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Mixed valence state in ironporphyrin aggregates
K Burda1, A Hrynkiewicz, H Kołoczek
1Institute of Nuclear Physics, Cracow, Poland.
Biochimica Et Biophysica Acta
|June 9, 1995
Summary
This study investigates iron coordination in ironporphyrins, revealing temperature-dependent electron transfer and iron valence states. Findings suggest metalloporphyrin aggregation influences these processes.
Area of Science:
- Biochemistry
- Materials Science
- Physical Chemistry
Background:
- Metalloporphyrins are crucial for biological energy and electron transfer.
- Understanding iron coordination effects on electron transfer is vital.
Purpose of the Study:
- To investigate the influence of ligands and iron coordination on electron transfer in ironporphyrins.
- To characterize the behavior of ironporphyrins using Mössbauer spectroscopy.
Main Methods:
- Mössbauer spectroscopy was employed to study lyophilized ironporphyrin (enriched to 90% 57Fe) across a temperature range of 2.8 K to 313 K.
Main Results:
- Above room temperature, bounded diffusion of ferric iron was observed.
- Below 293 K, a mixed Fe+3<==>Fe+2 valence state emerged with 10 meV activation energy for electron trapping.
- Below 4 K, magnetic ordering was detected with a broad hyperfine field distribution.
Conclusions:
- The observed temperature-dependent phenomena are discussed in the context of metalloporphyrin aggregation.
- Iron coordination and ligand environment significantly impact electron transfer dynamics in ironporphyrins.