Imidaole- and alkylamine-ligated iron(II,III) chlorin complexes as models for histidine and lysine coordination to iron in dihydroporphyrin-containing proteins: characterization with magnetic circular dichroism spectroscopy

The magnetic circular dichroism (MCD) spectra of five- and six- coordinate chlorin complexes with nitrogenous axial ligands to ferric and ferrous ions are studied. The complexes examined are bis(1-methylimidazole)ferrous, (1,2-dimethylimidazole)ferrous, bis(1-methylimidazole)ferric and 1-methylimidazole/CO or NO compounds. The results show unique MCD signals for determining the presence of histidine or axial ligands in iron chlorine-containing protein.