Chiral Discrimination of Penicillamine Enantiomers: The Role of Aggregation-Caused Quenching in Achieving High Selectivity

Abstract

The recognition and separation of chiral isomers are of great importance in both industrial and biological applications. In this study, a chiral recognition system based on electrochemiluminescence was established for the detection of penicillamine (PA) enantiomers. The system utilized a homochiral [Zn2(BDC)(d-lac)] (Zn-BL) platform for the uniform distribution of Ru(bpy)3 2+ nanoparticles, effectively mitigating aggregation-caused quenching. The chiral recognition ability of Zn-BL was tested to distinguish between PA enantiomers, and the results indicated a substantial increase in the chiral electrochemiluminescence (ECL) signal when l-PA was present, in contrast to d-PA. The mechanism underlying ECL chiral discrimination was investigated using water contact angle measurements, DFT calculations, and electrochemical characterization. The system exhibited high selectivity, stability, and reproducibility for PA enantiomer detection. Furthermore, the proposed method can accurately identify one enantiomer of PA in a mixture. This study provides a reliable and sensitive approach for achieving the highly selective detection of chiral molecules.

Postsynthetic Modification Strategy for Constructing Electrochemiluminescence-Active Chiral Covalent Organic Frameworks Performing Efficient Enantioselective Sensing

“…In previous studies, the ECL-active chiral platform was employed for the enantioselective sensing of amino acids such as proline, , penicillamine, ascorbic acid, phenylalanine, , alanine, and histidine . With the enantioselective sensing strategy established, more different chiral molecules that include amino alcohols (Val-OH) and amino acids (Asp, Glu, Leu, Val, and Ser) were examined at the working electrode Ph-triPy + -( R )-Ru­(II)-GCE in 15 mM Na 2 S 2 O 8 aqueous solution.…”

“…ECL Enantioselective Sensing of Other Amino Acids and Amino Alcohols. In previous studies, the ECL-active chiral platform was employed for the enantioselective sensing of amino acids such as proline, 26,58 penicillamine, 33 ascorbic acid, 35 phenylalanine, 27,36 alanine, 38 and histidine. 59 similar to Leu-OH was obtained at pH = 7 (Figure 7A), namely, the ECL intensity of the D-enantiomer was higher than the L-enantiomer.…”

“…Different from other methods, the ECL response is derived from electron transfer reactions to produce excited states followed by light emission on the working electrode surface. This means that the ECL-active materials need specific units as the ECL luminophores. − For example, tris­(2,2′-bipyridyl) ruthenium­(II) (Ru­(bpy) 3 2+ ) is the most utilized ECL-active reagent due to its good chemical stability and high luminescence efficiency. − However, only a few examples have been reported for ECL enantioselective sensing based on Ru­(bpy) 3 2+ or its derivatives. − It can be ascribed to the reason that the Ru­(bpy) 3 2+ structure is hardly modified to integrate the chiral unit together. When Ru­(bpy) 3 2+ was only exploited as the ECL-active unit, it resulted in a low recognition efficiency.…”

Sulfonic Acid-Functionalized Tetraphenylethylene-Amplified Electrochemiluminescence by Regulating π–π Interaction

“…18 The interaction sites of Ru(bpy) 3 2+ can be provided by using the exposed metal nodes of a MOF and covalent organic frameworks (COFs) surfaces with different coordination environments and organic ligands with different functional groups. 10 In addition, Ju et al applied mesoporous and hollow MIL-101(Al)-NH 2 to ECL systems for the abundant and stable loading of Ru(bpy) 3 2+ . Poly(ethylenimine) was covalently linked to MIL-101(Al)-NH 2 to prevent the leakage of Ru(bpy) 3 2+ and form a self-enhanced Ru complex, thus obtaining a stable ECL signal.…”

“…22 . 10 This strategy utilized a homochiral MOF platform to evenly distribute Ru(bpy) 3 2+ nanoparticles, which effectively reduced the level of quenching caused by aggregation. By modifying Ru(bpy) 3 2+ and using Ru(bpy) 3 2+ as a ligand or guest molecule to synthesize new luminescent materials, such as MOFs, it was also a common way for researchers to enhance the ECL intensity of the system by regulating and increasing the distance between Ru(bpy) 3 2+ molecules.…”