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Mono-hydroxychlorins are uncommon macrocycles that have only been synthetically realized by modifying porphyrin rings using the harsh oxidizing agent OsO4. We show here that a more directed delivery of the mono-hydroxychlorin may be concomitantly obtained from the oxidation of porphyrinogen using the mild conditions of the high dilution Lindsey porphyrin forming reaction where water content is minimized by using dry CHCl3within the environment of a glovebox. We now report the direct synthesis of 17,18-dihydro-18-hydroxy-5,10,15,20-tetrakis-(4-fluoro,2,6-dimethylphenyl)-porphyrin (2H-TFChl-[Formula: see text]OH) together with the corresponding freebase porphyrin TFP. The TFP has been metalated with FeBr2and MgBr2•OEt2resulting in metalloporphyrins Fe(III)TFP(Cl) and Mg(II)-TFP which have been structurally characterized by single-crystal X-ray crystallography. We find that the excited state properties of the mono-hydroxychlorin are similar to that of its parent TFP and Mg(II)TFP porphyrin congeners. Excited state deactivation by vibronic coupling to the high energy O-H oscillator is circumvented with the hydroxyl group remote to the 18[Formula: see text]-electron framework of the chlorin ring. These results reveal that strong H-bonding groups may be introduced on the periphery of the chlorin ring while maintaining the light-gathering properties that lie at the heart of photosynthesis of the chlorin ring.
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This content will become publicly available on July 1, 2026
One-flask synthesis of zinc metalated mono - and di -hydroxychlorins
Lewis acid catalyzed condensation of pyrrole and 4-fluoro-2,6-dimethylbenzaldehyde followed by chemical oxidation afforded the corresponding chlorin along with the parent porphyrin. The subsequent metalation of the porphyrin-chlorin mixture in the presence of Zn(OAc)2•2H2O afforded Zn monoand di-hydroxychlorins in addition to the Zn porphyrin in a one-flask synthesis. This new direct hydroxylation reaction eliminates the need for highly toxic OsO4and H2S that are traditionally used for the generation of hydroxy chlorins. In addition to the full characterization of the zinc chlorins, we present cyclic voltammograms, steady-state absorption, and emission profiles of this rarely available class of compounds. Our findings show that Zn mono- and di-hydroxychlorins are stable compounds that possess exceptionally long triplet excited states in solution, making them promising candidates for photodynamic therapy.
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- Award ID(s):
- 2216066
- PAR ID:
- 10659089
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- World Scientific
- Date Published:
- Journal Name:
- Journal of Porphyrins and Phthalocyanines
- Volume:
- 29
- Issue:
- 07
- ISSN:
- 1088-4246
- Page Range / eLocation ID:
- 814 to 823
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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