SYNTHETIC IONOPHORES PART 19 - SYNTHESIS AND IONOPHORE CHARACTER OF 2-AMINOTHIOPHENOL BASED SILVER SELECTIVE ACYCLIC AND CYCLIC RECEPTORS

The phase transfer catalysed nucleophilic displacements of 1,5-dibromo -3-oxapentane, 1,8-dibromo-3,6-dioxaoctane and 1,11-dibromo-3,6,9-trio xaundecane with thiophenol and 2-aminothiophenol provide respective ac yclic receptors ,omega-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 macro cyclic (14) receptors, respectively. alpha,omega-(2-Aminophenylthio) o xaalkanes (9-11) undergo intermolecular cyclodehydrochlorination with thiodiglycolyl dichloride and pyridine-2,6-dicarbonyl dichloride.HCl t o provide respective macrocycles 16-18 and 20-22. The acyclic receptor s 6-11 show strong complexation with Ag+ and Pb2+ with poor specificit y towards Ag+. The conversion of amine units to amides in 12 significa ntly lowers the complexation but increases Ag+/Mz+ selectivities. The organisation of ligating sites by converting acyclic receptor 12 to it s cyclic analogs and the presence of additional ligating sites in cycl ic receptors 16-18 and 20-22 not only restores the extraction abilitie s but also leads to high Ag+/Mz+ slectivities. The macrocycles 17 and 21 respectively exhibit the highest transport (425) and extraction (56 4) Ag+/Pb2+ selectivites. (C) 1998 Elsevier Science Ltd. All rights re served.