超高真空条件下表面辅助反应

在金属单晶表面上直接合成制备各种共价键连接聚合结构，由于其独特的路线及在电子学、光电子学等方面的潜在应用价值而得到了广泛的关注。与传统的有机合成反应不同，表面辅助反应能够在一定程度上控制产物的结构，知悉具体的反应过程，更重要的是还能制备一些采用传统方法所不能得到的新型材料。前驱体分子的种类、衬底的选择以及反应条件等因素都与反应的发生紧密相关。在表面上制备出的有序共价组装结构除了比传统的自组装单层膜(SAMs)结构具有更高的机械强度及热力学稳定性外，分子间连接的共价键还能作为电子传输的通道，使其应用范围得到很大地扩展。本文对近年来报道的超高真空环境下的一些表面辅助反应进行了介绍，分析了各个反应发生的机理，并将其与溶液中发生的反应相对比，讨论了衬底表面在反应过程中所起到的重要作用。

Surface Assisted Reaction under Ultra High Vacuum Conditions

The construction of covalently bonded molecular structures on single crystal metal surfaces has attracted increasing attention because of the synthetic strategies used and their potential application to molecular electronics and optoelectronics. Unlike traditional organic synthesis, surface-assisted reactions have advantages for structural control of the produced polymers, providing detailed understanding of reaction processes, and, most importantly, they produce new materials that cannot be synthesized by traditional means. The types of reactant, the choice of metal surface, and the initial conditions are critical controlling parameters in surface-assisted reactions. Covalent bonds formed in the reaction ensure that the produced structures have higher mechanical and thermodynamic stability compared with self-assembled monolayers (SAMs). Meanwhile, some conjugated polymers are ideal candidates for semiconductors in next-generation carbon-based electronics. In this review, we summarize the surface assisted reactions reported in recent years and analyze the mechanisms involved, comparing them with the corresponding reactions that occur in solution. Finally, we discuss the important role of substrate surface played in the reaction process.