2,2′,3,3′-Tetrakis(4-bromophenyl)-6,6′-biquinoxaline based novel Donor–Acceptor–Acceptor−Donor (DAAD) Blue−Orange emitting molecules: Opto-electrochemical, AIE and theoretical investigation

A series of six novel donor‒acceptor‒acceptor‒donor (DAAD) based biquinoxaline amine derivatives 2–7 were obtained by employing palladium catalyzed Buchwald‒Hartwig coupling amination reaction. The synthesized compounds were characterized by spectroscopic and electrochemical techniques. The characteristic absorption spectra of dyes 2–7 display intramolecular charge transfer (ICT) transitions in the range of 415–461 nm. Dyes 2–7 show positive solvatochromism in emission and emit in blue−Orange region with emission maxima 492–598 nm in various solvents and neat solid film. Herein, dyes 2, 3 and 4 which possess intense emission in solid state were further studied for aggregation‒induced emission (AIE) effect in THF–water system due to the formation of nanoparticles, as confirmed by FEG‒SEM technique. The HOMO and LUMO energy levels for compounds 2–7 were measured by cyclic voltammetry (CV) and are found in the range of −4.96 to −5.35 eV and −3.33 to −3.46 eV which further correlated by density functional theory calculations. On the basis of comparable HOMO and LUMO energy levels to reported ambipolar materials, efficient solid state emission with good AIE and AIEE properties of the synthesized dyes signify their potential to be used as solid state emitters and ambipolar materials in opto−electronics. [Display omitted] •Design and synthesis of novel biquinoxaline amine derivatives.•Absorption spectra of dyes 2–7 showed characteristic ICT transition.•Dyes exhibit solvatochromism and covered broad scale of fluorescence from blue–orange in solution and solid state.•AIE characteristic possessed by dyes 2, 3 and 4 attribute towards nanoaggregate formation.•The HOMO and LUMO value of dyes well matches with reported ambipolar materials.