Institute of Physical Chemistry, University of Goettingen, Tammannstr. 6, 37077 Goettingen, Germany.
Phys Chem Chem Phys. 2020 Nov 18;22(44):25538-25551. doi: 10.1039/d0cp04825a.
A combination of linear infrared and Raman spectroscopy in supersonic slit jet expansions is used to clarify the conformational preferences in the dimer of the transiently chiral benzyl alcohol (phenylmethanol) under vacuum isolation. By experimentally exploring close analogies with the permanently chiral 1-phenylethanol, which is conformationally locked in the jet through intramolecular chirality induction, and by computational analysis of their conformational energy landscapes, several conclusions are drawn. The lowest energy dimer is confirmed to be cooperatively OHOHπ-bonded and shown to be homochiral. Its heterochiral counterpart is slightly higher in energy and can be spectrally assigned as a minor constituent. A metastable heterochiral OHπ/OHπ structure with weakly coupled hydrogen bonds is efficiently trapped behind a Ci symmetry-enhanced barrier and can be assigned by IR/Raman mutual exclusion. Its homochiral counterpart is kinetically less stable but might be addressed by rotational spectroscopy. Ratings of standard density functionals with a standard basis set in terms of reproducing these experimental chirality synchronization benchmarks are presented.
采用线性红外和拉曼光谱相结合的方法，在超音速狭缝射流膨胀中研究了在真空中隔离的瞬态手性苯甲醇（苄醇）二聚体的构象偏好。通过与通过分子内手性诱导在射流中构象锁定的永久性手性 1-苯乙醇的实验探索，以及对它们的构象能景观的计算分析，得出了几个结论。证实最低能量二聚体是协同的 OHOHπ 键合的，并且是同手性的。其异手性对应物的能量略高，并且可以通过光谱分配为次要成分。一种具有弱耦合氢键的亚稳态异手性 OHπ/OHπ 结构可以有效地被 Ci 对称增强的势垒捕获，并可以通过 IR/Raman 互斥来分配。其同手性对应物的动力学稳定性较差，但可以通过旋转光谱来解决。提出了标准密度泛函在重现这些实验手性同步基准方面的评级，使用标准基组。
