近日，韩国科学技术院Hyotcherl Ihee团队报道了X射线液相术解码偶氮苯异构化中的复杂运动。2026年9月30日，《自然》杂志发表了这一成果。

捕获溶液中机分子的超快结构重排仍然是一项核心挑战，异构化就是其中一个关键例子。然而，尽管已有数十年研究，对于大多数分子而言，异构化如何发生的详细原子级结构理解仍然难以获得。即使对于偶氮苯——一个教科书式的反式–顺式异构化案例，其结构看似简单，仅由两个苯环通过偶氮桥连接——其机理仍然存在争议。大量实验和理论研究提出了多种不同路径，包括旋转、翻转、呼啦扭转以及翻转辅助旋转，但由于缺乏直接的结构证据，始终未能达成共识。

研究组应用飞秒X射线液相术研究溶液中的反式偶氮苯，并以原子级精度解析了连接反式和顺式形式的两个瞬态中间体的分子结构。所揭示的结构表明，反式到顺式的转化通过一系列不同的运动进行，首先由C–N扭转引发——这一运动在以往研究中很少受到关注——随后由N–N旋转主导。这项工作为偶氮苯异构化的体积守恒性质提供了结构见解，并确立了X射线液相术作为一种通用工具，可用于对缺乏重原子的溶质中的结构动力学进行分子“拍摄”，克服了溶剂散射占主导所施加的限制。

附：英文原文

Title: X-ray liquidography decodes complex motions in azobenzene isomerization

Author: Kim, Jungmin, Ki, Hosung, Lee, Seonggon, Segalina, Alekos, Lee, Yunbeom, Ihee, Hyotcherl

Issue&Volume: 2026-09-30

Abstract: Capturing ultrafast structural rearrangements of organic molecules in solution remains a central challenge, with isomerization being a key example. Yet, despite decades of studies, a detailed atomic-level structural understanding of how isomerization occurs remains elusive for most molecules. Even for azobenzene, a textbook case of trans–cis isomerization with its deceptively simple structure of two phenyl rings linked by an azo bridge, the mechanism remains contentious. Extensive experimental and theoretical studies have proposed disparate pathways, including rotation, inversion, hula twist and inversion-assisted rotation, without reaching consensus owing to the lack of direct structural evidence. Here we apply femtosecond X-ray liquidography to trans-azobenzene in solution and resolve, with atomic-level precision, the molecular structures of two transient intermediates bridging the trans and cis forms. The unveiled structures reveal that the trans-to-cis conversion proceeds through a sequence of distinct motions, initiated by C–N torsion, a motion that has received little attention in previous studies, and subsequently dominated by N–N rotation. This work provides structural insights into the volume-conserving nature of azobenzene isomerization and establishes X-ray liquidography as a versatile tool for molecular filming of structural dynamics in solutes lacking heavy atoms, overcoming the limitations imposed by dominant solvent scattering.

DOI: 10.1038/s41586-026-11068-4

Source: https://www.nature.com/articles/s41586-026-11068-4

期刊信息

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504

官方网址：http://www.nature.com/

投稿链接：http://www.nature.com/authors/submit_manuscript.html