Synthesis, characterization, antimicrobial activities and computational studies of some carbamoyl phosphonates

Four carbamoyl phosphonates, namely diethyl p-tolylsulphonyl carbamoyl phosphonate (NA), dimethyl p-tolylsulphonyl carbamoyl phosphonate (NC), dimethyl p-tolyl carbamoyl phosphonate (ND) and dimethyl p-tolylsulphonylmethane carbamoyl phosphonate (NE) were synthesized and characterized using FTIR, 1H- and 13C-NMR. The products were screened in vitro for their growth-inhibitory activity against nine Gram-positive strains, three Gram-negative bacteria strains, and a fungus isolate. Some compounds exhibited broad-spectrum (in vitro) activity against the bacterial strains, and all showed activity against the only fungus used. It was observed that NC showed the highest overall activity against the microorganisms. Density functional theory (DFT) calculations conducted at ωB97XD/def2-TZVP level of theory corroborated the structural conformations of the molecules deduced from spectroscopic analyses. Predicted reactivity indices of the compounds also correlate fairly with the observed biological activities.