Driving Forces for Covalent Assembly of Porphyrins by Selective C-H Bond Activation and Intermolecular Coupling on a Copper Surface
Driving Forces for Covalent Assembly of Porphyrins by Selective C-H Bond Activation and Intermolecular Coupling on a Copper Surface
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DOI：
10.1021/jacs.5b11594
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发表时间：
2016-05-11
影响因子：
15
通讯作者：
Kantorovich, Lev
中科院分区：
文献类型：
--
作者：
Floris, Andrea;Haq, Sam;Kantorovich, Lev
最近在表面合成共价有机组装体为生产功能性界面的坚固纳米结构开辟了前景。为了揭示这种新化学如何在表面发挥作用，并了解控制参与分子特定位置的断键和成键过程的潜在机制，我们在这里研究了四(异三叉基)卟啉分子的偶联反应，该反应利用 4-甲基作为独特的连接点在 Cu(110) 表面上创建共价连接的网络。利用扫描隧道显微镜 (STM)、最先进的密度泛函理论 (DFT) 和微推弹性带 (NEB) 计算，我们发现共价键的独特方向性源于一系列高度选择性的 C-H 活化和脱氢过程，然后是表面、空间约束和各向异性分子扩散促进的特定分子间 C2C 偶联反应。这些见解为开发复杂二维共价有机化学的合成规则提供了第一步，这些规则可以直接在表面上制定，以提供为特定功能设计的特定大分子结构。
Recent synthesis of covalent organic assemblies at surfaces has opened the promise of producing robust nanostructures for functional interfaces. To uncover how this new chemistry works at surfaces and understand the underlying mechanisms that control bond-breaking and bond-making processes at specific positions of the participating molecules, we study here the coupling reaction of tetra(mesityl)porphyrin molecules, which creates covalently connected networks on the Cu(110) surface by utilizing the 4-methyl groups as unique connection points. Using scanning tunneling microscopy (STM), state-of-the-art, density functional theory (DFT), and Nudged Elastic Band (NEB) calculations, we show that the unique directionality of the covalent bonding is found to stem from a chain of highly selective C-H activation and dehydrogenation processes, followed by specific intermolecular C C coupling reactions that are facilitated by the surface, by steric constraints, and by anisotropic molecular diffusion. These insights provide the first steps toward developing synthetic rules for complex two-dimensional covalent organic chemistry that can be enacted directly at a surface to deliver specific macromolecular structures designed for specific functions.