The title polymers, prepared by an electrochemical oxidation of the corresponding 1,3-dithiole derivatives with low oxidation potentials, exhibit high conductivities by doping.
通过电化学氧化低氧化势的相应1,3-二硫杂环戊二烯衍生物
Preparation and properties of novel polythiophenes containing 1,3-dithiol-2-ylidene moieties
4-(1,3-Dithiol-2-ylidene)-4H-cyclopenta[2,1-b;3,4-b']dithiophenes 1 and 7-(1,3-dithiol-2-ylidene)-7H-cyclopenta[l,2-b;4,3-b'] dithiophenes 2 were prepared by Wittig-Horner or Wittig reactions. The X-ray structural analyses of the parent compounds 1a and 2a reveal that both molecules have planar structures with short intermolecular S...S contacts, and 2a additionally has short intramolecular S...S contacts. They have low oxidation potentials and absorptions in a long wavelength region due to the 1,3-dithiole skeleton. Electrochemical oxidation of 1 and 2 afforded the corresponding polymers 3 and 4, which have low oxidation potentials. Electrochemically dedoped films of 3 and 4 have interband absorptions at 610-690 nn and 420-590 nm, respectively, in their electronic spectre. Some films of 3 and 4 exhibited high electrical conductivities with doping, for instance, 3c.(PF6-)(x) 33 S cm(-1) and 3e.(BF4-)(x), 52 S cm(-1). Derivatives 3f-h, containing linear alkyl chains, were synthesized in order to enhance solubilities in organic solvents and were found to be somewhat soluble in THF and chloroform. Dedoped 3g showed broad peaks in the H-1 NMR spectrum, assigned to the alkyl protons. MNDO-PM3 calculations showed that the torsion angles between the neighbor monomer fragments in the dimers and trimers of 1a and 2a are about 30 degrees. However, the oligomers derived from 1a have more extended conjugated systems than those from 2a, which was indicated by INDO/1 calculations.