Inorganic–Organic Interactions

Okada, Tomohiko; Ogawa, Makoto

doi:10.1007/978-4-431-56496-6_6

Cited by 8 publications

(4 citation statements)

References 152 publications

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“…The smectite group of layered clay minerals has been studied widely because of their cation exchange capability, atomic-level smoothness of the surface, , and ability to form molecular assembly on the surface. − Recently, clay nanosheets have been studied as ideal host materials for the construction of a unique assembly of dyes, especially under the exfoliated conditions in water. For example, by controlling electrostatic interactions at the molecular level, certain dyes are adsorbed on the exfoliated clay nanosheet surface with high density and without aggregation, which is difficult to be achieved by other methods.…”

Section: Introductionmentioning

confidence: 99%

Monolayer Modification of Spherical Amorphous Silica by Clay Nanosheets

Nishida,

Arakawa,

Shimada

et al. 2024

Langmuir

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Clay-silica nanocomposite materials (CSiN) were prepared by an electrostatic interaction between negatively charged clay nanosheets and positively charged spherical silica, which was modified with an alkyl ammonium group by silane coupling. By optimization of the preparation conditions, 84% coverage of the silica surface by the clay nanosheets was achieved. Adsorption experiments using cationic porphyrin dyes on the CSiN revealed that the clay nanosheet covers the spherical silica as a single layer and does not detach from the silica surface under aqueous conditions. In addition, it turned out that the cationic porphyrin dye did not penetrate the space between the silica surface and the clay nanosheet. Porphyrin molecules were adsorbed only at the outer surface of the clay nanosheet without molecular aggregation even under the high-density adsorption conditions. By combining spherical silica and clay nanosheets, it is possible to prepare novel hybrid materials where the surface can act as a unique adsorption field for dyes.

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Section: Introductionmentioning

confidence: 99%

Monolayer Modification of Spherical Amorphous Silica by Clay Nanosheets

Nishida,

Arakawa,

Shimada

et al. 2024

Langmuir

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“…The soft–hard interfaces present in the periodic structures are important in bio(chemo)selective reactions and account for the high stability and low cost of the artificial enzymes. , To facilitate catalytic redox reactions, we focus on a coenzymatic 2D layered inorganic solid that undergoes assembly with a redox-active amino acid. The alternate, stacked, layer structures are expected to participate in the molecular recognition catalytic reactions. , These assemblies comprise amino acids accumulated in the interlayer space of the coenzymatic nanosheets, and the hybrids from the discrete organic and inorganic components are substantially different from the enzyme-supported inorganic solids …”

Section: Introductionmentioning

confidence: 99%

Acceleration of the Dehydrogenation of d-Glucose to 2-Keto-d-gluconate in Aqueous Amino Acid via Hydrated Stacked Clay Nanosheets

et al. 2022

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The assembly of discrete active species to form periodical nanostructures is essential in realizing low-cost artificial enzymes that mimic natural enzymatic functions in extraordinary bio(chemo)selective reactions. In this study, we developed artificial bifunctional glucose/gluconic acid dehydrogenase from naturally abundant resources: L-aspartic acid (Asp) and montmorillonite (a subgroup of smectite natural clay minerals). β-D-Glucose (Glc) was dehydrogenated to 2-keto-D-gluconate (2-KGA) at 25 and 30 °C in an aqueous acidic solution (pH = 3, 4, and 5). The reaction involved sequential steps that yielded D-gluconic acid (GA) as an intermediate. The second step of the dehydrogenation (GA to 2-KGA) occurred at a higher rate than the first (Glc to GA), which is comparable to the natural process. A negatively charged carboxylate in Asp was required for the dehydrogenation, which donates an electron pair (COO: − ) to the hydroxyl group bonded to the C(1)-position of Glc. The acidic sites in clay served as coenzymatic sites (electron acceptor), promoting the Glc dehydrogenation as the Glc reduced by Asp approached the clay coenzymatic sites. The active coenzymatic structures were developed in 48 h (induction period) through the rearrangement of the adsorbed Asp and Glc molecules on montmorillonite in water (intermediate structure). The spontaneous assembling of the intermediate structures facilitated the one-pot dehydrogenation of Glc to 2-KGA via periodic "hydrated stacked layers" comprising clay nanosheets, Asp, and Glc. The facile synthetic route proposed here is inexpensive and would be beneficial without using both GDH and GADH enzymes bound to a cell membrane.

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“…Confined water molecules may affect the molecular binding ability (especially in hydrophobic solute–sorbent interactions) of organic molecules because water apparently contacts (coexists) with the confining hydrophobic interlayers. Periodical laminates of hydrophobic ultrathin layers (nanosheets) with designed interlayer nanostructures can be controlled as adsorbents and/or dye supports in aqueous media. − Herein, we focus on the binding properties of an organic molecule in the hydrated interlayers of clay minerals in aqueous media. The smectite group of layered clay minerals is composed of negatively charged ultrathin (1.0 nm) silicate layers and intrinsically hydrated interlayers occupied by interlayer exchangeable cations.…”

Section: Introductionmentioning

confidence: 99%

Important Roles of Water Clusters Confined in a Nanospace as Revealed by a Synchrotron X-ray Diffraction Study

Okada¹,

Izumi²,

Kawaguchi

et al. 2021

Langmuir

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States of water molecules confined in a nanospace designed by montmorillonite (negatively charged silicate layer) and charge compensating benzylammonium were investigated. Caffeine was used as a probe because of its compatibility for the fine structure of the interlayer water. Powder synchrotron radiation X-ray diffraction (SXRD) and adsorption isotherms of the water vapor revealed a metastable structure of bimolecular water layers (2WLs) in the interlayer space. Water molecules readily penetrated to expand the interlayer space to 0.56 nm. The interlayer space did not increase further even in the presence of excess water. According to the isosteric heat of water, the expansion was limited because of moderate hydration as forming 2WLs. Caffeine molecules replaced a part of the water molecules in the 2WLs to expand the interlayer space to 0.65 nm. Time-resolved SXRD with an accumulation time of 500 ms revealed that the interlayer expansion reached a steady state within a few minutes. The caffeine intercalation proceeded, involving a change in the molecular orientation that increased the contact area of the caffeine molecules. The interlayer expansion was limited in all the solvents examined (mixtures of water with methanol, ethanol, acetone, and tetrahydrofuran), while the packing density of the incorporated caffeine was maximized in the absence of an organic solvent. The water molecules confined in the interlayer space acted as an actuator to accommodate a large quantity of amphiphilic molecules by adapting the nanostructure, which was achieved by releasing the confined water molecules.

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Inorganic–Organic Interactions

Cited by 8 publications

References 152 publications

Monolayer Modification of Spherical Amorphous Silica by Clay Nanosheets

Monolayer Modification of Spherical Amorphous Silica by Clay Nanosheets

Acceleration of the Dehydrogenation of d-Glucose to 2-Keto-d-gluconate in Aqueous Amino Acid via Hydrated Stacked Clay Nanosheets

Important Roles of Water Clusters Confined in a Nanospace as Revealed by a Synchrotron X-ray Diffraction Study

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