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

The application of binaphthol derivatives 6′-tert-butyl-3-[2-(2-hydroxyethoxy)-ethoxymethyl]-[1,1′-binaphthalenyl]-2,2′-diol (1) and 2-(2,2′-dimethoxy-1,1′-binaphthalenyl-3-ylmethoxy)phenol (2) as novel multitopic receptors for amino acid esters within plasticized PVC membranes is described. Potentiometric 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 α-carbon of the target substrate (amino acid ester). In addition, a 1H NMR investigation served to (i) confirm the potentiometric data, concerning the key binding modes for molecular recognition of amino 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.