Estrutura eletrônica de oligoanilinas

TL;DRAbstract

In this work we present electronic structure calculations and conformational studies of polyaniline oligomers to investigate the influence of oligomer size, oxidation state, substituents and solvent effects in the UV-Visible absorption spectrum. Torsion barrier and solvent effect calculations are carried out within AMl semi-empirical technique. Absorption spectra are simulated through ZINDO/S-CI calculations. Based upon the analysis of the torsion potential curves, an interpretation is given for the diverse thermochromic behavior observed in insulating polyanilines as a function of oxidation state. Pernigraniline base, the fully oxi.dized form of polyaniline, has been reported to present an unusual red-shift in its spectrum with increasing temperature. The potential energy associated to ring twisting calculated for pernigraniline exhibits a double well shape, which is different from the potentials obtained for the other forms. We concluded that the chain flexi.bility depends strongly o

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