π–π+ Interaction Promoting the Absorption of Electroactive Chiral Selectors into the Cavity of Conductive Covalent Organic Framework for Enantioselective Sensing of Electrochemically Silent Molecules

• Published in: Analytical chemistry (Washington) Vol. 96; no. 19; pp. 7626 - 7633
• Main Authors: Wang, Fangqin, Tan, Lilan, Li, Junyao, Cai, Wenrong, Wu, Datong, Kong, Yong
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14.05.2024
• Subjects: Absorption; Alcohols; Amino acids; Cations; Charge transfer; Density functional theory; Electroanalysis; Electrochemistry; Electrolytic analysis; Electron transfer; Enantiomers; Hydrogen bonding; Hydrogen bonds; Methionine; Oxidoreductions; Phenylenediamine; Pyridinium; Reagents; Selectors; Serine
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.4c00526

To date, achieving enantioselective electroanalysis for electrochemically silent chiral molecules is still highly desired. Here, an ionic covalent organic framework (COF) consisting of the pyridinium cation was derived from the tripyridinium Zincke salt and 1,4-phenylenediamine in a one-pot reaction. The electrochemical measurements revealed that the ionic backbone contributed to the electron transfer with a low charge transfer resistance. Besides, the π–π+ interaction between the pyridinium cation and ferrocenyl unit can promote the absorption of electroactive chiral ferrocenyl reagents into the hole of COF, so as to afford the electrochemical signals by themselves, replacing the testing enantiomers. As a result, the electroactive complex used as an electrochemical platform was highly effective at enantiomerically recognizing amino alcohols (prolinol, valinol, leucinol, and alaninol) and amino acids (methionine, serine, and penicillamine), giving the ratios of current intensity between l- and d-enantiomers in the range of 1.46–1.72. Moreover, the density functional theory calculations determined the possible intermolecular interactions between the testing enantiomers and chiral selector: namely, hydrogen bonds and electrostatic attractions. Overall, the present work offers an effective strategy to enlarge the electrochemical scope for chiral recognition based on electroactive chiral COFs.