Síntese de dipirrol e pirrol ancorado ao corante Azo Para-Red visando a síntese de polímeros conjugados com propriedades eletrocrômicas

Abstract

Polypyrrol is one of the polymers of interest to researchers because it has good thermal stability, magnetic, electrical and optical properties. Concomitantly, they have structural variety which can be modified by incorporating electrochromic substituents, such as azo dye, and by chain extension, such as dipyrrolS, in order to optimize their electronic and electrochemical properties. Thus, the preparation of pyrrol derivatives allows new polymeric materials to be obtain for application in optoelectronic devices, sensors, capacitors, LEDs, solar cells, artificial muscles, among others. To this end, two pyrrol-derived monomers were synthesized, one linked to the Para-Red azo dye by the substitution reaction between the Para-Red azo dye and 1- (Iodinepropyl) pyrrol and the 1,6-dipyrrol alkyl monomer which occurred through the Clauson-Kaas reaction between 1,6-hexanediamine and 2,5-dimethoxytetrahydrofuran. Monomers were characterized by 1 H NMR, 13 C NMR and FTIR. Chemical polymerization of the monomers led to the polypyrrole derivatives and were confirmed by FTIR. The band decrease of 714 cm-1 was observed regarding the C-H bond of positions 2 and 5 of the pyrrol, which indicates that there was α-α coupling of the monomer units. Electrochemical studies of 1,6-di (pyrrol) hexane (1,6-ByPy) and Pyrrole/ Para-Red (PyPR) monomers were performed. The respective films were electroplated using the potentiodynamic method. During the potentiodynamic deposition experiment, oxidation of the monomers to potentials of 0.9 V (1.6-ByPy) and 1.0V (PyPR) with subsequent polymer formation was evidenced. After spectraelectrochemical characterization of these films, the energy gap was observed, being 1.66 eV for 1.6-ByPY and 2.29 eV for PyPR. Moreover, in the characterization of polymeric films, it was possible to observe the changes in the tone of the films during the experiments were observed. During characterization, the 1,6-PByPy and PPyPR films did not show interesting properties to be applied in electrochromic devices, but the voltammograms showed the characteristic feature of capacitive material.