New 1,2,4-triazole-based azo-azomethine dyes. Part I: Synthesis, characterization and spectroscopic studies

► In this study four new 1,2,4-triazole-based azo-azomethine dyes have synthesized. ► The tautomerism equilibrium between azo and hydrazone forms in DMSO/EtOH solution was studied. ► The TG results indicate that the dyes are thermally stable.