Preparation of a series of group XIII metal-quinolate complexes in natural and synthetic smectites

The preparation of metal-quinolate complexes, Mq₃ (M=Al(III), Ga(III) and In(III); q=8-hydroxyquinoline) in the interlayer spaces of smectites (natural montmorillonite and synthetic saponite), as well as their optical properties were investigated. The basal spacings of the products increased through solid-solid reactions between M(III)-smectites and 8-hydroxyquinoline, indicating the intercalation of 8-hydroxyquinoline. The photoluminescence maxima and intensities of the intercalation compounds varied depending on the metal ions and nature of clay minerals. The PL intensities of Mq₃ complexes in synthetic saponite were higher than those of the complexes in montmorillonite because of the difference in molecular structure and/or molecular packing, as well as the presence of the quenching impurities in montmorillonite.