Metal complexation by tripodal N-acyl(thio)urea and picolin(thio)amide compounds:: Synthesis/extraction and potentiometric studies

The synthesis and binding properties towards different cations of a series of tripodal ligands functionalized with N-acyl(thio)urea and picolin(thio)amide moieties are described. For the extraction of Am3+ and Eu3+ the compounds are not efficient. However, N-acylurea derivative 10 exhibit a significant selectivity for Am3+ over Eu3+. Upon addition of the synergistic hexabrominated his (dicarbollide) cobalt anion (Br-6-COSAN) the distribution coefficients for Am3+. and Eu3+ increase up to 1000 for picolinamide derivative 11. Extraction studies with metal picrates (Pb2+, Cu2+, Ag+, Hg2+, Cd2+, Eu3+, Fe3+, K+, Na+, and Ca2+) or the incorporation in ion selective electrodes (ISEs), show that picolinamide derivative 11 is a very selective and strong ionophore for Hg2+ and that N-acylthiourea 8 is a very good ionophore for Ag+. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)