1 Department of Physics and Astronomy, Science and Technology, Aarhus University2 unknown3 Department of Physics and Astronomy, Science and Technology, Aarhus University
Scanning tunneling microscopy (STM) data are reported for the room-temperature adsorption of 2,2,2-trifluoroacetophenone (TFAP), 2,2,2-trifluorovinylbenzene (TFVB), octafluoroacetophenone (OFAP), and methyl benzoate (MB) on Pt(111). The objective of the study is to establish the role of aryl−CH···O bonding in forming self-assembled low-nuclearity structures at room temperature and to compare aryl−CH···O bonding by ester and ketone carbonyl functions. The STM images clearly evidence the formation of homochiral dimers and trimers of TFAP, and density functional theory (DFT) calculations reveal aryl−CH···O bonding as the driving force for dimer formation. In contrast to TFAP, chemisorbed TFVB and OFAP do not form such self-assembled structures as they lack carbonyl and aryl−CH groups, respectively. The self-assembly of MB on Pt(111) differs from that of TFAP, in that it can form structures stabilized by one, as distinct from two, aryl−CH···O bonds. The results are discussed with respect to the enantioselective hydrogenation of α-ketoesters on cinchona modified Pt catalysts.
Journal of Physical Chemistry Part C: Nanomaterials and Interfaces, 2010, Vol 115, Issue 4