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Science 26 February 1993:
Vol. 259. no. 5099, pp. 1302 - 1305
DOI: 10.1126/science.8446898
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Articles

Science, Vol 259, Issue 5099, 1302-1305
Copyright © 1993 by American Association for the Advancement of Science

articles

A mixed-valent polyiron oxo complex that models the biomineralization of the ferritin core

KL Taft, GC Papaefthymiou, and SJ Lippard

Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139.

A novel polyiron oxo complex, [FeIII4FeII8(O)2(OCH3)18(O2CCH3)6(CH3OH) 4.67] (1), has been prepared from ferrous acetate and lithium methoxide in methanol by slow addition of dioxygen. The three-dimensional close-packed layered structure found in 1 closely mimics that proposed for the inorganic core in the iron storage protein ferritin. The Mossbauer spectra of 1 reveal superparamagnetic relaxation at temperatures below 15 K, a property characteristic of the ferritin core. The small size and mixed-valent nature of 1 suggest that it is a reasonable model for intermediates formed in the biomineralization of iron during ferritin core formation. A related compound, with the same iron-oxygen framework found in 1 but containing only two ferric ions, has also been structurally characterized. Because the clusters exhibit properties of both discrete molecules and extended solids, they are representative of a new class of nanometer-sized compounds that bridge the molecular solid-state boundary.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Large Clusters of Metal Ions: The Transition from Molecular to Bulk Magnets.
D. Gatteschi, A. Caneschi, L. Pardi, and R. Sessoli (1994)
Science 265, 1054-1058
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Metalloenzymes, structural motifs, and inorganic models.
K. Karlin (1993)
Science 261, 701-708
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Transition metals in control of gene expression.
T. O'Halloran (1993)
Science 261, 715-725
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