Solvent extraction of silver(I) over lead(II) by oxygen-sulfur mixed donor podands

A quinoline-bearing podand with five oxygen donors, 1,13-bis(8-quinoly)-1,4,7,10,13-pentaoxatridecane (L-1), showed high extractability for both Ag(I) and Pb(II) due to the excellent coordination ability of the quinolyl nitrogen. The introduction of sulfur donor atoms and the exclusion of nitrogen from the ligand structure based on the skeleton of L-1 clearly offered not only high extraction efficiency but also excellent selectivity in the separation of Ag(I) over Pb(II). H-1 NMR was used to evaluate the binding properties of the podands, and the spectral changes obtained on complexation indicate Ag(I)-specific binding to sulfur donor or pseudocyclization encased Ag(I) which seems to be reflected in the enhanced extractability. (C) 1999 Academic Press.