Electrochemical-chemical synthesis

Li Q, Walter EC, van der Veer WE, Murray BJ, Newberg JT, Bohannan EW, Switzer JA, Hemminger JC, Penner RM (2005) Molybdenum disulfide nanowires and nanoribbons by electrochemical/chemical synthesis. J Phys Chem B 109 3169-3182 Tenne R, Homyonfer M, Feldman Y (1998) Nanoparticles of layered compounds with hollow cage structures (inorganic fuUerene-like structures). Chem Mater 10 3225-3238 Shibahara T (1993) Syntheses of sulphur-bridged molybdenum and tungsten coordination compounds. Coord Chem Rev 123 73-147... 

Penner RM (2001) Hybrid electrochemical/chemical synthesis of semiconductor nanocrystals on graphite. In Hodes G (ed) Electrochemistry of Nanostructures, Wiley-VCH,... 

Penner RM (2000) Hybrid electrochemical/chemical synthesis of quantum dots. Acc Chem Res 33 78-86... 

Gorer S, Ganske JA, Hemminger JC, Penner RM (1998) Size-selective and epitaxial electrochemical/chemical synthesis of sulfiir-passivated cadmium sulfide nanocrystals on graphite. J Am Chem Soc 120 9584-9593... 

Gorer S, Penner RM (1999) Multipulse electrochemical/chemical synthesis of CdS/S core/sheU nanocrystals exhibiting ultranarrow photoluminescence emission lines. J Phys Chem B 103 5750-5753... 

Li Q, Walter EC, van der Veer WE, Murray BJ, Newberg IT, Bohannan EW, Switzer lA, Hemminger JC, Penner RM (2005) Molybdenum disulfide nanowires and nanoribbons by electrochemical/chemical synthesis. J Phys Chem B 109 3169-3182... 

The hybrid electrochemical/chemical synthesis of epitaxially oriented CdS nanocrystallites-size selectively on graphite surface was described by Anderson etal. [164]. A schematic diagram of such synthesis is presented in Fig. 6. 

Electrodeposition [309-311] and chemical bath deposition (CBD) [312, 313] are two other attractive routes for the preparation of nanocrystalline films. Oxides such as ZnO and Ti02 [314-318] and other Group II-VI (12-16) semiconductors (e.g., CdS, CdSe, CdTe) [319, 320] can be prepared in nanocrystalline form via these routes. Hybrid electrochemical chemical synthesis routes have also been devised [321]. 

The structure of CP films is directly related to the synthesis method. There are currently a variety of methods being explored to fabricate CP films. The two major categories are chemical and electrochemical. Chemical synthesis proceeds from condensation or addition polymerization. Condensation polymerization is driven by the thermodynamically favorable formation of small stable molecules such as HCl or water. Addition polymerization can involve radical, cation, or anion intermediates which are characteristic of the polymerization mechanism. A common alternative to chemical polymerization is through electrochemical methods. The most attractive... 

Anderson MA, Gorer S, Penner RM (1997) A hybrid electrochemical/chemical synthesis of supported, luminescent cadmium sulfide nanocrystals. J Phys Chem B 101 5895... 

The method of incorporation of ARs into the polymer matrix has been demonstrated by the polymerisation of pyrrole [118]. In the presence of protons, radical IV causes polymerisation of pyrrole to polypyrrole with the incorporated reduced (hydroxylamine) form and oxidised (nitrosonium ion) form of ARs in the polymer matrix. In electrochemical oxidation of pyrrole in the presence of ARs, a coupled electrochemical-chemical synthesis produces polypyrrole films with incorporated nitrosonium ions. They can by reduced to ARs by partial film reduction. 

S. Gorer, J. A. Ganske, J. C. Henuninger and R. M. Penner, Size-selective and epitaxial electrochemical/chemical synthesis of sulfur-passivated cadimum sulfide nanociystals on graphite, J. Am. Chem. Soc. 130,9584-9593 (1998). 

Gorer, S., Hsiao, G.S., Anderson, M.G., Stiger, R.M., Lee, J. and Penner, R.M. (1998) A hybrid electrochemical/chemical synthesis of semiconductor nanocrystals on graphite a new role for electrodeposition in materials synthesis. Electrochimica Acta, 43, 2799-809. 

Electrochemical synthesis of P3ATs was accompHshed in 1986 (81). In the same year, a technique was reported for the chemical synthesis of P3ATs as shown in equation 7. 

There are, however, numerous appHcations forthcoming ia medium- to small-scale processiag. Especially attractive on this scale is the pharmaceutical fine chemical or high value added chemical synthesis (see Fine chemicals). In these processes multistep reactions are common, and an electroorganic reaction step can aid ia process simplification. Off the shelf lab electrochemical cells, which have scaled-up versions, are also available. The materials of constmction for these cells are compatible with most organic chemicals. 

Synthesis Basically, two methods are available, which both start (evidently) from suitable monomers (1) chemical synthesis, followed by doping, and (2) electrochemical synthesis directly in a doped state. 

The synthesis of conducting polymers can be divided into two broad areas, these being electrochemical and chemical (i.e., non-electrochemical). Whilst the latter may be considered to be outside the scope of this review, it is worth noting that many materials which are now routinely synthesised electrochemically were originally produced via non-electrochemical routes, and that whilst some may be synthesised by a variety of methods many, most notably polyacetylene, are still only accessible via chemical synthesis. In view of this it is useful to have an appreciation of the synthesis of these materials via routes which do not involve electrochemistry. 

New electrochemical processes are also of interest in inorganic chemical synthesis. 

We do not claim that the Co(III) method is superior to modern methods of chemical synthesis. However it does provide an alternative. The Co(III)-active ester, once made, can be stored for long periods of time, it provides both N-terminal protection and carbonyl-O activation in the one system, it is orange in color (e480 —100 M l cm"1), generally quite water soluble (it is a salt ), and the Co(III) metal plus ancillary ligands can easily be removed by chemical or electrochemical (—1.0 V vs SCE) reduction methods. 

Sulfonated EPDMs are formulated to form a number of rubbery products including adhesives for footwear, garden hoses, and in the formation of calendered sheets. Perfluori-nated ionomers marketed as Nation (DuPont) are used for membrane applications including chemical-processing separations, spent-acid regeneration, electrochemical fuel cells, ion-selective separations, electrodialysis, and in the production of chlorine. It is also employed as a solid -state catalyst in chemical synthesis and processing. lonomers are also used in blends with other polymers. 

The use of controlled potential electrolysis of fullerenes has thus far been used as a synthetic tool in two general ways. One method has involved the preparation of fullerene derivatives from the reaction of electrochemically generated anions of the pristine cages with electrophiles. The second method has involved an electrochemically induced retro-synthetic reaction of fullerene derivatives, which results in a number of different products, some of which have not been achieved by chemical synthesis. Both methods are described in the following, but special... 

Fig. 6 Schematic diagram illustrating the three-step electrochemical/chemical expitaxial synthesis of CdS nanocrystals [154].

Wnek 180> proposed that the structure of the oxidized insulating form of conventionally formed polyaniline is approximately a 50 % copolymer of diamine and diimine units, corresponding to the emeraldine structure and Hjertberg et al.180 obtained CPMAS NMR evidence for this conclusion. Some confirmation of the structure has also been obtained by chemical synthesis of the polymer182). However, Kitani et al.183) have suggested that the normal electrochemical synthesis leads to partially cross-linked polymers. 

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