A sustainable and multifunctional magnetic sulfonated tragacanth–MWCNT-COOH/ZnCuFe₂O₄ nanobiocatalyst for the efficient synthesis of bioactive polyhydroquinolines

The development of efficient heterogeneous catalysts plays a crucial role in facilitating sustainable and high-yield organic syntheses. In this study, a multifunctional nanocomposite based on sulfonated tragacanth, carboxylated multi-walled carbon nanotubes, and ZnCuFe₂O₄ nanoparticles (STrag/MWCNT-COOH/ZnCuFe₂O₄) was designed and synthesized. The fabrication involved a modified sol–gel synthesis of ferrite nanoparticles, chemical functionalization of tragacanth and MWCNTs, and subsequent integration into a hybrid composite. Characterization using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), energy-dispersive X-ray spectroscopy (EDX), elemental mapping, and vibrating sample magnetometry (VSM) confirmed the formation of a well-dispersed, porous, and magnetically responsive nanocomposite. The material demonstrated excellent catalytic efficiency in the one-pot synthesis of diverse polyhydroquinolines under mild reflux conditions, providing high yields (87–95%) in short reaction times (35–70 min). The resulting polyhydroquinolines exhibited antioxidant activity (DPPH scavenging up to 79.4%) and antibacterial activity (inhibition zones of 8–14 mm). Furthermore, the nanocomposite maintained its catalytic performance over multiple reuse cycles, highlighting its potential as a versatile platform for environmentally friendly catalysis and bioactive molecule development.