Aggregation-induced emission characteristics and solvent triggered hierarchical self-assembled chiral superstructures of naphthalenediimide amphiphiles

Abstract

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. Bottom-up supramolecular self-assembly formation approach of NDI-TA1 amphiphile exhibited biomimetic hairy caterpillar-like superstructures in THF/MCH solvent system 30:70 v/v whereas, long uniform helical ribbons were also yielded at higher volume percentage of MCH in THF (90:10 v/v). Circular dichroism (CD) spectroscopy study revealed a chiral aspect of the self-assembled supramolecular structures at wavelength corresponding to their absorptions. Interestingly, NDI-TA1 aggregates at higher amount of MCH in THF exhibited AIE property because of excimer formation. On the other hand, NDI-TA2 amphiphile displays total quenching of emission i.e. aggregation cause quenching (ACQ) effect. The SEM images of deacylated amphiphile NDI-TA2 produces belts and sheets-like supramolecular self-assembled microstructures.