Selective growth of a C70 crystal in a mixed solvent system: From cube to tube

Abstract

Cube- and tube-shaped C70 crystals were obtained selectively by reprecipitation using a combination of mesitylene (good solvent) and isopropyl alcohol (poor solvent). Both crystals include mesitylene molecules in their lattices; the ratios of C70 to mesitylene were 1:2 in C70 cubes and 1:0.7 in C70 tubes. The volume ratio of mesitylene to IPA is a key parameter for the selective growth of C70 cubes and C70 tubes, rather than the supersaturation ratio, which governs crystal morphology in many other cases. Thus, we propose that the absolute amount of mesitylene near C70 molecules determines the crystallization pathways for forming the C70·2(mesitylene) or C70·0.7(mesitylene) phase, which finally result in C70 cubes or C70 tubes, respectively. © 2015 American Chemical Society