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Design and synthesis of fluorescent β‐cyclodextrins for the enantioselective sensing of α‐amino acids
Author(s) -
Corradini R.,
Paganuzzi C.,
Marchelli R.,
Pagliari S.,
Sforza S.,
Dossena A.,
Galaverna G.,
Duchateau A.
Publication year - 2003
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.10272
Subject(s) - chemistry , enantioselective synthesis , amino acid , synthon , phenylalanine , stereochemistry , enantiomer , glycine , amine gas treating , cyclodextrin , organic chemistry , catalysis , biochemistry
Fluorescent monofunctionalized β‐cyclodextrins bearing a copper(II) binding side arm and a dansyl group (CD‐NH‐AA‐CH 2 CH 2 NH‐DNS) were designed as enantioselective sensors for unmodified α‐amino acids. The side arm was derived from amino acid synthons (AA = L‐ and D‐phenylalanine ( 1 and 2 ), L‐ and D‐phenylglycine ( 3 and 4 ), L‐proline ( 5 ), and L‐cyclohexylglycine ( 6 )) and was chosen in order to contain an amide, an amine, and a sulphonamide group. Enantioselectivity was evaluated by addition of copper(II) complexes of D‐ or L‐valine and D‐ or L‐proline. Chiral discrimination in the fluorescence response was observed in all cases, due to a ligand exchange process. The best conditions for these experiments were found to be the use of an excess (10:1) of the copper complex. The cyclodextrin 4 containing a D‐phenylglycine unit was found to be poorly enantioselective, as found for 2, suggesting that the best design can be obtained by using L‐amino acids. All L‐amino acid containing cyclodextrins showed good enantioselectivities, some of which were higher than those already reported for 1. Other analytes related to amino acids were studied using cyclodextrins 1 and 3. Enantiomers of α,α‐disubstituted amino acids, N ‐methylamino acids, and amino acid amides were found to be discriminated, while β‐phenylalanine and other molecules bearing a poor anchoring group at the α‐carbon gave poor enantioselectivity. On the basis of the present data a model for the recognition process, based on the formation of ternary diastereomeric complexes, is proposed. Chirality 15:S30–S39, 2003. © 2003 Wiley‐Liss, Inc.