title: Multi-frequency high-field EPR study of iron centers in malarial pigments.
abstract: The multi-frequency high-field electron paramagnetic resonance (HFEPR) was used to study the magnetic properties of malarial pigment hemozoin and its synthetic analogue, beta-hematin. (FeIII-protoporphyrin-IX)2 dimers containing five-coordinate high-spin FeIII, S = 5/2, are the building blocks of these pigments. The fit of EPR spectra that were acquired in an unprecedented wide range of microwave frequencies of 34 and 94 GHz for hemozoin and 27-500 GHz for beta-hematin yielded a complete set of intrinsic spin Hamiltonian parameters: D = +5.85(1) cm-1, E = 0, g perpendicular = 1.95(1), g parallel = 2.00(1). These results point to the existence of largely axial symmetry of the iron environment in the bulk phase of hemozoin and beta-hematin.
authors.affiliation: Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Sienkiewicz
authors.forename: J
authors.initials: J
authors.lastname: Krzystek
authors.forename: Bertrand
authors.initials: B
authors.lastname: Vileno
authors.forename: Guillaume
authors.initials: G
authors.lastname: Chatain
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Kosar
authors.forename: D Scott
authors.initials: DS
authors.lastname: Bohle
authors.forename: Laszló
authors.initials: L
authors.lastname: Forró
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000737:chemistry*; D006420:Hemeproteins / Q000737:chemistry*; D010860:Pigments, Biological / Q000737:chemistry*; D010963:Plasmodium falciparum / Q000737:chemistry; D011524:Protoporphyrins / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D005290:Ferric Compounds; D006420:Hemeproteins; D010860:Pigments, Biological; D011524:Protoporphyrins; C020753:hemozoin; C028025:protoporphyrin IX