Porphyrin monolayers as platforms for the supramolecular organization of fullerenes at interfaces

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The Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division supports the project 'Porphyrin Monolayers as Platforms for the Supramolecular Organization of Fullerenes at Interfaces' by Professor Michael D. Hopkins, a faculty member in the Department of Chemistry at the University of Chicago. Fullerenes are molecules comprised of a specific number of carbon atoms (i.e., 60, 70, 84, etc.) that are widely studied for their potential technological applications, such as in electronics and solar energy conversion. The goal of this project is to develop a general method for creating specific patterns of fullerenes on flat surfaces, which will allow their technologically relevant properties to be controlled and provide a means to connect these nanometer-scale materials to conventional- scale electronics. The project provides interdisciplinary training for graduate students at the intersection of chemical synthesis, surface science, and materials science. Undergraduate students are also routinely involved in research projects in the PI's laboratory. Professor Hopkins is involved in organizing an outreach clearinghouse for doctoral students in the physical sciences at the university that will connect them with STEM-focused broader-impacts activities. An impediment to the development of technological applications of fullerenes is the lack of general methods for spatially organizing them into arrays with controllable patterns and dimensions at an addressable interface. This project investigates whether 5-coordinate gallium-porphyrin monolayers on highly oriented pyrolytic graphite will template the self- assembly of fullerenes into organized arrays at the interface. Porphyrins containing axial ligands that coordinate fullerenes via noncovalent interactions (e.g., polycyclic aromatics) are synthesized, and their surface chemistry in the absence and presence of fullerenes (especially C60) are investigated via scanning-probe microscopy. These studies aim to elucidate the fundamental relationships between fullerene patterning and: 1) the electronic and structural characteristics of the axial ligands; 2) the lattice dimensions and steric properties of the underlying porphyrin monolayers; and 3) the presence of capping porphyrins that could encapsulate the particles. These relationships will allow elucidation of design principles for this class of materials. The PI also leads the continued development of an internal portal that has proven successful in connecting physical-sciences graduate students with K-12 educational outreach opportunities in surrounding neighborhoods.