Enantioselective Fluorescent Sensors for Chiral Carboxylates Based on Calix[4]arenes Bearing an <scp>L</scp>‐Tryptophan Unit

Abstract

Abstract Two‐armed chiral calix[4]arenes ( 3a – c ) functionalized at the lower ring with L ‐tryptophan units have been prepared and the structures of these receptors characterized by IR, MS, 1 H, and 13 C NMR spectroscopy and elemental analysis. The enantioselective recognition of these receptors has been studied by fluorescence titration and 1 H NMR spectroscopy. The receptors exhibited different chiral recognition abilities towards some enantiomers of chiral materials and formed 1:1 complexes between host and guest. Receptor 3a exhibits excellent enantioselective fluorescent recognition ability towards the N ‐Boc‐protected alanine anion and 3b reveals good enantioselective recognition ability towards the enantiomers of mandelate.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)