Interaction of CUn, Agn and AUn (n=1-4) nanoparticles with ChCl:Urea deep eutectic solvent

In this study, the interaction of noble metal nanoparticles (M-n, M = Cu, Ag, and Au; n = 1-4) with ChCl:Urea deep eutectic solvent was investigated using density functional theory (DFT) method. We find that ChCl:Urea mostly interact with the M-n nanoparticles through [Cl](-) anion ([Cl]M--(center dot center dot center dot)n) and nonconventional H-bonds of C-H center dot center dot center dot M-n and N-H center dot center dot center dot M-n. NBO, QTAIM, NCI and EDA analyses show that [Cl]M--(center dot center dot center dot)n interactions are stronger than the nonconventional H-bonds interactions. Our results indicate that the nature of [Cl]M--(center dot center dot center dot)n interactions is electrostatic, while the nonconventional H-bonds of C-H center dot center dot center dot M-n and N-H center dot center dot center dot M-n are van der Waals in nature. The negative values of enthalpy (Delta H) and free energy (Delta G) for the ChCl:Urea(center dot center dot center dot)M(n) complexes reveal that the formation of ChCl:Urea(center dot center dot center dot)M(n) complexes is exothermic and proceeds spontaneously. The calculation of binding energy (Delta E-b) of M-n nanoparticles with ChCl:Urea shows that the strength of interaction of Au-n nanoparticles with ChCl:Urea is more favorable than Cu-n and Ag-n, following the order ChCl:Urea(center dot center dot)center dot Au-n > ChCl:Urea(center dot center dot center dot)Cu(n) > ChCl:Urea(center dot center dot center dot)Ag(n). Furthermore, the Delta E-b, Delta H and Delta G values enhance with increasing nanoparticle size from n = 1 to n = 4, ChCl:Urea(center dot center dot center dot)M(4) > ChCl:Urea(center dot center dot center dot)M(3) > ChCl:Urea(center dot center dot center dot)M(2) > ChCl:Urea(center dot center dot center dot)M(1) (M Cu, Ag, and Au). (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

This study investigated the interaction of noble metal nanoparticles with ChCl:Urea deep eutectic solvent using density functional theory. It was found that the ChCl:Urea interacted with the nanoparticles mainly through anions and nonconventional hydrogen bonds, with larger nanoparticles exhibiting stronger interactions.