CAREER: Enabling High-Sensitivity Force Sensing Through Force-Stereochemistry Coupling

Funded by the Chemical Mechanism, Function, and Properties Program of the Chemistry Division, Professor Xiaoran Hu of the Department of Chemistry at Syracuse University is developing a new class of force-sensitive molecules (called mechanophores) that respond to mechanical forces by changing their stereochemical structures, leading to measurable or observable changes in material properties (e.g., color changes). The proposed research could establish “force-stereochemistry coupling” as a foundational mechanism for designing highly sensitive molecular force probes, with the most mechanosensitive structures having the potential to significantly enhance sensitivity of irreversible mechanophores and enable the study of previously unobservable nanoscale mechanical behaviors. These high-sensitivity force-sensing molecules could facilitate our understanding of nanoscale mechanical behaviors across scientific disciplines ranging from polymer physics to mechanobiology. Moreover, covalent doping of mechanosensitive structures in polymers holds promise for enhancing sustainability by enabling plastics to autonomously monitor and report mechanical damage, thereby enhancing safety and reducing the need for unnecessary preventive replacements. The proposed research is also integrated with innovative and interactive outreach and education activities. Outreach initiatives at the local museum and a local high school will educate a broad audience about smart responsive materials and their applications, enhancing scientific literacy and curiosity about cutting-edge science. Additionally, the proposed research will create research opportunities for graduate, undergraduate, and high-school students, directly contributing to training the next generation of scientists and promoting careers in STEM. This CAREER project could advance the fundamental understanding of mechanochemical reactivities by systematically investigating a mechanistically distinct type of noncovalent-yet-chemical force-matter interactions—specifically, force-triggered stereochemical conversion in atropisomeric mechanophores. It could establish “force-stereochemistry coupling” as a general strategy for designing highly sensitive mechanochemical transformations and could develop comprehensive structure-property relationships elucidating the effects of regiochemistry, “lever-arm” length, and steric factors on mechanically induced stereochemical conversions. Rational variation of mechanophore structures to exhibit diverse readout modes—including changes in color, circular dichroism, and fluorescence—could establish a framework for tailoring these structures for advanced signal analysis techniques, paving the way for applying the “force-stereochemistry coupling” mechanism in high-sensitivity force sensing across complex environments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.