Synthesis and binding properties of a calix[4]crown-6-functionalized polymeric ion acceptor

Calix[4]crown-6-2,4-bis(2-hydroxyethyl ether) (2), which has crown-6 moieties at the 1- and 3-positions and hydroxyethyl functions at the 2- and 4-positions, was prepared for the syntheses of polyester 3 and polyurethane 4 by reactions with adipoyl chloride and hexamethylene diisocyanate, respectively. The ion binding characteristics of monomer 2 and polymers 3 and 4 toward alkali and alkali earth metal ions were measured by liquid-liquid extraction from the aqueous phase into the organic phase. We observed that the polyurethane 4 has a higher binding affinity toward various metal cations when compared to polyester 3, which exhibits cesium ion selectivity.