Synthesis and chiral recognition properties of a novel colorimetric chiral sensor for carboxylic anions

Chiral colorimetric sensor 4 has been synthesized, and the structure characterized by IR and H-1 NMR spectroscopy, mass spectrometry, and elemental analysis. The chiral recognition of the receptor was studied by H-1 NMR and UV-vis spectroscopy. The results of non-linear curve fitting indicate that the receptor 4 and L- or D-mandelate and alanine anions form a 1: 1 stoichiometric complex. The obvious colour change of receptor 4 can be observed by the naked eye when the enantiomers of mandelate and alanine anions are added, which demonstrates that receptor 4 may be used as the colorimetric sensor for the two carboxylic anions.