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

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 ν 4 along with the characteristic bands of C β ‐substituted hemes in the ranges of 1621–1639 cm −1 for ν as (C α C m ) 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. Copyright © 2017 John Wiley & Sons, Ltd.