Structural manifestations and biological screening for newly synthesized heteroleptic bismuth(V) bis-carboxylates

Six new heteroleptic tri-organobismuth(V) complexes (1-6), of general formula, R3Bi(OOCR')(2) where R = C6H5 (1-3), p-CH3C6H4 (4-6) and R' represents deprotonated 2-(methylthio)nicotinic acid (1, 4); 3-thiophenecarboxylic acid (2, 5) and 4-chlorosalicylic acid (3, 6) have been synthesized and characterized by FT-IR, NMR (H-1, C-13) and single crystal XRD techniques in addition to elemental analyses. The solid-state structure for 3 has also been elucidated by crystallographic data, manifesting its distorted trigonal bipyramidal molecular geometry with a five-coordinate bismuth center. The carboxylate ligand(s) assume a monodentate coordination mode as predicted by IR and then confirmed by XRD data. The antibacterial, antifungal and antileishmanial potential for 1-6 have been evaluated and the preliminary screening data suggest significant to average biological activities. The antileishmanial activity data manifest comparatively lower IC50 value for 5 than the standard drug. A comprehensive study for 1-6 was also undertaken to testify their stability both in solid and solution phases as well as in leishmanial culture M199, which demonstrate high degree of stability that may ensure their significant antileishmanial effect. The % viability values of the organobismuth(V) bis-carboxylates highlight their role as significantly effective compounds, having potential candidature for future drug discovery and development processes.