Motivated by the promising pharmaceutical potential of organotin(IV) compounds, a novel class of twelve diorganotin(IV) complexes (5–16) was prepared by employing four Schiff base ligands (1–4), obtained via the condensation of 4-ethoxybenzhydrazide with substituted salicylaldehydes. The Schiff base ligands and their corresponding diorganotin(IV) complexes were thoroughly characterized through a combination of spectroscopic and physicochemical techniques, including mass spectrometry, XRD, NMR spectroscopy (1H, 13C and 119Sn), molar conductance measurements, and FT-IR spectroscopy. The spectroscopic data demonstrated that the Schiff base ligands act as tridentate donors, coordinating to the tin centre via ONO donor sites, which is consistent with the formation of pentacoordinated structures in the organotin(IV) complexes. XRD analysis of compounds (3) and (13) indicated their crystalline nature. In vitro antimalarial activity against Plasmodium falciparum was evaluated using a microassay protocol, which revealed that the diorganotin(IV) complexes exhibited superior activity compared to the corresponding hydrazone ligands. Complexes (7) and (13) exhibited the highest potency, with IC₅₀ value 0.64 μg/mL. Broth dilution method was used for the evaluation of antimicrobial activity of the synthesized compounds against four bacterial and two fungal strains taking ciprofloxacin and nystatin as reference standard drugs. With minimum inhibitory concentration (MIC) values of 0.0997 μmol/mL, complex (13) showed the strongest action against the strains under consideration among the studied compounds. To support the experimental findings, a molecular docking study was conducted on the most potent ligand (3) and its corresponding complexes (11), (12), and (13) against Plasmodium falciparum lactate dehydrogenase. The binding energies obtained from the molecular docking analysis − 7.2 kcal/mol for the free ligand (3) and − 7.7, − 8.1, and − 8.6 kcal/mol for complexes (11), (12), and (13), respectively are in agreement with the experimentally observed biological results. All these findings suggested that the diorganotin(IV) complexes represent promising candidates that warrant further investigation in the context of drug development. Graphical Abstract Organotin(IV) complexes derived from Schiff base ligands have been synthesized and investigated efficiently. Computational studies, including DFT and molecular docking studies were carried out for the synthesized compounds. Furthermore, the biological potential of the designed compounds, antimicrobial and antimalarial activities were successfully assessed.

Insights into the biological potential of diorganotin(IV) Schiff base complexes: synthesis, structural characterization, molecular docking and DFT studies

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发表日期：

2026年3月28日

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Shweta Sharma,
Sonika Asija,
Jai Devi,
Ram Kumar Tittal,
Bajrang Lal

摘要

Motivated by the promising pharmaceutical potential of organotin(IV) compounds, a novel class of twelve diorganotin(IV) complexes (5–16) was prepared by employing four Schiff base ligands (1–4), obtained via the condensation of 4-ethoxybenzhydrazide with substituted salicylaldehydes. The Schiff base ligands and their corresponding diorganotin(IV) complexes were thoroughly characterized through a combination of spectroscopic and physicochemical techniques, including mass spectrometry, XRD, NMR spectroscopy (¹H, ¹³C and ¹¹⁹Sn), molar conductance measurements, and FT-IR spectroscopy. The spectroscopic data demonstrated that the Schiff base ligands act as tridentate donors, coordinating to the tin centre via ONO donor sites, which is consistent with the formation of pentacoordinated structures in the organotin(IV) complexes. XRD analysis of compounds (3) and (13) indicated their crystalline nature. In vitro antimalarial activity against Plasmodium falciparum was evaluated using a microassay protocol, which revealed that the diorganotin(IV) complexes exhibited superior activity compared to the corresponding hydrazone ligands. Complexes (7) and (13) exhibited the highest potency, with IC₅₀ value 0.64 μg/mL. Broth dilution method was used for the evaluation of antimicrobial activity of the synthesized compounds against four bacterial and two fungal strains taking ciprofloxacin and nystatin as reference standard drugs. With minimum inhibitory concentration (MIC) values of 0.0997 μmol/mL, complex (13) showed the strongest action against the strains under consideration among the studied compounds. To support the experimental findings, a molecular docking study was conducted on the most potent ligand (3) and its corresponding complexes (11), (12), and (13) against Plasmodium falciparum lactate dehydrogenase. The binding energies obtained from the molecular docking analysis − 7.2 kcal/mol for the free ligand (3) and − 7.7, − 8.1, and − 8.6 kcal/mol for complexes (11), (12), and (13), respectively are in agreement with the experimentally observed biological results. All these findings suggested that the diorganotin(IV) complexes represent promising candidates that warrant further investigation in the context of drug development.

Graphical Abstract

Organotin(IV) complexes derived from Schiff base ligands have been synthesized and investigated efficiently. Computational studies, including DFT and molecular docking studies were carried out for the synthesized compounds. Furthermore, the biological potential of the designed compounds, antimicrobial and antimalarial activities were successfully assessed.