Synthesis of calix[4]arene mono and diamide derivatives and selective complexation of alkali and alkaline earth cations

The synthesis of mono and diamide derivatives of the p-tert-butylcalix[4]arenes/calix[4]arenes from the reaction of 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonyl-methoxy-26,28-dihydroxycalix[4]arene 1 and 25,27-diethoxycarbonyl-methoxy-26,28-dihydroxycalix[4] arene 2 with various primary amines were reported. The effect of reaction time and steric hindrance of the primary amines used on the reactions have been investigated. All the amide derivatives of calix[ 4] arene are in a cone conformation according to the H-1-NMR doublet-doublet pattern of the protons of the methylene groups between the aromatic rings. The complexing properties of these compounds toward selected alkali and alkaline earth metal cations are also studied. It has been observed that receptor 8 is a selective extractant for Cs+ and Sr2+ cations.