An improved model for malaria pigment and β-hematin: Fe(OEP)picrate

Ratchadaporn Puntharod, Kenneth J Haller, Evan Robertson, Eunice S H Gwee, Ekaterina I Izgorodina, Bayden R Wood

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Abstract

Synthesis and crystallographic and spectroscopic structural characterization, along with spectral band assignments calculated by using density functional theory (M06L/cc-pVDZ and B3LYP/6-31G(d)), are reported for Fe(OEP)picrate as a model for hemozoin (malaria pigment) and its synthetic analog β-hematin, which are spectroscopically identical. The average Fe–N distance, 2.044(12) Å, and the Raman modes indicate a high-spin five-coordinate iron(III) complex. Resonance enhancement is observed for the totally symmetric oxidation state marker band ν4 along with the characteristic bands of Cβ-substituted hemes in the ranges of 1621–1639 cm−1 for νas(CαCm) and 750–756 cm−1 for ν(pyr breathing) similar to β-hematin and hemozoin when using near-IR excitation wavelengths. The similarity of the resonance Raman spectral profiles for Fe(OEP)picrate and β-hematin, along with the structural results, indicates that Fe(OEP)picrate is an excellent model for understanding the stereochemistry and intermolecular interaction of β-hematin.

Original languageEnglish
Pages (from-to)1148-1157
Number of pages10
JournalJournal of Raman Spectroscopy
Volume48
Issue number9
DOIs
Publication statusPublished - 1 Sep 2017

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