Factors influencing the binding of a potassium cation to a polyethylene glycol type podand in liquid-liquid extraction-a molecular dynamics study

• 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: Theoretical Chemistry Accounts

Vol. 127 No. 5

Pages: 681-687

ISSN: 1432-881X

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 4 Citations

Scopus - 4 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-003-1RV

DOI: 10.1007/s00214-010-0778-7

Abstract (EN): The potassium cation complexation using a potentially octadentate polyethylene glycol type podand (1,2-bis-{2-[2-(2-metoxy-etoxi)-etoxy]-etoxy}-benzene, hereafter b33) in an organic (dichloromethane) phase is studied by molecular dynamics (MD). Specifically, the influence of the picrate (2,4,6-trinitrophenolate) anion and of water molecules on the complexation of K(+) by b33 is analyzed. The results point out to a strong influence of the picrate anion on the K(+) complexation as this anion competes with the podand for the cation, reducing its mean denticity (here defined as the number of strong interactions established between the cation and the podand oxygen atoms, e.g. with inter-atomic K(+)-O distances less than 4 angstrom) from 8 to c.a. 7. The presence of a water micro-droplet (comprising twelve water molecules) exerts a stronger effect on the podand mean denticity, reducing it to c.a. 5. The simultaneous presence of a picrate anion and the water micro-droplet dramatically reduces the podand denticity toward the cation to c.a. 2. When present, the water molecules effectively bind K(+), and it is the hydrated cation that is complexed: the podand becomes the second coordination sphere by establishing hydrogen bonds with the first coordination sphere of water molecules. In some simulations, pi-stacking between the picrate anion and the podand aromatic ring was observed, as was, in others, the formation of "water fingers".

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7