Galeotti G, Ebrahimi M, Lipton-Duffin J, MacLeod J M, Rondeau-Gagné S, Morin J-F, Rosei F
Centre Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, QC J3X 1S2, Canada.
Phys Chem Chem Phys. 2017 Apr 19;19(16):10602-10610. doi: 10.1039/c7cp01058c.
The two-dimensional (2D) surface-directed self-assembly of dibenzonitrile diacetylene (DBDA) on Ag(111) under ultrahigh vacuum (UHV) conditions was investigated by combining scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and theoretical simulations based on density functional theory (DFT) calculations. The molecule consists of two benzonitrile groups (-CH-C[triple bond, length as m-dash]N) on each side of a diacetylene (-C[triple bond, length as m-dash]C-C[triple bond, length as m-dash]C-) backbone. The terminating nitrile (-C[triple bond, length as m-dash]N) groups at the meta position of the phenyl rings lead to cis and trans stereoisomers. The trans isomer is prochiral and can adsorb in the R or S configuration, leading to the formation of enantiomeric self-assembled networks on the surface. We identify two simultaneously present supramolecular networks, termed parallel and chevron phases, as well as a less frequently observed butterfly phase. These networks are formed from pure R (or S) domains, racemic mixtures (RS), and cis isomers, respectively. Our complementary data illustrates that the formation of the 2D supramolecular networks is driven by intermolecular hydrogen bonding between nitrile and phenyl groups (-C[triple bond, length as m-dash]NH-CH). This study illustrates that the molecular arrangement of each network depends on the geometry of the isomers. The orientation of the nitrile group controls the formation of the most energetically stable network via intermolecular hydrogen bonding.
通过结合扫描隧道显微镜（STM）、X射线光电子能谱（XPS）以及基于密度泛函理论（DFT）计算的理论模拟，研究了二苯甲腈二乙炔（DBDA）在超高真空（UHV）条件下于Ag(111)表面的二维（2D）表面定向自组装。该分子在二乙炔（-C≡C-C≡C-）主链的每一侧由两个苯甲腈基团（-CH-C≡N）组成。苯环间位的末端腈基（-C≡N）导致顺式和反式立体异构体。反式异构体是前手性的，可以以R或S构型吸附，从而在表面形成对映体自组装网络。我们识别出两种同时存在的超分子网络，称为平行相和人字形相，以及一种较少观察到的蝶形相。这些网络分别由纯R（或S）域、外消旋混合物（RS）和顺式异构体形成。我们的补充数据表明，二维超分子网络的形成是由腈基和苯基之间的分子间氢键（-C≡NH-CH）驱动的。这项研究表明，每个网络的分子排列取决于异构体的几何形状。腈基的取向通过分子间氢键控制能量最稳定的网络的形成。
