Theoretical investigation of nitrogen-containing polyisothianaphthene derivatives

We use a quantum-chemical approach to investigate the geometric and electronic structure of aza and diaza derivatives of polyisothianaphthene (PITN). Semiempirical Austin Model 1 (AM1) calculations are performed on a series of oligomers of increasing chain length; the oligomers are capped by various end groups that lead to either aromatic or quinoid geometric structures. The relative stabilities of the aromatic and quinoid polymers are estimated on the basis of the energy per repeat unit (Epru) and the electronic properties are evaluated with the Valence Effective Hamiltonian (VEH) method.