Ruthenium polymers

All of the ruthenium polymers show emission when excited at (absorption). A large Stokes shift and a small quantiun yield characterize the emission behavior the luminescence quantum yield of the polymers is 1%. Thermo-gravimetric analyses in air indicate high thermal stabihty of the polymers, with thermal decomposition starting at approximately 290 °C. The polymers have no glass transition temperature. 

Fig. 3. (A) Unfiltered ex-situ STM image of an HOPG electrode modified with an electropolymerized film of [[(v-tpy)Ru]2(tppz)](PF6)4- Tip bias = 100 mV, tunneling current = 500 pA, scan rate = 60.3 Hz. (B) Structure of the symmetric ruthenium polymer.

This is illustrated in Fig.l for the determination of nitrite at a ruthenium polymer modified electrode where it can be seen that the oxidation response for nitrite is shifted to a less positive (and hence more analytically useful) potential coinciding with the Ru(II)/Ru(III) couple. Although there is an obvious improvement in the peak shape for nitrite oxidation, the response is set on top of a large background current. 

Upon photolysis of the ruthenium polymers in CH3CN-based electrolytes, this solvent is the incoming ligand. In CH3CN the counterion CIOJ can also bind under certain conditions. For the analogous PVI polymer, similar reactions are observed. Interestingly, on photolysis of [Ru(bipy)2(PVI)5Cl]Cl in sulphuric acid, an equilibrium is established between the aquo and a sulphato complex. The latter species converts fully reversible into the aquo species in the dark. ... 

Many researchers have focused on the preparation and catalytic properties of polymer-bound ruthenium and osmium species because of their proven ability to catalyze homogeneous reactions and the vast synthetic chemistry available for their preparation. A series of preformed polymers of [M(bpy)2(pol)nCl]Cl, where M can be a Ru(II) or Os(II) metal center coordinated to 2,2 -bipyridine ligands (bpy) and anchored to a pyridine or imidazole nitrogen of a PVP or poly(N-vinylimidazole) polymer (pol), have been prepared and characterized with respect to charge transport rates and mechanisms in drop-coated films on electrode surfaces. Electrodes coated with films of the ruthenium polymer have been shown to mediate the oxidation of nitrite, and nickel bis(2-hydroxyethyl)dithiocarbamate. ... 

Carbon paste electrode modified with a ruthenium polymer Griess/Cu-Cd No reagent... 

More recently, a new class of polymers has been synthesized involving cyclization reactions. This method of polymerization ealled metallacycliza-tion has led to the formation of polymers containing metal units linked to aromatic units. Thus, the reaction of [ ii C5H4(C6Hi3) - Ru(COD)Br] with 4,4 -diethynylbiphenyl leads to an air-sensitive, thermally imstable polymeric product by a metallacyclization reaction (Fig. 8.47) [72]. This ruthenium polymer undergoes a reversible reduction. It has also been shown that such reduced ruthenium centers interact with each other in a ferromagnetic manner. 

A series of azodicarbonyl dinuclear ruthenium polymers were synthesized. Spectroscopic and electrochromic properties of these polymers were studied. These polymers were found to exhibit good thermal stability and electrochromic properties such as good coloration efficiency in the near infrared region. Furthermore, long-term switching trials were performed, which indicated good chemical stability of the material and potential application for attenuation of near infrared light. 

O Shea XJ, Leech D, Smyth MR, Vos JG (1992) Determination of nitrite based on mediated oxidation at a carbon paste electrode modified with a ruthenium polymer. Xalanta 39 443-447... 

Cj Hydroformation of CO with high-molecular weight olefins on either a cobalt or ruthenium complex bound to polymers. 

Acyclic diene molecules are capable of undergoing intramolecular and intermolec-ular reactions in the presence of certain transition metal catalysts molybdenum alkylidene and ruthenium carbene complexes, for example [50, 51]. The intramolecular reaction, called ring-closing olefin metathesis (RCM), affords cyclic compounds, while the intermolecular reaction, called acyclic diene metathesis (ADMET) polymerization, provides oligomers and polymers. Alteration of the dilution of the reaction mixture can to some extent control the intrinsic competition between RCM and ADMET. 

