This study introduces an efficient and sustainable catalytic system utilizing cobalt ferrite nanoparticles (CoFe₂O₄-NPs) for the synthesis of valuable 6-amino-2-oxo-4-phenyl (or 4-chlorophenyl)-1,2,3,4-tetrahydropyrimidine-5-carbonitrile derivatives. Recognizing the limitations of traditional methods for the Biginelli reaction, we thoroughly characterized CoFe₂O₄-NPs, alongside individual iron oxide nanoparticles (Fe₂O₃-NPs) and cobalt oxide nanoparticles (CoO-NPs), using FTIR, XRD, TEM, SEM, XPS, TGA, and BET analysis. These characterizations revealed the unique structural, morphological, and physicochemical properties of CoFe₂O₄-NPs, including an optimized porous structure and significant bimetallic synergy between Fe and Co ions. Catalytic studies demonstrated that CoFe₂O₄-NPs significantly outperformed individual Fe₂O₃-NPs and CoO-NPs under mild conditions. While the latter only catalyzed the Knoevenagel condensation, CoFe₂O₄-NPs uniquely facilitated the complete Biginelli reaction. This superior performance is attributed to the synergistic electronic environment within CoFe₂O₄-NPs, which enhances reactant activation, intermediate stabilization, and proton transfer during the multi-step reaction. This work highlights the potential of CoFe₂O₄-NPs as highly efficient and selective nanocatalysts for synthesizing biologically relevant 1,2,3,4-tetrahydropyrimidines, offering a greener synthetic route in organic chemistry.

Biogenic synthesis of nanoparticles using plant extract is a promising trend in research to reduce chemical consumption and avoid wastewater treatment complications. In this work, the zero-valent Fe/Fe₃O₄ nanoparticles (Fe⁰/Fe₃O₄ NPs) were synthesized using Caralluma acutangula (CA) plant, widespread in the Jazan region in Saudi Arabia. The synthesis process involves hydrothermal treatment of plant extract and iron (III) mixture at 80 °C to facilitate the reduction reaction of iron (III) cations. The Fe⁰/Fe₃O₄ NPs were characterized by XRD, FTIR, SEM, EDX, TEM, XPS, TGA, UV, and S_BET. The obtained data support the formation of Fe⁰/Fe₃O₄ NPs crystal structure with an average particle size of 9.6 nm and surface area of 89 m².g⁻¹. The biosynthesized Fe⁰/Fe₃O₄ NPs were then applied for the photodegradation of Methylene blue (MB) dye as one of the most common organic dyes in wastewater due to several industrial human activities. Different parameters for MB degradation were performed, such as kinetics and thermodynamics studies. The data obtained reflect the nonspontaneous endothermic process with 87.8 KJ. mol⁻¹ activation energy (E_a).