Soft Chemistry Routes

DSC Endothermic transition not observed for structures that are already condensed (H.T.,0.3) 

FIGURE 2.2 Mechanism of formation of metastable TiOj (B) from KjTi O, (From Ref. 7, J. Solid State Chem., 101 (1992) 275. 1992 Elsevier). 

Many of the chemical methods such as the sol-gel synthesis and intercalation are soft-chanicals routes. The synthesis of HAIO from a-LiAlO is an interesting 

FIGURE 2.4 Preparation of layered double hydroxides (LDH). The thickness of the Nlj COyOj slab varies with the oxidation state of nickel and cohalt (From Ref. 11, 7. Solid State Chem., 104 (1993) 345. 1992 Elsevier). 

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J J. O. Besenhard, in Soft Chemistry Routes to New Materials (Eds. J. Rouxel, M. Toumoux, R. Brec), Materials Science Volumes 152-153, Trans-Tech Publications, Switzerland, 1994, p. 13. 

Long et al. reported the synthesis of tungsten oxychloride clusters via a soft-chemistry route [60], which confirms the potential for wide applications of the ligand combination strategy in cluster chemistry. 

Rouxel, J., Tournoux, M. and Brec, R. (eds)(1994) Soft Chemistry Routes to New Materials Chimie Douce, Trans Tech Publications, pp. 422. 

In this edition, we have incorporated new material in all the chapters and updated references to the literature. New sections dealing with porous solids, fullerenes and related materials, metal nitrides, metal tellurides, molecular magnets and other organic materials have been added. Under preparative strategies, we have included new types of synthesis reported in the literature, specially those based on soft chemistry routes. We have a new section covering typical results from empirical theory and electron spectroscopy. There is a major section dealing with high-temperature oxide superconductors. We hope that this edition of the book will prove to be a useful text and reference work for all those interested in solid state chemistry and materials science. 

D.S. Bern, J.D. Houmes and H.-C. zur Loye. In Soft Chemistry Routes To New Materials, (Trans Tech Publications, Universite de Nantes, 1994), 183. 

The use of organic molecules in the synthesis of zeotype solids is an especially interesting preparative method for extended inorganic solid materials. Organic molecules cannot survive the harsh conditions of the classical high-temperature route involving reaction of the components in the solid state. Structure-directed synthesis thus belongs to the "soft chemistry" routes for the preparation of solid-state compounds [12, 13]. 

Metal-polymer nanocomposites can be obtained by two different approaches, namely, in situ and ex situ techniques. In the in situ methods, metal particles are generated inside a polymer matrix by decomposition (e.g., thermolysis, photolysis, radiolysis, etc.) or chemical reduction of a metallic precursor dissolved into the polymer. In the ex situ approach, nanoparticles are first produced by soft-chemistry routes and then dispersed into polymeric matrices. Usually, the preparative scheme allows us to obtain metal nanoparticles whose surface has been passivated by a monolayer of -alkanethiol molecules (i.e., Crfiin+i-SH). Surface passivation has a fundamental role since it avoids aggregation and surface oxidation/contamination phenomena. In addition, passivated metal particles are hydrophobic and therefore can be easily mixed with polymers. The ex-situ techniques for the synthesis of metal/polymer nanocomposites are frequently preferred to the in situ methods because of the high optical quality that can be achieved in the final product. 

Soft-chemistry routes, which the French call chimie douce, are indeed desirable because they lead to novel prodncts, many of which are metastable and cannot otherwise be prepared. Soft-chemistry rentes essentially make nse of simple reactions such as intercalation, ion exchange, hydrolysis, dehydration and rednction that can be carried out at relatively low temperatures. The topochemical nature of certain... 

It was pointed out earlier that soft-chemistry routes have been receiving considerable attention recently. It would be instructive to examine a few typical examples of soft-chemical methods of material synthesis (chimie douce). Marchand et al. [6] obtained a new form of TiO by the dehydration of H TiOg-xH O, which in turn was prepared by the exchange of K+with H-tin K Ti O. The mechanism of this transformation has been described recently by Fiest and Davis [7] and we show this schematically in Figure 2.2. Rebbah et al. [8] prepared Ti Nb O by the dehydration of HTiNbOj, the... 

Y. Fujiki, JSAE Rev., Nov. 91 (1981). Also see M. Watanabe in Proceedings of International Symposium on Soft Chemistry Routes to New Materials, Nantes, France, 1993 (Trans Tech Publications). 

Soft chemistry route for the preparation of highly dispersed transition metals on zirconia. 

P. Afanasiev, C. Geantet, and M. Breysse, in "Proceedings, Int. Symp. Chimie douce. Soft chemistry routes to new materials" 6-10 Sept 1993, Nantes, France. 

D. Matteuzzi, F. Trifiro, A. Vaccari, M. Gazzano and O. Clause, in Proc. Litem. Symposium Soft Chemistry Routes to New Materials, Nantes (F), September 1993, in press. 

From Solid-State Chemistry to Soft Chemistry Routes... 

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