Eco-friendly synthesis of <i>Cinnamomum zeylanicum</i> -stabilized gold nanoparticles as recyclable catalysts for ultrasound-assisted synthesis of functionalized pyridine derivatives

The increasing environmental impact, high cost and toxicity associated with conventional nanoparticle synthesis and metal-based catalysts have created an urgent need for sustainable, green and recyclable alternatives in nanomaterials and organic synthesis. The current study developed an eco-friendly method to produce gold nanoparticles (AuNPs) using Cinnamomum zeylanicum extract as a natural reducing and stabilizing agent. The synthesis was optimized by adjusting extract concentration, volume, pH, temperature and reaction time, with UV–Vis spectroscopy confirming nanoparticle formation at 539nm. TEM revealed well-dispersed spherical particles (3.12−20.32nm), while XRD, FTIR and EDX confirmed their crystalline structure, functional group involvement and elemental composition. The AuNPs showed excellent catalytic activity with concentration (10 wt% = 0.0196 g) in the ultrasound-assisted one-pot synthesis of 2-amino-6-mercaptopyridine-3,5-dicarbonitrile derivatives, achieving 89%–98% yields within 10–25 min. They outperformed traditional catalysts, and retained efficiency for five reuse cycles without leaching. This study highlights C. zeylanicum–AuNPs as a sustainable, recyclable and highly effective catalyst for rapid heterocyclic synthesis, offering a green alternative for advanced organic transformations.