Urgel José I, Di Giovannantonio Marco, Segawa Yasutomo, Ruffieux Pascal, Scott Lawrence T, Pignedoli Carlo A, Itami Kenichiro, Fasel Roman
Empa, Swiss Federal Laboratories for Materials Science and Technology , 8600 Dübendorf , Switzerland.
Merkert Chemistry Center , Boston College , Chestnut Hill , Massachusetts 02467-3860 , United States.
J Am Chem Soc. 2019 Aug 21;141(33):13158-13164. doi: 10.1021/jacs.9b05501. Epub 2019 Aug 5.
We report the investigation of a conjugated polycyclic hydrocarbon containing multiple nonbenzenoid rings and exhibiting negative curvature-the warped nanographene CH-adsorbed on several noble metal surfaces in an ultrahigh vacuum environment. From a detailed analysis of the molecular self-assembly at different molecular coverages via scanning tunneling microscopy and spectroscopy measurements in combination with theoretical modeling, the nature of the intermolecular interactions is unraveled. For high molecular coverages on Cu(111), the formation of homochiral porous networks is observed, which is rationalized by (i) intermolecular π-π interactions between neighboring CH molecules that promote the formation of molecular dimers and (ii) enantioselective intermolecular CH···π interactions between the dimers. Such interactions are also observed after deposition of CH molecules on Au(111) and Ag(111) substrates. Our results provide perspectives for the on-surface study of negatively curved nanographenes which open new avenues to the design of novel and functional chiral structures with potential use in the field of organic optoelectronics.
我们报告了对一种含有多个非苯环且呈现负曲率的共轭多环烃——翘曲纳米石墨烯CH在超高真空环境中吸附在几种贵金属表面的研究。通过扫描隧道显微镜和光谱测量，并结合理论建模，对不同分子覆盖度下的分子自组装进行了详细分析，从而揭示了分子间相互作用的本质。对于在Cu(111)上的高分子覆盖度，观察到了同手性多孔网络的形成，这可以通过以下方式来解释：(i)相邻CH分子之间的分子间π-π相互作用促进了分子二聚体的形成；(ii)二聚体之间的对映选择性分子间CH···π相互作用。在CH分子沉积在Au(111)和Ag(111)衬底上后也观察到了这种相互作用。我们的结果为负曲率纳米石墨烯的表面研究提供了前景，这为设计新型功能性手性结构开辟了新途径，这些结构在有机光电子领域具有潜在应用。
