Synthesis and electropolymerization of 3,4-substituted quinoxaline functionalized pyrrole monomer and optoelectronic properties of its polymer

We synthesized a new electroactive pyrrole functionalized monomer; 2-butyl-5,12-dihydro-2H-pyrrolo[3′,4′:2,3][1,4]dioxocino[6,7-b]quinoxaline (BuDQP) where β-positions of the pyrrole ring are blocked. With the help of this strategy, formation of α–β linkages during polymerization was prevented, resulting in a more regiochemically defined material. Characterization of newly synthesized compounds was performed by FTIR, GC–MS, 1H NMR, 13C NMR techniques and elemental analysis. Polymerization and copolymerization of BuDQP and characterization of the resulting polymers were also performed. Spectroelectrochemical investigations, switching abilities, colorimetry studies and stability experiments were performed on both for polymer and copolymer. Spectroelectrochemical analysis of P(BuDQP) reflected electronic transitions at 328 nm (π–π* transition) and 500 nm (polaron bands) with an electronic band gap of 2.30 eV, while copolymer (P(BuDQP-co-Py)) revealed electronic transitions at 346 nm (π–π* transition) and 518 nm (polaron bands) with an electronic band gap of 2.24 eV. Colorimetry studies revealed that P(BuDQP) has only two colors (blue and yellow) whereas copolymer film has six different colors in its oxidized and neutral states.