Kinetic and Thermodynamic Stabilization of Metal Complexes by Introverted Coordination in a Calix[6]azacryptand

Alex Inthasot, Emilio Brunetti, Manuel Lejeune, Nicolas Menard, Thierry Prangé, Luca Fusaro, Gilles Bruylants, Olivia Reinaud, Michel Luhmer, Ivan Jabin, Benoit Colasson

Research output: Contribution to journalArticle

Abstract

The Huisgen thermal reaction between an organic azide and an acetylene was employed for the selective monofunctionalization of a X6-azacryptand ligand bearing a tren coordinating unit [X6 stands for calix[6]arene and tren for tris(2-aminoethyl)amine]. Supramolecular assistance, originating from the formation of a host–guest inclusion complex between the reactants, greatly accelerates the reaction while self-inhibition affords a remarkable selectivity. The new ligand possesses a single amino-leg appended at the large rim of the calixarene core and the corresponding Zn2+ complex was characterized both in solution and in the solid state. The coordination of Zn2+ not only involves the tren cap but also the introverted amino-leg, which locks the metal ion in the cavity. Compared with the parent ligand deprived of the amino-leg, the affinity of the new monofunctionalized X6tren ligand 6 for Zn2+ is found to have a 10-fold increase in DMSO, which is a very competitive solvent, and with an enhancement of at least three orders of magnitude in CDCl3/CD3OD (1:1, v/v). In strong contrast with the fast binding kinetics, decoordination of Zn2+ as well as transmetallation appeared to be very slow processes. The monofunctionalized X6tren ligand 6 fully protects the metal ion from the external medium thanks to the combination of a cavity and a closed coordination sphere, leading to greater thermodynamic and kinetic stabilities.
Original languageEnglish
Pages (from-to)4855-4862
Number of pages8
JournalChemistry: A European Journal
Volume22
Issue number14
Early online date16 Mar 2016
DOIs
Publication statusPublished - 24 Mar 2016

Keywords

  • calixarenes, coordination chemistry, host–guest systems, selective functionalization, supramolecular chemistry

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    CCDC 1034581: Experimental Crystal Structure Determination

    Inthasot, A. (Contributor), Brunetti, E. (Contributor), Lejeune, M. (Contributor), Menard, N. (Contributor), Prangé, T. (Contributor), FUSARO, L. (Contributor), Bruylants, G. (Contributor), Reinaud, O. (Contributor), Luhmer, M. (Contributor), Jabin, I. (Contributor) & Colasson, B. (Contributor), Cambridge Crystallographic Data Centre, 1 Jan 2016

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    Cite this

    Inthasot, A., Brunetti, E., Lejeune, M., Menard, N., Prangé, T., Fusaro, L., Bruylants, G., Reinaud, O., Luhmer, M., Jabin, I., & Colasson, B. (2016). Kinetic and Thermodynamic Stabilization of Metal Complexes by Introverted Coordination in a Calix[6]azacryptand. Chemistry: A European Journal, 22(14), 4855-4862. https://doi.org/10.1002/chem.201505057