Specific site binding of metal ions on the intramolecular charge transfer fluorophore in micelles‡

The binding interactions of Cu2+, an essential trace metal ion, and Cd2+, a deleterious metal ion, with 2-(4′-N,N-dimethylaminophenyl)oxazolo[4,5-b]pyridine (DMAPOP) were studied in acetonitrile and sodium dodecyl sulphate (SDS). The studies show that the surfactant can formulate the metal ions to bind at a specific binding site. In acetonitrile, the Cu2+ binds at the dimethylamino nitrogen and pyridine nitrogen to form two different types of complexes with DMAPOP. On the other hand, Cd2+ coordinates through the dimethylamino nitrogen and oxazole nitrogen to form two different types of complexes with DMAPOP in acetonitrile. But SDS effectively controls the binding site and both metal ions bind at the same ring nitrogen in SDS. The binding affinities of both metal ions with DMAPOP vary with the concentration of SDS.