New Strategy for Synthesis of Atomically-Precise Graphene Nanoribbons

化学系的大分子、超分子和纳米化学项目正在支持芝加哥大学的董广斌教授开发制备原子精度、水溶性石墨烯纳米带的新方法。这些纳米带是石墨烯条（比人类头发细5 -10万倍）：石墨烯是一层碳原子，排列成类似铁丝网的刚性结构。石墨烯纳米带有两种不同的结构形式，扶手椅和之字形。扶手椅石墨烯纳米带已经成为一种有吸引力的有机材料，在高速、轻量化和柔性电子设备中具有潜在的应用前景。之字形石墨烯纳米带是开发高效自旋电子（自旋电子）器件的理想材料。到目前为止，高效和实用的水溶性和可加工石墨烯的合成还不可能。董团队将物理有机化学知识与先进的过渡金属催化工具相结合，以克服合成挑战和可加工性问题。用于生产纯扶手椅和之字形纳米带的可扩展合成方法的发展，为这些材料在纳米电子学、自旋电子学和量子计算设备中的新应用开辟了道路。在这项研究的过程中，董小组积极参与领导联盟暑期研究计划，以鼓励不同群体的少数民族本科生探索科学和工程的职业生涯。董氏集团还积极参与芝加哥大学的研究生“ChiS&amp；E”项目，为当地公立中学的学生提供教育推广活动。该研究项目旨在提供高效和可扩展的合成方法，以制备原子精确的水溶性扶手椅和之字形石墨烯纳米带（aGNRs和zGNRs），最终可用于高性能电子和自旋电子器件。目的是实现具有精确安装哌嗪侧链的aGNRs和zGNRs的溶液相合成。关键的合成挑战是利用新开发的钯/降冰片烯（Pd/NBE）催化制备这些独特的单体用于合成GNR。与现有的GNR合成方法相比，新策略的优点包括：以流线型方式从市售化学品制备单体；避免多余的笨重侧链，以便更好地成像材料边缘结构；以及期望在水溶液中表现出高溶解度和可加工性的产品。该研究的成功实施可能会解决两个长期存在的挑战：水溶性gnr的合成和zgnr的固相制备，这是这些材料溶液可加工性和石墨烯基自旋电子器件发展的关键因素。这项研究促进了这些有趣材料的物理和理论研究，因为许多agnr和zgnr可能是第一次在实验室中制造出来，然后用于验证或检验物理学家和物理化学家先前提出的各种理论模型和假设。从这些研究中获得的知识可能会提高我们对这些类石墨烯一维聚合物的理解。这反过来又可能进一步启发和刺激其他新型共轭有机半导体材料的发展。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.