Abstract
Mechanochromophores based on bichromic molecular switches,such as bis-naphthopyanes,allow multi-modal mechanochromic behavior beyond the typical binary response from single chromophores,which is important for distinguishing between multiple stress states through discrete changes in color.Sponta-neously generated persistent and distinguishable multi-colors from activated bis-naphthopyanes remain challenging.And the versatility of bis-mechanophore design for advanced optical molecular systems and the fundamental insights into the corresponding mechano-reactivity are not enough.Here,we identify a dihydroanthracene bridged bis-naphthopyrans as a multimodal mechanochromophore in polymers.Bridg-ing two pyrans with the sterically constrained dihydroanthracene is helpful to control the steric effect for the favorable formation of a distinctly appreciable bis-merocyanine(bis-MC)product.By varying the length of the polymer chains,the force delivered to the mechanophore is modulated,resulting in a gradient change in the relative distribution of two distinctly colored MC products and a multicolor mechanochromism.Mechanical activation of this bis-naphthopyanes proceeds via a mechanistically dis-tinct pathway compared to the photochemical process.In addition,the bulk films can also achieve pro-nounced color changes when subjected to mechanical force.This study thus further expands the molecu-lar diversity of mechanochromophores and tune the multimodal switch properties of bis-naphthopyrans based polymers.
基金项目
国家自然科学基金(22275068)
国家自然科学基金(21975178)
中央高校基本科研业务费专项()
Open Project of the State Key Laboratory of Supramolecular Structure and Materials()
维普
万方数据