Tunable self-assembly hierarchical superstructures of benzene-1,3,5-tricarboxamide-containing fullerene block molecules: from flower to urchin and rod-like morphologies

Abstract

The precise modulation of different hierarchical superstructures relying on the synergy of multiple noncovalent interactions between basic building units is both elusive and highly desirable. Herein, we report a series of novel benzene-1,3,5-tricarboxamide (BTA)-containing fullerene block molecules with different alkyl spacer and tail chain lengths, which could self-assemble into diverse hierarchical superstructures in selective solvents, forming flower, urchin, or rod-like morphologies based on the π–π interactions between fullerene moieties and threefold hydrogen bonds between BTA units. The fullerene-BTA block molecules with long spacers and tail chains self-assemble into several micrometer sized flower-like superstructures with a nanoflake outer surface morphology. With decreasing spacer and tail chain length, the superstructures gradually transform from flower-like to urchin and rod-like structures. Further investigations show that these morphologies are constructed by different building blocks, where flower-like structures are formed by lamellar nanosheets while others are formed by strip-shaped assemblies due to the enhanced hydrogen bonding interactions. Additionally, the transition between different hierarchical superstructures could also be tuned by changing the ratio of the mixed solvent.