Zhang Cijun, Kouznetsova Tatiana B, Zhu Boyu, Sweeney Liam, Lancer Max, Gitsov Ivan, Craig Stephen L, Hu Xiaoran
Department of Chemistry, BioInspired Institute, Syracuse University, Syracuse, New York 13244, United States.
Department of Chemistry, Duke University, Durham, North Carolina 27708, United States.
J Am Chem Soc. 2025 Jan 22;147(3):2502-2509. doi: 10.1021/jacs.4c13480. Epub 2025 Jan 10.
Understanding structure-mechanical activity relationships (SMARs) in polymer mechanochemistry is essential for the rational design of mechanophores with desired properties, yet SMARs in noncovalent mechanical transformations remain relatively underexplored. In this study, we designed a subset of diarylethene mechanophores based on a lever-arm hypothesis and systematically investigated their mechanical activity toward a noncovalent-yet-chemical conversion of atropisomer stereochemistry. Results from Density functional theory (DFT) calculations, single-molecule force spectroscopy (SMFS) measurements, and ultrasonication experiments collectively support the lever-arm hypothesis and confirm the exceptional sensitivity of chemo-mechanical coupling in these atropisomers. Notably, the transition force for the diarylethene featuring extended 5-phenylbenzo[]thiophene aryl groups is determined to be 131 pN ± 4 pN by SMFS. This value is lower than those typically recorded for other mechanically induced chemical processes, highlighting its exceptional sensitivity to low-magnitude forces. This work contributes a fundamental understanding of chemo-mechanical coupling in atropisomeric configurational mechanophores and paves the way for designing highly sensitive mechanochemical processes that could facilitate the study of nanoscale mechanical behaviors across scientific disciplines.
了解聚合物机械化学中的结构-机械活性关系（SMARs）对于合理设计具有所需特性的机械基团至关重要，然而非共价机械转变中的SMARs仍相对未得到充分探索。在本研究中，我们基于杠杆臂假说设计了一组二芳基乙烯机械基团，并系统地研究了它们对阻转异构体立体化学的非共价但化学转化的机械活性。密度泛函理论（DFT）计算、单分子力谱（SMFS）测量和超声实验的结果共同支持了杠杆臂假说，并证实了这些阻转异构体中化学-机械耦合的异常敏感性。值得注意的是，通过SMFS测定，具有扩展的5-苯基苯并噻吩芳基的二芳基乙烯的转变力为131 pN±4 pN。该值低于其他机械诱导化学过程通常记录的值，突出了其对低强度力的异常敏感性。这项工作有助于对阻转异构构型机械基团中的化学-机械耦合有基本的理解，并为设计高度敏感的机械化学过程铺平道路，这些过程可以促进跨学科对纳米级机械行为的研究。
