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)计划的支持下，芝加哥大学的董广斌教授正在开发高效和可扩展的合成方法，以制备原子精密的石墨烯纳米带(GNR)。这些纳米带是一条非常薄的石墨烯：一片碳原子排列在坚硬的结构中，类似于铁丝网。石墨烯纳米带已成为一种极具吸引力的有机材料，在高速、轻质、柔性电子器件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过渡金属催化的先进工具相结合，以开发制造这些有趣材料的有效策略。如果成功，这项研究将解决一个长期存在的挑战，即制备窄的锯齿形石墨烯纳米带，用于研究它们的物理、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计划(Chis&amp；E)，为芝加哥公立中学学生提供早期化学教育，为高中生提供大学学者计划，以及领导力联盟暑期研究早期识别计划(SR-EIP)，为本科生提供实验室研究经验。将该项目与这些推广活动相结合，有可能极大地鼓励来自代表性不足群体的不同群体的学生在学习和积极为研究做出贡献的同时探索科学和工程领域的职业。研究项目将侧重于开发高效和可扩展的合成方法，以实现原子上的精确和窄N=3-5之字形石墨烯纳米带(ZGNR)。良好定义的原始zGNRs的制备和液相制备是非常具有挑战性的，也是不发达的。为了克服这些未解决的挑战，将设计逐步环脱氢方法，以从更稳定的氧化或还原前驱物带中获得zGNR。另一方面，将利用钯/降冰片烯催化来探索新型单体的合成。与现有的GNR合成方法相比，新策略的优点可能是相当重要的：(1)单体将以简化的方式从商业上可获得的原料制备；(2)合成将通过在溶液聚合中使用而可扩展；(3)将绕过对空气敏感的中间体，简化材料转移过程；(4)通过避免不稳定的间二甲苯型单元，最大限度地减少芳基−的芳基裂解缺陷。从这个项目中获得的知识有可能促进对这些类石墨烯类准一维聚合物的理解，这反过来又将进一步刺激其他新的共轭有机半导体材料的发展。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.