Platinum-palladium poly

Most mercaptides are not available as commercial products, since large-scale applications of these chemical compounds are quite limited (only mercaptides of tin and antimony are used industrially as thermal stabilizers for poly(vinyl chloride) [de Sousa et al., 2000 Qu L. et al., 2002]). However, these compounds can be synthesized in a very simple way. Owing to their low water solubility, mercaptides can precipitate by reacting thiols (or thiophenols) with aqueous solutions of the corresponding metal salts. In addition to the well-known mercaptides of mercury, lead, zinc, and copper, many others, such as mercaptides of silver, gold, platinum, palladium, iridium, nickel, iron, cobalt, antimony, bismuth, and cadmium, have been prepared. 

Organometal. Chem., 1992, 34, 1-65. Organometallic Chemistry of Palladium and Platinum with Poly(pyrazol-l-yl)alkanes and Poly(pyrazol-l-yl)borates. 

Porter, P.L., Guha, S., Kang, K. and Frazier, C.C., "Structural dependence of platinum and palladium poly-ynes on third-order nonlinearity," Polymer 32 1756 (1991). 

The poly(cyclodiborazane)s containing the transition metals palladium and platinum in their backbone were prepared (scheme 26).39 These polymers exhibited an extension of ir-conjugation length via their transition metal and cyclodiborazane moieties. 

By an essentially similar procedure, silica-supported poly-(methacrylic acid)-palladium and platinum complexes have been obtained [12]. 

In the acetylide polymers of square planar nickel, palladium, and platinum listed in Table X, the imaginary part of the nonlinearity is the major contributor, implying significant two-photon absorption. Some of the poly-... 

In contrast to nickel, simple homoleptic Tpx or Bpx, and heteroleptic pyrazolylborate-halide complexes of palladium and platinum are largely unexplored. Indeed, while for 3d metals these are "standard" targets for each successive generation of poly(pyrazolyl)borate ligand, for the... 

These are the most extensively studied class of poly(pyrazolyl)borate compounds for platinum and palladium, and rank among the most numerous and varied. The literature includes examples of M(II) and M(IV) centers in cationic, neutral, and anionic complexes, with all possible coordination numbers four to six represented moreover, many of these complexes are readily interconverted. This section will therefore be organized according to oxidation state, as the most logical approach. 

PtOEP is widely used as a PSP probe among the metalloporphyrins. The absorption and emission maximum of PtOEP are 381 and 535, and 646 nm, respectively. For examples of PSPs based on the OEP metal complexes in silicone polymer films, PSPs based on the platinum or palladium OEP immobilized in poly(TMSP) film have been reported. Oxygen permeability of poly(l-trimethylsily-l-propyne) (poly(TMSP)) film is about ten times larger than that of poly(dimethylsiloxane) (poly(DMS)) film, and provides a tough and thin film [14,15]. The poly(TMSP) film is a porous polymer matrix with a high oxygen permeability and diffusion, indicating that the probe... 

Nanomaterials can also be applied to glucose biosensors to enhance the properties of the sensors and, therefore, can lead to smaller sensors with higher signal outputs. Carbon nanotubes have been incorporated in previously developed sensors and seen to increase the peak currents observed by threefold.89 Platinum nanoparticles and single-wall carbon nanotubes have been used in combination to increase sensitivity and stability of the sensor.90,91 CdS quantum dots have also been shown to improve electron transfer from glucose oxidase to the electrode.92,93 Yamato et al. dispersed palladium particles in a polypyrrole/sulfated poly(beta-hydro-xyethers) and obtained an electrode response at 400 mV, compared to 650 mV, at a conventional platinum electrode.94... 

Rhodium, palladium and platinum nanoparticles, stabilised with poly (TV-vinyl-2-pyrrolidone) (PVP), have also been evaluated in the hydrogenation of olefins and benzene.1741 After five catalytic runs, no aggregation and change in particle size was observed. 

Platinum vapor, (generated by electron beam evaporation of the molten metal at ca. 2x10 torr), or palladium vapor (by evaporation from a resistively heated hearth at ca.l0 torr)) was allowed to dissolve in a solution of poly(isobutyl-aluminoxane), [ C4H9A10]n ... 

As we have seen in Figure 5 the local densities of state in ordered 1 1 alloys AB are different on the two different sites (one site for constituent A, the other for B). It is easy to understand that in a disordered alloy of the same overall composition, there will be many different sites for each of the constituents, depending on, e.g., the composition of the surrounding layer of atoms. Indeed, the NMR lines in alloys are always broader than those in pure metals. A further complication is added when we make small particles of disordered alloys. The catalytic activity of Pti- Pd protected by films of poly(A-vinyl-2-pyrrolidone) (PVP) varies strongly with composition [75]. One would like to study both metals by NMR, but unfortunately lo pd NMR is very difficult and has not been attempted on small particles. Some information on small palladium particles is available from susceptibility measurements on catalysts [76] and on cluster molecules [77]. In both cases it was concluded that the susceptibility of the surface atoms is less than that of the bulk, just as is found for platinum particles from their NMR data. It is then reasonable to assume that in these systems the Pd susceptibility heals back when going from the surface to the interior, and that also for Pti Pdx particles an expression like Eq. (17) is valid. 

Non-conjugatively linked 9,9/-dibenzosilole polymers have also been reported [44,45]. In an early paper, a dehydrogenation catalyst, bis(l,5-cyclo-octadiene)palladium, was used in the synthesis of poly(9,9-dibenzosilole) 52 (Scheme 6) [45]. Recently, poly(dibenzosilole-vinylene)s 54 were obtained from the platinum-catalysed hydrosilylation of 9,9-dihydrodibenzosilole 51 with 9,9-diethynyldibenzosilole 53 (Scheme 6) [44]. 

We have pursued the study of polycatenar metallomesogens using poly(alkoxy) stilbazoles [177], and have recently imdertaken a systematic study of the complexes of series of these ligands with palladium(ll), platinum(II) and silveifl) ions. 

The growth of gold, palladium, and platinum nanoparticles in the nanostructured matrix of poly(octadecylsiloxane) (PODS) was demonstrated by Bronstein et al.102 PODS, an amphiphilic polymer with nonpolar alkyl chains and hydrophilic silanol moieties (—SiOl OH) forms a bilayer nanostructure composed of these two moieties in its hydrated form. In the presence of an aqueous solution of metal salt (e.g., Na2PdCl4, K2PtCl4, AuC13), the siloxy layer absorbed metal anions by hydrogen bonding (Scheme 5.9). After reduction, the metal ions were reduced into nanoparticles, and TEM results revealed that the nanoparticles were distributed in layer structures. The sizes of the particles were measured to be about 1-2 nm, and the narrow size distribution was attributed to the volume availability within the ordered bilayers of PODS. 

Colloidal palladium can also be stabilized with poly(7V-vinyl-2-pyrrolidone).78 Other polymeric stabilizers have also been used with palladium, platinum, and other metals. These include poly(2-ethyl-2-oxazoline), poly(methacrylic acid),79 block copolymers containing COOH groups,80 poly(Wisopropyl acrylamide),81 and poly(styrene-b-4-vinylpyridine).82 Colloidal iron has been stabilized not only by poly(Wvinyl-2-pyrrolidone) but... 

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