Synthesis and characterization of molecular materials derived from dendrimers, [60]fullerene, and linear π-conjugated oligomers

Mahmud, Ilias (2009) Synthesis and characterization of molecular materials derived from dendrimers, [60]fullerene, and linear π-conjugated oligomers. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

This thesis reports the studies of a series of novel π-conjugated organic hybrid materials undertaken throughout my PhD research. In the synthetic work, the Cu(I)-catalyzed azide-alkyne [3+2] cycloaddition, one of the most popular click reactions, has been successfully utilized to covalently attach a series of azido-pendant Frechet-type dendrimers to various alkynylated π-conjugated building-blocks, ranging from [60]fullerene, porphyrin, tetrathiafulvalene (TTF) analogues, and linear/star-shaped conjugated phenylene ethynylene oligomers (OPEs), in a modular fashion. The resulting hybrid macromolecules show rich photophysical, electrochemical, and surface morphological properties, which are potentially useful for the application in molecular optoelectronic devices. The most remarkable finding resulting from the "click synthesis" comes from a class of dendro[60]fullerenes, which show interesting surface self-assembly behavior to form controllable nanostructures. The correlation between aggregation behavior and molecular parameters has been examined, and the results indicate that the surface self-assembling properties of these dendro[60]fullerenes are dependent on dendron generation, the nature of the end-groups, and acidity. Moreover, a class of electron-rich polyynes has been synthesized, in which redox active 1,3-dithiole and ferrocenyl end groups are incorporated into the polyynes. Potential of these polyyne-TTF hybrids in making electrochemically active conducting polymer materials has been explored based on voltammetric and spectroscopic characterization. Finally, the thesis work has developed the synthesis of a series of poly(ethylene glycol) (PEG) functionalized conjugated arylene polymers as well as a group of imidazolium-based ionic liquids. These materials are specially designed for functionalization of single-walled carbon nanotubes (SWNTs) through non-covalent and covalent approaches.

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