THIOPHENE OLIGOMERS AS POLYTHIOPHENE MODELS .2. ELECTROCHEMISTRY AND INSITU ESR OF END-CAPPED OLIGOTHIENYLS IN THE SOLID-STATE - EVIDENCE FOR PI-DIMERIZATION OF HEXAMERIC POLARONS IN POLYTHIOPHENE
G. Zotti et al., THIOPHENE OLIGOMERS AS POLYTHIOPHENE MODELS .2. ELECTROCHEMISTRY AND INSITU ESR OF END-CAPPED OLIGOTHIENYLS IN THE SOLID-STATE - EVIDENCE FOR PI-DIMERIZATION OF HEXAMERIC POLARONS IN POLYTHIOPHENE, Chemistry of materials, 5(5), 1993, pp. 620-624
Thin films of thiophene oligomers (n = 4, 6, 8, and 10) methyl-protect
ed toward anodic coupling at the terminal alpha positions were investi
gated by cyclic voltammetry and in situ ESR in acetonitrile. Reversibl
e oxidation goes from a single one-electron step (tetramer) to a singl
e two-electron step (octamer and decamer) through two separate one-ele
ctron steps (hexamer). ESR indicates strong magnetic dimerization for
the one-electron-oxidized hexamer. The close resemblance of the electr
ochemical and ESR behavior of the hexamer with that of polythiophene s
uggests that oxidation of the latter occurs via hexameric spin-dimeriz
ed polarons. The hexameric model is discussed taking account of the ol
igomeric nature of polythiophene.