Smart Chiral Sensing Platform with Alterable Enantioselectivity

A quinine (QN)-based chiral sensing platform with alterable enantioselectivity is constructed for electrochemical chiral recognition of tryptophan (Trp) isomers. The electrochemical signals of l- and d-Trp on the QN modified electrode depend closely on temperature, and more particularly are reversed at certain temperatures, which could be attributed to the temperature-sensitive H-bonds and π–π interactions between QN and the Trp isomers. The mechanisms of the reverse chiral recognition are investigated by density functional theory (DFT), variable-temperature UV spectra, and variable-temperature 1H NMR spectra. In addition, the chiral recognition is highly specific to the isomers of Trp compared with other chiral amino acids. This study is the first example showing how temperature influences the reverse recognition of electrochemical chiral interfaces.