Soft chemistry processes

Using a soft chemistry process, we succeded in controlling the stoichiometry of Lax (fsa)2en,N03.H20 heterobinuclear complexes (M = Ni, Cu (fsa)2en = N,N - bis (3-carboxysaIicydene)ethylene diamine). The thermal treatment of these complexes led to perovskite type LaNi03 or La2Cu04 type structures, which parameters have been computed and found in go agreement with the data given in the litterature. 

Metal chalcogenides, apart from their technological significance in industrial applications, have played an important role in the development of new synthetic concepts and methods in the area of solid-state chemistry. A great example is alkali metal intercalation into TiS2 (Chap. 6) first reported three decades ago, which highlighted the then-novel synthetic approach called soft chemistry chimie douce). This low-temperature process allows for new compounds to be obtained while retaining the structural framework of the precursor. Related to this concept is the... 

Soft Chemistry , proximity to nature and bionics contain the idea that chemical-technical solutions from nature can provide a stimulus for industrial processes and products. 

The success of API is due, at least in part, to the fact that both ion-spray and heated-nebulizer involve soft ionization processes that provide an abundance of molecular ions. This results in simple, easy-to-interpret spectra affording molecular weight information. Because of these features, this interface is perfectly suited to natural products chemistry. We use LC-MS on the material in those tubes identified as having biological activity. The combination of molecular weight and UV-visible data of biological active fractions is used for identification. 

It occurs catalytically on the surface of Fe nanoparticles grown from Fe(CO)5. Also, the conventional synthesis of nanotubes by catalytic CVD from acetylene or methane can be formally considered as redox reaction. Nevertheless, the electrochemical model of carbonization (Sections 4.1.1 and 4.1.2) is hardly applicable for CVD and HiPco, since the nanotubes grow on the catalyst particle by apposition from the gas phase, and not from the barrier film (Figure 4.1). The yield and quality of electrochemically made nanotubes are usually not competitive to those of catalytic processes in carbon arc, laser ablation, CVD and HiPco. However, this methodology demonstrated that nanotubes (and also fullerenes and onions (Section 4.3)) can be prepared by soft chemistry" at room or sub-room temperatures [4,5,101]. Secondly, some electrochemical syntheses of nanotubes do not require a catalyst [4,5,95-98,100,101]. This might be attractive if high-purity, metal-free tubes are required. 

Not only are Li+ intercalation and H+ intercalation in these solids closely similar processes, but topotactic Li+/H+ exchange has been observed on complex oxides [614] this is further evidence that soft chemistry is related to properties of the radial Schrodinger equation, the occupied angular wavefunctions being the same throughout the reversible redox cycle, so that bonds are not broken and bond directions, in particular, are hardly altered. In this respect, soft chemistry resembles physisorption, as opposed to chemisorption (see section 11.3). 

Another way of obtaining suspensions of anisotropic mineral moieties is by the spontaneous condensation of dissolved molecular species. A typical example of this process is the synthesis of V2O5 ribbons by using chimie douce (soft chemistry) techniques (Fig. 6) [35,36]. At pH=2, V(V) species exist in an octahedral coordination with a V=0 bond pointing along the Oz axis, three V-OH bonds in the xOy plane, and two bonded H2O molecules to fill the coordination sphere. Beyond a concentration threshold of 10 mol 1 , these vanadate species spontaneously condense in the xOy plane by two different reactions respectively called olation and oxolation reactions (olation V-0H-l-V-0H2 V-0H-V-i-H20 oxola-tion V-OH-l-V-OH—>V-0-V-i-H20) to form ribbons 1 nm thick, about 25 nm... 

The methods of soft chemistry include sol-gel, electrochemical, hydrothermal, intercalation and ion-exchange processes. Many of these methods are employed routinely for the synthesis of ceramic materials. - There have been recent reviews of the electrochemical methods, intercalation reactions, and the sol-gel technique. The sol-gel method has been particularly effective with wide-ranging applications in ceramics, catalysts, porous solids and composites and has given rise to fine precursor chemistry. Hydrothennal synthesis has been employed for the synthesis of oxidic materials under mild conditions and most of the porous solids and open-framework structures using organic templates are prepared hydro-thermally. The advent of supramolecular chemistry has started to make an impact on synthesis, mesoporous solids being well known examples. ... 

In a solid state reaction at low temperatures a solid reactant may be entirely converted to a solid product that keeps the original structure of the reactant. In such a thermal process new nonequilibrium solids can be made that cannot form when the system would be close to equilibrium. The temperature cannot be too low so that the reaction remains possible (sufficient mobility), and it should not be so high as to prevent crystallization to equilibrium structures. This procedure is called chimie douce or soft chemistry. An example of chimie douce from industrial chemistry is the oxidation of magnetite (a mixed valence form of iron oxide, FCjOJ to the ferromagnetic y-Fe203 (maghemite) in a microstructure that renders it suitable for... 

In last years the attribute soft has become of widespread use in natural sciences soft sciences (like ecology, meteorology, etc.) have had great attendances, soft processing has become the major indication for sustainable industrial development, soft computing has proposed itself as a practically valid alternative to exact numerical computing, soft matter has attracted large interest [34, 35], and the methods of soft chemistry have become of widespread use for the preparation of new materials [36]. 

One of the most attractive properties of the sol/gel process is its unique low-temperature processing capability. The soft-chemistry characteristic of the sol/gel route provides opportunities to develop molecular level organic-inorganic materials wherein chemical modification allows physical encapsulation of biological molecules in these hybrid matrices. Another key property of sol/gel-derived materials is die freedom to tune the properties of the micro environment where the organic- or bio-molecules are confined and/or immobilized. The scale of porosity can be tailored from the nano to the micro scale for specific applications. 

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