Tuning the gelation ability of racemic mixture by melamine: enhanced mechanical rigidity and tunable nanoscale chirality.

Understanding the relationship between molecular chirality of the gelators and the properties of the assembled supramolecular gels could be very important for developing novel functional soft matters. Although mixing the enantiomers with different molar ratios has been proved to be useful for modulating supramolecular assemblies, usually the racemates of different chiral molecules are not good gelators. In this study, the coassembly of the glutamic acid-based bolaamphiphile racemate and melamine was found to form hydrogels, while the assembly of the racemate only produced precipitates. Remarkably, the racemic hydrogels show lower CGC value, enhanced mechanical rigidity, and dual pH-responsive ability compared to the pure enantiomer hydrogels. The gelation properties, nanoscale chirality, and nanostructures of the racemic hydrogels can be regulated flexibly by changing molar ratios of different molecular building blocks.