Department of Physics; Institute of Computational and Theoretical Studies
We present a comparative study, combining density functional theory with scanning tunneling microscopy/spectroscopy, of two aromatic molecules bonded with a variable number of Cu adatom(s) on a Cu(111) surface. The two molecules, 1,3,5-tris(pyridyl)benzene (TPyB) and 1,3,5-tris(4-radical-phenyl)benzene (TPB), possess the same aromatic backbone but bond weakly versus strongly to Cu with different terminal groups, respectively. We find that TPyB and TPB exhibit, respectively, small versus large charge transfers between the surface and the molecule; this contrast results in opposite shifts in the calculated density of states distributions and thus explains the opposite STS peak shifts observed in our experiments. The two molecules exhibit weak donor versus strong acceptor characters. This work provides a fundamental understanding, on a single-molecule level, of the principle that selecting specific functional groups can effectively and intentionally modify the molecular electronic properties in a wider class of molecule–metal interfaces.
Source Publication Title
American Chemical Society
Copyright © 2016 American Chemical Society
This work is supported in part by project no. 9041650 of the Research Grants Council of Hong Kong. M.A.V.H. and Y.L.Z. were supported in part by the HKBU Strategic Development Fund. We thank Prof. Klaus Hermann for very fruitful discussions. We acknowledge the National Supercomputing Center in Shenzhen and the High Performance Cluster Computing Centre in Hong Kong Baptist University, which receives funding from the RGC and UGC of Hong Kong and Hong Kong Baptist University, for providing the computational resources.
Link to Publisher's Edition
Zhao, Yan-Ling, Weihua Wang, Fei Qi, Jian-Fu Li, Guowen Kuang, Rui-Qin Zhang, Nian Lin, and Michel A. Van Hove. "Donor/acceptor properties of aromatic molecules in complex metal–molecule interfaces." Langmuir 33.2 (2017): 451-458.