Synthetic ionophores part 19: Synthesis and ionophore character of 2- aminothiophenol based silver selective acyclic and cyclic receptors

Article abstract of DOI:10.1016/S0040-4020(98)00229-4

The phase transfer catalysed nucleophillic displacements of 1,5-dibromo- 3-oxapentane, 1,8-dibromo-3,6-dioxaoctane and 1,11-dibromo-3,6,9- trioxaundecane with thiophenol and 2-aminothiophenol provide respective acyclic receptors α,ω-bis(phenylthio/2-aminophenylthio)oxaalkanes (6-11). 1,8-Bis(2-aminophenylthio)-3,6-dioxaoctane (10) reacts with acetic anhydride and isophthaloyl chloride to provide acyclic (12) and macrocyclic (14) receptors, respectively. α,ω-(2-Aminophenylthio) oxaalkanes (9-11) undergo intermolecular cyclodehydro-chlorination with thiodiglycolyl dichloride and pyridine-2,6-dicarbonyl dichloride HCl to provide respective macrocycles 16- 18 and 20-22. The acyclic receptors 6-11 show strong complexation with Ag⁺ and Pb²⁺ with poor specificity towards Ag⁺. The conversion of amine units to amides in 12 significantly lowers the complexation but increases Ag⁺/M²⁺ selectivities. The organisation of ligating sites by converting acyclic receptor 12 to its cyclic analogs and the presence of additional ligating sites in cyclic receptors 16-18 and 20-22 not only restores the extraction abilities but also leads to high Ag⁺/M²⁺ selectivities. The macrocycles 17 and 21 respectively exhibit the highest transport (425) and extraction (564) Ag⁺/Pb²⁺ selectivities.