 The orbital energies of phosphole containing conjugated systems can be tuned through synthetic modification at the phosphorous center, such as oxidation. Existing synthetic methods for 1,2,5-triphenylphosphole require refluxing at elevated temperature (>170�C) for a prolonged time, resulting in decomposition of the phosphole product to form large amounts of oligomeric byproduct. Using microwave heating, phosphole oligomers with phenyl, p-methoxyphenyl, p-fluorophenyl, or thienyl groups were prepared. This method shortens reaction times and lowers the amount of oligomeric byproduct formation. The prepared phosphole containing oligomers were modified at the phosphorous center to provide the corresponding sulfides and oxides. The oxidized phospholes substituted with thienyl groups can be polymerized electrochemically to yield the corresponding conjugated polymer. When the aryl group of the butadiene is phenyl or thienyl, electrochemical data shows either stabilization or a destabilization of the HOMO after annulation to form the phosphole, respectively. After oxidation of the phosphorous center of the phosphole, we observe a stabilization of the LUMO and destabilization of the HOMO. New phosphole oligomers can be tailored based on these electrochemical properties, along with an optimized synthetic procedure for each step of the preparation.

Microwave assisted synthesis and electrochemical characterization of phosphole containing conjugated oligomers

248th National Meeting (2014)

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