Mechanochemical Synthesis, Characterization and Antifungal Studies of Organotin (iv) Carboxylates Obtained from Citric Acid

The morbidity and mortality caused by invasive fungal infections are increasing across the globe due to developments in transplant surgery, the use of immunosuppressive agents, and the emergence of drug-resistant fungal strains, which have led to a challenge in terms of treatment. This study investigates the mechanochemical synthesis, characterization, and antifungal properties of organotin (IV) citrate complexes. Four complexes were synthesized via solvent-free grinding: Bu2SnCTR-30, Bu2SnCTR-60, Bu3SnCTR-30, and Bu3SnCTR-60. Characterization using FTIR, thermal analysis, XRF, and PXRD confirmed successful synthesis and provided structural insights. Longer reaction times improved yields, crystallinity, and tin content. Antifungal studies revealed activity against Aspergillus niger and A. flavus, with Bu2SnCTR-60 showing the highest potency (MIC: 12.5 mg/mL, MFC: 25 mg/mL). The complexes were inactive against Candida albicans, indicating potential for targeted applications. This green synthesis approach offers an environmentally friendly alternative for producing antifungal organotin compounds, with implications for agricultural and medicinal use. Further optimization of reaction conditions, expanded antifungal testing, and toxicity assessments are recommended for future research.