Robust Axially Chiral Scaffolds for High-Fidelity Circularly Polarized Electrochemiluminescence

Generating circularly polarized electrochemiluminescence (CP-ECL) from purely organic emitters is a significant challenge, requiring molecules that not only are chiral and luminescent but also retain their structural integrity and chiroptical properties within radical ion states. Here, we demonstrate the successful translation of a CPL-active, axially chiral scaffold to the domain of ECL. We investigate a binaphthyl core tetrasubstituted with pyrene units (R/S-B4p) and show that it forms stable radical anions that preserve the ground state's axial chirality, a prerequisite for CP-ECL that was previously undemonstrated for this class of molecules. This structural robustness allows for efficient electrochemical generation of a chiral excimer, resulting in intense mirror-image CP-ECL signals (λ_max = 555 nm) with an exceptional electrochemiluminescence dissymmetry factor (|g_ECL|) of 1.2 × 10^-2. Density functional theory calculations reveal that the binaphthyl core remains conformationally locked upon reduction. By directly comparing with a bis-substituted analogue (B2p) that fails to generate excimer ECL, we confirm the design rationale. The obtained R/S-B4p platform achieved the enantioselective sensing of chiral 2-amino-2'-hydroxy-1,1'-binaphthyl (NOBIN). This work validates rigid axial chirality as a robust strategy for organic CP-ECL, establishing a high-performance platform for advanced chiroptical sensing and background-free enantioselective analysis.