Angove Eloise, Grillo Federico, Früchtl Herbert A, Veinot Alex J, Singh Ishwar, Horton J Hugh, Crudden Cathleen M, Baddeley Christopher J
EaStCHEM School of Chemistry, University of St. Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom.
Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario Canada, K7L 3N6.
J Phys Chem Lett. 2022 Mar 3;13(8):2051-2056. doi: 10.1021/acs.jpclett.1c04073. Epub 2022 Feb 24.
The benzannulated N-heterocyclic carbene, 1,3-dibenzylbenzimidazolylidene (NHC) forms large, highly ordered domains when adsorbed on Cu(111) under ultrahigh vacuum conditions. A combination of scanning tunnelling microscopy (STM), high-resolution electron energy loss spectroscopy (HREELS), and density functional theory (DFT) calculations reveals that the overlayer consists of vertical benzannulated NHC moieties coordinating to Cu adatoms. Long-range order results from the placement of the two benzyl substituents on opposite sides of the benzimidazole moiety, with their aromatic rings approximately parallel to the surface. The organization of three surface-bound benzyl substituents from three different NHCs into a triangular array controls the formation of a highly ordered Kagome-like surface lattice. By comparison with earlier studies of NHCs on Cu(111), we show that the binding geometry and self-assembly of NHC are influenced by intermolecular and adsorbate-substrate interactions and facilitated by the flexibility of the methylene linkage between the N-heterocycle and the aromatic wingtip substituents.
苯并稠合的N-杂环卡宾1,3-二苄基苯并咪唑亚基（NHC）在超高真空条件下吸附在Cu(111)上时会形成大的、高度有序的畴。扫描隧道显微镜（STM）、高分辨率电子能量损失谱（HREELS）和密度泛函理论（DFT）计算相结合表明，覆盖层由与铜吸附原子配位的垂直苯并稠合NHC部分组成。长程有序源于两个苄基取代基位于苯并咪唑部分的相对两侧，其芳环大致平行于表面。来自三个不同NHC的三个表面结合苄基取代基排列成三角形阵列，控制了高度有序的类 Kagome 表面晶格的形成。通过与早期关于NHC在Cu(111)上的研究比较，我们表明NHC的结合几何结构和自组装受分子间和吸附质 - 底物相互作用的影响，并由N-杂环与芳族翼尖取代基之间亚甲基连接的灵活性所促进。
