Synthesis, Structure and Ion Extraction Properties of Novel Monooxa-diselkylene-1,ω-dioxy Substituted Calix[4]arene Derivatives

Novel macrocyclic monooxa-diselkylene-1,ω-dioxy substituted calix[4]arene derivatives 1a–5a were synthesized by the reaction of calix[4]arene dibromides 1–5 with the disodium salt of bis(2-selenylethyl)ether in the yields between 28% and 64%. Their structures were characterized by proton and carbon NMR spectra. X-Ray structure analysis of 1a further confirmed the cone conformation of compounds 1a–5a. An interesting host-guest complex of 1a with dichloromethane via CH/π and Cl/π interactions was elucidated. Extraction experiments showed that these novel monooxa-diselkylene-1,ω-dioxy substituted calix[4]arene derivatives 1a–5a had strong extraction ability towards mercury ion. The interaction of Hg2+with the calix ligand has also been investigated by 1H NMR titration.