Electronic and Topological Complexity in Nanocarbon Materials

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professor T. Don Tilley of the University at California at Berkeley will develop synthetic routes for efficient preparation of nanocarbon compounds that exhibit optical and electronic properties like those of graphene. Graphene is a material that consists of a single layer of carbon atoms arranged in a honeycomb planar nanostructure. It is known for its remarkable properties, being about 200 times stronger than steel yet 1,000 times lighter than paper. The targeted molecular systems consisting of multiple aromatic rings fused together will be designed to interact with light in a controlled and unique way and to possess previously unknown and well-defined 3-dimensional structures. The studies outline in this work have the potential to reveal innovative ways to integrate the transport of charge with photon excitations and provide novel strategies to enable development of next-generation electronic devices. The activities involved in this work will contribute to the training of young scientists and technologists, while generating useful and fundamental chemistry knowledge. The educational aspects of this project will provide opportunities to inspire high school and undergraduate students toward careers across various chemistry and nanotechnology fields. This project will develop synthetic methodologies for the controlled, efficient and scalable introduction of fused aromatic rings into large, tailored polycyclic aromatic hydrocarbons (PAHs). The synthetic methods will utilize high yielding [2+2+n] cycloadditions that simultaneously introduce multiple aromatic rings in a single synthetic step. This methodology should allow access to a wide range of carbon nanostructures, including examples that contain antiaromatic rings or helically chiral graphene-type systems. The elaboration of PAHs with fused antiaromatic rings is to be explored in the context of accessing radicaloid character and mechanisms for spin-state manipulation, of current interest for potential applications in quantum information science. The helical PAHs that will be studied are “expanded” to provide avenues to host-guest chemistry and new chiroptical properties, with the potential to function as spin filters and charge carriers in thin-film devices. Other synthetic studies will explore strategies for spatially orienting nanocarbon units by way of supramolecular assembly and dynamic covalent chemistry (DCvC). The DCvC approach will be used to generate new molecular topologies featuring entangled, knotted nanocarbons and strategies for spatially orienting nanocarbon units. Overall, this research aims to understand the behavior of new nanocarbon materials from a fundamental perspective, and in the long term rationally tune these structures for desired applications in organic electronics and quantum information science (QIS). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.