Synthesis and properties of coil-shaped 2,3-thienylene-ethynylene oligomers

A series of 2,3-thienylene-ethynylene oligomers have been synthesized by repeated application of the Pd-catalyzed coupling reaction of terminal alkynes and thienyl iodides as the key building steps. The analytical GPC molecular weights, much deflated relative to the actual molecular weights, strongly suggest a coil shape for the conformation of the oligomers in solution. Their electronic absorption and emission spectral features are discussed.