Nanocars: Towards photoactive, directionally-controlled surface rolling molecules
Guerrero, Jason Matthew
Tour, James M.
Doctor of Philosophy
Described in this thesis are efforts to advance our understanding of single molecule machines through the synthesis and study of an array of nanovehicles. In the first chapter, nanoscale transport is explored through the synthesis and solution-based studies of a photoactive, metal-ion-chelating nanocar. Utilizing an appended photoactive dipyridylethylene moiety as a metal chelating unit, it is expected that this molecule, upon photoirradiation, will form a strong bidentate ligand for carrying metal ions along surfaces. Following this, in the second chapter, directional control and propulsion are explored through the synthesis of motorized nanocars. Studies towards a dual-motored nanocar as well as the synthesis of an ultra-fast motorized nanocar are described. The third chapter covers our efforts to complement previous STM studies, where single molecule fluorescence spectroscopy is used for imaging and mechanistic elucidation of translational movement of fluorescently-tagged nanovehicles. The synthetic routes towards these molecules are covered, as well. In chapters 4 and 5, various nanovehicles are synthesized using contrasting approaches. In chapter 4, self-assembly methods mirroring those used in biological construction are used to produce nanocars and nanotrains. Moieties of 2-pyridones and terpyridyl groups were used for self-assembling via hydrogen bonding and metal complex formation, respectively. Traditional organic synthesis is used to build carborane-wheeled nanovehicles in chapter 5. These molecules are expected to move in predetermined patterns on atomically smooth surfaces, depending on their specific configuration of axles and wheels. Finally, in chapter 6, nanocomponentry is explored through the synthesis and studies of molecular devices such as azobenzene-fullerene switches and fullerene-oligo(phenylene ethynylene) molecular wires. The presence of fullerenes and oligo(phenylene ethynylene)s (OPEs) in azobenzene derivatives was found to have a large effect on the photoisomerization behavior of the molecules. Lastly, a series of fullerene-terminated oligo(phenylene ethynylene) (OPEs) molecular wires have been synthesized as potential molecular electronic devices. Electronic properties such as the energy levels and the distribution of HOMOs and LUMOs of fullerene-terminated OPEs have been calculated using ab initio method at the B3LYP/6-31G(d) level.
Molecular chemistry; Chemistry; Organic