New Synthetic Methodologies for the Development of Novel Nanoscale Electronic/Energy Materials

Two dominant themes in the synthesis of molecules for efficient, thin-layer organic devices are the ability to control their HOMO-LUMO gap and to achieve superior charge mobilities. Two synthetic methodologies have been devised to promote these desirable properties. First, a cascade cyclization route to fused aromatic systems has been designed. Molecules synthesized via this route can exhibit extended conjugation and efficient, intermolecular orbital overlap. These properties result in decreased HOMO-LUMO gaps and enhanced charge mobility within the bulk material and at metal contacts. The second focuses on the discovery and use of terminal alkyne functional groups capable to promote strong electronic coupling between molecules and metals.;The first approach explores efficient chemistry for cascading cyclization to produce fused, polycyclic aromatic structures. A synthetic methodology was developed for the production of poly-cyano precursor molecules capable of undergoing acid-mediated cyclization to form fused aromatic systems. Polymerization of polycyclic aromatic molecules was complicated by the competition between formation of linear and cyclic oligomers. Subsequently, a route to ketene-imine derivatives of poly-cyano precursors was explored to facilitate cascading cyclization under mild conditions.;The second approach investigated terminal alkynes as functional groups designed to provide strong metal-molecule electronic coupling. Terminal alkynes form self-assembled monolayers on planar gold substrates and stabilize nanoparticles as the sole ligand via direct synthesis. Terminal alkynes exhibit a low interfacial dipole moment with both sigma and pi type bonding which should enhance the molecule-metal electronic coupling. Solution-based UV/vis studies have demonstrated similar chemical stability of the alkyne ligand compared to the well-studied thiol ligand.