Theoretical Investigations of Hydroxymethyl Urea-Water Clusters

The synthesis of urea and its derivatives gave rise to modern organic chemistry and led to a number of important molecules used in many areas of chemistry, from analytical to medicinal. This paper presents the results of a theoretical study of aqueous hydroxymethyl urea (HMEU) clusters. Studies of crystalline hydrates of some organic substances can help in understanding their role in catalysis, hydration, etc. HMEU aqueous clusters in the gas phase were studied within the framework of density functional theory at the B3LYP/6-31+ G (d,p) level and the theory of atoms in molecules. The nature of water and methyl urea molecular interactions via hydrogen bonds has been studied using the electron localization function and noncovalent reduced density gradient. Atoms in Molecules (AIM) analysis was used to determine the relative strength of hydrogen bonds in the aqueous clusters of hydroxymethyl urea. Topological analyses (AIM, NCI, RDG, ELF and LOL) show that O-H∙∙∙O, O-H∙∙∙N and N-H∙∙∙O type hydrogen bonds provide stability to clusters. The energies of such hydrogen bonds vary between 2.23 and 17.95 kcal/mol. The topological parameters (EHB, ρ, and ∇^2 ρ) were found to be a cubic polynomial function of the H-bond length with a high correlation coefficient (R1=0.9923, R2=0.9892 and R3=0.991).