PHOTOREDUCTION OF PORPHYRINS TO CHLORINS BY TERTIARY AMINES IN THE VISIBLE SPECTRAL RANGE. OPTICAL AND EPR STUDIES |
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| Authors: | Yaacov Harel Joost Manassen Haim Levanon |
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| Institution: | Plastics Research Department, The Weizmann Institute of Science, Rehovoth, Israel;Department of Physical Chemistry, The Hebrew University, Jerusalem, Israel |
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| Abstract: | Abstract— The photoreduction of free base porphyrins by tertiary amines in the visible spectral range leads to the formation of chlorin. The increase of the apparent first order rates to yield chlorin is correlated with the inductive effect on the nitrogen of the amine used. A mechanism involving a charge transfer interaction between the photoexcited singlet of the prophyrin and the amine is proposed. The porphyrin radicals formed recombine to form a light sensitive dimer which disproportionates in the dark to yield chlorin and porphyrin. The mechanism is elucidated by the use of EPR, laser and flash photolysis. |
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