Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
Department of Chemistry, Stanford University, Stanford, CA, USA.
Science. 2021 Oct 8;374(6564):178-182. doi: 10.1126/science.abk3132. Epub 2021 Oct 7.
Conformational isomers (conformers) of molecules play a decisive role in biology and organic chemistry. However, experimental methods for investigating chemical reaction dynamics are typically not conformer-sensitive. We report on a gas-phase megaelectronvolt ultrafast electron diffraction investigation of α-phellandrene undergoing an electrocyclic ring-opening reaction. We directly imaged the evolution of a specific set of α-phellandrene conformers into the product isomer predicted by the Woodward-Hoffmann rules in real space and time. Our experimental results are in quantitative agreement with nonadiabatic quantum molecular dynamics simulations, which provide considerable detail of how conformation influences the time scale and quantum efficiency of photoinduced ring-opening reactions.
构象异构体（构象）在生物学和有机化学中起着决定性的作用。然而，用于研究化学反应动力学的实验方法通常对构象不敏感。我们报告了在气相中使用兆电子伏特超快电子衍射研究α-水芹烯进行电环化开环反应的情况。我们直接在实空间和实时间中观察到了一组特定的α-水芹烯构象转化为符合伍德沃德-霍夫曼规则预测的产物异构体的过程。我们的实验结果与非绝热量子分子动力学模拟定量一致，这些模拟提供了构象如何影响光诱导开环反应的时间尺度和量子效率的详细信息。
