Theoretical study on the CH⋯NC hydrogen bond interaction in thiophene-based molecules

Results on a detailed investigation of the CH⋯NC hydrogen bond interaction in functional thiophene-based molecules are presented by employing quantum-mechanical ab initio and DFT-based calculations. Dimers of 1-cyano-thiophene are studied to evaluate the influence of the computational method, of the chosen basis set and of substitution in 3-position on the structure and stability of the hydrogen bond. Furthermore, we focus on the intermolecular hydrogen bond in a chain of α,ω-dicyano-β,β′-dibutylquarterthiophene (DCNDBQT) molecule, which was found to be a promising organic semiconducting material for thin-film organic field-effect transistors. In particular, the intermolecular structure and the electronic properties of the material are determined employing the efficient SCC-DFTB method. We demonstrate the highly local character of the hydrogen and found that the weak CH⋯NC interaction links the molecules into extended ribbons perpendicular to the support.