【作者】 范其瑭； 代景亚； 王涛； J.Michael Gottfried； 朱俊发；

【Author】 Qitang Fan;Jingya Dai;Tao Wang;J.Michael Gottfried;Junfa Zhu;National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China;Fachbereich Chemie, Philipps-Universit?t Marburg;

【机构】 中国科学技术大学国家同步辐射实验室与苏州纳米技术协同创新中心； Fachbereich Chemie,Philipps-Universit?t Marburg；

【摘要】 外部刺激诱导的超分子系统结构相变在分子存储器件开发领域有巨大潜在应用价值。在此研究中,我们利用超高真空扫描隧道显微镜(UHV-STM)在Cu(111)与Ag(111)表面直接观察到4,4’’-二溴间三联苯(DMTP)分子从卤键结构转化为DMTP-Cu/Ag混合结构的相变过程;并进一步利用X射线光电子能谱(XPS)以及密度泛函理论计算(DFT)研究了此过程发生的机理。表面上形成的两种结构都含有完整的DMTP分子;它们分别通过Br…Br键和Br…H氢键结合Br…Cu弱配位键进行自我稳固。DMTP-Cu/Ag混合结构含有间隔排列的DMTP分子与Cu/Ag吸附原子;如果将此混合结构退火至更高温度,金属吸附原子将会高效的催化C-Br键的裂解。因此,我们认为这种特殊的DMTP-Cu/Ag混合结构是启动表面乌尔曼反应的直接前驱态。这为理解表面乌尔曼反应的机理提供了重要参考。更多还原

【Abstract】 The structural transformation of supramolecular system triggered by external stimuli, maintains great potential application in fabrication of molecular storage devices. Here, using combined ultrahigh vacuum scanning tunneling microscopy(UHV-STM), X-ray photoemission spectroscopy(XPS) and density functional theory(DFT) calculation, we directly observed the surface adatom induced structural transformation of 4,4’’-dibromo-m-terphenyl(DMTP) molecules from halogen bonded networks to DMTP-Cu/Ag mixed structure on both Cu(111) and Ag(111) surface. Both of the two structures contain intact DMTP molecules and are stabilized by triple Br…Br bonds and Br…H hydrogen together with an unprecedented weak Br…Cu coordination bonds, respectively. The DMTP-Cu/Ag mixed structures contain alternatively arranged DMTP molecules and Cu/Ag adatoms, which thus can effectively induce the scission of C-Br bonds if were annealed to higher temperatures. This unique DMTP-Cu/Ag mixed structure has been demonstrate to be an important precursor phase ready for the initiation of surface Ullmann reaction.更多还原