Pm. Marcos et al., Synthesis, NMR conformational analysis, complexation and transport studiesof an inherently chiral dihomooxacalix[4]arene triester, TETRAHEDRON, 57(32), 2001, pp. 6977-6984
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.