Tao Feng, Wang Zhong Hai, Lai Yee Hing, Xu Guo Qin
Department of Chemistry, National University of Singapore, 10 Kent Ridge, 119260 Singapore.
J Am Chem Soc. 2003 Jun 4;125(22):6687-96. doi: 10.1021/ja0208759.
The interactions of styrene and phenylacetylene and their isotope substitutions with a Si(111)-7 x 7 surface have been studied as model systems to mechanistically understand the chemical binding of conjugated pi-electron systems to di-radical-like silicon dangling bonds of the adjacent adatom-rest atom pair. Vibrational studies show that styrene mainly binds to the surface through a diradical reaction involving both the external C=C and its conjugated internal C=C of the phenyl ring with an adjacent adatom-rest atom pair, forming a 5-ethylidene-1,3-cyclohexadiene-like skeleton. On the other hand, phenylacetylene was shown to be covalently attached to Si(111)-7 x 7 through the external C[triple bond]C, forming a styrene-like conjugation system. These experimental results are consistent with density functional theory calculations. The different binding mechanisms for styrene and phenylacetylene clearly demonstrate that reaction channels for multifunctional organic molecules are strongly dependent on the chemical and physical properties of the functional groups. The resulting pi-electron conjugation structures may possibly be employed as intermediates for further organic syntheses and fabrication of multilayer organic films on semiconductor surfaces.
作为模型系统，已对苯乙烯和苯乙炔及其同位素取代物与Si(111)-7×7表面的相互作用进行了研究，以便从机理上理解共轭π电子体系与相邻吸附原子-静止原子对的双自由基类硅悬键的化学结合。振动研究表明，苯乙烯主要通过双自由基反应与表面结合，该反应涉及苯环的外部C=C及其共轭的内部C=C与相邻的吸附原子-静止原子对，形成类似5-亚乙基-1,3-环己二烯的骨架。另一方面，已表明苯乙炔通过外部C≡C共价连接到Si(111)-7×7上，形成类似苯乙烯的共轭体系。这些实验结果与密度泛函理论计算结果一致。苯乙烯和苯乙炔不同的结合机制清楚地表明，多功能有机分子的反应通道强烈依赖于官能团的化学和物理性质。所得的π电子共轭结构可能用作进一步有机合成以及在半导体表面制备多层有机膜的中间体。
