Self-assembly, structure and solution dynamics of tetranuclear Zn2+ hydrazone [2x2] grid-type complexes.
Fiche publication
Date publication
février 2006
Auteurs
Membres identifiés du Cancéropôle Est :
Pr LEHN Jean-Marie
Tous les auteurs :
Barboiu M, Ruben M, Blasen G, Kyritsakas N, Chacko E, Dutta M, Radekovich O, Lenton K, Brook DJR, Lehn JM
Lien Pubmed
Résumé
We describe the self-assembly processes as well as the structural and physico-chemical properties of [2x2]Zn2(4)(+) grid complexes involving the bis-tridentate ligands 7-12, based on bis(hydrazone)pyrmidine complexation subunits and octahedrally coordinated Zn2+ ions. The NMR spectroscopic data and the X-ray crystal structure results indicate that in solution and in the solid state the complexes 13-18 adopt a very compact arrangement providing stable [2x2] hydrazone-grid arrays. The pi-pi stacking between the phenyl ring and the hydrazone units of the perpendicular ligands in the complexes induces a perfect orthogonal arrangement suitable for applications in self-organized metallosupramolecular systems. Zinc complexes provide an opportunity to study the acid-base chemistry without the added effects due to paramagnetism or redox chemistry. The intermediate protonated grids undergo relatively rapid proton exchange on the NMR timescale, the presence of a sharp pyrimidine proton resonance suggesting that there is significant delocalization of the negative charge along the backbone of the ligand. Rotation of the phenyl ring is observed. It involves probably a mechanism in which one of the ligands partially dissociates allowing the initially intercalated phenyl group to rotate, before recoordination of the terminal pyridine. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).
Référence
Eur J Inorg Chem. 2006 Feb 20;4:784-92.