Phenyl- and Thienyl-Ended Symmetric Azomethines and Azines as Model Compounds for n-Channel Organic Field-Effect Transistors: An Electrochemical and Computational Study

The formation energy and stability of radical anions in a series of 12 phenyl- and 2-thienyl-ended linear, symmetric azomethines and azines were investigated by cyclic voltammetry. Replacing 1,4-phenylene with 2,5-thienylene cores and substitution with cyano or methyl moieties have allowed the lowering of lowest unoccupied molecular orbital energy levels even by 1 eV. Methyl capping stabilizes electron carriers (radical anions) toward dimerization, and the mechanism of such radical anion dimerization has been clarified by cyclic voltammetric kinetic analysis. The results have been compared with optical parameters and supported by density functional theory calculations.