Formation and nanoscale characterization of self-assembled molecular structures on Au(111) and Ag(111) surfaces

Abstract

The growing interests in nanomaterials stem from remarkable properties arising from reduced dimensionality. On-surface synthesis utilizes surface/nanoscale science techniques to design and make nanomaterials through a bottom-up approach. The overall research objective of the present thesis was to create and characterize different molecular nanostructures on surfaces, and to investigate the chemical phenomena involved in the process. This research reports the

formation of a variety of nanomaterials including self-assembled monolayers (SAMs) and surface- confined self-assembled molecular networks (SAMNs) on Au(111) and Ag(111).

The nanoscale formation of SAMs on Au(111)/mica was performed through solution chemistry methods to anchor thiol molecules to gold surface atoms. Three thiols with different alkyl chain and terminating functional group (carboxyl, trimethylammonium) were studied to form SAMs on Au(111)/mica. Investigated by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), the thiolated SAMs with the end group of a tertiary ammonium serve as a stable molecular scaffold. The thiolated SAM was further studied for the adsorption of a stable prototype organic radical, Tris(8-carboxyl-2,2,6,6-tetra(2-(1-hydroxyethyl))-benzo[1,2- d:4,5-d’]bis(dithiole-4-yl)methyl sodium salt, known as OX063, interacting with the carboxyl groups of OX063. Our findings can be used to create spin-based materials for future integration in devices. This will create the foundation for future determination of how the characteristic of spin sites might change depending on whether they are surrounded by other molecules in solutions, directly placed on the surface, or located with a distance to the surface. [...]