FT-Raman spectroscopic study, aided by quantum chemical DFT calculations, of a series of oligothiophenes end-capped by nitriles

We report on the FT-Raman spectroscopic characterization, aided by DFT model chemistry calculations, of a bunch of α,ω-dicyano end-capped oligothiophenes, ranging in length from the dimer to the hexamer, which have been previously shown to display quite promissing amphoteric redox properties for their potential use in new technological applications. The attention is mainly focused to the role played by the CN⋯H hydrogen bonding interactions between adjacent molecules on various molecular properties, such as the minimum-energy geometry, atomic charges equilibrium distribution,topologies/energies of the frontier molecular orbitals and the Raman scattering spectral profile. To this end we have performed to two sets of quantum chemical calculations, at the DFT//B3LYP/3-21G* level, on: (a) a single terthiophene in the vacuum and (b) a suited dimeric model with a fully coplanar array of the two terthienyl segments interacting through the cyano end-caps.