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.