Binding properties of amide and amide–ester N-functionalised polyaza macrocycles

Abstract
A series of amide and amide–ester N-functionalised coronads has been prepared based on [12]- N2O2, [15]-N2O3 and [18]- N2O4 polyazoaxa macrocycles. Complexation of certain alkali and alkaline-earth metal cations has been monitored by 13C NMR and IR spectroscopy, enthalpies of complexation measured in methanolic solution by calorimetry and stability constants measured in aqueous solution by potentiometric methods. Strong complexation of Ca2+ in aqueous solution was observed with high selectivities (ca. 102 to 103.5) over Na+ and K+.