The effect of water solvation on the structure and stability of cyclic dimers of urea has been investigated with the aid of density functional theory at the B3LYP/ 6-311 + + G** level. Several hydration models have been discussed. Specific solvent effects have been simulated through single and multiple water - urea interactions involving all the hydration sites of urea. The bulk solvent effects have been estimated through polarised continuum models. Under all the hydration patterns cyclic dimers continue to be stable structures although the solvent weakens the urea - urea interaction. Single and multiple specific urea - water interactions are competitive with urea dimerisation. The anticooperative nature of the two intermolecular interactions is largely due to the changes on sigma- and pi- electron density of urea caused by hydrogen bonding with water. The stability of the dimer is however, lost within a few ps when the hydrated dimer is described by a quantum mechanical molecular dynamics approach (ADMP). The cyclic dimer evolves towards structures where urea molecules are linked not more directly but through water molecules which have a bridge function.

Dimerisation of urea in water solution: a quantum mechanical investigation

CAMINITI, RUGGERO;GONTRANI, LORENZO
2007-01-01

Abstract

The effect of water solvation on the structure and stability of cyclic dimers of urea has been investigated with the aid of density functional theory at the B3LYP/ 6-311 + + G** level. Several hydration models have been discussed. Specific solvent effects have been simulated through single and multiple water - urea interactions involving all the hydration sites of urea. The bulk solvent effects have been estimated through polarised continuum models. Under all the hydration patterns cyclic dimers continue to be stable structures although the solvent weakens the urea - urea interaction. Single and multiple specific urea - water interactions are competitive with urea dimerisation. The anticooperative nature of the two intermolecular interactions is largely due to the changes on sigma- and pi- electron density of urea caused by hydrogen bonding with water. The stability of the dimer is however, lost within a few ps when the hydrated dimer is described by a quantum mechanical molecular dynamics approach (ADMP). The cyclic dimer evolves towards structures where urea molecules are linked not more directly but through water molecules which have a bridge function.
2007
INITIO MOLECULAR DYNAMIC; AQUEOUS URE; AB INITIO; GAUSSIAN ORBITALS; DENSITY MATRIX; GUANIDINIUM CHLORIDE; ENERGY DECOMPOSITION; HYDROGEN BOND; THERMODYNAMICS; SIMULATION
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/87441
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? 2
  • Scopus 36
  • ???jsp.display-item.citation.isi??? 36
social impact