Our attempts in the preparation of smectite intercalation compounds by solid-solid reactions are reviewed. Various guest substances, including both cationic and nonionic species, metal complexes, and metal sulfide nanoparticles, have been immobilized in the interlayer spaces of smectites. Organoammonium ions were incorporated in the interlayer spaces by the solid-state cation exchange process. The adsorption of nonionic molecules into pristine and organically modified smectites was also possible. Solid-state intercalation was completed within a few minutes at room temperature. The interactions of sulfide ions with the interlayer cations of smectite via adsorption led to smectite-metal sulfide hybrids. Adsorption and in situ formation of both complexes and metal sulfides in smectites were observed, when homoionic (Na(I)-, K(I)-, Rb(I)-, NH_4(I)-, Ca(II)-, Co(II)-, Cu(II)-, Ni(II)-, Cd(II)-, Li(I)-, Al(III)-, Zn(II)- and Mn(II)-) smectites were ground with the appropriate ligands (diimines, 18-crown-6-ether, thioacetamide, thiourea, 8-hydroxyquinoline, as well as sodium sulfide).

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A carbonate-type layered double hydroxide (CO_3^<2->LDH) was converted into organic sulfate and sulfonate/ LDH hybrids (org-LDHs) by decarbonation using an acetate buffer. A CO_3^<2->LDH suspension in a mixed solution of acetate buffer, and an organic sulfate or sulfonate salt was stirred at room temperature for 1 day under N_2 flow. The organic anions - dodecyl sulfate (DS), dodecyl benzene sulfonate (DBS), octane sulfonate (OS) and p-toluene sulfonate (PTS) - were used as the intercalants. Carbonate-type MgAl-LDH with Mg/Al = 1.86 was used as the initial CO_3^<2->LDH. The organic anions were successfully incorporated into the MgAl-LDH interlayer without any appreciable remaining CO_3^<2-> contamination, and the morphology of the initial CO_3^<2->LDH was retained. Only for DS, several % of remaining CO_3^<2-> was observed, but by addition of NaClO_4, full incorporation of DS was attained.

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Excited energy transfer reaction from tetrakis(1-methylpyridinium-2-yl) porphyrin (o-TMPyP) to tetrakis(1-methylpyridinium-4-yl) porphyrin (p-TMPyP) on an anionic clay surface was investigated. The energy transfer efficiency and quenching efficiency due to an electron transfer were quantitatively estimated. Both the energy transfer efficiency and quenching efficiency increased as the dye loadings increased. By a comparison with the results of other porphyrin combination systems, it was found that the major factor for lowering the energy transfer efficiency was the self-quenching of the donor porphyrin on the clay surface. Since the self-quenching was effectively suppressed by the strong adsorption of porphyrin on the clay surface due to the Size-Matching Effect, relatively efficient energy transfer was achieved. For constructing an efficient energy transfer system, such as an artificial light-harvesting system, a suppression of the self-quenching of dyes on the clay surface should be important.

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Origin of tosudite is controversy and two hypotheses have been postulated including the diagenesis of precursor materials or the direct precipitation from hydrothermal solutions. The newly-discovered dioctahedral Li-tosudite from the kaolin deposits of north-west of Gonabad, Mashhad, Iran was studied in the current paper to examine its origin on the light of these hypotheses. The studied tosudite occurs as soft, white to grayish white and fine-grained lenses ranged in diameter from 30 cm up to 2 m in diameter. The lenses are composed of thin uniform flakes (up to 5 μm in size) with very fine and rounded anatase crystals between flakes. In the XRD pattern, the characteristic basal spacing of 27.6Å for the air-dried mineral was changed to 30.1Å when glycolated and to 22.5Å upon heating. Infrared and differential thermal analyses confirmed the occurrence of tosudite and suggested that it is Li-tosudite. Chemical analysis indicated that the studied tosudite is composed mainly of Al_2O_3 and SiO_2 with relatively high TiO_2 content (0.9%) due to the presence of anatase. The high Li_2O content (1.4%) confirmed the Li nature of the tosudite. Ba, Pb, V, and Zr were detected in relatively high concentrations compared to other trace elements. Chondrite-normalized REEs patterns exhibited LREE enrichment relative to HREE as shown by (La/Yb)_N ratio of 35 and negative Eu anomaly (Eu/Eu* = 0.57). The occurrence of tosudite as uniform and homogeneous lenses as well as the absence of any preexisting minerals suggests the authigenic origin of the studied tosudite as direct precipitation from hydrothermal solutions that was previously reported in association with the magmatic activities of the studied locality. The relative enrichment of LREE relative to HREE and the Eu anomaly suggests an acidic igneous rock as a possible source of the studied tosudite.

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