Date of Award
Doctor of Philosophy (PhD)
Hughes, Thomas S.
Polyaromatic hydrocarbons (PAH) are useful molecules for supramolecular assemblies and nanoscale electronics materials. Due to their high degree of symmetry and lack of heteroatoms characterization is fairly simple and calculated properties very closely match experimental values. By utilizing a controlled, stepwise synthesis, which enables the regioselective incorporation of solubilizing side chains and electron donating or withdrawing groups, we were able to access many novel PAHs of various shapes and sizes. Using an unprecedented asymmetric protected alcohol-benzyl bromide Collman coupling strategy we have accessed linear oligocyclopentadienones and oligophenylenes not accessible through current methodology. Monomers of these two classes were studied both spectroscopically and computationally in order to fully characterize their electronic structure and see how perturbation of the PAH scaffold affected their respective molecular orbitals. Using a harsher unsymmetrical carbonylative coupling of α,α'-dibromoxylene we were able to access the two previously unknown low molecular weight polymers: Poly(para-phenylene)(2-isocyano-2-tosylpropane-1,3-diyl) (PPIT), and Poly(paraphenylene)( 2-oxopropane-1,3-diyl) (PPOD). PPIT and PPOD were demonstrated to be possible precursors of high molecular weight polycyclopentadienones and polyphenylenes. Small macrocycles of these polymers were also produced through the same methodology at high dilution. Conversion of the polymers and oligomers to linear and cyclic polycyclopentadienones and polyphenylenes has been demonstrated in two prototypic examples. While universal methodology for larger oligomers and polymers is still under study, we believe the ultimate goal of discrete isomer carbon nanotubes and linear graphite to be possible due in part by the work reported in this thesis.
Potter, Robert G., "Synthesis and Study of Linear and Cyclic Polycyclopentadienones and Polypheylenes" (2008). Graduate College Dissertations and Theses. 184.