Sulfonic acid grafted on silica-shell silver nanoparticles as a novel catalyst for the preparation of pyrimido[4,5-b]quinolines

Abstract

In this research, Ag@SiO₂ nanoparticles were prepared by a sol–gel method (a wet chemical method) at room temperature. The nanoparticles were functionalized by chlorosulfonic acid to introduce acidic sites on the surface to obtain sulfonic acid grafted on silica-coated silver nanoparticles (Ag@SiO₂–SO₃H). Ag@SiO₂–SO₃H was identified and characterized by FT-IR, DLS, ZP, FE-SEM, EDX-mapping, TEM, XRD, BET, BJH and TGA analyses. Ag@SiO₂–SO₃H performed well as a reusable catalyst for the multi-component synthesis of pyrimido[4,5-b]quinoline derivatives with high efficiency and satisfactory results.