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 10^3.5) over Na⁺ and K⁺.