Synthesis and antimicrobial evaluation of some new N-pyridinium, quinolinium, and isoquinolinium sulfonate derivatives

GRAPHICAL ABSTRACT ABSTRACT 1,3-propane- and/or 1,4-butane sultone (sultones are internal esters of hydroxyl sulfonic acid) are used as a chemical intermediate to introduce sulfopropyl and/or sulfobutyl groups into heterocyclic molecules and to confer water solubility and anionic character to the molecules. Therefore, the synthesis of three novel functionalized N-sulfonates is described. These sulfonates contain pyridyl (2a–f), quinolyl (4a–m), and isoquinolyl (6a,b) functional groups with potential biological activity. The synthesized quaternary ammonium salts, 3-(2 or 4-arylpyridinium-1-yl)propane or butane-1-sulfonate (2a–f), 3-(alkylquinolinium-1-yl)propane or butane-1-sulfonate (4a–m), and 3-(alkylisoquinolinium-1-yl)propane or butane-1-sulfonate (6a,b), were screened for their antimicrobial and antifungal activities. Among all tested compounds, it was found that compound 4-(4-carboxypyridinium-1-yl)butane-1-sulfonate (2f) showed high activity against Gram-positive bacteria, Gram-negative bacteria, and tested fungi. Most of the compounds showed a moderate degree of antimicrobial activity. The structures of these compounds were confirmed on the basis of their analytical and spectral data (infrared, 1H-NMR and 13C-NMR spectroscopy, and mass spectral data).