Electrochemical Studies of New Donor-Acceptor Oligothiophenes

Electrochemical studies on a series of new conjugated oligothiophene derivatives are reported. The molecular architectures (D-A and A-D-A) of these compounds present different donor cores (thiophene, bithiophene) with different numbers of 3-octylthiophene units (that act as ?-bridge and solubilizing components). The acceptor end groups adopted were, in all the cases, ethyl cyanoacrylate units. The results from voltammetric experiments confirm the close relationship between the structure of these oligothiophenes and their electrochemical behavior. Furthermore, we carried out quantum mechanical calculations to be able to obtain the HOMO/LUMO characteristics of some of our compounds in order to confirm our hypotheses on their electrochemical behavior. Moreover, the roles of the oligothiophene backbone and the ethyl cyanoacrylate group in cyclic voltammetry were elucidated by carrying out two different electrolyses at anodic and cathodic peak potentials. In particular, we were successful in the anodic dimerization of a tetrathiophene (D-A) to an octithiophene (A-D-A) (in high yield) with a considerable shortening of the chemical synthesis.