Spin-switchable Hofmann-type Fe(II)-networks based on M(CN)4 (M=Ni, Pd, Pt) as square planar building block and a ditopic N-heterocycle as e.g. pyrazine, 4,4’-bipyridine,… combine magnetism with host-guest chemistry. Methods for introduction of complementary properties such as luminescence, magnetism or host-guest chemistry into spin-switchable metal organic frameworks involve the proper selection of the building blocks, as well as suitable design of pore structure and diameter. A second generation of extended Hofmann-type networks was obtained by introduction of an acetylene-unit in the M-CN bond (fig.1), resulting in metallated tetrakis(cyanoacetylides) as expanded building blocks. Thereby, not only a notable increase in pore volume of about 120 % was achieved, but the polarity of the PCP’s inner surface could also be modified. This enables incorporation of larger guest molecules as e.g. small fluorophores. For the growth of single-crystals a novel electrolytic crystallization approach was developed, providing the necessary Fe(II)-ions by anodic oxidation of Fe in a non-aqueous medium (fig.2). In the contribution the second generation of bimetallic Fe-M, (M=Ni, Pd, Pt) Hofmann-type networks is presented and discussed with regard to its structural, magnetic and spectroscopic properties. The special emphasis of this contribution is placed on the host-guest chemistry of the networks, as governed by the extended pores bearing alkyne-moieties.

Spin-switchable Hofmann-type networks based on tetrakis(cyanoacetylides): Larger pores for larger guests

2019 Spring National Meeting

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