| Chapter 1 describes the solution-phase syntheses and characterization of oligo(2-dodecylphenylene-ethynylene)s up to 128 A long. We have used a novel iterative divergent/convergent approach to rapidly synthesize the oligomers with controlled length and constitution. The molecular length doubles at each iteration. Once the key monomer was synthesized, only three sets of reaction conditions were needed to double the molecular length; namely, an iodination, a protodesilylation, and a Pd/Cu-catalyzed cross coupling. Four iterations provided the 128 A long 16-mer.; Chapter 2 describes the solid-phase syntheses and characterization of oligo(2-dodecylphenylene-ethynylene)s via an iterative divergent/convergent approach. Synthesized were the monomer, dimer, tetramer, octamer and 16-mer. Compared to the solution-phase synthetic route discussed in Chapter 1, the synthetic protocol is far easier to execute. The optical properties are presented which show the point of absorbance and emission saturation. The size exclusion chromatography values of the number average molecular weights, relative to polystyrene, illustrate the tremendous differences in the hydrodynamic volume of these rigid rod oligomers verses the random coils of polystyrene. These differences become quite apparent at the octamer stage.; Chapter 3 describes the syntheses and attachment of molecular alligator clips, thiol end groups protected as thioacetyl moieties, to potential molecular wires. These serve as binding sights for adhesion to gold surfaces. In some cases, one end of the oligomeric chains were capped with a thiol group so that the surface attachments to gold could be studied. In other cases, thiol groups were affixed to both ends of the molecular chains so that future conduction studies could be done between proximal metallic probes. These functionalized rigid rod conjugated oligomers have the potential to serve as molecular wires in molecular scale electronic devices. |
