Synthesis, crystal structure, DFT and biological activity of E-pyrene-1-carbaldehyde oxime and E-2-naphthaldehyde oxime

Abstract

The aldoximes E-pyrene-1-carbaldehyde oxime 1 and E-2-naphthaldehyde oxime 2 were synthesized, in ca. 90% yield, by treatment of pyrene-1-carbaldehyde or 2-naphthaldehyde, respectively, with hydroxylamine hydrochloride and sodium carbonate in MeOH. Compounds 1 and 2 were characterized by IR, 1H and 13C{1H} NMR spectroscopies, elemental analyses and single crystal X-ray diffraction (in the case of 1). The studied system (compound 1) showed significant amounts of H⋯H (44.4%), C⋯H (25.4%) and C⋯C (13.3%) intermolecular interactions in addition to the short N⋯H (5.9%) and O⋯H (6.2%) intermolecular interactions. These interactions affect the molecular packing of the studied system in the crystal. The structure of 1 was optimized using DFT calculations and the calculated structure was found to well agree with the reported X-ray structure. Moreover, compound 1 is polar with dipole moment of 0.764 Debye using B3LYP/6-311G(d,p) method. The antimicrobial activities of the newly synthetized oximes 1 and 2 and the previously reported E-1-naphthaldehyde oxime 3 and E-9-phenanthrenecarboxaldehyde oxime 4 were examined against various pathogenic microbes. The oximes 1 and 3 were recorded to be the most effective oximes as antimicrobial agents against the tested microorganisms. The increase of compound concentration lead to a higher antimicrobial activity and an increase of K+ flow from the microorganism.