SYNTHESIS, CHARACTERIZATION, AND BIOLOGICAL ACTIVITY OF ORGANOTIN(IV) COMPLEXES DERIVED FROM N-PHTHALOYLAMINE LIGANDS

N-Phthaloylamine derivatives were synthesized through the condensation of an equimolar amount of phthalic anhydride with 2,4-dinitrophenylhydrazine, aniline, and hydrazine (1:1 molar ratio) in glacial acetic acid using excess tetrahydrofuran (THF) as solvent. The reactions afforded the corresponding ligands in good yields (60–68.6%) after purification by column chromatography and recrystallization. The synthesized ligands were subsequently complexed with organotin(IV) compound, including dibutyltin(IV) dichloride, to afford stable organotin(IV) complexes. The compounds were characterized by melting point determination, thin-layer chromatography (TLC), column chromatography, and Fourier Transform Infrared (FT-IR) spectroscopy. The IR spectra of the free ligands exhibited characteristic imide carbonyl bands in the 1715–1730 cm⁻¹ region and N–H stretching bands at 3200–3300 cm⁻¹. Upon complexation, the carbonyl stretching frequencies shifted to lower wavenumbers (1680–1700 cm⁻¹), indicating coordination through the carbonyl oxygen atom. The appearance of new bands in the 450–550 cm⁻¹ region, assignable to Sn–O and Sn–N vibrations, supports ligand coordination. Changes in the N–H region suggest possible involvement of the amide nitrogen in bonding, suggesting coordination through oxygen donor atoms. Antimicrobial screening against Klebsiella pneumoniae, Escherichia coli, and Staphylococcus aureus revealed enhanced activity of the complexes compared to the free ligands. The ligands exhibited inhibition zones of 12–18 mm, whereas the organotin(IV) complexes showed larger zones of 16–22 mm, with maximum activity observed against Klebsiella pneumoniae. These findings demonstrate that complexation with organotin(IV) significantly enhances the antimicrobial efficacy of the ligands.