Zirconium Doped Ceria Nanoparticles: An Efficient and Reusable Catalyst for a Green Multicomponent Synthesis of Novel Phenyldiazenyl–Chromene Derivatives Using Aqueous Medium

Zirconium doped ceria nanoparticles are found to be efficient heterogeneous catalysts for the multicomponent reaction of 1,3-dicarbonyl compounds with 4-hydroxy-3-methoxy-5-(substituted-phenyl-diazenyl) benzaldehydes and malononitrile to yield the corresponding 2-amino-4-(4-hydroxy-3-methoxy-5-(substituted-phenyl-diazenyl)-chromene-3-carbonitrile derivatives in water medium. The results show that nanosized CeO₂–ZrO₂ is a potential catalytic material for synthesis of title compounds in high yields. The used catalyst was recovered and reused several times without significant loss of catalytic activity, which is an essential parameter of green synthesis. The formation, size, and oxidation state of the metal ions present in the material is confirmed by powdered X-ray diffraction, transmission electron spectroscopy, and X-ray photoelectron spectroscopy techniques