In situ formation of bis(8-hydroxyquinoline) zinc(II) complex in the interlayer spaces of smectites by solid-solid reactions

Bis(8-hydroxyquinoline) zinc(II) complex (Znq₂), an electroluminescent material used for organic light emitting devices (OLEDS), formed in the interlayer spaces of smectites by solid-solid reactions between Zn(II)-smectites (Zn(II)-synthetic saponite and Zn(II)-montmorillonite) and 8-hydroxyquinoline at ambient condition. The intercalation of 8-hydroxyquinoline molecules into Zn(II)-smectites and the in situ complex formation of Znq₂ chelate in smectites were confirmed by powder XRD, FT-IR, TG-DTA, UV-vis absorption and photoluminescence spectroscopies, and elemental (CHN) analysis. The photoluminescence intensity of the Znq₂ complex in synthetic saponite was higher than that of the complex in montmorillonite, suggesting the very low content of quenching impurities in synthetic saponite. The difference in the luminescence bands were thought to be caused by the different molecular structure and molecular packing of the complex formed in the interlayer spaces.