COMPUTATIONAL STUDY OF A TERPHENYL-BASED EU3- EFFECT OF SMALL AMOUNTSOF WATER( COMPLEX )

Citation
Fcjm. Vanveggel et al., COMPUTATIONAL STUDY OF A TERPHENYL-BASED EU3- EFFECT OF SMALL AMOUNTSOF WATER( COMPLEX ), The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 102(18), 1998, pp. 3060-3066
Citations number
42
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry Physical
ISSN journal
1089-5639
Volume
102
Issue
18
Year of publication
1998
Pages
3060 - 3066
Database
ISI
SICI code
1089-5639(1998)102:18<3060:CSOATE>2.0.ZU;2-N
Abstract
The shielding properties of the terphenyl-based complex L . Eu3+ in me thanol solution have been studied by computer simulations with an emph asis on the influence of small amounts of water on the shielding prope rties. The theoretical studies were carried out in explicit solvent mo dels by molecular mechanics and dynamics simulations (up to 2000 ps), Monte Carlo free energy perturbations, and a potential of mean force c alculation. In dry methanol solutions, complex L . Eu3+ is predicted t o have one methanol coordinated to the Eu3+. Th, presence of 1.0 +/- 0 .5 OH groups (from methanol) is in agreement with fluorescence measure ments, Millimolar concentrations of water lead to a monohydrated compl ex and possibly to a dihydrated complex. At these concentrations of wa ter in the methanol solutions of L . Eu3+, the luminescence intensitie s decrease, which supports the conclusion that one and possibly two wa ters are preferentially coordinated to the Eu3+ ion. This study also s hows that molecular dynamics runs of 1 ns or more are needed to allow major transitions in the first coordination sphere of Eu3+ to occur, b ut even simulations up to 2 ns do not guarantee that the global energy minimum is calculated.