Self-assembly mechanism of a bimetallic europium triple-stranded helicate.
We report the self-assembly process of a supramolecular edifice based on the coordination of europium(III) by a ditopic strand L bearing tridentate bis(benzimidazolyl)pyridine subunits. Varying the metal/ligand ratio and using a fruitful combination of electrospray mass spectrometry and absorption spectrophotometry, we characterized three major complexes (EuL(2), Eu(2)L(2), and Eu(2)L(3)) in acetonitrile. Kinetic investigations showed an alternative "braiding" and "keystone" mechanism leading to Eu(2)L(3). The formation mechanism of the dinuclear triple-stranded helicate, which is mainly governed by electrostatic interactions, goes via the "side-by-side" Eu(2)L(2) intermediate. Our thermodynamic and kinetic data allow the prediction of the apparent "magic" self-assembly of Eu(2)L(3) which is fast and efficient only under a strict set of conditions.
Hamacek
Josef
J
Laboratoire de Physico-Chimie Bioinorganique, UMR 7509 du CNRS, ECPM, Université Louis Pasteur, 25 rue Becquerel, 67200 Strasbourg, France.
Blanc
Sylvie
S
Elhabiri
Mourad
M
Leize
Emmanuelle
E
Van Dorsselaer
Alain
A
Piguet
Claude
C
Albrecht-Gary
Anne-Marie
AM