A thin layer deposited between the electrode and the charge transport material can be used to modify the injection process. Some of these arc (relatively poor) conductors and should be viewed as electrode materials in their own right, for example the polymers polyaniline (PAni) [81-83] and polyethylenedioxythiophene (PEDT or PEDOT) [83, 841 heavily doped with anions to be intrinsically conducting. They have work functions of approximately 5.0 cV [75] and therefore are used as anode materials, typically on top of 1TO, which is present to provide lateral conductivity. Thin layers of transition metal oxide on ITO have also been shown [74J to have better injection properties than ITO itself. Again these materials (oxides of ruthenium, molybdenum or vanadium) have high work functions, but because of their low conductivity cannot be used alone as the electrode. 

We will focus on the development of ruthenium-based metathesis precatalysts with enhanced activity and applications to the metathesis of alkenes with nonstandard electronic properties. In the class of molybdenum complexes [7a,g,h] recent research was mainly directed to the development of homochi-ral precatalysts for enantioselective olefin metathesis. This aspect has recently been covered by Schrock and Hoveyda in a short review and will not be discussed here [8h]. In addition, several important special topics have recently been addressed by excellent reviews, e.g., the synthesis of medium-sized rings by RCM [8a], applications of olefin metathesis to carbohydrate chemistry [8b], cross metathesis [8c,d],enyne metathesis [8e,f], ring-rearrangement metathesis [8g], enantioselective metathesis [8h], and applications of metathesis in polymer chemistry (ADMET,ROMP) [8i,j]. Application of olefin metathesis to the total synthesis of complex natural products is covered in the contribution by Mulzer et al. in this volume. 

In the theoretical treatment of ion exchange polymers the roles of charge propagation and of migration of ions were further studied by digital simulation. Another example of proven 3-dimensional redox catalysis of the oxidation of Ks[Fe(CN)5] at a ruthenium modified polyvinylpyridine coated electrode was reported... 

Chen S., Cao T., and Jin Y., Ruthenium tetraoxide staining technique for transmission electron microscopy of segmented block copoly(ether-ester), Polym. Commun., 28, 314, 1987. 

Ruthenium-NHC complexes exhibit activity in a very wide field of applications. Due to their unique ability to break and reassemble olefin bonds under reaction conditions very favourable to design simple processes, applications in nearly any chemical discipline can be foreseen. This field may span from manufacturing of specialty polymers and rabbers to pharmaceuticals, pharmaceutical intermediates, agrochemicals, fragrances, dyes, specialty chemicals for electronic applications or fine chemicals from natural feedstock and many more. Below are described Ru-NHC catalysed reactions applied from pilot to full commercial scale. 

Peter, K. and Thelakkat, M. (2003) Synthesis and characterization of bifunctional polymers carrying tris (bipyridyl)ruthenium(ll) and triphenylamine units. Macromolecules, 36, 1779-1785. 

Yonemura, H., Yamamoto, Y. and Yamada, S. (2008) Photoelectrochemical reactions of electrodes modified with composites between conjugated polymer or ruthenium complex and single-walled carbon nanotube. Thin Solid Films, 516, 2620-2625. 

The choice of the metals is strictly related to the catalytic application. As we shall show later, the catal54ic reaction most commonly investigated with polymer supported M / CFP catalysts is hydrogenation (Table 3). The overwhelming majority of catalytic studies concerns the hydrogenation of alkenes and by far the most commonly employed metal is palladium, followed by platinum. Examples of rhodium and ruthenium hydrogenation catalysts supported on pol5uneric supports are very rare. 

Polymeric polyolefins, such as polybutadiene, secondary amines, and synthesis gas, are reacted in the presence of a catalyst system comprising a ruthenium-containing compound, a rhodium-containing compound, a steri-cally hindered phosphine, and a solvent [1191]. Preferred polybutadiene feedstocks are those with a predominance of main chain, rather than pendant olefin groups and in particular, those polymers containing both the 1,2-polybutadiene and 1,4-polybutadiene units. These polymers of high amine content are useful as down-hole corrosion inhibitors. 

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