Estudo e síntese de polímeros heteroaromáticos com EDOT baseados em sistemas híbridos moleculares doador-aceptor (D-A)

Abstract

The development and application of novel conjugated polymers entail large research efforts on the relevant area of Organic Electronics, allowing the manufacture of flexible and efficient devices. In the present work, the chemical polymerization of conjugated heteroaromatic amides with ethylenedioxythiophene (EDOT) was realized, with the main purpose of obtaining new and potentially applicable materials on various electronic devices such as solar cells (OPV’s) and organic light emitting diodes (OLED’s), etc. The dissertation also includes a chemical exploration of phenothiazine (PTZ) as a widely available fluorescent heteroaromatic compound on the synthesis of conjugated new substances, through functionalization reactions, such as N-functionalization, nitration and reduction. The methyl, nitro and reduced compounds, respectively, were characterized by Nuclear Magnetic Resonance and Infrared Spectroscopy. The aminated phenothiazine lead to the elaboration of a novel aromatic compound, N-(10-methyl-10H-phenothiazin-3-yl)thiophen-3-carboxamide (3-Tf-CO-NH-MPTZ), by addition reaction with the 3-thiophene carboxylic acid chloride. 3-Tf-CO-NH-MPTZ was characterized through melting point analysis, Nuclear Magnetic Resonance, Ultraviolet and Visible region Spectroscopy and electrochemically by Cyclic Voltammetry. The novel compound had good electrochemical stability with a low oxidation potential (0,48V). The monomer 3-Tf-CO-NH-MPTZ, and also its analog derivates from fluorene 3-Tf-CO-NH-FLU, dibenzofuran 3-Tf-CO-NH-DBF and 2-nafthalene 3-Tf-CO-NH-2NFT, were successfully copolymerized with EDOT on a 2:1 mol ratio and the four copolymers presented good thermal stability until approximately 367-384°C. Also, all the copolymers had absorptions of good intensity on the Ultraviolet region (250-300 nm), including an intense emission on the Orange region of the spectrum (PEDOT-co-2NFT, λem ~ 615 nm). The Raman spectra for the PEDOT-co-FLU, PEDOT-co-MPTZ, PEDOT-co-DBF and PEDOT-co-2NFT were consistent with typical Raman spectra for PEDOT, with vibrational modes on 988, 1263, 1425 and 1504 cm-1, commonly associated with this kind of material.