Construction of an aminal-linked covalent organic framework-based electrochemiluminescent sensor for enantioselective sensing phenylalanine

The common covalent organic frameworks (COFs) cannot achieve high luminescence signal because they are usually connected by imine bonds and rotationally labile imine linkages with the tendency of nonradiative relaxation-mediated self-quenching. Herein, we demonstrate the construction of an aminal-linked COF-based electrochemiluminescent sensor for enantioselective sensing phenylalanine. The aminal-linked COF is con-structed via the condensation of emission monomers tetraphenylethylene (TPE) derivative (4 ',4 '',4 ',4 '-(1,2-ethenediylidene)tetrakis [1,1 '-biphenyl]-4-carboxaldehyde (ETBC) and piperazine. The obtained aminal-linked COF generates a higher ECL signal than the individual components (i.e., ETBC and piperazine), single pore imine-linked COFs (SP-COF), and dual-pore imine-linked COFs (DP-COF). Notably, the ECL signal generated by the aminal-linked COF with higher crystallinity exhibits 4.5-fold enhancement compared with that generated by amorphous-conjugated microporous polymer (CMP), suggesting that crystalline framework can function as an efficient ECL emitter. Moreover, the aminal-linked COF can be employed for the construction of a novel ECL sensor for selective discrimination of enantiomer L-phenylalanine (L-Phe) from D-phenylalanine (D-Phe), providing a new avenue for chiral recognition.