Optically Pure Co(III)\nComplex Absorbed by Electrochemiluminescence-Active\nCovalent Organic Framework as an Enantioselective Recognition Platform\nto Give Opposite Responses Toward Amino Alcohol Enantiomers

Although covalent organic frameworks (COFs) accompanied\nby electrochemiluminescence\n(ECL) behavior have been introduced in recent years, they are still\nrarely applied for ECL-based enantioselective sensing, especially\ngiving high recognition efficiency. In the current study, an achiral\nionic COF comprised of the pyridinium unit is synthesized in the linkage\nof the carbon–nitrogen cation bond through the Zincke reaction.\nInterestingly, the synthesized ionic COF can generate clear ECL owing\nto the presence of electroactive species. Then, the ECL-active achiral\nCOF is employed to absorb the chiral Co(III) complex for enantioselective\nsensing. As a result, the developed ECL sensor displays discriminative\nresponses toward amino alcohol enantiomers. When the chiral Co(III)\ncomplex with (<i>R</i>)-configuration is used, the examined\n(<i>S</i>)-amino alcohols result in ECL enhancement, whereas\n(<i>R</i>)-amino alcohols lead to ECL quenching. The maximum\nECL intensity ratio between (<i>S</i>)- and (<i>R</i>)-amino alcohols is up to 47.7. In addition, the recognition mechanism\nis investigated in detail. Finally, a good linear relation between\nenantiomeric composition and ECL intensity is developed and appropriate\nfor the accurate analysis of the enantiomeric purities of unknown\nsamples. In short, we believe that this study constructs an effective\nstrategy to combine the respective advantages of COFs and ECL for\nhigh-efficiency enantioselective sensing.