INVESTIGADORES
PERUCHENA Nelida Maria
artículos
Título:
Preferential Formation of the Different Hydrogen Bonds and Their Effects in Tetrahydrofuran and Tetrahydropyran Microhydrated Complexes
Autor/es:
VALLEJOS, MARGARITA; PERUCHENA, N. M.
Revista:
JOURNAL OF PHYSICAL CHEMISTRY A
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2012 vol. 116 p. 4199 - 4210
ISSN:
1089-5639
Resumen:
The
role of cycloether−water
(c−w) and water−water
(w−w) hydrogen bonds (H-bonds) on the stability of the tetrahydrofuran
THF/(H2O)n and the tetrahydropyran THP/(H2O)n complexes with n = 1−4 was investigated herein
using the density functional and ab initio methods and the atoms in molecules
theory. Geometry optimizations for these complexes were carried out with
various possible initial guess structures. It was revealed that the major
contributions of the mono and dehydrated complexes came from c−w H-bonds. A competition between c−w and w−w H-bonds contribution was
observed for trihydrated complexes. For most of tetrahydrated complexes, the
inter-water H-bonds provided the greatest contribution, whereas the c−w contributions were small but not negligible. It was confirmed that to produce a hydrophobic hydration of cycloethers, the C−H···Ow H-bond should be associated with a network of H-bonds that connects both
portions of the solute, through the formation of a bifunctional H-bond. A
linear correlation is obtained for the sum of electron density at the bond
critical points (ñb) with the interaction
energy (ÄE)
and with the solute−solvent
interaction energy (ÄEs−w) of the microhydrated
complexes. In addition, a new way to estimate the energetic contribution as
well as the preferential formation of the different H-bonds based completely on ñb was found. Even more, it
allows to differentiate
the contribution from c−w
interactions in both hydrophilic and hydrophobic contributions, it is therefore
a useful tool for studying the hydration of large biomolecules. The analysis of
the modifications in the atomic and group properties brought about by successive
addition of H2O molecules allowed to pinpoint the atoms or molecular groups that
undergo the greatest changes in electron population and energetic
stabilization. It was identified that the remarkable stabilization of the water oxygen atoms is
crucial for the stabilization of the complexes.