Quinoxaline based amines as blue-orange emitters: Effect of modulating donor system on optoelectrochemical and theoretical properties

A series of eight novel donor-acceptor based quinoxaline-amine derivatives 2-9 were prepared by modulating donor species on quinoxaline core with Buchwald-Hartwig coupling amination reaction. The synthesized molecules were fully characterized and studied for impact of D-A interaction on optoelectrochemical properties of derivatives. Absorption spectra of 2-9 display intramolecular charge transfer (ICT) transitions in the range of 377-456 nm. Dyes 2-9 show positive solvatochromism in emission and emit in blue-orange region with emission maxima 472-592 nm on excitation at their respective ICT maxima in toluene, chloroform, DCM and neat solid film. Herein, dyes 2, 3 and 7 which possess intense emission in solid state were further studied for Aggregation Induced Emission (AIE) effect. The HOMO and LUMO energy level for compound 2-9 obtained by CV were found in the range of -5.23 to -5.83 eV and -3.55 to -3.74 eV. Theoretical studies of molecules were also carried out by using TD-DFT calculations. The comparable HOMO and LUMO energy level of 2-9 with reported ambipolar materials and efficient solid state emission make synthesized compounds potential candidate for solid state emissive, ambipolar materials in organic electronics.