New Strategy for Synthesis of Atomically-Precise Graphene Nanoribbons

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With this award, the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry is supporting Professor Guangbin Dong at the University of Chicago to develop new approaches for preparing atomically-precise, water-soluble graphene nanoribbons. These nanoribbons are strips (50-100 thousand times thinner than a human hair) of graphene: a sheet of carbon atoms arranged in a rigid structure that resembles chicken wire. Graphene nanoribbons come in two different structural forms, armchair and zigzag. Armchair graphene nanoribbons have emerged as attractive organic materials for potential applications in high-speed, light-weight and flexible electronic devices. Zigzag graphene nanoribbons represent promising materials for developing efficient spintronic (spin-electronic) devices. To date, the efficient and practical synthesis of water-soluble and processable graphene has not been possible. The Dong group is combining physical organic chemistry knowledge with advanced tools of transition-metal catalysis to overcome the synthetic challenges and the processability problem. The development of scalable synthetic approaches for the production of pure forms of armchair and zigzag nanoribbons opens the way for novel applications of these materials in nanoelectronics, spintronic and quantum computing devices. During the course of this research, the Dong group is actively participating in the Leadership Alliance Summer Research Program to encourage diverse groups of minority undergraduate students to explore careers in science and engineering. The Dong group is also actively engaged in the University of Chicago's graduate student “ChiS&E” program providing educational outreach activities to students from local public middle schools.This research project seeks to offer efficient and scalable synthetic approaches for preparing atomically-precise, water-soluble armchair and zigzag graphene nanoribbons (aGNRs and zGNRs) that could be ultimately used in high performance electronic and spintronic devices. The objectives are to realize solution-phase synthesis of aGNRs and zGNRs with precisely installed piperazine side chains. The key synthetic challenge is to exploit the newly developed palladium/norbornene (Pd/NBE) catalysis to prepare these unique monomers for GNR synthesis. Compared to the existing approaches of GNR synthesis, the merits of the new strategies include: monomers that are prepared in a streamlined manner from commercially available chemicals; redundant bulky side chains that are avoided for better imaging of the material edge structures; and products that are expected to exhibit high solubility and processability in aqueous solutions. The successful implementation of the research may address two long-standing challenges: synthesis of water-soluble GNRs and solution-phase preparation of zGNRs, which are critical factors for solution processability of these materials and the development of graphene-based spintronic devices. The research facilitates the physical and theoretical studies of these intriguing materials, as many of those aGNRs and zGNRs may be made for the first time in the lab and then used to validate or examine various theoretical models and hypotheses proposed previously by physicists and physical chemists. The knowledge obtained from these investigations may improve our understanding of these graphene-like one-dimensional polymers. This, in turn, may further inspire and stimulate the development of other new conjugated organic semiconducting materials.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.