Synthesis, Characterization, Photophysics and Photochemistry of Pyrylogen Electron Transfer Sensitizers

Journal Article · Wed Jan 01 00:00:00 EST 2014 · PHOTOCHEMISTRY AND PHOTOBIOLOGY

DOI:https://doi.org/10.1111/php.12174· OSTI ID:1134190

Clennan, Edward L. ^[1]; Liao, Chen ^[2]

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1. University of Wyoming, Laramie
2. ORNL

A series of new dicationic sensitizers that are hybrids of pyrylium salts and viologens has been synthesized. The electrochemical and photophysical properties of these "pyrylogen" sensitizers are reported in sufficient detail to allow rationale design of new photoinduced electron transfer reactions. The range of their reduction potentials (+0.37-+0.05V vs SCE) coupled with their range of singlet (48-63 kcal mol(-1)) and triplet (48-57kcalmol(-1)) energies demonstrate that they are potent oxidizing agents in both their singlet and triplet excited states, thermodynamically capable of oxidizing substrates with oxidation potentials as high as 3.1eV. The pyrylogens are synthesized in three steps from readily available starting materials in modest overall 11.4-22.3% yields. These sensitizers have the added advantages that: (1) their radical cations do not react on the CV timescale with oxygen bypassing the need to run reactions under nitrogen or argon and (2) have long wavelength absorptions between 413 and 523nm well out of the range where competitive absorbance by most substrates would cause a problem. These new sensitizers do react with water requiring special precautions to operate in a dry reaction environment.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1134190
• Journal Information: PHOTOCHEMISTRY AND PHOTOBIOLOGY, Vol. 90, Issue 2; ISSN 0031-8655
• Country of Publication: United States
• Language: English