A comparative molecular dynamics study on the complexation of alkali metal cations by a poly-ethylene-glycol type podand in water and in dichloromethane

• Type: Article in International Scientific Journal
• Date: 2010

Authors

Mario Valente (Author) Other; Sergio Filipe Sousa (Author) FCUP; Magalhaes, AL (Author) FCUP; Cristina Freire (Author) FCUP

Journal

Title: Journal of Molecular Structure: THEOCHEM

Vol. 946

Pages: 77-82

ISSN: 0166-1280

Publisher: Elsevier B.V.

Indexing

ISI Web of Knowledge - 6 Citations

Scopus - 7 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-003-7CX

DOI: 10.1016/j.theochem.2009.10.025

Abstract (EN): Molecular dynamics (MD) was used to study the complexation of the alkali metal cations (Li(+), Na(+), K(+), Rb(+) and Cs(+)) by a poly-ethylene-glycol type podand with eight potential donor oxygen atoms, in water and dichloromethane. MD simulations for the free podand in water provided evidence for a solvent driven stabilizing effect of certain conformations. The complexes in water proved to be unstable as they all dissociated well within the simulation time used. In contrast, the complexes proved to be stable in the organic solvent. Analysis of the MD trajectories for the complexes in dichloromethane showed: (i) an enlargement of the podand DC-CO dihedral angles as the cation size increases: (ii) an increase of the number of strong interactions between the oxygen atoms as the cation size increases; (iii) a considerable degree of solvent penetration into the inner coordination sphere from the potassium to cesium complexes. Quantum calculations showed a higher energetic destabilization for the lithium and sodium complex forms. The results support the experimental evidence that the extraction efficiency shown by this podand (from water to dichloromethane) is higher for potassium, rubidium and cesium than for lithium or sodium.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6