Combine experimental and theoretical investigation on an alkaloid–Dimethylisoborreverine

• Conformational analysis and vibrational assignment along with PED has been presented by employing DFT.
• Spectroscopic investigations have been done using FT−IR and 1H/13C NMR.
• Molecular stability and reactive sites of the molecule has been analysed using natural bond orbital (NBO) and MESP plot.
• UV–Vis spectra have been computed on various solvents and analyse their effect on compound.
• Molecular docking has been studied to predict the reactivity on the title molecule.

A combined experimental (FT–IR, 1H and 13C NMR) and theoretical approach is used to study the structure and properties of antimalarial drug dimethylisoborreverine (DMIB). Conformational analysis, has been performed by plotting one dimensional potential energy curve that was computed using density functional theory (DFT) with B3LYP/6–31G method and predicted conformer A1 as the most stable conformer. After full geometry optimization, harmonic wavenumbers were computed for conformer A1 at the DFT/B3LYP/6–311++G(d,P) level. A complete vibrational assignment of all the vibrational modes have been performed on the bases of the potential energy distribution (PED) and theoretical results were found to be in good agreement with the observed data. To predict the solvent effect, the UV–Vis spectra were calculated in different solvents by polarizable continuum model using TD–DFT method. Molecular docking studies were performed to test the biological activity of the sample using SWISSDOCK web server and Hex 8.0.0 software. The molecular electrostatic potential (MESP) was plotted to identify the reactive sites of the molecule. Natural bond orbital (NBO) analysis was performed to get a deep insight of intramolecular charge transfer. Thermodynamical parameters were calculated to predict the direction of chemical reaction.

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