Determination of the electronic structure of oligo(2-thienyl ketones) and extrapolation to poly(thienylene ketone)

Gas-phase ionization and attachment energy (IE and AE) values of the first few oligomers of 2-thienyl ketone have been determined experimentally. The assignments of the ultraviolet photoelectron spectra agree with the results of theoretical HF/6-31G** calculations. The constant value of the HOMO ene rgy allows extrapolation to the corresponding polymer. A combined analysis of the AE values, the electrochemical reduction data, and the results of ab initio 6-31G** and semiempirical calculations allows one to obtain the LUM O energy for-the oligomers and for an ideal gas-phase poly(thienylene keton e). The narrow valence band and the high LE value of the polymer are not pr opitious to p-doping. On the other hand,the high electron affinity of the o ligomers and the polymer, the reversibility of the oligomer electrochemical reduction, and the large conduction band of the polymer indicate that the oligomers, and likely the polymer, could give rise to n-doped materials hav ing high electrical conductivity.