Synthesis, spectral characterisations of 3t-pentyl-2r,6c-diarylpiperidin-4-one oxime picrates: DFT studies and potent anti-microbial agents

In this paper, various substituted 3t-pentyl-2r,6c-diarylpiperidin-4-one oxime picrates were synthesised and characterised by elemental analysis, FT-IR, NMR, UV–Visible and Fluorescence spectral techniques. For compound 1, NMR spectral assignments were made unambiguously by their one-dimensional (1H and 13C NMR) and two-dimensional (1H–1H COSY, NOESY, HSQC and HMBC) spectra. The observed chemical shifts and coupling constants suggest that compounds 1–7 adopt normal chair conformation with the equatorial orientation of all the substituents like aryl group at C(2) and C(6) and pentyl group at C(3). Compounds 2 and 7 exhibited potent anti-bacterial activity and fungal activity against all the tested strains while all the other compounds showed moderate activity. The molecular structure of compounds (1–7) was optimised at the density functional theory (DFT)/B3LYP/6-311++G(d,p) level of basis set. The calculated first hyperpolarisability (β0) values show that all the molecules might have non-linear optical (NLO) behaviour. The HOMO–LUMO transition implies that intra-molecular charge transfer takes place within the molecule. The molecular electrostatic potential (MEP) surface is used to understand the reactive sites of a molecule.</p

Synthesis, spectral characterisations, biological evaluation, DFT calculation and molecular docking analysis of 3,5-diethyl-2,6-di(2-bromophenyl)piperidin-4-one picrate with topological indices studies

The 3,5-diethyl-2,6-di(2-bromophenyl)piperidin-4-one picrates (3,5-DEBPP) compound was synthesised and characterised by spectral techniques. The title molecule adopt a normal chair conformation with all of its substituents, such as the bromophenyl group at positions C-2 and C-6 and the ethyl group at locations C-3 and C-5, orientated equatorially, according to the measured chemical shifts and coupling constants. The DFT/B3LYP/6-311++G(d,p) basis set was used to optimise the molecular structure. The non-linear optical behaviour of the material was assessed by computing the first order hyperpolarisability. Using NBO analysis, it was determined whether the molecule's stability as a result of hyper conjugative interactions and charge delocalisation was satisfactory. The HOMO and LUMO values were used to compute the physico-chemical parameters. The electrophilic and nucleophilic attack of the current molecule is visible on the MEP surface. The Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Vibreo cholerae, Pseudomonas aeruginosa, Candida albicans, Aspergillus niger, Aspergillus flavus and Trichophyton rubrum were among the bacterial strains that the 3,5-DEBPP was tested against. Docking investigations were thoroughly conducted to establish knowledge regarding the interactions between protein and this new chemical theoretically. Structure-based topological indices enable prediction of chemical properties and the bioactivities of this compound through quantitative structure–activity and structure–property relationships methods.</p