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

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.