Dehydroabietic acid and triphenylamine combined BioAIEgens with an imine linker and RIM: mechanochromism and acidichromism

The petrochemical-based multi-stimuli responsive materials have been widely explored as advanced functional materials in the past several decades, but they inevitably face problems like complicated synthesis, non-renewability, and non-sustainability. On this basis, the bio-based materials used to construct multi-stimuli responsive due to the unique natural structures have come to the fore. In this work, three novel triphenylamine-based salicylideneanilines have been simply designed with aggregation-induced emission (AIE) properties. Among all, DAMB-TPAOH and DAMB-TPA possessing the natural structure of dehydroabietic acid from rosin are bioproduct-inspired AIE luminogens (BioAIEgens). Derived from the excited-state intramolecular proton transfer (ESIPT) and restriction of intramolecular motion (RIM) dual-mechanism caused by the hydroxyl group and rigidification of alicyclic moiety, respectively, the solid-state DAMB-TPAOH exhibits red-shifted (compared to DAMB-TPA) and stronger (compared to BA-TPAOH) emission, endowing this BioAIEgen with the best fluorescence behavior. Further, the introduction of the natural skeleton, propeller TPA, and imine group results in the high-contrast mechanochromic and acidichromic properties of DAMB-TPAOH. The multi-stimuli responsive properties endow DAMB-TPAOH with potential utilization in the manufacture of rewritable paper and multi-color ink. The current work contributes greatly to the development of BioAIEgens with both mechanochromism and acidichromism.