Ligand-aided photoreduction of iron-porphyrin complexes probed by resonance Raman spectroscopy

Journal Article · Wed Sep 16 00:00:00 EDT 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00253a004· OSTI ID:5889860

Ozaki, Y; Iriyama, K; Ogoshi, H; Kitagawa, T

Photoreduction has been observed for the first time for an iron porphyrin with a biologically relevant axial ligand by using resonance Raman (RR) spectroscopy (for Fe/sup III/(OEP)(2-MeIm), OEP = octaethylporphyrin and 2-MeIm = 2-methylimidazole). The action spectrum for the photoreduction obtained by visible absorption spectra exhibited a broad maximum around 420-460 nm, which was appreciably shifted from the Soret band of Fe/sup III/(OEP)(2-MeIm) at 395 nm. Similar photoreduction was observed for Fe/sup III/(OEP)(1,2-Me/sub 2/Im) (1,2-Me/sub 2/Im = 1,2-dimethylimidazole) but not for Fe/sup III/(OEP)L/sub 2/ (L = imidazole and 1-methylimidazole) and Fe/sup III/(OEP)X (X = F, Cl, Br, I, and ClO/sub 4/). The coincidence of the RR spectrum of the photoreduced species with that of the ferrous porphyrin rules out the possibility of ring reduction to a porphyrin anion radical or chlorin. The dependence of the photoreduction on the concentration of 2-MeIm suggested that the ligand-free Fe/sup II/(OEP) is a likely intermediate and thus that the light-induced charge transfer from the axial ligand to the iron ion is the primary process of photoreduction.

• Research Organization: Jikei Univ. School of Medicine, Tokyo, Japan
• OSTI ID: 5889860
• Journal Information: J. Am. Chem. Soc.; (United States), Vol. 109:19
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IRON COMPLEXES
PHOTOCHEMICAL REACTIONS
REDUCTION
PORPHYRINS
ABSORPTION SPECTROSCOPY
EXPERIMENTAL DATA
LIGANDS
PHOTOCHEMISTRY
QUANTITY RATIO
QUANTUM EFFICIENCY
RAMAN SPECTROSCOPY
REACTION INTERMEDIATES
VISIBLE SPECTRA
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DATA
EFFICIENCY
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
LASER SPECTROSCOPY
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
SPECTRA
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
400500* - Photochemistry