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X‐Ray Near‐Edge Absorption Study of Temperature‐Induced Low‐Spin‐to‐High‐Spin Change in Metallo‐Supramolecular Assemblies |
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| Authors: | Dr Bahia Arezki Dr Guntram Schwarz Dr Yves Bodenthin Dr Dirk Luetzenkirchen‐Hecht Dr Christian Markert Dr Ralph Wagner Prof Ronald Frahm Prof Dirk G Kurth Prof Ullrich Pietsch |
| Institution: | 1. Physics Department, Universtiy of Siegen, Walter‐Flex Str. 3, 57072 Siegen (Germany), Fax: (+49)?271‐740 37 63;2. Chemical Technology of Advanced Materials, University of WürzburgD‐97070 Würzburg (Germany);3. LDM, NUM Department, Paul Scherrer Institute, CH‐5232 Villigen‐PSI, Switzerland;4. Physics Department, Bergische University of Wuppertal, Gau?stra?e 20,D‐42097 Wuppertal (Germany) |
| Abstract: | X‐ray absorption near the iron K edge (XANES) was used to investigate the characteristics of temperature‐induced low‐spin‐to‐high‐spin change (SC) in metallo‐supramolecular polyelectrolyte amphiphile complexes (PAC) containing FeN6 octahedra attached to two or six amphiphilic molecules. Compared to the typical spin‐crossover material Fe(phen)2(NCS)2 XANES spectra of PAC show fingerprint features restricted to the near‐edge region which mainly measures multiple scattering (MS) events. The changes of the XANES profiles during SC are thus attributed to the structure changes due to different MS path lengths. Our results can be interpreted by a uniaxial deformation of FeN6 octahedra in PAC. This is in agreement with the prediction that SC is originated by a structural phase transition in the amphiphilic matrix of PAC, but in contrast to Fe(phen)2(NCS)2, showing the typical spin crossover being associated with shortening of all the metal–ligand distances. |
| Keywords: | bis‐terpyridine ligands iron(II) complexes molecular magnetism spin crossover X‐ray absorption spectroscopy |