近日，华东师范大学王威团队研究了最小的分子三叶结是否实际上最紧。相关论文于2025年6月24日发表在《德国应用化学》杂志上。

紧密性工程已经发展成为一种有效的策略，用于设计具有所需性能和功能的打结、编织和纠缠分子和材料，因为紧密性是决定打结链性能的主要参数。然而，作为一个吸引人的话题，这激发了数学家、物理学家、化学家和生物学家的灵感，最小的结是否就是最紧的结，在实验上仍然没有得到解决。

为了解决这一挑战，研究组通过开发一种新的模块化自组装方法，成功地合成了一系列具有短至70个主原子的有机三叶草结。令他们惊讶的是，在梯度串联质谱的帮助下，定量紧密度评价表明，骨架交叉比（BCR）为24.0的分子三叶结甚至比BCR为23.3的分子三叶结更紧密。这是迄今为止合成的最小的有机三叶结（绳长最短），研究组展示了一个意想不到的有趣的奇偶效应，以增强对分子结紧密性调节的理解。

附：英文原文

Title: Is the Smallest Molecular Trefoil Knot Actually the Tightest One

Author: Wei-Tao Xu, Chenxing Guo, Yefei Jiang, Wei-Jian Li, Xiao-Qin Xu, Xue Li, Siqi Luo, Lianrui Hu, Xiujun Yu, Xiaopeng Li, Hai-Bo Yang, Wei Wang

Issue&Volume: 2025-06-24

Abstract: Tightness engineering has evolved as an efficient strategy for the design of knotted, woven, and entangled molecules and materials with desired properties and functions since tightness is a primary parameter that determines the property of a knotted strand. However, as an attractive topic that inspires mathematicians, physicists, chemists, and biologists, whether the smallest knot is exactly the tightest one remains unaddressed experimentally. To tackle this challenge, a series of organic trefoil knots with the backbone-atom as short as 70 have been successfully synthesized by developing a new modular self-assembly approach in this study. To our great surprise, with the help of gradient tandem mass spectrometry, the quantitative tightness evaluation suggested that the molecular trefoil knot with a backbone crossing ratio (BCR) of 24.0 is even tighter than the one with a BCR of 23.3 (i.e. the smallest organic trefoil knot with the shortest ropelength synthesized so far), thus demonstrating an unexpected yet interesting odd-even effect to enhance the understanding of the tightness regulation of molecular knots.

DOI: 10.1002/anie.202512327

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202512327