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Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
Hydrogen-bonded networks of [Fe(bpp)2]2+ spin crossover complexes and dicarboxylate anions: structural and
Verónica Jornet-Mollá1, Yan Duan, Carlos Giménez-Saiz
1Instituto de Ciencia Molecular, Universitat de València, P. O. Box 22085, 46071-Valencia, Spain. fmrm@uv.es.
Abstract:
The paper reports the syntheses, crystal structures, thermal and (photo)magnetic properties of spin crossover salts of formula [Fe(bpp)2](C6H8O4)·4H2O (1·4H2O), [Fe(bpp)2](C8H4O4)·2CH3OH·H2O (2·2MeOH·H2O) and [Fe(bpp)2](C8H4O4)·5H2O (2·5H2O) (bpp = 2,6-bis(pyrazol-3yl)pyridine; C6H8O4 = adipate dianion; C8H4O4 = terephthalate dianion). The salts exhibit an intricate network of hydrogen bonds between low-spin iron(ii) complexes and carboxylate dianions, with solvent molecules sitting in the voids. Desolvation is accompanied by a low-spin (LS) to high-spin (HS) transformation in the materials. The dehydrated phase 2 undergoes a two-step transition with a second step showing thermal hysteresis (T1/2↑ = 139 K and T1/2↓ = 118 K). 2 displays a quantitative LS to HS photomagnetic conversion, with a T(LIESST) value of 63 K.
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