Scanning Tunneling Microscopy Studies of Self-assembly and Intramolecular Charge Localizaton
This talk will focus on two projects. The first project involves large mixed-valence iron-based organometallic molecules that were studied on gold surfaces using low temperature ultra-high-vacuum scanning tunneling microscopy (STM). Oxidation of these molecules results in mixed-valence complexes with an asymmetric distribution of electron density. STM was used to image the electronic properties of individual molecules and it was found that the details of a molecule's internal structure determined whether the charge distribution was symmetric or asymmetric when placed on a metal surface in the absence of bulk solvent. Further investigation of mixed-valence dinuclear organometallic molecules with asymmetric electron state density may open up the possibility for their use in molecularly based electronic devices.
The second part of the talk will focus on hydrogen-bonded networks of ferrocenecarboxylic acid that form both dimers and five-membered rings (pentamers) on a gold surface with longer-range quasicrystalline ordering. Five-membered rings are stabilized by C--HO hydrogen bonding and the combination of dimers and pentamers on the surface allow for two-dimensional self-assembled quasicrystalline ordering with five-fold symmetry. This is the first example of two-dimensional quasicrystalline ordering of a small self-assembling molecule.