PASTEUR, Département de Chimie, Ecole Normale Supérieure, CNRS, PSL University, Sorbonne Université, 75005, Paris, France.
Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, 91405, Orsay, France.
Angew Chem Int Ed Engl. 2023 Jan 26;62(5):e202215599. doi: 10.1002/anie.202215599. Epub 2022 Dec 27.
Solid-State Vibrational Circular Dichroism (VCD) can be used to determine the absolute structure of chiral crystals, but its interpretation remains a challenge in modern spectroscopy. In this work, we investigate the effect of a twofold screw axis on the solid-state VCD spectrum in a combined experimental and theoretical analysis of P2 crystals of (S)-(+)-1-indanol. Even though the space group is achiral, a single proper symmetry operation has an important impact on the VCD spectrum, which reflects the supramolecular chirality of the crystal. Distinguishing between contributions originating from molecular chirality and from chiral crystal packing, we find that while IR absorption hardly depends on the symmetry of the space group, the situation is different for VCD, where completely new non-local patterns emerge. Understanding the two underlying mechanisms, namely gauge transport and direct coupling, will help to use VCD to distinguish polymorphic forms.
固态振动圆二色性（VCD）可用于确定手性晶体的绝对结构，但在现代光谱学中，其解释仍然是一个挑战。在这项工作中，我们通过对（S）-（+）-1-茚醇 P2 晶体的实验和理论分析，研究了双重螺旋轴对固态 VCD 谱的影响。尽管空间群是非手性的，但单个适当的对称操作对 VCD 谱有重要影响，这反映了晶体的超分子手性。通过区分来源于分子手性和手性晶体堆积的贡献，我们发现虽然 IR 吸收几乎不依赖于空间群的对称性，但 VCD 的情况则不同，其中会出现全新的非局域模式。理解这两种潜在机制，即规范输运和直接耦合，将有助于利用 VCD 来区分多晶型形式。
