Metal Ion Complexation Studies of Novel 8-Hydroxyquinoline-Containing Diaza-18-Crown-6 Ligands and Analogues

摘要

Interaction of some 8-hydroxyquinoline-substituted and related ligands with various metal ions was evaluated by a calorimetric titration technique at 25 deg C in MeOH. Bis-(8-hydroxyquinoline- 2-ylmethyl)- substituted ligand 13 forms a very strong complex with Ba(2+) (log K = 11.6 in MeOH) and is highly selective for Ba(2+) over Na(+), K(+), Zn(2+) and Cu(2+) (selectivity factor > 1 million). The H1 NMR spectral studies of the Ba(2+) complexes with bis-(8-hydroxyquinoline- 2-ylmethyl)- and bis(5,7-dichloro-8- hydroxyquinoline- 2-ylmethyl)-substituted diaza-18-crown-6 ligands (13 and 10) suggest that these complexes are cryptate-like structures with two overlapping hydroxyquinoline rings forming a pseudo second.