New Structural Model of Malaria Pigment

Ratchadaporn Puntharod, Bayden R Wood, Evan G Robertson, Kenneth J Haller

Research output: Contribution to conferencePoster


The crystal structure of five-coordinate high-spin iron(III) Fe(OEP)picrate has been studied as a model system for malaria pigment due to intense interest the molecular structure of malaria pigment (hemozoin) which is indistinguishable with β-hematin. To examine the conformation of porphyrin plane and ethyl groups substituted in beta-pyrrole positions with a picrate as axial ligand was studied by single crystal X-ray crystallography and resonance Raman spectroscopy. The macrocyclic porphyrin structure is the out-of-plane normal deformations of the saddle-shaped. The axial ligand orientation is the role in controlling the unequal distance of Fe−N bond (2.040(2), 2.028(2), 2.055(2), and 2.053(2) Å). The distance of axial Fe−O bond is 1.93(2) Å. The Fe(OEP)picrate molecules interact in pairs via π−π stacking interaction and nitro-nitro interaction. Fe(OEP)picrate exhibits the enhancement of totally symmetric oxidation state marker band, ν4 at 1370 cm−1 for ν(pyr half ring) when using near-IR excitation laser and the characteristic bands of beta substituted hemes in the ranges of 1621−1639 for ν(CαCm)asym and 750−756 cm−1 for ν(pyr breathing) similar with β-hematin.

Crystal data for Fe(OEP)picrate: C42H46FeN7O7, monoclinic space group C2/c, a =26.3997(20), b = 13.7806(18), c = 25.4126(20) Å, β = 119.955(9)°, V = 8010.2(14) Å3, Z = 8 at 298 K.
Original languageEnglish
Number of pages1
Publication statusPublished - 2009

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