Enantioselective Immobilization of Nonprecious Metal Complexes on Chiral Covalent Organic Frameworks for Improved Single‐Site Photocatalytic Hydrogen Evolution

Abstract

Abstract The noncovalent assembly of molecular catalysts into photocatalytic systems represents a pivotal strategy for exploring single‐site heterogenous catalysts, excluding the need for elaborate functionalization design. However, the reliance on weak noncovalent interactions (e.g., van der Waals forces) often leads to inefficient outer‐sphere electron transfer and inferior structural stability. Herein, we report the enantioselective immobilization of cobalt‐based molecular catalysts with chiral tetradentate ligands onto the surface of a β ‐ketoenamine‐linked chiral covalent organic framework (COF) synthesized through chirality induction. The enantiomeric assembly enables axial coordination between the molecular catalysts and the chiral COF, accompanied by enamine‐to‐imine tautomerization. Leveraging efficient inner‐sphere electron transfer, the resulting composite exhibits a significantly enhanced H 2 evolution rate (5.70 mmol g −1  h −1 ) and sustained performance without the use of precious metals. The enantiomeric assembly strategy on a COF platform demonstrates a viable approach to improve both the stability and activity of molecular catalysts, thereby expanding the design paradigm of single‐site photocatalysts.