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Krishnamurthy, Vidya

Chemistry

2006

MS

Organic semiconductor materials are part of a rapidly growing field, with applications in field-effect (FET) and thin film transistors (TFT) in particular. Organic FETs are similar to silicon-based TFT transistors which contain amorphous silicon as the semiconductor material. Currently the most developed and studied organic FETs are based on pentacene. Pentacene crystallizes with the herringbone packing motif in the solid state. Pentacene precursors with alkoxy substituents (R = OCH₃, O(CH₂)₅CH₃) in the 2,3,9,10 positions will be synthesized, since these substituents do not disturb the herringbone solid-state packing motif of pentacene. Increasing the length of the alkoxy substituent improved the solubility of the pentacene derivative in common organic solvents. These alkoxy substituted pentacene precursors can be synthesized by successive Cava reactions between dialkoxy substituted bis(bromomethyl) benzene derivatives andp-benzoquinone, and dialkoxy substituted 1,4-anthraquinone. Geometrically well-defined or "shape-persistent" macrocyclic skeletons have a welldefined interior separated from a non-collapsible exterior. Several application oriented findings, include self-aggregation into columnar stacks, formation of ordered monolayers, and usage as rigid and orientation-mediating scaffolds. Tribenzocyclynes with anhydride units attached will be synthesized, so that the macrocycle unit can be extended to from cross-linked chains. These cycles can serve as building blocks, and may be used as rigid scaffolds to hold metals at defined distance. They also have an inherent ability to form diverse macromolecular structures.