Solid State Intercalation of 4,4′-Bipyridine into the Interlayer Space of Montmorillonites

Abstract

Intercalation of 4,4′-bipyridine into the interlayer spaces of cobalt(II), nickel(II) and copper(II)-montmorillonites by solid-solid reactions was investigated. The successful intercalation of 4,4′-bipyridine and the complex formation in the interlayer spaces of montmorillonites was confirmed by powder XRD (the change in the basal spacings) as well as IR and the thermal analysis of the products.     

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.     

Formation of mono(8-hydroxyquinoline) lithium(I) complex in smectites by solid-solid reactions

Lithium quinolate including mono(8-hydroxyquinoline) lithium(I) complex (Liq) formed in the interlayer spaces of two smectites via solid-solid reactions and in situ complex formation by reacting Li-smectites (Li(I)-synthetic saponite and Li(I)-montmorillonite) with 8-hydroxyquinoline at room temperature. The incorporation of 8-hydroxyquinoline into Li(I)-smectites was proved by powder X-ray diffraction, infrared spectroscopy, thermal and elemental (CHN) analysis. UV-vis absorption and photoluminescence spectra indicated that 8-hydroxyquinoline ligand formed Liq chelate in the interlayer spaces of smectites. The higher luminescence intensity of the Liq complex in synthetic saponite confirmed the very low content of quenching impurities such as iron in the synthetic saponite. The variation of the photoluminescence bands supported the difference in molecular packing and/or crystal structure of the complex formed in the interlayer spaces of smectites.     

Simple preparation of a cadmium selenide-montmorillonite hybrid

The immobilization of organically modified cadmium selenide on montmorillonite was investigated by the reaction of modified cadmium selenide nanoparticles with montmorillonite. The intercalation of the nanoparticles was indicated by the expansion of the interlayer space and spectroscopic observations. The diffuse reflectance absorption spectrum of the product showed absorption onset at 567 nm. In comparison to the bulk cadmium selenide, the blue shift of the absorption onset of the hybrid was ascribed to the quantum size effect of the modified cadmium selenide nanoparticles. This study provides a new method for introducing nanoparticles into the interlayer space of layered inorganic materials.     

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.