Simple route to a novel class of pyrazolidine-3,5-dione based azo dyes

We report an easiest synthesis strategy of a new class of synthetic dyes by coupling of functionalized pyrazolidine-3,5-dione derivatives via diazotization reaction with aromatic diamine for the azoic dyes or via dimerization reaction to synthesize the H chromophore dyes. Electron delocalization between the two coupled components has been studied using UV–vis spectroscopy, infrared, and NMR spectroscopy. In addition, the formation mechanism of such compounds has been discussed.