Infrared spectra of two sexithiophenes in neutral and doped states: a theoretical and spectroscopic study

The FT-infrared spectra of two sexithiophenes having their end alpha,alpha'-positions substituted by it-hexyl or -thiohexyl groups, in neutral and doped states, are studied with the main aim of deriving information about the pi-electrons delocalization and about the electronic structure of the charged defects created upon doping with iodine. The analysis of the experimental data is aided by Density Functional Theory calculations. The modifications in the electronic structure of the sexithiophene backbone induced by the n-thiohexyl encapsulation are discussed from the point of view of single molecule interactions in thiol-terminated pi-conjugated oligomers bound to metallic or cluster electrodes. (C) 2002 Elsevier Science B.V. All rights reserved.