New Synthetic Routes to Well-Defined Nanocarbon Materials

在美国国家科学基金会化学系大分子、超分子和纳米化学项目的支持下，加州大学伯克利分校的T. Don Tilley教授正在探索制备大尺寸多环芳烃（PAHs）的合成路线，这是分子纳米碳材料家族的代表。石墨烯是一种扩展的二维纳米碳材料，以其有趣的电子特性而闻名；然而，它的结构是不规则的，这使得它在纳米电子器件中的应用变得复杂。相比之下，所研究的多环芳烃表现出明确的分子结构，具有类似石墨烯的电子特性。该项目旨在提供有关特定分子结构特征对所需电子性质影响的基础知识。该项目预计将影响纳米科学领域，特别是碳基半导体有机材料的可用性，作为量子信息科学、通信和传感等领域新兴应用的组件。在进行这项研究的过程中，参与的学生将接受高级有机合成和材料表征技术的培训。相关的外展活动包括参加ACS的经济弱势群体暑期体验项目（SEED）和针对小学生的伯克利湾地区学校科学家项目（BASIS）。该项目开发了一种合成方法，用于有效地引入多个融合的芳香环，以控制大型、定制的多环芳烃（PAHs）的构建。这是通过高产的[2+2+n]环加成来完成的，在一个合成步骤中产生多个融合的芳香环。可伸缩反应可用于获得广泛的新型碳纳米结构，包括螺旋烯、纳米带、环芳烃和纳米带。一个特定的目标是一个扩展的，螺旋多环芳烃家族，将在主客体化学和与偏振光的相互作用的背景下进行研究。其他目标包括大环多环芳烃及其通过超分子相互作用的组装，以及有望表现出一维半导体特性的细长纳米带结构。代表碳纳米管分子切割的纳米带结构正在被合成和研究。另一个兴趣是开发将多环芳烃连接在一起以形成定义明确的扩展结构的策略，以帮助弥合自下而上的有机合成和自上而下的碳同素异形体合成之间的差距。该研究旨在首先从基本角度了解新型纳米碳材料的行为，然后（作为长期目标）利用合成的模块化来合理调整结构，以满足有机电子学和量子信息科学（QIS）的期望应用。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 Program in the Division of Chemistry at the National Science Foundation, Professor T. Don Tilley of the University of California, Berkeley is exploring synthetic routes to prepare large-sized polycyclic aromatic hydrocarbons (PAHs), which represent a family of molecular nanocarbon materials. Graphene, an extended two-dimensional nanocarbon material, is well known for interesting electronic properties; however, its structure is irregular, which complicates its utility in nanoelectronic devices. In contrast, the PAHs under investigation exhibit well-defined molecular structures with graphene-like electronic properties. The project is geared toward providing fundamental knowledge regarding the effect of specific molecular structural features on desired electronic properties. The project is expected to impact the field of nanoscience, and especially the availability of carbon-based semiconducting organic materials as components for emergent applications in areas such as quantum information science, communications, and sensing. During the course of conducting this research, the students involved will be trained in advanced organic synthesis and material characterization techniques. The associated outreach activities include participation in the ACS Summer Experiences for the Economically Disadvantaged (SEED) Project and the Bay area scientists in school at Berkeley (BASIS) Program targeting elementary school students.The project develops synthetic methodologies for the efficient introduction of multiple fused aromatic rings in the controlled construction of large, tailored polycyclic aromatic hydrocarbons (PAHs). This is accomplished with high yielding [2+2+n] cycloadditions that produce multiple fused aromatic rings in a single synthetic step. The scalable reactions are used to access a wide range of new carbon nanostructures, including helicenes, nanobelts, cycloarenes, and nanoribbons. A specific target is a family of expanded, helical PAHs that are to be studied in the context of host-guest chemistry and interactions with polarized light. Other targets include macrocyclic PAHs and their assembly by way of supramolecular interactions, and elongated, nanoribbon structures expected to exhibit properties as 1-dimensional semiconductors. Nanobelt structures that represent molecular cut-outs of carbon nanotubes are being synthesized and studied. An additional interest is development of strategies for linking the PAHs together to form well-defined, extended structures that help bridge the gap between bottom-up organic synthesis and top-down synthesis of carbon allotropes. The research aims to first understand the behavior of new nanocarbon materials from a fundamental perspective, and then (as a longer-term goal) take advantage of the modularity of the syntheses to rationally tune structures for desired applications in organic electronics and quantum information science (QIS).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.