A Novel Architectural Approach to the Organic Synthesis of Short Segments of Carbon Single-Walled Nanotubes with Well-Defined Lengths, Diameters and Chiral Vectors

通过这一奖项，有机和高分子化学项目支持了佛蒙特州大学的托马斯·S·休斯教授的工作。这项研究涉及对碳单壁纳米管片段进行新的合成方法，这些碳单壁纳米管片段具有特定和可控的结构参数，如长度、直径和手性向量，或者碳原子的六元环相对于管轴的取向。这些应变纳米管段的方法依赖于合成含有炔烃或环戊二酮官能团的平面、无张力的亚苯基大环。这些平面大环将被合成，然后通过Diels-Alder环加成反应添加额外的苯基。苯基以一种将允许随后的氧化反应将环熔合在一起形成目标管状结构的排列引入。通过控制前驱体大环的直径和辅助含苯类反应物的尺寸，可以实现对产物纳米管的直径和长度的控制。因此，纳米管片段中固有的应变将以高度递增的方式并入。一旦合成，将对纳米管片段的固态填充和导电性进行评估。对这些片段的化学修饰也将类似于目前对结构较不明确的较大纳米管进行的化学修饰；这些模型系统的这种化学修饰将阐明较大纳米管中发生的化学事件。该项目的更广泛影响部分是对研究生进行有机合成和表征以及有机材料表征方面的培训。此外，产品纳米管片段是目前生产的较大的碳单壁纳米管的模型，对其直径和长度的控制相对较少。用所提出的方法生产的管段可能适合作为生产大量具有特定结构的纳米管的种子。由于碳纳米管的结构影响了其作为有机电子应用材料的潜在用途，如场效应管、发光二极管和光伏，这些较小的模型系统可以用来进一步了解这些现象的物理基础，并可能成为最终器件中材料的潜在原料。

With this award, the Organic and Macromolecular Chemistry Program supports the work of Professor Thomas S. Hughes of the University of Vermont. This research involves carrying out novel synthetic approaches to carbon single-walled nanotube segments with specific and controllable structural parameters such as the length, diameter and chiral vector, or the orientation of the six-membered rings of carbon atoms relative to the axis of the tube. These approaches to the strained nanotube segments rely on the synthesis of planar, unstrained phenylene macrocycles containing alkyne or cyclopentadienone functional groups. These planar macrocycles will be synthesized and then additional phenyl groups will be added using a Diels-Alder cycloaddition. The phenyl groups are introduced in an arrangement that will allow a subsequent oxidation reaction to fuse the rings together into the target tubular structures. Control over the diameter and length of the product nanotubes will be achieved by controlling the diameter of the precursor macrocycle and the size of the auxiliary phenyl-containing reactants. The strain inherent in the nanotube segments will thus be incorporated in a highly incremental fashion. Once synthesized, the solid-state packing and the conductivity of the nanotube segments will be evaluated. Chemical modifications of the segments will also be performed analogous to those currently carried out on larger nanotubes with less well-defined structures; such chemical modifications of these model systems will elucidate the chemical events taking place in the larger nanotubes.The broader impacts of this project are in part the training of graduate students in organic synthesis and characterization, and in the characterization of organic materials. In addition, the product nanotube segments are models of the larger carbon single-walled nanotubes currently produced with relatively little control over their diameters and lengths. The segments produced by the method proposed may be suitable as "seeds" for the production of large amounts of nanotubes with specific structures. Since the structure of the carbon nanotube affects its potential usefulness as a material for organic electronic applications such as field-effect transistors, light-emitting diodes and photovoltaics, these smaller model systems could be used to further the understanding of the physical bases of these phenomena and could be potential feedstocks for materials in eventual devices.