Solid NMR technique was applied to elucidate the ion exchange reactions, especially those that relate to the hydration reaction in the solid phase. First, solid NMR was applied to observe the hydration reaction of alkali metal ions intercalated in the layered transition metal disulfides, such as TaS₂ and NbS₂, and NMR spectra of monolayer and bilayer form water molecules were examined. Then the characteristic ion exchange property of titanium and tin antimonic acids was examined by multinuclear solid NMR and the presence of two exchange sites for the Li⁺ ion was elucidated. The 3rd and the 4th examples were concerned with H⁺/Li⁺ ion exchange reaction of monoclinic HSbO₃ and cubic HNbO₃ where the accommodation of the Li⁺ ion occurred in the completely dehydration state. The ion exchange process was clearly elucidated due to the simultaneous observation of ¹H and ⁷Li NMR spectra. As the integration of solid NMR study, ⁷Li/⁶Li isotope separation reaction was examined based on the dehydration reaction of inorganic ion exchangers. It was found from the study that ⁷Li/⁶Li isotope separation coefficient increased with increasing dehydration degree on occasion of the accommodation of lithium ions where the hydration property in the solid phase was definitely clarified by solid NMR spectra.

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Nano-structured catalysts were prepared by the intercalation of metal complexes into clays such as hectorite and taeniolite. The intercalation of metal complexes has been carried out by means of simple ion exchange and ligand exchange methods. The synthesized inorganic-organic hybrid compounds were characterized FT-IR, XRD, TEM, elemental analysis and MAS NMR.
We have intercalated metal complexes as well as structural tuning guests which control the interlayer space of clays to supply enough space for various catalytic reactions. We also found that the stereo conformation of pillar complexes was rigidly fixed in the interlay of clays and thus successfully prepared nano-sized reaction space.

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An epoxy-group-containing monomer, glycidyl methacrylate (GMA), was grafted onto the pore surface of a porous hollow-fiber membrane made of polyethylene by radiation-induced graft polymerization. Two reagents for the introduction of chelating groups capable of capturing poly-trans- [ (2-carboxyethyl) germanium sesquioxide] (p.t-CEtGeO) were reacted with the epoxy group of the poly-GMA chain: 2-nitrilopropanol-2-nitriloisopropanol (PAIPA) and N, N2-hydroxy-isopropyl-2, 3-dihydroxy-n-propylamine (THDPA) . The reagents were dissolved in a mixture of dioxane and water at various dioxane volume fractions, defined by dividing the dioxane volume by the total volume. The equilibrium binding capacity (EBC) for p.t-CEtGeO of the two chelating porous hollow-fiber membranes was evaluated in a permeation mode. The THDPA-type hollow fiber prepared with a dioxane volume fraction of 0.4 exhibited a maximum EBC of 0.48mmol/g which was equivalent to 3.9-fold compared to the THDPA-type hollow fiber prepared with dioxane-free solvent. The permeation of p.t-CEtGeO solution through the pores of the chelating porous hollowfiber membrane minimized the diffusional path of p.t-CEtGeO in the pore interior to the chelating group of the polymer chain grafted onto the pore surface, resulting in a high-speed collection of p.t-CEtGeO.

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We carried out the structural analysis of /β-1, 3-D-glucan/Polynucleotide complexes by molecular mechanics, semiempirical molecular orbital, and molecular dynamics methods.
The calculation results of semi-empirical molecular orbital method exhibited that two types of hydrogen bonds are formed between the curdlan and the Poly (C) ; the 3rd nitrogen (N3) in cytosine forms a hydrogen bond with the 2nd OH of one curdlan chain and the proton of N4 is interacting with the O2 of another curdlan chain. In our model, the helix diameter of Poly (C) is expanded from 11.0 to 15.3Å upon complexation. Despite of such large conformational changes, the 6₁ helix structure of Poly (C) was maintained even after the complexation. The chain length dependence of the reaction enthalpy indicated that the complexation becomes thermodynamically more favorable with the chain length increasing. These features are consistent with the experimental data.
The calculation results of molecular dynamics simulation exhibited that the pitch of, 8-1, 3-D-glucan/Poly (C) complex is almost the same as that of the, β-1, 3-D-glucan crystal structure, while β-1, 3-D-glucan by itself is significantly stretched in aqueous solution. The β-1, 3-D-glucan/Poly (C) complexes maintained triple helices throughout the simulation period, and the dynamic behavior of the complex such as the pitch fluctuation was much different depending on a structural difference of β-1, 3-D-glucan.

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Molecular recognition based on self-assembly exists widely in the biological systems such as double helix formation of DNA and DNA-protein interaction. By mimicking these supramolecular functions, the development of various artificial receptors is expected for design of chemical sensing systems. In this paper, recent progresses in the design of ionrecognition probes are reviewed based on two types of molecular design concepts: one is “molecular built-up” probes, in which ion recognition is achieved by a single molecular receptor function. The other is “molecular assembled” probes, which are based on a supramolecular interaction derived from probe molecules such as (1) self-assembly by molecular stacking, (2) G-quartet assembly by oligonucleoside derivatives, (3) dispersion and aggregation of nanoparticles, and (4) supramolecular assembly by cyclodextrin and surfactant complexes. For these probes, the principles of response mechanisms upon ion recognition are summarized.

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