Experimental and computational investigation of Z/E isomerism, X-ray crystal structure and molecular docking study of (2-(hydroxyimino)cyclohexyl)diphenylphosphine sulfide, a potential antibacterial agent

•The structure of a novel thiophosphoryl oxime was studied by FT-IR, NMR and XRD.•The title compound equilibrates in solution to give a mixture of E and Z isomers.•Nitrogen inversion is the most probable mechanism for Z/E isomerization.•DFT calculations predicted better antibacterial activity for the Z isomer.•Molecular docking in EcFabH enzyme showed high inhibitory effect for the Z isomer. (2-(hydroxyimino)cyclohexyl)diphenylphosphine sulfide [C18H20NOPS (2)] is a novel oxime derivative that has been identified, in a recent work from our group, as a potential antibacterial agent. Herein, we report the in-depth structural analysis of compound (2) by using various spectroscopic tools including FT-IR, NMR (1H, 31P, 13C), mass spectrometry and single crystal X-ray diffraction, which indicate that it is obtained as a mixture of Z and E isomers. The different mechanisms, inversion, rotation, or mixed inversion-rotation, by which could occur the Z/E isomerization, have been investigated computationally with DFT method. Total and frontier molecular orbitals energies for both isomers were derived in order to gain more insights into their relative stabilities and biological activities. In silico molecular docking studies in E. coli FabH enzyme active site were also performed to predict the possible interaction modes and binding energies for both Z and E isomers as compared with those of a reference FabH inhibitor. [Display omitted]