Alkyl-Fullerene Materials of Tunable Morphology and Function

Abstract

The self-assembly of molecules into complex superstructures underpins the functionality of many biological processes and physical materials. Many such structures stem from amphiphilic monomer units, with attractions and repulsions between their ends determining the structure and state of the assembled system under equilibrium, which affect its function. The photophysical and electronic properties of fullerene (C60) have been extensively studied and proven useful in the fabrication of a variety of devices. The simple attachment of alkyl side chains can convert this highly crystalline solid into an alkyl-C60 hydrophobic amphiphile, in which alkyl-alkyl and C60-C60 interactions determine the state, phase, morphology, or architecture of the substance, while the optoelectronic properties of C60 are retained. In this award article, lipid membranes, crystalline nanostructures, mesophases, and even room-temperature liquid alkyl fullerenes formed through this approach are described. In each case, the effects of chain selection and substitution on morphology and function are explained. The ways in which the inherent properties of C60 can be adapted for particular applications are detailed, such as in superhydrophobic surfaces and photoconductive devices. Thereafter, drawing on these advances, the application of the alkyl chain attachment approach to other functional π-conjugated cores is demonstrated using some examples of functional molecular liquids.