Pd-Decorated Ag-CeO ₂ /PANI Nanocomposite: Fabrication, Application in the Synthesis of 2,3-Dihydroquinazolin-4(1 <i>H</i> )-ones and Tetrahydrobenzo[ <i>b</i> ]pyrans, Antimicrobial Activity Evaluation, and Computational Study

The nanocomposite catalyst containing silver-doped cerium dioxide (Ag-CeO 2 ) nanoparticles decorated by Pd nanoparticles and supported within a polyaniline (PANI) matrix, Pd@Ag-CeO 2 /PANI, was synthesized and extensively characterized by Fourier-transform Infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), high-resolution tunneling electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), elemental mapping, and optical analyses. The nanocomposite exhibited remarkable catalytic efficiency and selectivity toward the synthesis of two classes of biologically important heterocyclic compounds, namely, 2,3-dihydroquinazolin-4(1 H )-ones and tetrahydrobenzo[ b ]pyrans, under mild, green reaction conditions. Furthermore, the nanocomposite displayed significant antibacterial activity, highlighting its potential multifunctional applications. The catalyst retained excellent recyclability and activity over multiple cycles, aligning with principles of sustainable green chemistry. The detailed density functional theory (DFT) study of the nanocomposite model, namely, charge and spin distributions, molecular electrostatic potential (MEP), and global reactivity parameters (GRPs), showed potential activity of the nanocomposite as a catalyst. The DFT study of non-covalent interactions within the nanocomposite model showed the presence of various interactions between the components of the nanocomposite responsible for its stabilization. This integrated experimental and computational study demonstrates Pd@Ag-CeO 2 /PANI to be an efficient, versatile, and sustainable nanocatalyst platform for organic synthesis and antimicrobial applications.