Intermolecular interaction study of L-Threonine in polar aprotic Solvent: Experimental and theoretical study

The present paper accounts for the interacting nature of C=O, C-H and O-H vibrational modes of L-Threonine in polar aprotic solvent Dimethyl Formamide(DMF) using Raman spectroscopic and infrared(IR) techniques. The intermolecular interaction between L-Threonine and DMF are analyzed using Density Functional Theory (DFT), IEFPCM and M062X methods, each with a basis set 6-311++G (d, p) to predict the favourable interacting sites of the two molecules and to validate the experimental data with the theoretical calculations. The variation in peak frequencies has been explained for neat L-Threonine and their interactions at different concentrations (0.1 M, 0.3 M, 0.5 M, 0.7 M and 0.9 M). The wavenumbers of all the stretching modes (C=O, C-H and O-H vibrational modes of L-Threonine in polar aprotic solvent Dimethyl Formamide(DMF) using Rama) shows a redshift. The intensity and the topology parameters of the intermolecular hydrogen bond at the bond critical points have been analyzed using the AIM theory of DFT and M062X methods. The intermolecular hydrogen bonding for the mentioned complexes and the study of the surface charge that encompasses the molecular cavity has also been carried out using the IEF-PCM solvation model under the same basis set. Electronic properties such as MEP surface study, frontier orbital analysis, and their corresponding energy gap have also been analyzed using DFT calculation. The frequencies derived from the computational and experimental data are found in good correlation to each other. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This paper explores the interaction of C=O, C-H, and O-H vibrational modes of L-Threonine in polar aprotic solvent DMF using Raman spectroscopy and IR techniques. Density Functional Theory, IEFPCM, and M062X methods are employed to analyze the intermolecular interactions, hydrogen bonding, and electronic properties. The computational frequencies correlate well with experimental data.