[Zurück]

E. Felbermair, A. Sidorenko, J. Akbarzadeh, H. Peterlik, S. Paschen, U. Schubert:
"Ni²⁺-Fe³⁺ Cyanometallates exhibiting intriguing magnetic properties covalently embedded in silica by sol-gel processing";
Vortrag: Fourth International Conference on Multifunctional, Hybrid and Nanomaterials, Sitges, Spain; 09.03.2015 - 13.03.2015; in: "Fourth International Conference on Multifunctional, Hybrid and Nanomaterials - Programme Book", Elsevier, (2015), S. OB1.13.01.

Cyanometallate networks of [Ni(polyamine)_n]²⁺ and [Fe(CN)₆]³⁺ often exhibit ferromagnetism caused by interactions between Ni2+ and Fe³⁺ through the cyanide bridges Fe-CN-Ni. [1, 2] In these structures the polyamine ligands block coordination sites of Ni²⁺ and thereby favour a low dimensional (1D or 2D) arrangement of the cyanometallates.
We are studying whether the cyanometallate structures can be embedded in silica by covalently tethering them to the silica matrix, without disrupting the previous collocation of the cyanometallate network and thus preserving its magnetic properties. To this end, we introduce trialkoxysilyl groups into the organic blocking ligands and subsequently perform sol-gel reaction. The obtained materials are analysed regarding their structure (IR, SEM, SAXS, powder XRD) as well as magnetic susceptibility (SQUID).
Results for [Ni(AEAPTS)₂]₃[Fe(CN)₆]₂ in silica show magentic ordering below ~22 K indicating ferromagnetism. The effective magnetic moment μ_eff is 4.46 μ_B at room temperature and 8.60 μ_B at the maximum at ~15 K (μ_B ... Bohr magneton). [3] Similar compounds with 2,3,2-tetramine, with one or two dangling trialkoxysilyl groups, (Fig. 1) as blocking ligands show similar magnetic behaviour at high temperature, but no magnetic ordering at low temperature.

Projektleitung Ulrich Schubert:
Sol-Gel Prozesse mit vor-organisierten Metall-Alkoxid-Vorstufen