Millheim, Alexandra C.Ponzano, EnricMoyano i Baldoire, Albert2025-01-302025-01-302024-08-041420-3049https://hdl.handle.net/2445/218246Porphyrins were identified some years ago as a promising, easily accessible, and tunable class of organic photoredox catalysts, but a systematic study on the effect of the electronic nature and of the position of the substituents on both the ground-state and the excited-state redox potentials of these compounds is still lacking. We prepared a set of known functionalized porphyrin derivatives containing different substituents either in one of the meso positions or at a β-pyrrole carbon, and we determined their ground- and (singlet) excited-state redox potentials. We found that while the estimated singlet excited-state energies are essentially unaffected by the introduction of substituents, the redox potentials (both in the ground- and in the singlet excited-state) depend on the electron- withdrawing or electron-donating nature of the substituents. Thus, the presence of groups with electron-withdrawing resonance effects results in an enhancement of the reduction facility of the photocatalyst, both in the ground and in the excited state. We next prepared a second set of four previously unknown meso-substituted porphyrins, having a benzoyl group at different positions. The reduction facility of the porphyrin increases with the proximity of the substituent to the porphine core, reaching a maximum when the benzoyl substituent is introduced at a meso position.1 p.application/pdfengcc-by (c) Millheim, A. C. et al., 2024http://creativecommons.org/licenses/by/4.0/ElectroquímicaPorfirinesCatàlisiElectrochemistryPorphyrinsCatalysisinfo:eu-repo/semantics/article7537482025-01-30info:eu-repo/semantics/openAccess