Interaction of mixed-donor macrocycles containing the 1,10-phenanthroline sub-unit with selected transition and post-transition metal ions: metal ion recognition in competitive liquid-liquid solvent extraction of Cu(II), Zn(II), Pb(II), Cd(II), Ag(I), and Hg(II)

Two new mixed aza-thia crowns 5-aza-2,8-dithia[9]-(2,9)-1,10-phenanthrolinophane (L4) and 2,8-diaza-5-thia[9]- (2,9)-1,10-phenanthrolinophane (L7) have been synthesized and characterized. The coordination behavior of L4 and L7 toward the metal ions CuII, ZnII, PbII, CdII, HgII, and AgI was studied in aqueous solution by potentiometric methods, in CD3CN/D2O 4:1 (v/v) by 1H NMR titrations and in the solid state. The data obtained were compared with those available for the coordination behavior toward the same metal ions of structurally analogous mixed donor macrocyclic ligands L1-L3, L5, L6: all these contain a phenanthroline subunit but have only S/O/N(aromatic) donor groups in the remaining portion of the ring and are, therefore, less water-soluble than L4 and L7. The complexes [Cd(NO3)2(L5)], [Pb(L7)](ClO4)2 · 1/2MeCN, [Pb(L4)](ClO4)2 · MeCN, and [Cu(L7)](ClO4)2 · 3/2MeNO2 were characterized by X-ray crystallography. The efficacy of L1-L7 in competitive liquid-liquid metal ion extraction of CuII, ZnII, CdII, PbII, AgI, and HgII was assessed. In the absence of HgII, a clear extraction selectivity for AgI was observed in all systems investigated.