Morphology Engineering of Fullerene[C70] Microcrystals: from Perfect Cube, Defective Hopper to Novel Cruciform-pillar.

Controlled crystallization of fullerene molecules into ordered molecular assemblies is important for their applications. However, the morphology engineering of fullerene[C 70 ] assemblies is challenging and complicated architectures have rarely been reported due to the low molecular symmetry of C 70 molecules which makes their crystallization difficult to control and the low production yield as well. Herein, with the assistance of solvent intercalation, we report a general reprecipitation approach to prepare morphologically controllable C 70 microcrystals with mesitylene as a good solvent and n-propanol as a poor solvent in one solvent system without replacing specific solvents. A series of C 70 microcrystals with high uniformity from perfect cubes and defective hoppers to novel cruciform-pillars are obtained by intentionally tuning C 70 concentration and the volume ratio of mesitylene to n-propanol. Among them, novel cruciform-pillar-shaped microcrystals are obtained for the first time by further decreasing the amount of mesitylene in the solvent-intercalated microcrystals. Noteworthily, the C 70 concentration is a key parameter for the selective growth of C 70 hopper, rather than the volume ratio of mesitylene to n-propanol. Interestingly, the hopper-shaped microcrystals exhibit excellent photoluminescence properties relative to those of cubes and cruciform-pillars owing to the enhanced light absorption, proving their potential applications in optoelectronic devices.