Aggregation-induced emission characteristics and solvent triggered hierarchical self-assembled chiral superstructures of naphthalenediimide amphiphiles†
Herein, we report the design and synthesis of two naphthalene diimide amphiphiles NDI-TA1 and NDI-TA2 bearing acylated and deacylated hydroxyl groups of tartaric acid, respectively. Furthermore, we investigated the influence of acylation and deacylation of hydroxyl groups of tartaric acid over UV-vis, aggregation induced emission (AIE), chirality and supramolecular self-assembly formation. A bottom-up supramolecular self-assembly formation approach of the NDI-TA1 amphiphile exhibited biomimetic hairy caterpillar-like superstructures in a THF/MCH 30 : 70 v/v solvent system, whereas long uniform helical ribbons were also yielded at a higher volume percentage of MCH in THF (90 : 10 v/v). Circular dichroism (CD) spectroscopy studies revealed a chiral aspect of the self-assembled supramolecular structures at wavelengths corresponding to their absorptions. Interestingly, NDI-TA1 aggregates at higher amounts of MCH in THF exhibited AIE properties because of excimer formation. On the other hand, the NDI-TA2 amphiphile displays total quenching of emission, i.e. the aggregation cause quenching (ACQ) effect. The SEM images of deacylated amphiphile NDI-TA2 show belt and sheet-like supramolecular self-assembled microstructures.