Structural and Electronic Properties of Poly[N-(2-cyanoalkyl)pyrrole]s Bearing Small Alkyl Groups

The electronic and structural properties of poly[N-(2-cyanoalkyl)pyrrole]s bearing short alkyl groups have been investigated using different methodologies. Specifically, the electronic properties of poly[N-(2-cyanoethyl)pyrrole], which was prepared by anodic polymerization, have been determined using both electrochemical and spectroscopic techniques. On the other hand, quantum mechanical calculations on model oligomers of poly[N-(2-cyanomethyl)pyrrole] have been used to propose the conformation of an idealized polymer chain and to examine the influence of the conformation on the predicted electronic properties. Results indicated that the electronic properties of poly[N-(2-cyanoalkyl)pyrrole]s are not only influenced by effect of the conformation in the conjugation of the pi-system but also by the existence of secondary oxidative processes on the pyrrole ring of selected repeating units. In this case, the combination of experimental information and quantum mechanical calculations proved to be essential to propose a structural model. This consists of a cross-linked structure formed by small branches of around nine repeating units in each one, with a carbonyl group at the last repeating unit of each branch.