| Abstract
| - By copolymerization of 3-octylthiophene with thiophene containing aniline tetramer in the3-position we have prepared a hybrid copolymer, poly(3-octyl-2,5-thienylene-co-3-oligoaniline-2,5-thienylene), exhibiting very interesting spectroscopic and spectroelectrochemical properties. The UV−vis−NIR spectrum of this new hybrid copolymer, in addition to the band ascribed to the π−π* transition inthe poly(2,5-thienylene) chain, shows two bands at 330 nm and ca. 580 nm which can be attributed tothe transitions in the pendant oligoaniline groups, namely to the π−π* transition in the benzoid ringand to the excitonic-type transition between the HOMO orbital of the benzoid ring and the LUMO orbitalof the quinoid ring. Electrochemical activity of poly(3-octyl-2,5-thienylene-co-3-oligoaniline-2,5-thienylene)was tested in nonaqueous electrolytes combining cyclic voltammetry, UV−vis−NIR spectroelectrochemistry, and Raman spectroelectrochemistry. All techniques unequivocally show that both the oligoanilineside chains and the poly(2,5-thienylene) main chain can be electrochemically doped. The doping startsby the oxidation of aniline tetramer substituents and is followed by the oxidation of the poly(2,5-thienylene)main chain. Because of strong resonance effect Raman spectroelectrochemistry turned out to be a veryselective probe of the polymer doping. The blue excitation line probes selectively the vibrations originatingfrom undoped segments of the poly(2,5-thienylene) main chain whereas the red one probes only theundoped and doped oligoaniline substituents. The infrared excitation line enhances resonantly signalsdue to vibration of the doped parts of the polymer and reveals the sequence of doping. Protonation ofpending oligoaniline groups with diphenyl phosphate lowers the potential of the onset of the doping asrevealed by cyclic voltammetry and UV−vis−NIR spectroelectrochemistry.
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