Liu Jing, Chen Qiwei, He Qilin, Zhang Yajie, Fu Xiangyu, Wang Yongfeng, Zhao Dahui, Chen Wei, Xu Guo Qin, Wu Kai
BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Phys Chem Chem Phys. 2018 Apr 25;20(16):11081-11088. doi: 10.1039/c7cp07972a.
The activation of C-H bonds in terminal alkynyl groups at room temperature was achieved in the reaction of 2,5-diethynyl-1,4-bis(4-bromophenylethynyl)benzene on Ag(111). Scanning tunneling microscopy studies showed the formation of organometallic species, whose stabilization was confirmed by density functional theory calculations, at room temperature as the product of C-H bond activation. The partial conversion of organometallic structures into covalent products of the homocoupling between the terminal alkynes was achieved by further annealing the sample at 420 K. Detached Br adatoms were suggested to play a key role in promoting the C-H bond activation. This proposal was supported by the theoretical study based on a simplified model of the system, showing the weakening of the C-H bond in the alkynyl group by an approaching Br atom. The results provide a new strategy for on-surface C-H bond activation under mild conditions, which register great potential applications in on-surface synthesis and bottom-up preparation of functional nanomaterials.
在Ag(111)表面上，2,5-二乙炔基-1,4-双(4-溴苯乙炔基)苯的反应实现了室温下末端炔基中C-H键的活化。扫描隧道显微镜研究表明，室温下作为C-H键活化产物形成了有机金属物种，密度泛函理论计算证实了这些物种的稳定性。通过在420 K下进一步退火样品，实现了有机金属结构向末端炔烃之间均偶联的共价产物的部分转化。研究表明，脱离的Br吸附原子在促进C-H键活化中起关键作用。基于该体系的简化模型进行的理论研究支持了这一观点，该研究表明靠近的Br原子会使炔基中的C-H键减弱。这些结果为温和条件下的表面C-H键活化提供了一种新策略，在表面合成和功能纳米材料的自下而上制备方面具有巨大的潜在应用价值。
