| This thesis discusses five sections, spanning two fields, all linked intellectually. Functional organic molecules are proposed, synthesized and their supramolecular structure is elucidated and electronic properties are studied.;Part I. Foldamers. A general method is developed to synthesize a new class of folded oligomers from crowded aromatics. Unlike most foldamers, each subunit of these oligomers is highly substituted and functional. Moreover, this new folded motif, formed through a synergy between hydrogen bonds and pi-stacking, is so robust that even dimers have secondary structures in solution. Results from dimers and a trimer indicate that rigidifying linkers and unhindered side chains are the two critical ingredients to produce a stable columnar secondary structure from these oligomers.;A hexamer from crowded aromatics, due to its longer dimension, is desired for biological applications. Such a hexamer is synthesized and has shown to fold into secondary structure in dichloromethane by site-selective fluorescence spectroscopy. In dichloromethane, unfolding of the hexamer occurs upon heating or addition of methanol. Titration experiments indicate a cooperative folding of the hexamer in dichloromethane. The free energy difference between the folded and the unfolded states is estimated to be --2.0 kcal mol -1.;Part II. Acenes. This section involves acenes, functionalized for desired electronic properties and other applications.;A stable pentacene derivative containing long ether chains is prepared in 6 steps. It can be simply drop-cast onto silicon wafers to make organic field-effect transistors (OFETs). A top-contact single-wire device shows a field-effect mobility of 1.4 x 10-2 cm2 V-1 s-1 and an on/off current ratio of 3 x 103. Bottom-contact devices have repeatable photoresponse. The crystal structure of this derivative shows a co-facial packing and the charge carrier transport is likely through the alkynyl bonds sandwiched between aromatic rings.;2,3,9,10-Tetrakis(trifluoromethyl)pentacene is synthesized in 11 steps. This compound is soluble in a variety of solvents and relatively stable in solution. It adopts co-facial stacking in single crystals.;A facile route to tetracene derivatives with 2,3-dicarbonyl substituents is put forth. N-Phenyl-2,3-tetracenedicarboximide is prepared by condensation of anthracene-2,3-dialdehyde and N-phenylmaleimide. Functional group transformations and simple purifications give the tetracene bisamide, diacid, anhydride, dicarboximide and alkyl dicarboximide. These compounds, bearing both a tetracene moiety and functional groups, may be useful in OFETs, chiral fluorescent labeling or molecular recognition. |
