Investigation of hydrogen bonded structure of urea-water mixtures through Infra-red spectroscopy and non-covalent interaction (NCI) theoretical approach

• Published in: Computational and theoretical chemistry Vol. 1199; p. 113218
• Main Authors: Hammami, Ferid, Issaoui, Noureddine, Nasr, Salah
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2021
• Subjects: DFT; Hydrogen bonding; IR spectroscopy; NCI-RDG analysis; Urea-water mixtures; DFT; Urea-water mixtures; IR spectroscopy; Hydrogen bonding; NCI-RDG analysis
• ISSN: 2210-271X
• DOI: 10.1016/j.comptc.2021.113218

Reduced density gradient analysis (RDG) to know weak and strong interaction in urea-(H2O)4 complex. [Display omitted] •NCI-RDG analysis is an important tool to study interactions in biological systems.•H-bonds and van der Waals interactions stabilize urea-water complexes.•IR spectra prove that water structure is feebly perturbed in presence of urea. In the current work, an experimental and theoretical study is performed on the urea-water mixtures by using non-covalent interactions (NCI) and reduced density gradient (RDG) analysis associated to IR spectroscopy. Specific molecular arrangements are formed between urea and water molecules and are stabilized by both hydrogen bonding and strong electrostatic interactions. Experimental IR spectra are collected for different molar urea fractions going from 10% to 60% of the mixture. The harmonic vibrational frequencies of urea-(H2O)n complexes are computed using B3LYP method with 6-311 G++ (d, p) as a basis set and a suitable scale factor is used to yield good coherence with the observed values. Our IR analysis can be interpreted in term of feebly perturbation of the molecular structure of water when urea is added in solutions.