Metal–Ligand Cooperative Control of Reactivity in a Porphyrin Manganese(IV)–Oxo–Phenoxyl Radical Complex for Water Activation
Abstract
The Oxygen Evolving Complex (OEC) is a Mn 4 Ca cluster at the heart of Photosystem II that catalyzes the water oxidation reaction. Recent studies suggest the formation of a Mn(IV)-oxyl species in the OEC, accompanied by a nonbonded tyrosinyl radical in the S 3 ′ state, prior to O─O bond formation and O 2 release. In this study, we designed and synthesized a manganese-based porphyrin laterally appended with an imidazole-phenol pair. We found that the [Mn III PImiPhOH] + can promote electrocatalytic water oxidation in basic medium, resulting in O 2 evolution. UV-Vis, EPR, and resonance Raman spectroscopic studies support the formation of a doubly oxidized intermediate, best described as a Mn IV ═O species weakly coupled to a neighboring phenoxyl radical, formulated as [Mn IV (O)PImiPhO • ] + . DFT calculations provided further insight into the electronic structure of this reactive intermediate and revealed that its reaction with OH -should lead to the formation of a Mn III -OOH species. For comparison, the parent Mn III TPP does not exhibit water oxidation activity under identical experimental conditions. This study therefore provides new perspectives for the rational design of first-row transition-metal complexes catalysts for the water oxidation reaction, highlighting the important role of secondary sphere functionalities in promoting O─O bond formation and catalytic activity.
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BibTeX
@article{trapali2026metalligand,
title = {{Metal–Ligand Cooperative Control of Reactivity in a Porphyrin Manganese(IV)–Oxo–Phenoxyl Radical Complex for Water Activation}},
author = {Adelais Trapali and Rongning Lin and Georgios Charalambidis and Christian Herrero and Régis Guillot and Sylvain Bertaina and Manuel J Llansola‐portoles and Athanassios Coutsolelos and Maylis Orio and Ally Aukauloo},
journal = {ChemistryEurope},
year = {2026},
month = sep,
doi = {10.1002/ceur.70358},
url = {https://hal.science/hal-05744576v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Metal–Ligand Cooperative Control of Reactivity in a Porphyrin Manganese(IV)–Oxo–Phenoxyl Radical Complex for Water Activation
AU - Adelais Trapali
AU - Rongning Lin
AU - Georgios Charalambidis
AU - Christian Herrero
AU - Régis Guillot
AU - Sylvain Bertaina
AU - Manuel J Llansola‐portoles
AU - Athanassios Coutsolelos
AU - Maylis Orio
AU - Ally Aukauloo
PY - 2026
DA - 2026/09/09
JO - ChemistryEurope
DO - 10.1002/ceur.70358
UR - https://hal.science/hal-05744576v1
AB - The Oxygen Evolving Complex (OEC) is a Mn 4 Ca cluster at the heart of Photosystem II that catalyzes the water oxidation reaction. Recent studies suggest the formation of a Mn(IV)-oxyl species in the OEC, accompanied by a nonbonded tyrosinyl radical in the S 3 ′ state, prior to O─O bond formation and O 2 release. In this study, we designed and synthesized a manganese-based porphyrin laterally appended with an imidazole-phenol pair. We found that the [Mn III PImiPhOH] + can promote electrocatalytic water oxidation in basic medium, resulting in O 2 evolution. UV-Vis, EPR, and resonance Raman spectroscopic studies support the formation of a doubly oxidized intermediate, best described as a Mn IV ═O species weakly coupled to a neighboring phenoxyl radical, formulated as [Mn IV (O)PImiPhO • ] + . DFT calculations provided further insight into the electronic structure of this reactive intermediate and revealed that its reaction with OH -should lead to the formation of a Mn III -OOH species. For comparison, the parent Mn III TPP does not exhibit water oxidation activity under identical experimental conditions. This study therefore provides new perspectives for the rational design of first-row transition-metal complexes catalysts for the water oxidation reaction, highlighting the important role of secondary sphere functionalities in promoting O─O bond formation and catalytic activity.
SN - 2751-4765
ER -