Banca de QUALIFICAÇÃO: LUIS PAULO ALVES DA SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUIS PAULO ALVES DA SILVA
DATE: 27/02/2023
TIME: 09:00
LOCAL: Google Meet
TITLE:

Synthesis and characterization of new -conjugated polymers based on poly(2,5- di(2-thienyl)pyrrole) (PSNS) and polypyrrole (PPy) derivatives with electrochromic/fluorescent properties

KEY WORDS:

Hybrid monomer; electrochromism; polymerization.

PAGES: 91
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

Conjugated polymers are gaining attention for their promising application as an optically active layer in optoelectronic devices. These materials can feature high optical contrast, low response time, greater processability and electrochromism. The optical and electrical properties of -conjugated polymers can be manipulated through modifications in the structures of their monomers/polymers, which can be accomplished with the insertion of substituents with electrode-leaving and/or electro-withdrawing groups. Among the alternative methodologies reported in the literature, we highlight in particular the synthesis of monomers derived from pyrrole (Py) and 2,5-di(2-tienil)pirrol (SNS). Derivatives of SNS have been gaining attention because they have a 'trimeric' structure that guarantees low oxidation potentials and allows their functionalization through the insertion of substituents in the central portion (pyrrole) with less steric hindrance, which makes them good candidates for use as electrochromic/electrochromic materials. One of the functionalization alternatives is based on the preparation of hybrid monomeric systems through the insertion of polyaromatic substituents with a rigid and conjugated structure, aiming at obtaining materials with electrochromic/fluorescent properties. In this work two new monomers derived from Pyrrole (Py) and Thiophene-pyrrole-Thiophene (SNS) were synthesized. The first was obtained through three reaction steps: clauson-kaas condensation, halide exchange and second-order nucleophilic substitution. The second was obtained through three steps: Friedel-Crafts acylation, Paal-Knorr reaction and acyl nucleophilic substitution. All compounds were characterized by 1H NMR, 13C NMR and FTIR. The PSNS-CM film was obtained by electrochemical means from the cyclic voltammetry technique in a solution containing 0.01 M of the SNS-CM monomer and 0.1 M of the supporting electrolyte (C4H9)4NBF4 in ACN using a scanning speed of 20 mV.s-1 and potential range from 0.0 V to 0.7 V. The PSNS-CM film was characterized by cyclic spectrovoltametry in a system containing a monomer-free solution with 0.1 M of (C4H9)4NBF4 in ACN. The film showed electrochromism with a change from yellow-green in the undoped state (0.0 V) to blue-gray in the doped state (0.50 V). The study of the electrochromic properties, using the double potential jump spectrochronoamperometry technique, is ongoing. As future prospects, we intend to complete the synthesis of SNS-IN (SNS linked to an indole) and SNS-Fl (SNS linked to fluorescein) monomers, optimize the synthesis of SNS-CM and PY-RES and carry out the fluorescence study of all monomers. In addition, it is intended to carry out the polymerization of PSNS-IN, PSNS-Fl and PY-RES films, as well as their characterization by Fourier Transform Infrared Spectroscopy (FTIR-ATR), Scanning Electron Microscopy (SEM), spectroelectrochemistry and fluorescence.

BANKING MEMBERS:
Interno(a) - 1543737 - ADRIANA SANTOS RIBEIRO
Presidente - 2089941 - DIMAS JOSE DA PAZ LIMA
Interno(a) - 1820117 - ISIS MARTINS FIGUEIREDO
Externo(a) ao Programa - 2458049 - ITALO MARCOS NUNES DE OLIVEIRA
Externo(a) à Instituição - MARCELO NAVARRO - UFPE