Molecular recognition of amino acid esters in liquid polymeric membrane ion-selective electrodes

The application of binaphthol derivatives 6'-tert-butyl-3-[2-(2-hydroxyetho xy)-ethoxymethyl]-[1,1'-binaphthatenyl]-2,2'-diol (1) and 2-(2,2'-dimethoxy -1,1'-binaphthalenyl-3-ylmethoxy)phenol (2) as novel multitopic receptors f or amino acid esters within plasticized PVC membranes is described. Potenti ometric experiments have shown that the recognition behavior of amino acid esters was significantly controlled by intermolecular interactions between the receptor and the NH3+ group and the residual "R" group on the a-carbon of the target substrate (amino acid ester). In addition, a H-1 NMR investigation served to (i) confirm the potentiometr ic data, concerning the key binding modes for molecular recognition of amin o acid esters by binaphthol receptors, (ii) determine the stoichiometry of the complex binaphthol derivative-amino acid ester (1: 1 and 1:2) and (iii) evaluate corresponding binding constants for AlaOMe. (C) 2001 Elsevier Sci ence B.V. All rights reserved.