Tuning of gel morphology with supramolecular chirality amplification using a solvent strategy based on an Fmoc-amino acid building block

Abstract

Gel formation by an N-fluorenyl-9-methoxycarbonyl (Fmoc)-based molecule was investigated and the chirality amplification observed during the self-assembly process could be switched on and off by controlling the solvent environment. The molecules could form gel in mixed solvents of water and dimethyl sulfoxide (DMSO) at either a high water fraction to afford flat nanofibers or a low water fraction to generate nanofibers with supramolecular chirality. At a moderate fraction of water, the molecules self-assemble into a precipitate composed of nanosheets. Furthermore, the gels showed different mechanical properties and thermal stabilities. Mechanism studies showed that π–π stacking interactions between the aromatic Fmoc groups and hydrogen bondings between the amide groups played important roles in the self-assembly process of the different gels. This study strives to shed light on the tuning of chiral gels with various nanostructures via controlled self-assembly, which might have potential use in smart materials.