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- Title
The Valence and Spin State Tuning of Iron(II/III) Porphyrazines with Bulky Pyrrolyl Periphery in Solution and Solid State.
- Authors
Koczorowski, Tomasz; Szczolko, Wojciech; Bakun, Pawel; Wicher, Barbara; Sobotta, Lukasz; Gdaniec, Maria; Teubert, Anna; Mielcarek, Jadwiga; Tykarska, Ewa; Korecki, Jozef; Burda, Kvetoslava; Goslinski, Tomasz
- Abstract
Iron(III) porphyrazines containing peripheral 2,5-dimethyl-, 2-methyl-5-phenyl-, and 2,3,5-triphenyl-1H-pyrrol-1-yl substituents were synthesized and subjected to physicochemical characterization. This was accomplished by high-resolution mass spectrometry, nuclear magnetic resonance (as diamagnetic Fe(II) derivatives), HPLC purity analysis, and UV-Vis spectroscopy, accompanied by the solvation study in dichloromethane and pyridine. X-ray structure analysis was performed for a single crystal of the previously obtained 2,5-diphenyl-substituted derivative of porphyrazine complex (5d). The octahedral geometries of iron cation, present in the porphyrazine core, influenced the packing mode of molecules in the crystals. Mössbauer studies, performed for solid samples of iron porphyrazines, indicated that low-spin reduced iron states might occupy low- or high-symmetry binding sites. It was found that the hyperfine parameters and the subsequent contribution of the iron cations depend on the number of phenyl groups surrounding the pyrrolyl moiety. For iron(II) porphyrazine 2,3,5-triphenylpyrrol-1-yl substituents (5b), a high-spin ferrous state fraction was observed. Temperature-dependent measurements showed that the freed rotation of the peripheral porphyrazine ligands and the increased flexibility of the macrocycle ring result in the Fe2+ ion being stabilized in a diamagnetic state at a binding site of high symmetry at room temperature in the solid state. This process is most probably stimulated by the range of collective motions of the polymeric ribbons consisting of iron(II) porphyrazines observed in the X-ray.
- Subjects
SOLID solutions; NUCLEAR magnetic resonance spectroscopy; PORPHYRAZINES; NUCLEAR magnetic resonance; IRON; HYPERFINE interactions; MOSSBAUER effect; SPIN crossover
- Publication
Molecules, 2022, Vol 27, Issue 22, p7820
- ISSN
1420-3049
- Publication type
Article
- DOI
10.3390/molecules27227820