Porphyrins-cyclodextrin. 2. Dissociation, reduction, and proton relaxivity of an iron(III) porphyrin. mu. -oxo dimer in cyclodextrin solutions. [Pulsed gamma radiation]
- CEA-CEN Saclay, Gif-sur-Yvette (France)
- Howard Univ., Washington, DC (United States)
Spectrophotometric evidence for the dissociation of an Fe(III) porphyrin {mu}-oxo dimer induced by porphyrin-cyclodextrin complexation in aqueous solution is reported. Depending on the pH, the monomer may be in a diaquo monohydroxo or diaquo dihydroxo form with pK values of 6.4 or 8.5, respectively. In the absence of {beta}-cyclodextrin ({beta}-CD), the {mu}-oxo dimer exists as mono- or dihydroxo species with a pK of 11.7. {gamma}- and pulse radiolysis techniques are used to study the Fe(III)/Fe(II) reduction. Fe{sup III}TSPP(H{sub 2}O){sub 2} (TSPP is tetrakis(4-sulfonatophenyl)porphyrin) is reduced by hydrated electrons and CH{sub 2}OH{sup {sm bullet}} radicals into Fe{sup II}TSPP(H{sub 2}O){sub 2} whereas Fe{sup III}TSPP(OH{sup {minus}}){sub 2} and (H{sub 2}O)FeTSPP-O-FeTSPP(OH{sup {minus}}) are both reduced to the monohydroxo Fe{sup II}TSPP(H{sub 2}O)(OH{sup {minus}}) monomer. The Fe{sup II}-O-Fe{sup II} dimer may be formed in strongly alkaline solution. Measurements of the proton (NMR) relaxivity values of this Fe(III) porphyrin in the absence and in the presence of {beta}-CD indicate the possibility of using Fe{sup III}TSPP in conjunction with {beta}-CD as a paramagnetic contrast agent for in vivo imaging of tumors and tissue.
- OSTI ID:
- 5889396
- Journal Information:
- Journal of Physical Chemistry; (United States), Vol. 95:12; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DEXTRIN
PORPHYRINS
CHEMICAL REACTIONS
ABSORPTION SPECTROSCOPY
AQUEOUS SOLUTIONS
COBALT 60
DIMERS
DISSOCIATION
ELECTRIC CONDUCTIVITY
ELECTRON BEAMS
EXPERIMENTAL DATA
GAMMA RADIATION
HYDRATION
IN VIVO
IRON COMPLEXES
IRON OXIDES
NUCLEAR MAGNETIC RESONANCE
PARAMAGNETISM
PH VALUE
RADICALS
RADIOLYSIS
REDUCTION
SOLVATED ELECTRONS
VISIBLE SPECTRA
BEAMS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOHYDRATES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL RADIATION EFFECTS
COBALT ISOTOPES
COMPLEXES
DATA
DECOMPOSITION
DISPERSIONS
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
IRON COMPOUNDS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LEPTON BEAMS
LEPTONS
MAGNETIC RESONANCE
MAGNETISM
MINUTES LIVING RADIOISOTOPES
MIXTURES
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PARTICLE BEAMS
PHYSICAL PROPERTIES
POLYSACCHARIDES
RADIATION EFFECTS
RADIATIONS
RADIOISOTOPES
RESONANCE
SACCHARIDES
SOLUTIONS
SOLVATION
SPECTRA
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
YEARS LIVING RADIOISOT
400600* - Radiation Chemistry
400201 - Chemical & Physicochemical Properties