Sequence-independent synthesis of π-conjugated arylenevinylene oligomers using bifunctional thiophene monomers

Sequence-independent or "click" chemistry is applied for the preparation of a series of novel and structurally similar π-conjugated oligomers. The new oligomers are prepared using Wittig-Horner chemistry from bifunctional building blocks that can be interconnected to one another at any desired sequence. The bifunctional building blocks consist of aromatic skeletons with acetal protected aldehyde groups on one side and a phosphonic acid diethyl ester group para to the aldehyde functionality. The first step in the arylenevinylene formation is a Wittig-Horner coupling of a functionalized aldehyde with the methyl phosphonate ester ylide of a bifunctional monomer. A stepwise protection-deprotection process is applied for the preparation of structurally similar π-conjugated oligo-phenylene vinylenes. New di-, tri-, penta-, and hepta-phenylenevinylenes are prepared and characterized. Selected penta-arylenevinylenes are incorporated as the semiconductor channel in organic field-effect transistors.