Design, Synthesis and Opto-electrochemical Properties of Novel Donor–Acceptor Based 2,3-di(hetero-2-yl)pyrido[2,3-b]pyrazine amine derivatives as Blue-Orange Fluorescent Materials

We herein report the design and synthesis of novel donor‒acceptor (D‒A) type 2,3-di(thiophene-2-yl)pyrido[2,3-b]pyrazine and 2,3-di(furan-2-yl)pyrido[2,3-b]pyrazine amine derivatives by employing palladium catalyzed Buchwald‒Hartwig coupling reaction. The synthesized compounds have been characterized by spectroscopic, electrochemical and thermal methods. Absorption spectra of all dyes showed an intramolecular charge transfer (ICT) transitions (λmax = 438–473 nm) in solution and positive solvatochromism with emission maxima in blue‒orange region (λemm = 489–617 nm). Further, solid state emission was studied for aggregation‒induced emission (AIE) effect in THF–water system due to the nanoparticles formation, as confirmed by FEG‒SEM technique. The HOMO (−5.22 to −5.75 eV) and LUMO (−3.35 to −3.45 eV) energy level of these molecules were measured by cyclic voltammetry and correlated by DFT calculations. On the basis of comparable HOMO and LUMO energy level with reported ambipolar materials and efficient solid state emission warrants the application of synthesized compounds as emitter and ambipolar charge transport materials in organic electronics.