Regensburg 2013 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 8: Poster I: Glasses and Glass Transition (joint session DY/DF/CPP)
DY 8.14: Poster
Montag, 11. März 2013, 17:30–19:30, Poster C
Dissociation behavior of pyridine coordination compounds in aqueous solutions — •Manuel Gensler1, Christian Eidamshaus2, Artur Galstyan2, Ernst-Walter Knapp2, Hans-Ulrich Reissig2, and Jürgen P. Rabe1 — 1Institut für Physik, Humboldt-Universität zu Berlin — 2Institut für Chemie und Biochemie, Freie Universität Berlin
The pyridine core is ubiquitous in natural products and widely used for the construction of supramolecular structures [1]. We analyzed coordination compounds of mono- and bivalent pyridines with Cu(II) and Zn(II) by SFM based single molecule force spectroscopy (SMFS) in aqueous solutions. Using the Bell-Evans-Kramers model we determined surprisingly long rupture lengths from 0.25 nm for the monovalent pyridin with Cu(II) up to 0.52 nm for the bivalent pyridine with Cu(II). DFT calculations suggest a stepwise dissociation through an intermediate product in which a water ligand inserts in between the pyridine and metal ion. Such process is different to the known solvent-ligand-exchange mechanism of a pyridine-palladium complex in DMSO with a rupture length of only 0.17 - 0.19 nm [2]. Therefore additional water ligands may attribute to the mechanical properties of metallosupramolecular compounds and their corresponding natural systems.
[1] L.E. Kapinos and H. Sigel Inorg. Chim. Acta 2002, 337, 131-142.
[2] F.R. Kersey et al. J. Am. Chem. Soc. 2006, 128, 3886-3887.