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

Results on a detailed investigation of the CH center dot center dot center dot NC hydrogen bond interaction in functional thiophene-based molecules are presented by employing quantum-mechanical ab initio and OFT-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 alpha,omega-dicyano-beta,beta'-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 center dot center dot center dot NC interaction links the molecules into extended ribbons perpendicular to the support. (C) 2012 Elsevier B.V. All rights reserved.