Synthesis and biological evaluation of ternary silver compounds bearing N,N-chelating ligands and thiourea: X-ray structure of [{Ag(bpy)(μ-tu)}2](NO3)2 (bpy = 2,2′-bipyridine; tu = thiourea)

Compounds [{Ag(phen)(μ-tu)}2](NO3)2 (1), [{Ag(phen)(μ-tu)}2](CF3SO3)2 (2), [{Ag(bpy)(μ-tu)}2](NO3)2 (3) (where phen = 1,10-phenanthroline; bpy = 2,2′-bipyridine; tu = thiourea) were prepared by reacting the appropriate AgX salt (X− = NO3−, CF3SO3−), the N,N-chelating ligand (phen or bpy) and thiourea in a ca. 1:1:2 M ratio, respectively. The silver(I) complexes were characterized by elemental analysis, infrared (IR), 1H and 13C NMR spectroscopies, MS/ESI and conductivity measurements. The IR and NMR data were consistent with the presence of chelating phen (1 and 2) and bpy (3) ligands and demonstrated the S-coordination mode of thiourea. The crystal and molecular structures of compound [{Ag(bpy)(μ-tu)}2](NO3)2 (3) were determined by single-crystal X-ray diffraction. The complexes 1–3 were screened for their in vitro antimycobacterial (Mycobacterium tuberculosis), antileishmanial (Leishmania (L.) amazonensis), antibacterial (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa), antifungal activities (Candida albicans, Candida tropicalis, Candida krusei).

Graphical abstractThree new ternary silver(I) compounds were synthesised, characterized and had their antimycobacterial, antileishmanial, antifungal and antibacterial activities evaluated. Compound [{Ag(phen)(μ-tu)}2](CF3SO3)2 (2) was very effective against intracellular amastigote of L. amazonensis (IC50 = 4.77 ± 0.33 μM) and exhibited an excellent biological profile, with a selectivity index (SI) range of 15.5–13.8.Figure optionsDownload full-size imageDownload as PowerPoint slide