Phys.org September 11, 2023
Radical type mechanophores (RMs), molecules that can undergo small-scale chemical reactions upon exposure to a mechanical stimulus are studied due to their potential application in the fabrication of highly functionalized polymers. However, the lack of a rational design concept with pre-determined properties limits their development. Researchers in Japan have developed a rational design strategy of RMs with high thermal tolerance while maintaining mechanoresponsiveness. Through experimental and theoretical analysis, they found that the high thermal tolerance of RMs is related to the radical-stabilization energy (RSE) as well as the Hammett and modified Swain–Lupton constants at the para-position. The trend of the RSE values was in good agreement with the experimentally evaluated thermal tolerance of a series of mechanoresponsive RMs based on the bisarylcyanoacetate motif. The singly occupied molecular orbital levels clearly exhibited a negative correlation with modified Swain–Lupton constants at the para-position within a series of RMs that are based on the same skeleton. According to the researchers their work paves the way toward the development of RMs that can be handled under ambient conditions without peroxidation… read more. Open Access TECHNICAL ARTICLE
Schematic illustration of the change in the thermal tolerance according to the Hammond–Leffler postulate. Credit: Chemical Science, Issue 33, 2023