Enantioselective sensing of amino acids by copper(II) complexes of phenylalanine-based fluorescent β-cyclodextrins

The synthesis and full characterisation of two modified cyclodextrins 6-deoxy-6-N-[N-alpha-(N-2-dansylaminoethyl)-R-(or S)-phenylalaninamide]-beta-cyclodextrin, containing a metal binding site and a dansyl fluorophore, are described. Both cyclodextrins were shown to form copper(II) complexes with fluorescence quenching. Addition of D- or L-amino acids to the copper(II) complexes induced a 'switch on' of the fluorescence which was enantioselective for Pro, Phe and Trp. The enantioselective fluorescence effect was used for the determination of the optical purity of proline. (C) 2000 Elsevier Science Ltd. All rights reserved.