Metzger Tzuriel S, Batchu Harikrishna, Kumar Anil, Fedotov Daniil A, Goren Naama, Bhowmick Deb Kumar, Shioukhi Israa, Yochelis Shira, Schapiro Igor, Naaman Ron, Gidron Ori, Paltiel Yossi
Department of Applied Physics and Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem 9190401, Israel.
Institute of Chemistry and Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem 9190401, Israel.
J Am Chem Soc. 2023 Feb 22;145(7):3972-3977. doi: 10.1021/jacs.2c10456. Epub 2023 Feb 11.
Chirality ('handedness') is a property that underlies a broad variety of phenomena in nature. Chiral molecules appear in two forms, and each is a mirror image of the other, the two enantiomers. The chirality of molecules is associated with their optical activity, and circular dichroism is commonly applied to identify the handedness of chiral molecules. Recently, the chiral induced spin selectivity (CISS) effect was established, according to which transfer of electrons within chiral molecules depends on the electron's spin. Which spin is preferred depends on the handedness of the chiral molecule and the direction of motion of the electron. Several experiments in the past indicated that there may be a relation between the optical activity of the molecules and their spin selectivity. Here, we show that for a molecule containing several stereogenic axes, when adsorbed on a metal substrate, the peaks in the CD spectra have the same signs for the two enantiomers. This is not the case when the molecules are adsorbed on a nonmetallic substrate or dissolved in solution. Quantum chemical simulations are able to explain the change in the CD spectra upon adsorption of the molecules on conductive and nonconductive surfaces. Surprisingly, the CISS properties are similar for the two enantiomers when adsorbed on the metal substrate, while when the molecules are adsorbed on nonmetallic surface, the preferred spin depends on the molecule handedness. This correlation between the optical activity and the CISS effect indicates that the CISS effect relates to the global polarizability of the molecule.
手性（“手征性”）是一种构成自然界中多种现象基础的性质。手性分子以两种形式出现，且每种形式都是另一种的镜像，即两种对映体。分子的手性与其光学活性相关，圆二色性通常用于识别手性分子的手征性。最近，手性诱导自旋选择性（CISS）效应被确立，根据该效应，手性分子内的电子转移取决于电子的自旋。哪种自旋更受青睐取决于手性分子的手征性和电子的运动方向。过去的一些实验表明，分子的光学活性与其自旋选择性之间可能存在关联。在此，我们表明，对于含有多个立体轴的分子，当吸附在金属衬底上时，两种对映体的圆二色光谱中的峰具有相同的符号。当分子吸附在非金属衬底上或溶解在溶液中时，情况并非如此。量子化学模拟能够解释分子吸附在导电和非导电表面时圆二色光谱的变化。令人惊讶的是，当吸附在金属衬底上时，两种对映体的CISS性质相似，而当分子吸附在非金属表面时，更受青睐的自旋取决于分子的手征性。光学活性与CISS效应之间的这种相关性表明，CISS效应与分子的整体极化率有关。
