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