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Solvent and substituent effects on the redox properties of free-base tetraphenylporphyrins in DMSO and aqueous DMSO

Journal Article · · Journal of Physical Chemistry; (United States)
DOI:https://doi.org/10.1021/j100204a081· OSTI ID:6594547
;  [1]
  1. Portland State Univ., OR (United States)
+ Show Author Affiliations

Oxidation and reduction potentials have been measured by voltammetry for a series of substituted tetraphenylporphyrins in DMSO and aqueous DMSO solutions. Hammett substitutent effect correlations effectively describe the positions of the first and second reduction waves; more electron-withdrawing substituents shift the reduction waves to more positive potentials with reaction constants ([rho][prime]) of +60 and +57 mV, respectively. The oxidation potentials show a similar trend ([rho][prime] = +63 mV); however, a sharp break is observed for highly electron-donating substituents such as alkoxy and amino ([rho][prime] = +390 mV). We propose that these latter porphyrins undergo oxidation at the benzene ring rather than the porphyrin ring. Sovent effects are correlated by the E[sub T](30) solvent parameter, with the more highly polar solvent (more aqueous DMSO) shifting the reduction potentials to more positive values. 25 refs., 6 figs., 1 tab.

DOE Contract Number:
FG06-85ER13389; FG06-90ER14131
OSTI ID:
6594547
Journal Information:
Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 96:25; ISSN JPCHAX; ISSN 0022-3654
Country of Publication:
United States
Language:
English

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Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
CARBOXYLIC ACIDS
CATALYSTS
CHEMICAL REACTIONS
DMSO
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PORPHYRINS
REDOX POTENTIAL
SPECTROSCOPY
SULFOXIDES
SYNTHESIS