Graduate School of Science, Nagoya University, Nagoya, Japan.
JST-ERATO, Itami Molecular Nanocarbon Project, Nagoya, Japan.
Nature. 2019 Jul;571(7765):387-392. doi: 10.1038/s41586-019-1331-z. Epub 2019 Jun 26.
The properties of graphene nanoribbons (GNRs)-such as conductivity or semiconductivity, charge mobility and on/off ratio-depend greatly on their width, length and edge structure. Existing bottom-up methods used to synthesize GNRs cannot achieve control over all three of these parameters simultaneously, and length control is particularly challenging because of the nature of step-growth polymerization. Here we describe a living annulative π-extension (APEX) polymerization technique that enables rapid and modular synthesis of GNRs, as well as control over their width, edge structure and length. In the presence of palladium/silver salts, o-chloranil and an initiator (phenanthrene or diphenylacetylene), the benzonaphthosilole monomer polymerizes in an annulative manner to furnish fjord-type GNRs. The length of these GNRs can be controlled by simply changing the initiator-to-monomer ratio, achieving the synthesis of GNR block copolymers. This method represents a type of direct C-H arylation polymerization and ladder polymerization, activating two C-H bonds of polycyclic aromatic hydrocarbons and constructing one fused aromatic ring per chain propagation step.
石墨烯纳米带（GNRs）的性质，如导电性或半导体性、电荷迁移率和开/关比，很大程度上取决于其宽度、长度和边缘结构。现有的用于合成 GNRs 的自下而上的方法不能同时实现对这三个参数的控制，而长度控制尤其具有挑战性，因为这是逐步聚合的性质。在这里，我们描述了一种活的环状π-扩展（APEX）聚合技术，该技术能够快速且模块化地合成 GNRs，并控制其宽度、边缘结构和长度。在钯/银盐、邻氯苯醌和引发剂（菲或二苯基乙炔）的存在下，苯并萘噻咯单体以环状方式聚合，得到峡湾型 GNRs。通过简单地改变引发剂与单体的比例，可以控制这些 GNR 的长度，从而实现 GNR 嵌段共聚物的合成。这种方法代表了一种直接 C-H 芳基化聚合和梯形聚合，激活多环芳烃的两个 C-H 键，并在每个链延伸步骤中构建一个稠合芳环。
