Diorganotin(IV) complexes derived from thiazole Schiff bases: synthesis, characterization, antimicrobial and cytotoxic studies

Organotin(IV) complexes are gaining major attention as drug candidates, accordingly we have synthesized a cluster of novel diorganotin(IV) complexes R2SnClL (where R is Me, Et, n-Bu and Ph) of Schiff base ligands 2-{[4-(4-bromo-phenyl)-thiazol-2-ylimino]-methyl}-phenol (HL1), 4-{[4-(4-bromo-phenyl)-thiazol-2-ylimino]-methyl}-benzene-1,3-diol (HL2), 2-{[4-(4-bromo-phenyl)-thiazol-2-ylimino]-methyl}-4-nitro-phenol (HL3) and 2,4-dibromo-6-{[4-(4-bromo-phenyl)-thiazol-2-ylimino]-methyl}-phenol (HL4). The structural elucidation of the compounds was done by using different spectroscopic techniques (UV-Vis, FT-IR, H-1, C-13 and Sn-119 NMR), mass spectrometry, melting point and molar conductance measurement. The spectroscopic data recommend that Schiff bases are bidentate (NO) in nature and bind to tin metal via azomethine nitrogen, phenolic oxygen atom and have pentacoordinated environment around central tin metal. To check the biological utility, the synthesized compounds were tested for antimicrobial activity against different bacterial and fungal strains using serial dilution method and inhibitory activity noted in terms of MIC values (mu mol/mL) which displayed that the complexes were more efficient than corresponding Schiff bases and complex 20 (Ph2SnClL4) was most active antimicrobial agent. The compounds were also evaluated for cytotoxic activity against human cancer cell lines- A549 (Lung), PC-3 (Prostate), MDA-MB-231 (Breast), MIA PaCa-2 (pancreas) and human normal cell line fR2 by using MTT method. The results of cytotoxic activity showed that compounds 5, 6, 7, 10, 11 and 14 are active and compounds 10 and 11 having IC50 values ranging from 0.01 to 1.42 mu M are almost equally potent to the standard drug doxorubicin against all examined cell lines and are even less toxic against normal cell line. Graphic abstract Diorganotin(IV) complexes of 4-(4-bromophenyl)thiazol-2-amine and salicylaldehyde derivatives were synthesized. Complex 20 (Ph2SnClL4) is most active antimicrobial agent, and complex 11 (Bu2SnClL2) is most efficient cytotoxic agent against tested human cancerous cell lines.

Automated summary

Organotin(IV) complexes have been synthesized and structurally characterized in this study. The synthesized complexes exhibited significant antimicrobial and cytotoxic activities, with complex 20 showing the highest antimicrobial activity, and complex 11 demonstrating the most efficient cytotoxic activity against tested human cancerous cell lines.