Formation of mixed-ligand zinc(ii) complex-montmorillonite hybrids by solid-solid reactions

Two luminescent hybrids, Znqb- and Znqp-montmorillonites (q = 8-hydroxyquinoline, b = 2,2′-bipyridine, p = 1,10-phenanthroline), were prepared by solid-solid reactions between Zn(ii)-montmorillonite and two ligands (8-hydroxyquinoline and 2,2′-bipyridine or 1,10-phenanthroline) at room temperature. The intercalation and in situ complex formation of the two ligands into an interlayer space of Zn(ii)-montmorillonite were confirmed by powder XRD, TG-DTA, as well as FT-IR, UV-vis and photoluminescence spectroscopies. The emission band of Znqb-montmorillonite was red-shifted compared to that of the mixture of Znq-montmorillonite and Znb-montmorillonite, confirming the formation of Znqb complex in montmorillonite. The photoluminescence intensity of Znqb-montmorillonite was higher than that of Znqp-montmorillonite, indicating that 2,2′-bipyridine enhanced the emission intensity of zinc(8-hydroxyquinoline) complex in montmorillonite, while the coordination of 1,10-phenanthroline quenched the intensity of the immobilized chelate.