Structural and Functional Diversity in Well-Defined Graphene Nanostructures

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This award is funded by the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry. Professor T. Don Tilley of the University of California Berkeley is supported to develop a general approach for the synthesis of structurally well-defined and functionally diverse graphene nanostructures. The sought-after graphene nanostructures are carefully designed with an eye for novel or enhanced properties and future applications. The synthetic methods being developed target carbon-carbon bond formations, which are central to the advancement of polymer, materials, and medicinal chemistry. Graphene's extraordinary properties have generated considerable interest in this material and its substructures for many applications, including molecular electronics, catalysis, and sensing. However, progress in this area has been severely hindered by a lack of reliable synthetic methods that allow control over graphene's properties. The project provides young scientists with a broad overview of critical issues in science and technology as well as extensive technical skills in chemical synthesis, X-ray crystallography, electrochemistry, computational chemistry, and a range of spectroscopic techniques. The PI and the students involved in this project organize, lead, and participate in outreach activities, including hosting local high school summer students and teaching basic scientific principles through interactive lessons at nearby elementary schools. The construction and elaboration of graphene nanostructures using organic chemistry promises a much higher level of control over properties than that offered by top-down methods. The synthetic manipulation of electronic properties for graphene-based materials, by generation of structures with well-defined dimensionalities, edge structures, and dopants, is challenging given the inherent difficulty associated with fusion of many aromatic rings. In this project, Professor T. Don Tilley and coworkers at UC Berkeley are developing a general, organometallic approach to address this ring-fusion challenge, with a focus on [2+2+n] cycloadditions of alkynes and/or nitriles. This chemistry is being used to target several novel classes of graphene nanostructures and related large polycyclic aromatic hydrocarbons, and all syntheses are driven by the pursuit of novel or enhanced properties. Electronic and optical properties are firmly established at the molecular level using various absorption and emission spectroscopies and electrochemical methods. As appropriate, these properties are then probed at the supramolecular, monolayer, and/or solid-state levels. An important aspect to this work is the use of advanced physical methods in the characterization of electronic properties, and their relationship to structure.