Urea/Thiourea‐Functionalized BPPFA Ligands for Highly Efficient Chiral Extraction of Amino Acids

ABSTRACT The development of efficient chiral extractants is a central objective in the field of chiral extraction. In this study, a series of urea/thiourea functionalized BPPFA ligands (UT‐BPPFA) were synthesized and employed as chiral extractants for the enantioseparation of phenylalanine (Phe), homophenylalanine (Hph), 3‐chlorophenylglycine (3‐Cl‐Phg), and 4‐nitrophenylalanine (4‐NO 2 ‐Phe). The effects of metal precursors, organic solvents, aqueous phase pH, extractant concentration, and extraction temperature on enantioselectivity were systematically investigated. Under optimized conditions, the UT‐BPPFA extractants exhibited excellent enantioseparation performance, with separation factors ( α ) reaching 14.67, 10.01, 12.14, and 5.08 for Phe, Hph, 3‐Cl‐Phg, and 4‐NO 2 ‐Phe, respectively. Mechanistic analysis suggests that the excellent chiral recognition arises from synergistic effects, primarily involving coordination between the amino acid and the central metal ion, as well as hydrogen bonding between the N‐H of the urea group and the carbonyl oxygen of the substrate. This study has proposed a class of high‐performance chiral extractants and has provided new ideas for the design of novel and highly efficient chiral extractants in the future.