Fluorescent aromatic symmetrical azines: Synthesis and appraisal of their photophysical and electrochemical properties

There is an immense push for the development of innovative, convenient and high-performance organic electronics. In this study, we present the synthesis of two azines and the exploration of their photophysical, surface morphological, electrochemical and electroluminescence properties for application in organic electronic devices. A diphenol substituted azine, 2,2’-[hydrazine-1,2-diylidenedimethylylidene]diphenol was synthesized by refluxing ethanolic solution of hydrazine hydrate with ethyl 2-oxo-2H-chromene-3-carboxylate. It was then converted into an azine spacer incorporated new tetrazo dye, bis–[2-(iminomethyl)-4-(phenyl diazenyl)phenol] by coupling with benzenediazonium chloride. The structures of the symmetrical azines were confirmed by FT-IR, NMR and mass spectroscopic techniques. Both the azines in thin film states exhibited deep yellow photoluminescence on UV excitation at 570 nm. The HOMO and LUMO energy levels assessed by cyclic voltammetry measurements, conformed to the electrochemical band gap energies of 4.41–4.55 eV. The p-type conductivity of the azines were confirmed by hot probe technique. The transport properties of both the azines were investigated by fabricating a bi-layer device. The successful construction of diodes with azines suggest that they could play a significant role as organic materials in the construction of electronic devices.