Wang Peng, Fortner Jacob, Luo Hongbin, Kłos Jacek, Wu Xiaojian, Qu Haoran, Chen Fu, Li Yue, Wang YuHuang
Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States.
Department of Physics, Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, United States.
J Am Chem Soc. 2022 Jul 27;144(29):13234-13241. doi: 10.1021/jacs.2c03846. Epub 2022 Jul 13.
Aryl diazonium reactions are widely used to covalently modify graphitic electrodes and low-dimensional carbon materials, including the recent creation of organic color centers (OCCs) on single-wall carbon nanotube semiconductors. However, due to the experimental difficulties in resolving small functional groups over extensive carbon lattices, a basic question until now remains unanswered: what group, if any, is pairing with the aryl sp defect when breaking a C═C bond on the sp carbon lattice? Here, we show that water plays an unexpected role in completing the diazonium reaction with carbon nanotubes involving chlorosulfonic acid, acting as a nucleophilic agent that contributes -OH as the pairing group. By simply replacing water with other nucleophilic solvents, we find it is possible to create OCCs that feature an entirely new series of pairing groups, including -OCH, -OCH, -OCH, --OCH, and -NH, which allows us to systematically tailor the defect pairs and the optical properties of the resulting color centers. Enabled by these pairing groups, we further achieved the synthesis of OCCs with sterically bulky pairs that exhibit high purity defect photoluminescence effectively covering both the second near-infrared window and the telecom wavelengths. Our studies further suggest that these diazonium reactions proceed through the formation of carbocations in chlorosulfonic acid, rather than a radical mechanism that typically occurs in aqueous solutions. These findings uncover the unknown half of the sp defect pairs and provide a synthetic approach to control these defect color centers for quantum information, imaging, and sensing.
芳基重氮反应被广泛用于共价修饰石墨电极和低维碳材料，包括最近在单壁碳纳米管半导体上创建有机色心（OCCs）。然而，由于在广泛的碳晶格上解析小官能团存在实验困难，到目前为止一个基本问题仍未得到解答：在sp碳晶格上断裂C═C键时，与芳基sp缺陷配对的是哪个基团（如果有的话）？在这里，我们表明水在涉及氯磺酸的碳纳米管重氮反应中发挥了意想不到的作用，它作为亲核试剂贡献 -OH作为配对基团来完成反应。通过简单地用其他亲核溶剂代替水，我们发现有可能创建具有全新系列配对基团的OCCs，包括 -OCH₃、-OCH₂CH₃、-OCH₂CH₂CH₃、-OCH₂CF₃和 -NH₂，这使我们能够系统地调整缺陷对以及所得色心的光学性质。借助这些配对基团，我们进一步实现了具有空间位阻较大配对的OCCs的合成，这些OCCs表现出高纯度缺陷光致发光，有效地覆盖了第二近红外窗口和电信波长。我们的研究进一步表明，这些重氮反应是通过在氯磺酸中形成碳正离子进行的，而不是通常在水溶液中发生的自由基机制。这些发现揭示了sp缺陷对未知的另一半，并提供了一种合成方法来控制这些缺陷色心用于量子信息、成像和传感。
