Water soluble Schiff base complexes of 4-aminoantipyrine: Synthesis, characterization, and antibacterial activity

New water-soluble Schiff base complexes with potential antimicrobial applications were successfully synthesized. A modification was made by adding a sulfonate group to the ligand to increase the ligand solubility in water. The Schiff base ligand was synthesized from a 4-aminoantipyrine compound with salicylaldehyde (L1) and salicylaldehyde-5-sodium sulfonate (L2), while the complex was synthesized using metal Co(II) with L1 (Co-L1) and L2 (Co-L2). Analysis and characterization were performed using a UV-Visible spectrophotometer, Fouriertransform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), Powder X-ray diffraction (XRD), magnetic susceptibility balance, and elemental analysis. All the ligands and complexes produced were crystalline, the geometry of the Co(II) complex is octahedral, and the ligand coordinates via the oxygen atom of the phenolic hydroxyl group and the nitrogen atom of the azomethine group. The sulfonate group causes the compounds L2 and Co-L2 to have greater solubility in water than L1 and Co-L2. The Density functional theory (DFT) results show that the presence of sulfonate groups causes the Co-L2 complex to have a larger dipole moment, is more reactive than Co-L1, and confirms its significant solubility in water. In addition, adding a sulfonate group also increases its antibacterial activity and is supported by molecular docking studies.

Automated summary

New water-soluble Schiff base complexes with potential antimicrobial applications were successfully synthesized by modifying the ligand's solubility in water through the addition of a sulfonate group. The complexes showed greater solubility in water and increased antibacterial activity compared to the ligands without the sulfonate group. Meanwhile, theoretical calculations confirmed the improved solubility and reactivity of the complex with the sulfonate group, supporting its potential for antimicrobial applications.