Synthesis, NMR conformational analysis, complexation and transport studiesof an inherently chiral dihomooxacalix[4]arene triester

The synthesis of the inherently chiral triethyl ester monomethyl ether of p -tert-butyldihomooxacalix[4]arene (3) is reported. A distorted cone conform ation in solution at room temperature has been established for triester 3 b y NMR measurements (H-1, C-13, NOE 1D and 2D). The extracting and complexin g properties of 3 towards the entire alkali and alkaline earth cation serie s have been assessed by picrate extraction and stability constant determina tions. Transport experiments with metal picrates through a CH2Cl2 membrane have also been performed. Comparison is made with tetraethyl ester of p-ter t-butylcalix[4]arene (4) described in literature and also studied by us. 3 is a poor phase transfer agent and binder. In contrast, it is a good carrie r, mainly for the alkali cations and displays a selective transport for Ba2 +. (C) 2001 Elsevier Science Ltd. All rights reserved.