Synthesis, metal ion complexation and antibacterial activities of some thiapodands with lipophilic amide and ester end groups

A series of acyclic analogues of thiacrown ethers (podands) 7–12 with lipophilic amide and ester end groups were synthesized in high yield and in a simple way. Their transition metal ions complexation was studied using a conductometric method in acetonitrile at 25°C. Podands 7 and 11 showed a continuous decrease in the molar conductances in their complexation with Ag+, Cu2+, Cd2+, Hg2+, Zn2+ and Pb2+ which begins to level off at a mole ratio of 1:1 podand to metal indicating the formation of a stable 1:1 complexes. On the other hand, podand 9 also showed the formation of 1:1 complexes with above metal cations except with Hg2+ ion, which formed a 1:2 podand-to-metal ratio complex. An influence of end groups on metal ion selectivity is evident. Podands having ethoxy end groups (podands 8, 10 and 12 exhibit pronounced metal ion selectivity over podands having amino end groups (podands 7, 9 and 11). Compounds 10 and 12 with dithiaethylene units and ethoxy end groups provide the best selectivity for Hg2+ and A...