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E. Felbermair, J. Akbarzadeh, A. Sidorenko, U. Schubert:
"Covalent Embedding Of M2+-Iron(iii) Cyanide Networks In Silica By Sol Gel Processing";
Poster: 14th International Conference on Molecule-based Magnets, Saint Petersburg, Russia; 2014-07-05 - 2014-07-10; in: "The 14th International Conference on Molecule-based Magnets - Book of Abstracts", (2014), ISBN: 978-5-7692-1368-7; 279.

Complexes of Ni2+/Cu2+ with certain polyamine ligands form two-dimensional honeycomb-like structurcs with [Fe(CN)6]3- via Ni2+-NC-Fe3+ bridges. The polyamines block four coordination sites of Ni2+/Cu2+ and thereby favour the 2D arrangement. According to literature [l, 2], these networks exhibit ferromagnetism due to interactions between Ni2+/Cu2+ and Fe3+ ions.
We are studying whether the 2D structure may be embedded in a silica gel by covalently linking without disrupting the previous collocation of the cyanide network. To do so, we introduce trialkoxysilyl groups into the organic blocking ligands and subsequently perform sol-gel reaction. We aim at preserving the magnetic properties during this proecss. The obtained materials are analysed regarding their structure (IR, SEM, SAXS) as well as magnetic susceptibility(SQUID).
First results for [Ni(AEAPTS)2]3[Fe(CN)6]2 (1) in silica show a ferromagnetic behaviour (Figure 2, Figure 1) of the material wilh an effective magnetic moment µeff of 4.46 µB (2.50 emu K mol-1) at room temperature and a maximum of 8.60 µB (9.25 emu K mol-1) at -15 K (µB ... Bohr magneton). The same structure containing Cu2+ is paramagnetic. This is a common trend for similar structures with different polyamine ligands with Ni2+ containing materials exhibiting ferromagnetism while structures with Cu2+ tend to show paramagnetism.

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