Layered inorganic solids

Similar methods of encapsulation are also observed in pillared clays, which were also introduced as catalysts as long ago as the early 1980s. The field has been thoroughly reviewed up to 2000 [65], Layered double hydroxide structures have also been used for the entrapment of metal coordination compounds [66], 

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Layered inorganic solids have been used for site isolation, for example, nickel phosphine complexes confined within the interlayer spaces of sepiolite have been used as olefin hydrogenation catalysts [63], and similarly there has been the encapsulation of metal complexes into zirconium phosphates [64], The principal idea is illustrated in Figure 5.8. The metal complex can be encapsulated by covalent means (a) or by non-covalent interactions (b). 

A classification of methods for preparing polymer-layered inorganic solid compounds takes into account the main processes involved in the synthesis of the final hybrid material. The nature of both the 2D host solid and the guest polyma- determines the pathway applicable to obtain a particular nanocomposite and, in certain cases, is decisive in the behavior of the resulting material. In... 

Conductive electrodes based on metal oxide, e.g., indium-tin oxide (TTO), are widely used in electrochemistry as a support for surface modification with the goal to develop sensors with electrochemical transduction or combined spectroscopic and electrochemical responses or electrochemiluminescence. Inorganic thin films can also be prepared from the assembly of two-dimensional layered inorganic solids, such as cationic clays and layered double hydroxides (LDHs, also defined as anionic clays). These materials can be used to preconcentrate species on the basis of ion-exchange reactions and applied to heavy metal determination or for the detection of organic pollutants. 

This account of the kinetics of reactions between (inorganic) solids commences with a consideration of the reactant mixture (Sect. 1), since composition, particle sizes, method of mixing and other pretreatments exert important influences on rate characteristics. Some comments on experimental methods are included here. Section 2 is concerned with reaction mechanisms formulated to account for observed behaviour, including references to rate processes which involve diffusion across a barrier layer. This section also includes a consideration of the application of mechanistic criteria to the classification of the kinetic characteristics of solid-solid reactions. Section 3 surveys rate processes identified as the decomposition of a solid catalyzed by a solid. Section 4 reviews other types of solid + solid reactions, which may be conveniently subdivided further into the classes... 

Most of the parallel reactions described in Schemes 4.23 and 4.24 were performed as dry-media reactions, in the absence of any solvent. In many cases, the starting materials and/or reagents were supported on an inorganic solid support, such as silica gel, alumina, or clay, that absorbs microwave energy or acts as a catalyst for the reaction (see also Section 4.1). In this context, an interesting method for the optimization of silica-supported reactions has been described [83], The reagents were co-spotted neat or in solution onto a thin-layer chromatographic (TLC) plate. 

It has already been shown that PBDS can be usefully applied to a variety of organic and inorganic solids, corrosion layers, and... 

A number of inorganic solids having layered or a three-dimensional network... 

In addition to graphite, a wide variety of inorganic solids such as layered... 

To a stirred solution containing 49 gm (0.11 mole) of lead tetraacetate (supplied as a 90% solution in acetic acid) in 200 ml of methylene chloride is added a solution of 14.8 gm (0.10 mole) of acetone phenylhydrazone in 25 ml of methylene chloride over a 15 min period while maintaining the reaction temperature between 0° and 10°C with an ice bath. After the addition has been completed, the reaction temperature is raised to 20°-25°C and stirring is continued for an additional 15 min. Then to the reaction mixture is added 200 ml of water, the inorganic solids are filtered off, and the methylene chloride layer is separated. This product layer is washed in turn with water and with dilute aqueous sodium bicarbonate until all the acetic acid has been removed. After drying the methylene chloride solution with anhydrous sodium sulfate, the solvent is evaporated off at reduced pressure. The residue is distilled under reduced pressure. The product has b.p. 89°C (1 mm Hg) yield 17.0 gm (83 %). 

Figure 11.1. Schematic views of various ways in which an organic chemical, i, may sorb to natural inorganic solids (a) adsorption from air to surfaces with limited water presence, (b) partitioning from aqueous solutions to the layer of vicinal water adjacent to surfaces that serves as an absorbent liquid, (c) adsorption from aqueous solution to specific surface sites due to electron donor-acceptor interactions, (d) adsorption of charged molecules from aqueous solution to complementarily charged surfaces due to electrostatic attractions, and (e) chemisorption due to surface bonding or inner sphere complex formation.

Fig. 7 Schematic representation of the organic-inorganic solid state hybrid synthesized by Mallouk and co-work-ersj209 Absorption of a photon by any of the organic layers results in energy transfer to the electron donor layer.

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