Synthesis, optical, electrochemical and theoretical studies of 2,3-Di(pyridin-2-yl)quinoxaline amine derivatives as blue-orange emitters for organic electronics

Abstract

We herein report the design and synthesis of six new donor–acceptor (D–A) type, bipolar compounds containing 2,3-di(pyridin-2-yl)quinoxaline as an acceptor and diaryl/heterocyclic amine donors prepared by palladium catalyzed Buchwald‒Hartwig coupling reaction. The synthesized compounds have been characterized by different spectroscopic techniques, electrochemical analysis and thermal method. Further, the structure of compound 4 was confirmed by single crystal X−ray analysis. The characteristic absorption (λmax) with ICT feature and emission maxima (λemm) in various solvents of 2–7 are found in the range of 389–440 nm and 460–555 nm, respectively, with stoke's shift within 3664−6945 cm−1. The positive solvatochromism due to solvent polarity observed in dyes confirmed by the Mc−Rae and Weller's plots. The dyes 2–7 show cyan blue to orange emission (λemm = 493–581 nm) in solid film. The cyclic voltammetry (CV) was used to analyze the HOMO and LUMO energy levels of the molecules and further it was correlated by density functional theory (DFT) calculations. The excellent thermal stability and opto-electronic properties warrants the application of these dyes in opto−electronic devices.