2,6-Di(thiophenyl)-1,5-dihydrodipyrrolopyrazine (DT-DPP) structural isomers as donor–acceptor–donor molecules and their optoelectronic investigation

Abstract

Herein we report the synthesis and characterization of two new D–A–D molecules 1,5-dimethyl-2,6-di(thiophen-2-yl)-1,5-dihyrodipyrrolo[3,2-b:3′,2′-e]pyrazine (2DT-DPP) and 1,5-dimethyl-2,6-di(thiophen-3-yl)-1,5-dihyrodipyrrolo[3,2-b:3′,2′-e]pyrazine (3DT-DPP) via Pd catalyzed C–C and C–N coupling reactions. The dipyrrolopyrazine scaffold comprises an electron-accepting core flanked by two thiophene moieties. To reveal the molecular geometry and molecular packing of 3DT-DPP, X-ray single crystal analysis was carried out. The surface morphological analysis shows the formation of microrods. The photophysical properties of these systems were characterized by UV-vis, fluorescence spectroscopy, and cyclic voltammetry. The thermal properties reveal that both the isomers are thermally stable up to 300 °C. This study clearly demonstrates that DT-DPP can be used to build D–A molecules to produce promising conjugated materials for various optoelectronic applications.