Design, fabrication and characterization of lacunary phosphomolybdate on silica/g-C3N4 nanocomposite as reusable catalyst for synthesis of 4-hydropyrans under solvent-free conditions

The development of versatile and highly efficient catalytic systems for the construction of heterocyclic scaffolds remains a central pursuit in modern organic synthesis. In the present work, it was reported the preparation of a nanocomposite, H 3 PMo 11 O 39 @SiO 2 @g-C 3 N 4 , via a simple and practical synthetic route. Its structural and surface properties were comprehensively characterized by FT-IR spectroscopy, powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and nitrogen adsorption–desorption analyses. The resulting nanocomposite was then applied as a green and reusable Brønsted-acid nanocatalyst for a solvent-free, room-temperature multicomponent transformation between aromatic aldehydes, malononitrile, and dimedone, efficiently affording 4H-pyran derivatives in excellent yields (85–95%) within 2–7 minutes. Notably, the catalyst maintained its performance over seven consecutive runs without appreciable loss in activity or alteration in morphology. These findings underscore the promise of this nanocomposite as a sustainable platform for rapid and high-yielding heterocycle synthesis. Three-component condensation reaction of aldehyde, malononitrile, and dimedone was carried out in the presence of the H 3 PMo 11 O 39 @SiO 2 @g-C 3 N 4 nanocomposite as a green catalyst under solvent-free conditions at room temperature. This nanocatalyst was characterized using FT-IR, XRD, FE-SEM, EDX techniques. • H 3 PMo 11 O 39 @SiO 2 @g-C 3 N 4 nanocomposite is used as a green and recyclable nanocatalyst for the synthesis of 4-hydropyran derivatives. • The structure of H 3 PMo 11 O 39 @SiO 2 @g-C 3 N 4 nanocomposite was characterized using FT-IR, XRD, FE-SEM, and EDX analyses. • The catalyst can be recovered and reused seven reaction runs without any loss of catalytic activity. • The H 3 PMo 11 O 39 @SiO 2 @g-C 3 N 4 nanocomposite can be easily separated from the reaction mixture by filtration.