Optically Pure Co(III) Complex Absorbed by Electrochemiluminescence-Active Covalent Organic Framework as an Enantioselective Recognition Platform to Give Opposite Responses Toward Amino Alcohol Enantiomers.

Abstract

Although covalent organic frameworks (COFs) accompanied by electrochemiluminescence (ECL) behavior have been introduced in recent years, they are still rarely applied for ECL-based enantioselective sensing, especially giving high recognition efficiency. In the current study, an achiral ionic COF comprised of the pyridinium unit is synthesized in the linkage of the carbon-nitrogen cation bond through the Zincke reaction. Interestingly, the synthesized ionic COF can generate clear ECL owing to the presence of electroactive species. Then, the ECL-active achiral COF is employed to absorb the chiral Co(III) complex for enantioselective sensing. As a result, the developed ECL sensor displays discriminative responses toward amino alcohol enantiomers. When the chiral Co(III) complex with (R)-configuration is used, the examined (S)-amino alcohols result in ECL enhancement, whereas (R)-amino alcohols lead to ECL quenching. The maximum ECL intensity ratio between (S)- and (R)-amino alcohols is up to 47.7. In addition, the recognition mechanism is investigated in detail. Finally, a good linear relation between enantiomeric composition and ECL intensity is developed and appropriate for the accurate analysis of the enantiomeric purities of unknown samples. In short, we believe that this study constructs an effective strategy to combine the respective advantages of COFs and ECL for high-efficiency enantioselective sensing.