(191b) Formation of High-Aspect Ratio Helical Nanorods Via Peptide Driven Self-Assembly of Fullerodendrimers

Hilmer, A. J., Massachusetts Institute of Technology
Shimizu, S., Massachusetts Institute of Technology
McNicholas, T. P., Massachusetts Institute of Technology
Strano, M., Massachusetts Institute of Technology

The ability to selectively form contiguous, high aspect-ratio electron acceptor domains could aid in the control of active layer morphologies in polymer photovoltaics.  We have synthesized two novel, asymmetric methanofullerenes, which self-assemble into one-dimensional supramolecular structures in cyclohexane.   We show that, through the introduction of a dipeptide sequence to one terminus of the dendritic methanofullerene, it is possible to transform the assembly behavior of these molecules from poorly formed aggregates to high aspect ratio nanorods.  These nanorods have diameters of 3.76 ± 0.52 nm, and possess lengths which can exceed 10 µm.   Both direct AFM observations and circular dichroism (CD) measurements indicate that these structures are comprised of helical assemblies of dendritic fullerenes.  Temperature-dependent absorbance and CD measurements indicate that self-assembly is initiated by intermolecular peptide interactions, which simultaneously drive self-assembly and impart chirality to the resulting supramolecular structures.  Here, we present optical and morphological characterization of these assembled structures.