The design and synthesis of 2,3-diphenylquinoxaline amine derivatives as yellow-blue emissive materials for optoelectrochemical study

In this study, a series of bipolar, donor–acceptor–donor (D–A–D)-based quinoxaline diarylamine/heterocyclic amine derivatives were synthesized in good yield by the Buchwald–Hartwig amination reaction and fully characterized by different spectroscopic methods. The optoelectronic properties of the dyes were scrutinised using electronic absorption and fluorescence spectroscopy, cyclic voltammetry, thermogravimetric analysis, and differential scanning calorimetry and further by the DFT and TDDFT study. The photophysical properties of dyes are influenced by their peripheral amines and the nature of solvents used. The presence of intramolecular charge transfer (ICT) transitions in the absorption spectra of amine derivatives is attributed to the existence of the D–A building units, which induces blue to yellow emission in both the solution and the neat solid film. Strikingly intense solid-state emission in some of the dyes has moved the area of study toward aggregation induced emission (AIE) phenomenon and showed the formation of nanoaggregates at above 50% water fraction (fw) of THF/H2O solvent mixtures, which was further confirmed by the FEG-SEM technique. The linkage of different amines with the quinoxaline core moiety tunes the electrochemical properties with lower band gaps and comparable HOMO–LUMO energy levels in reported ambipolar materials. Thus, the existence of a strong solid-state emission with AIE activity, ambipolar nature and good thermal properties of dyes attribute their use as solid-state emitters and ambipolar materials in optoelectronic devices.