Calix[4]arene-based chromogenic chemosensor for the α-phenylglycine anion:: Synthesis and chiral recognition

Calix[4]arene-based two-armed chiral anion receptors 3a and 3b have been synthesized and examined for their chiral anion-binding abilities by UV/Vis absorption and H-1 NMR spectroscopy. The results of nonlinear curve fitting indicate that 3a and 3b form 1:1 stoichiometric complexes with the L- Or D-a-phenylglycine anion by multiple hydrogen-bonding interactions and exhibit good enantioselective recognition for the enantiomers of the alpha-phenylglycine anions (3a: K-ass(L)/K-ass(D) = 4.76; 3b: K-ass(D)/K-ass(L) = 2.84). The marked colour changes observed for the complexation of 3a with the chiral anions and the good enantio selective recognition reveal that receptor 3a could be used as a good chiral chromogenic chemosensor for the enantiomers of the a-phenylglycine anion. (c) Wiley-VCH Verlag GmbH & Co.