该偏振计的性能已通过在不同环境下（包括纯蒸气、开放空气和液相）对（+）-和（-）-α-蒎烯的比旋光度进行了验证；检测精度范围为每腔通过 10 到 10 度，具体取决于环境。该仪器是一种用于定量手性的强大而实用的工具，并且可以扩展到整个可见和近红外光谱区域。
