Magnetically Reusable Fe₃O₄‐CuO Nanoparticles as Catalyst for the Synthesis of Aryl‐Substituted Fluorescent Pyrazines for Fe Sensing and Ink Applications

Abstract

Abstract. Synthesis of substituted pyrazines from readily available methyl aryl/heteroaryl ketones and 1,2‐diamines were achieved using highly stable and reusable ferrite stabilized copper nanoparticles (Fe3O4‐CuO) as catalyst. The reaction proceeds via cascade imine formation‐oxidative cyclization method under oxygen atmosphere. The nanocatalysts were easily recovered and reused upto three consecutive cycles without any significant decrease in particle size, catalytic activity and reaction yield as evidenced from analytical techniques such as Transmission Electron Microscopy (TEM) and Powder X‐Ray Diffraction (PXRD). The synthesized pyrazines exhibited photophysical , behaviour, displayed large stoke shift and explored as fluorescent probe for the sensitive as well as selective “turn‐off” detection of iron with a limit of detection of 0.63 µM. The sensing method has also useful for the quantification of iron in spiked water samples. Furthermore, the application of luminescent pyrazine as fluorescent ink was successfully demonstrated.