Enantioselective Recognition of Aspartic Acids by Chiral Ligand Exchange Potentiometry

✍ Scribed by Yanxiu Zhou; Bin Yu; Kalle Levon; Tsutomu Nagaoka

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 119 KB
• Volume: 16
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/elan.200302904

✦ Synopsis

Abstract

Enantioselective resolution is realized by combining potentiometry with ligand exchange (CE) in a new method called chiral ligand exchange potentiometry (CLEP). A chiral selector, N‐carbobenzoxy‐L‐aspartic acid (N‐CBZ‐L‐Asp), preferentially recognizes D‐aspartic acid (D‐Asp) and undergoes ligand exchange with the enantiomeric labile coordination complexes of [Cu(II)(D‐Asp)~2~] or [Cu(II)(L‐Asp)~2~] to form a diastereoisomeric complex [(D‐Asp)Cu(II)(N‐CBZ‐L‐Asp)] (a) or [(L‐Asp)Cu(II)(N‐CBZ‐L‐Asp)] (b). Considerable stereoselectivity occurs in the formation of these diastereoisomeric complexes, and their net charges were −2 (a) and 0 (b), respectively, resulting in different Nernst factor (electrode slope), thus enabling chiral D‐Asp to be distinguished by potentiometry without any pre‐ or postseparation processes.