Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 40: Poster II: Bio- and Molecular Magnetism (1-9); Magnetic Coupling Phenomena/Exchange Bias (10-15); Magnetic Particlicles and Clusters (16-29); Micro and Nanostructured Magnetic Materials (30-51); Multiferroics (52-64); Spin Injection in Heterostructures (65-67); Spin-Dyn./Spin-Torque (68-93); Spindependent Transport (94-108)
MA 40.22: Poster
Freitag, 27. März 2009, 11:00–14:00, P1A
Tuning the Dimensionality and Magnetic Properties of Mixed Valence Mn(II)/Mn(III) Coordination Polymers — Sudarshana Mukherjee1, Yanhua Lan1, •George Kostakis2, Redolphe Clérac3, Christopher Anson1, and Annie Powell1,2 — 1Institut für Anorganische Chemie der Universität Karlsruhe, Engesserstr. 15, D-76131 Karlsruhe, Germany — 2Institut für Nanotechnologie, Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe, Germany — 3Université de Bordeaux, UPR 8641, Pessac, F-33600, France
Four 3D metal organic frameworks and the 1D coordination polymer have been synthesized. The 3D frameworks of compounds can be described as diamondoid networks. Magnetic studies show that weak MnII-MnIII antiferromagnetic interactions (in the range of -0.55 -0.22 K) mediated by syn-anti carboxylate bridges are present in all compounds. While the 1D coordiantion polymer remains paramagnetic down to 1.8 K, the 3D networks exhibit long-range ferrimagnetic ordering below 7.4 K (1), 4.6 K (2), 3.0 K (3) and 7.7 K for 4. The decrease of the critical temperature reflects the increase of the coordination sphere number around the Mn(II) site from four in 1, five in 2 and six in 3 that lower the bond strength and also the magnetic interactions. This result also reinforces the hypothesis that the structures of 1 and 4 are similar as also suggested by the X-ray analysis.