Green Chemistry Approach: Synthesis of Schiff Base Ligand Derived from 4-Hydroxy-3-Methoxybenzaldehyde and Glycine and its Cu (II), Zn (II) Complexes

This study presents the green synthesis and characterization of a Schiff base ligand derived from 4-hydroxy-3-methoxybenzaldehyde and glycine, along with its Copper (II) and Zinc (II) complexes, employing a mechanochemical approach. This method aligns with green chemistry principles by minimizing waste and energy consumption and avoiding hazardous reagents. The Schiff base ligand and metal complexes were synthesized through solvent-free grinding, producing a milky-colored ligand and distinctively colored complexes: dark green for Cu (II) and white for Zn (II). The synthesized compounds demonstrated high yields: 96% for the ligand, 98% for the Cu (II) complex, and 97% for the Zn (II) complex. Spectroscopic analyses, including infrared (IR) and ultraviolet-visible (UV-Vis) spectroscopy, confirmed the formation of the Schiff base and its metal complexes, revealing the presence of functional groups and electronic transitions indicative of complexation. The IR spectra showed characteristic bands for hydroxyl (O-H), imine (C=N), carbonyl (C=O), and aromatic groups, as well as metal-ligand (M-N, M-O) interactions. UV-Vis spectra indicated π →π*, n→π*, and d-d transitions, suggesting conjugated π-systems and electronic transitions within the metal ions. This study underscores the efficacy and environmental benefits of the mechanochemical method in synthesizing Schiff base ligands and their metal complexes.