π‐Extended Salphen Scaffolds Enable CO 2 Electroreduction and Singlet Oxygen Generation

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 CO 2 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 CO 2 binding at the imine nitrogen, forming an N‐bound CO 2 H 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 CO 2 electroreduction while simultaneously unlocking good photosensitizing capabilities.