Highly Stable Porphyrin-Confined Iridium Clusters Modified with Sodium Carboxymethyl Cellulose for Promoting Chiral Recognition.

The electrochemical chiral sensing platform constructed with a single chiral selector relies on static interactions to identify enantiomers, lacks signal amplification, and has limited sensitivity. Therefore, it is usually combined with a conductive substrate, and active sites are introduced to accelerate electron transfer, thereby amplifying the chiral recognition signal. Catalytically active sites typically require a highly unsaturated, high-energy state (e.g., single atoms), yet such sites readily agglomerate or become poisoned under the reaction conditions. Thus, beyond conductivity and loading stability, the stability of active sites and tolerance to acidic and basic environments are more critical. Compared with single atoms and large nanoparticles, nanoclusters maintain high activity while exhibiting superior long-term stability under harsh conditions, making them a key strategy for an efficient catalyst design. Herein, we introduce Ir nanoclusters into the 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (Tpyp) substrate to create catalytically active sites and anchor them through the coordination of Ir and N atoms to enhance the catalytic stability. In addition, Ir was oxidized to IrO2 to optimize the electronic structure of the catalytic sites of the clusters, resulting in more abundant synergistic active sites and improving the chemical stability of Ir nanoclusters under adverse conditions. Then, using modified sodium carboxymethyl cellulose as a chiral source, an electrochemical chiral sensing platform with high loading capacity and high catalytic activity was constructed.