Superstructures with diverse morphologies and highly ordered fullerene C60 arrays from 1 : 1 and 2 : 1 adamantane-C60 hybrid molecules.

Abstract

Superstructures from fullerene C60-containing compounds, especially those tethered to rigid functional groups with defined shapes, remain largely unexplored. Being the smallest diamondoid, adamantane (Ad) can be viewed as a promising building block for the construction of well-defined superstructures. Here, we report the syntheses of 1 : 1 (4a) and 2 : 1 (4b) Ad-C60 hybrid molecules, which were then used to construct superstructures in binary solvent mixtures via a modified liquid/liquid interfacial precipitation (LLIP) method using CHCl3 as a good solvent. Typically in the combination of DMSO/CHCl3 with a final concentration (cf) of 1.0 mmol L-1, 4a successively forms spheres, plates, nanoflowers and plicated particles with increasing content of DMSO while 4b forms cuboid blocks and microparticles with hierarchically organized surfaces. Changing from DMSO to other poor solvents including acetone, MeOH and EtOAc leads to variations of the morphology of the superstructures for both 4a and 4b. At the nanometer length scale, 4a and 4b adopt different organizations within the superstructures. While 4a tends to self-organize into lamellae with highly ordered C60 layers, the hexagonal phase is dominant in the superstructures formed by 4b. Wettability tests indicate that films formed by the superstructures of 4a and 4b show anti-wetting properties. Besides the solvent effect, the morphology of the superstructures can be also tuned by concentration. For example, when cf is lowered to 0.5 mmol L-1, a new form of superstructure, i.e., fibers, was detected for 4a. Our results also indicate that besides the solvent-induced aggregate transition, gravity-induced sedimentation and subsequent structure ripening can have a significant influence on the final morphology of the superstructures and the aggregate transition pathways.