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A novel method for the synthesis of soluble oligo(3-ethyl-2,5-thiophene ethylene)s was developed based on a rapid iterative divergent/convergent strategy that utilizes 3-ethyl-2-(trimethylsilylethynyl)thiophene. The synthetic strategy involved the iterative divergent/convergent process that doubles the framework after each stage of iteration. Furthermore, the synthetic strategy was characterized by iodination, protodesylation and Pd/Cu-catalyzed cross coupling reactions.

The synthetic organic phase of a project targetted toward the construction of molecular scale electronic devices is presented. A synthetic process for orthogonally fused conjugated organic oligomers is described. The final systems will have a potentially conducting chain fused perpendicularly to a second potentially conducting chain via a sigma bonded network. One of the core segments synthesized is based on a spirobithiophene moiety with a central silicon atom. The second core is a 9,9'-spirofluorene system.

Spectroscopical studies of the formation of self-assembled monolayers (SAMs) and multilayers on gold surfaces of oligomers that have thiol, alpha, omega-dithiol, thioacetyl or alpha, omega-dithioacetyl end groups shows that these monolayers help in the designing of molecular wires useful in bridging proximate gold surfaces. The deacylation of thioacetyl groups using NH4OH led to the formation of SAMs without isolating unstable free thiols. Rigid-rod conjugated molecules with a thiol terminus can form SAMs with high density packing.

We report studies on the modifications induced by the evaporation of copper overlayers on a self-assembled monolayer (SAM) of the oligo(phenylene-ethynyl) dithiol, 1-thio-4-[4'-[(4'-thio)phenylethynyl]-1'-ethynyl]-benzene (TTPEB). These SAMs were characterized after deposition from a tetrahydrofuran solution on polycrystalline gold substrates and after copper evaporation and its subsequent removal by nitric acid. Monolayers were studied via cyclic voltammetry (CV), UV-vis multiwavelength ellipsometry, external reflectance infrared (IR) spectroscopy, and ion scattering spectroscopy (ISS). The results obtained indicate that TTPEB SAMs display the same packing characteristics before and after copper evaporation and removal. However, as shown by IR spectroscopy, the monolayers undergo a reorganization process that involves an increase in tilt angle accompanied by rotation of aromatic rings that results in a decrease in the average molecular twist angle. ISS data suggest that copper diffuses through the monolayer after copper evaporation, a result that is significant for applications of this molecule in molecular electronic devices.