“Antibacterial properties of nine indium(III) complexes of substituted pyrazoles/pyrazolate and the structural and solution characterization of the mer- and trans‑indium(III) complexes of 4-Me-pzH”

Abstract

Two indium(III) complexes of formula mer-[InIIICl3(4-Me-pzH)3] and trans-[InIIICl2(4-Me-pzH)4]Cl·(4-Me-pzH)2·(H2O) were isolated from the same reaction mixture and crystallographically characterized. The two complexes exist in dynamic equilibrium and their dynamic behavior was probed by variable temperature 1H NMR spectroscopy in the 202 to 296 K range. Powder X-ray diffraction of the batch confirmed existence of both complexes in a 1:2 ratio. Antibacterial properties of both new complexes, in addition to seven other previously published indium(III) complexes, were investigated against three Gram-positive and four Gram-negative pathogenic bacterial strains. The results showed potential for the development of indium(III)-based antipseudomonal and antituberculosis drugs, with mer-[InCl3(4-Ph-pzH)3] being especially effective.