DeBoef, Brenton [faculty advisor, Department of Chemistry]
Polythiophenes, oxidative coupling
Polythiophenes are polymerization products (also known as polymers) of thiophenes (which are sulfur heterocycles). Polythiophenes become conducting as a result of electron interactions in the conjugated pi-orbitals (of the double bonds) via doping (intentionally adding elemental impurities).This semiconductor-type property of Polythiophenes makes them of special interest to material-science-type applications. They have been dubbed as “synthetic metals”. (www.wikipedia.com) The optical properties of Polythiophenes respond to environment stimuli such as changes in solvent, temperature and applied potential with prominent color shifts. These changes make Polythiophenes attractive sensors. They are also used in the LED display and semiconductor fields. The aim of this project is to device and document the possibility of a more cost efficient and environment friendly method of dimerization of thiophene for polythiophene synthesis- oxidative coupling. Optimal reaction conditions will be determined for the oxidative coupling. It will be tried to replace HMPV (the traditional catalyst) with a more chemically benign catalyst. In comparison to the Suzuki Reaction or the Grignard Metathesis, which are the most common methods of polythiophene synthesis present today, oxidative coupling produces hydrogen peroxide which decomposes to hydrogen and oxygen as chemical waste. As a result, oxidative coupling is environmentally friendly, and the non-toxic waste is cheaper to dispose of. In reactions involving the formation of a carbon-carbon bond between two organic molecules, the carbons in question have to be activated by a functional group (halides being a common functional group used to do this) to an intermediate product before being used in the final reaction. This creates unnecessary chemical waste and extra cost. In essence, this project proposes to eliminate the intermediate ‘middle man’ by studying the possibility of oxidative coupling of carbons. The DeBoef group at URI have been successful in devising such reactions; the results of these reactions have not yet been published.