Intercalation and in situ formation of coordination compounds with ligand 8-hydroxyquinoline-5-sulfonic acid in the interlayer space of layered silicate magadiite by solid-solid reactions

Abstract

Intercalation and in situ formation of three fluorescent complexes, Al(III)-, Ca(II)- and Zn(II)-8-hydroxyquinoline-5-sulfonic acid (M-8HqS, M = Al, Ca and Zn) in the interlayer spaces of magadiite (mag) were synthesized by solid-solid reactions between metal ions exchanged mags (M-mag, M = Al, Ca and Zn) and 8HqS at room temperature. The intercalation and in situ formation of 8HqS molecules into the interlayer spaces of M-mags were evaluated by XRD, ICP-AES, EDS, elemental mappings, TG/DTA, elemental analysis, FE-SEM, FTIR, UV-Vis, PL and XPS. Results show that the basal spacings of the intercalated composites increase after the intercalation of 8HqS into M-mags. A new peak at 1461 cm−1 is observed, supporting the formation of the coordination complexes between 8HqS and metal cations. The slight shift of the absorption and luminescence bands of the complexes suggests the different microstructures including molecular packing of the complexes in the interlayer spaces of mags, which indicating that the process is a host-guest interaction. The amount of 8HqS in the intercalated compounds is different due to the diversification of coordination ability of metal ions, and the order of the coordination ability of these three metal ions is Ca2+ > Zn2+ > Al3+. The amount of the metal cations (Al3+, Ca2+ and Zn2+) in the interlayer of mag is enough for the in situ complex formation of M-8HqS complexes. Thus, the intercalation and in situ formation of M-8HqS complexes (M = Al, Ca and Zn) in the interlayer space of mag are successfully achieved in the present work.