Surfactant ruthenium complex

Some of our initial studies in this area have involved the use of the surfactant ruthenium complexes J and 2 and the eleg ron acceptor N,N -dimethyl-4,4 -bipyridinium (methylviologen) (MV ) (28). Previously we and others (, 5 ) had... 

Cyclic water cleavage by visible light was also achieved in electron relay free systems (48). In this case the fraction of sensitizer that Is absorbed onto the particle surface is photoactive and electron injection occurs directly from its excited state into the Ti02 conduction band. Using the surfactant ruthenium complex depicted in Figure 10, a quantum yield of 7% was obtained for the water splitting process. 

The use of chiral ruthenium catalysts can hydrogenate ketones asymmetrically in water. The introduction of surfactants into a water-soluble Ru(II)-catalyzed asymmetric transfer hydrogenation of ketones led to an increase of the catalytic activity and reusability compared to the catalytic systems without surfactants.8 Water-soluble chiral ruthenium complexes with a (i-cyclodextrin unit can catalyze the reduction of aliphatic ketones with high enantiomeric excess and in good-to-excellent yields in the presence of sodium formate (Eq. 8.3).9 The high level of enantioselectivity observed was attributed to the preorganization of the substrates in the hydrophobic cavity of (t-cyclodextrin. 

Ruthenium tetroxide was shown to oxidize PCBs in water [20], Water-soluble ruthenium complexes, such as [Ru(H20)2(DMS0)4]2+, are effective catalysts for the KHSO5 deep oxidation of a number of chloroaliphatics, of a-chlorinated al-kenes, polychlorobenzenes, and polychlorophenols. When the reactions are carried out in water in the presence of surfactant agents, degradation of the substrates is definitely faster. Aromatic substrates are mainly converted into HC1 and C02, polychlorophenols being more sensitive to oxidation than substituted benzenes [21]. Replacement of the DMSO- solvated ruthenium by RuPcS results in a definite improvement of the reaction course with hydrogen peroxide, since dismutation of... 

The photoreduction of viologens in surfactant systems has also been described by Massini and Voorn [70]. An amphipathic derivative of methyl viologen (Ci4MV ) (XII) has been employed as an electron acceptor in reactions involving the charge-transfer excited state of the ruthenium complex Ru(bpy) the reaction products MV and Ru(bpy)3 of the reaction between and... 

A most significant advance in the alkyne hydration area during the past decade has been the development of Ru(n) catalyst systems that have enabled the anti-Markovnikov hydration of terminal alkynes (entries 6 and 7). These reactions involve the addition of water to the a-carbon of a ruthenium vinylidene complex, followed by reductive elimination of the resulting hydridoruthenium acyl intermediate (path C).392-395 While the use of GpRuGl(dppm) in aqueous dioxane (entry 6)393-396 and an indenylruthenium catalyst in an aqueous medium including surfactants has proved to be effective (entry 7),397 an Ru(n)/P,N-ligand system (entry 8) has recently been reported that displays enzyme-like rate acceleration (>2.4 x 1011) (dppm = bis(diphenylphosphino)methane).398... 

Another model compound, the tris(2,2 -bipyridine)ruthenium(II) complex, has prompted considerable interest because its water-splitting photoreactivity has been demonstrated in various types of photochemical systems (77,99,100,101). Memming and Schroppel (102) have attempted to deposit a monolayer of a surfactant Ru(II) complex on a Sn02 OTE. In aqueous solution, an anodic photocurrent attributable to water oxidation by the excited triplet Ru complex was observed. A maximum quantum efficiency of 15% was obtained in alkaline solution. 

From the point of view of light stability and range of absorptivity, inorganic redox systems might be more interesting. Photoinduced electron transfer in an aqueous solution of tris-(2, 2 -bipyridine) ruthenium (II) has been found to decompose water in to a mixture of H2 and 02. The Complex can serve both as an electron donor and electron acceptor in the excited state. The efficiency is low because of barrier to electron transfer. SVhen spread as a monolayer on glass slides after attaching to a surfactant... 

Some well-defined ruthenium carbene complexes have been used in the living ROMP in aqueous media using a cationic surfactant to yield polymer latex [46]. 

The interactions of various cationic species with polyacids, such as polyCmethacrylic acid), PMA and polyCacrylic acid), PAA have been studied. In particular, the effect of polyacid conformation on the interaction is discussed in detail, and also the nature of the aggregation of PMA and cationic surfactants al)tyltrimethylammonium bromide, C TAB. The effect of the intermediate conformation states of PMA around pH 4-6 is noted, where the photophysical properties of cationic probes bound to PMA dramatically change, effects such as a large enhancement of the fluorescence intensity of Auramine 0, Au 0 at pH 4.5, a blue shift of the luminescence spectra of tris(2,2 -bipyridine)ruthenium(II) complex, Ru(bpy)3 at pH 5, and a great increase of the excimer yield of 1-pyrenebutyltrimethyl ammonium bromide, C PN at pH 6. 

The remaining two examples of metathesis chemistry in water are related to the synthesis of polymers. In the first case, the solubility and stability of the ruthenium catalysts in water is exploited in the emulsion polymerization of norbor-nenes and cyclooctadiene. In emulsion polymerization, a water-soluble initiator is required. Claverie [58] used complex 11 or the related complex RuC12-(TPPTS)2(=CHC02Et) (where TPPTS = tris(3-sulfonatophenyl)phosphine, sodium salt). These two complexes were used with standard surfactants to product well... 

Further work on the use of the gcm-dimorpholine derivative of 2-thienylgly-oxal for the synthesis of gem-di(acylamino)- and other derivatives has appeared. In connection with work on surfactant complexes of ruthenium, thiophen-2-aldehydes were condensed with 4,4 -dimethyl-2,2 -bipyridyls. From the easily available 2,3,4-trichlorothiophen, the 5-formyl- and 5-acetyl-derivatives have been prepared, and from them a large number of derivatives. ... 

Although the well-defined water-resistant metal-alkylidene complexes do not dissolve in water, they can be used in emulsion polymerizations. Small size polymer particles and polymer latex can be prepared with this method in aqueous media in the presence of cationic surfactants (e.g., Dode cyltrimethylammonium bromide (DTAB)). Water-soluble, biologically active glycopolymers have been also synthesized with ruthenium-alkylidene complexes in... 

A series of surfactant trw(bipyridyl)ruthenium(II) complexes first reported by Seddon and Yousif, was shown to be mesomorphic in water. tUhc wur. tu. r.a/ Hr.n... 

Surfactant phenanthroline and mixed phenanthroline-bipyridine ruthenium(II) complexes have been reported (318a to The approach consisted in controlling the size of the surfactant... 

The photoreaction of 2-substituted-1,4-naphthoquinones is accelerated by ionic surfactants but suppressed by cationic ones. Conversely, the flash photolysis of an amphipathic dodecylcarboxamide derivative of a pyridine—ruthenium(ii) complex gives the highest yield for photoreduction in cationic micelles.Anionic micelles increase electron transfer from iron(n) to iron(iii) by ca. 10 —and also the oxidation of ferrocenes by iron(in), but inhibit the oxidation by ferrocyanide. 

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