Synthesis and complexation studies of 1,3-dialkylated p-tert-butylcalix[4]arene telomers

A series of cone structured lower rim dialkylated p-tert-butylcalix[4]arene (2a-5a) and their relative telomers (2b-5b) have been synthesized to estim ate extraction of alkali and transition metal cations from an aqueous phase to an organic phase (dichloromethane). The complexation studies were made by using a liquid-liquid extraction procedure. It has been deduced from the observations that the monomers 2a, 3a and 5a are selective for Hg2+, where as 4a is not selective but showed higher affinity towards transition metals than the alkali metal cations. The telomer 2b showed more affinity toward Cu2+, Hg2+ and Pb2+ but the telomer 3b is effective for Hg2+ and Pb2+. The telomers 4b and 5b are not selective but they are efficient extractants for the selected transition metal cations. The results indicate that the ligan d groups circularly arranged on the lower rim of calixarene cavity form nov el binding sites for transition metal cations. (C) 2000 Elsevier Science B. V. All rights reserved.