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Updated: Jul 14, 2026

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions
Published on: October 5, 2019
π-Extended Salphen Scaffolds Enable CO2 Electroreduction and Singlet Oxygen Generation
Vincenzo Langellotti1, André Korzun2, Morgan J McKee2
1Department of Chemical Sciences, University of Naples Federico II, University Campus of Monte S. Angelo, Naples, Italy.
Abstract:
π-Extended conjugation offers the opportunity to unveil new frontiers in materials, coupling redox activity with tunable photophysical properties. Here, we report a new family of π-conjugated salen ligands bearing phenylene bridges and tunable substituents, together with their corresponding boron difluoride complexes. Owing to the extended π-delocalization, these new compounds show promising results in electrochemical CO2 reduction to CO, achieving a remarkable Faradaic efficiency for an organocatalyst (up to 56%). Electrochemical, spectroscopic, and computational analyses support a ligand-centered mechanism in which single-electron reduction activates the framework for CO2 binding at the imine nitrogen, forming an N-bound CO2H intermediate. Beyond electrocatalysis, coordination to boron rigidifies the π-framework, producing emissive boron-salphen complexes with large Stokes shifts (>7000 cm- 1). These complexes function as efficient photosensitizers for singlet-oxygen generation, enabling mild oxidative cleavage of alkenes under blue-light irradiation. This work demonstrates that π-extension transforms the traditional salphen framework into a redox-active engine for small-molecule activation, bypassing the need for transition metals in CO2 electroreduction while simultaneously unlocking good photosensitizing capabilities.
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