Structure of N ′ -(adamantan-2-ylidene)benzohydrazide, a potential antibacterial agent, in solution: Molecular dynamics simulations, quantum chemical calculations and Ultraviolet–visible spectroscopy studies

The molecular dynamics simulations of the structure of the N ′ -(adamantan-2-ylidene) benzohydrazide followed by the quantum chemical calculations at the DFT level of theory have identified four stable conformers of this potential antibacterial agent in solution: one “central” cis - and three (“central”, “left” and “right”) trans -conformers. The UV-Vis absorption spectrum in the 220–320 nm region in the ethanol solution reveals two bands that can be primarily explained based on the ab initio calculations of the spectral characteristics of the “side” trans -conformers at the MRPT level of theory. However, the close energy values for the calculated cis - S 1 ← S 0 and “side” trans - S 2 ← S 0 transitions cannot exclude the presence of cis -conformer in solution. Therefore, the data obtained show that the coexistence of both trans -conformers and cis -conformer should be taken into consideration when studying the pharmaceutical properties of the title molecule. Graphical Abstract Results of theoretical and experimental studies of the N ′ -(adamantan-2-ylidene)benzohydrazide, a newly synthesized potential antibacterial agent. We have calculated the structures and UV-Vis spectra for four conformers of the title molecule at the DFT and MRPT levels of theory. Our calculations for the “side” trans -conformers were found to describe the two observed UV-Vis absorption bands in the ethanol. The study is valuable for spectroscopists since adamantane-containing molecules are important for applications in the pharmaceutical chemistry.