Bismuth(III) Thiobenzoates and their Activity against Helicobacter pylori

Abstract

Two new substituted thiobenzoic acids, m-nitrothiobenzoic and m-sulfothiobenzoic acid, and six (four new) homo- and heteroleptic bismuth(iii) compounds derived from thiobenzoic acid and substituted thiobenzoic acid have been synthesised and fully characterised using both solvent free and solvent mediated methods; Bi(SC(=O)C6H5)3 (3), PhBi(SC(=O)C6H5)2 (4), Ph2Bi(SC(=O)C6H5) (5), Bi(SC(=O)C6H4-m-NO2)3 (6), PhBi(SC(=O)C6H4-m-NO2)2 (7), and PhBi(SC(=O)C6H4-m-SO3) (8). The solid-state structures of the previously reported Bi(SC(=O)C6H5)3 (3) and PhBi(SC(=O)]C6H5)2 (4) complexes have now been confirmed by X-ray crystallography. In the solid-state complex 3 forms a column-like polymeric structure resembling stacked bowls through pyramidal intermolecular Bi–S3 bonds of distance 3.359 Å, providing a Bi(iii) centre with a nine coordinate environment. Complex 4 forms discrete tetrameric units cemented by long intermolecular Bi–S (3.774 Å), Bi–O(= C) (3.030, 3.071 Å) and Bi–C bonds (3.627 Å). The complexes were assessed for their activity against three strains of Helicobacter pylori and all show a minimum inhibitory concentration of 6.25 µg mL–1, indicating that the high level of bactericidal activity is insensitive to the degree of substitution at the Bi(iii) centre.