New Strategy for Synthesis of Atomically Precise Graphene Nanoribbons

在化学系大分子、超分子和纳米化学（MSN）项目的支持下，芝加哥大学董广斌教授正在开发高效、可扩展的合成方法来制备原子精度的石墨烯纳米带（gnr）。这些纳米带是非常薄的石墨烯条：一层碳原子以类似铁丝网的刚性结构排列。石墨烯纳米带作为一种有吸引力的有机材料，在高速、轻量化、柔性电子和自旋电子器件中具有潜在的应用前景。在这个项目中，物理有机化学知识将与先进的过渡金属催化工具相结合，制定有效的策略来制造这些有趣的材料。如果成功，该研究将解决一个长期存在的挑战，即制备窄之字形石墨烯纳米带，用于研究其物理、电子、光学和磁性。研究团队还将积极参与芝加哥大学预科科学与工程项目（ChiS&amp；E），为芝加哥公立中学生提供早期化学教育；参与大学学者项目（Collegiate Scholars Program），为高中生提供早期化学教育；参与领导力联盟暑期研究早期识别项目（SR-EIP），为本科生提供实验室研究经验。该项目与这些外展活动相结合，有可能极大地鼓励来自代表性不足群体的多元化学生在学习和积极参与研究的同时，探索科学和工程领域的职业。该研究项目将专注于开发高效和可扩展的合成方法，以实现原子精度和窄N=3-5之字形石墨烯纳米带（zgnr）。在液相中制备和制造具有良好定义的原始zgnr是非常具有挑战性和不发达的。为了克服这些未遇到的挑战，将设计逐步环脱氢的方法，从其更稳定的氧化或还原前体带中获得zgnr。另一方面，将探索用钯/降冰片烯催化合成新的单体。与现有的GNR合成方法相比，新策略的优点具有相当显著的潜力：(i)单体将以一种简化的方式从市售的起始材料制备；（ii）通过在溶液聚合中使用，合成将可扩展；（iii）将避免空气敏感的中间体，从而简化物料转移过程；（iv）通过避免不稳定的间二甲苯型单元，将芳基-芳基裂解缺陷降至最低。从该项目中获得的知识有可能促进对这些类石墨烯准一维聚合物的理解，这反过来又将进一步刺激其他新型共轭有机半导体材料的开发。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 the support of the Macromolecular, Supramolecular and Nanochemistry (MSN) program in the Division of Chemistry, Professor Guangbin Dong at the University of Chicago is developing efficient and scalable synthetic approaches for preparing atomically precise graphene nanoribbons (GNRs). These nanoribbons are exquisitely thin strips of graphene: a sheet of carbon atoms arranged in a rigid structure that resembles chicken wire. Graphene nanoribbons have emerged as attractive organic materials for potential applications in high speed, lightweight, flexible electronic, and spintronic devices. In this project, physical organic chemistry knowledge will be combined with advanced tools of transition metal catalysis to develop efficient strategies for making these interesting materials. If successful, the research will address a long-standing challenge of preparing narrow zig-zag graphene nanoribbons for studying their physical, electronical, optical, and magnetic properties. The research team will also be actively engaged in the Chicago Pre-College Science & Engineering Program (ChiS&E) to provide early chemistry education to Chicago public middle-school students, the Collegiate Scholars Program to teach high school students, and the Leadership Alliance Summer Research Early Identification Program (SR-EIP) to offer lab research experience to undergraduate students. Integration of the project with these outreach activities has the potential to greatly encourage diverse and students from underrepresented groups to explore careers in science and engineering while learning and actively contributing to research.The research project will focus on the development of efficient and scalable synthetic approaches towards atomically precise and narrow N=3-5 zigzag graphene nanoribbons (zGNRs). The preparation and fabrication in liquid phase of well-defined pristine zGNRs are very challenging and underdeveloped. To overcome these unmet challenges, stepwise cyclodehydrogenation approaches to access zGNRs from their more stable oxidized or reduced precursor ribbons will be devised. The novel monomer synthesis, on the other hand, will be explored using palladium/norbornene catalysis. Compared to the existing approaches for GNR synthesis, the merits of the new strategies have the potential to be quite significant: (i) monomers will be prepared in a streamlined manner from commercially available starting materials; (ii) the syntheses will be scalable by using in solution polymerization; (iii) air sensitive intermediates will be circumvented, easing the material transfer process; (iv) aryl−aryl cleavage defects are to be minimized by avoiding labile m-xylene-type units. The knowledge gained from this project has the potential to advance the understanding of these graphene-like quasi-one-dimensional polymers, which in turn will further 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.