Ruthenium bipyridine complexes

Organic synthesis via transition metal complex-catalyzed electrochemical and photochemical reduction of CO2 has been developed [2,122b, 145-147]. Among transition metal complexes, ruthenium bipyridine complexes show high catalytic activity a typical reaction is shown in Eq. 11.79. [Ru(bpy)2(CO)2] and [Ru(bpy)2(CO)Cl] efficiently catalyze the electrochemical reduction of CO2 to CO and HC02. The nature of the products is dependent upon the pH of the solution. A catalytic cycle involving [Ru(bpy)2(CO)]°, ]Ru(bpy)2(C0)(C02 )] and [Ru(bpy)2(C0)C02H] was proposed (Eq. 11.79) [1461]. 

Spectroscopic techniques are used to probe the degree and rate of interaction between a molecule and a modified surface, most often as a model for chromatographic processes. For example, fluorescence spectroscopy has been used to determine the extent of interaction between a charged complex, ruthenium bipyridine, and both the silanols and a bonded organic moiety on a silica surface [55]. An example of the results obtained for bare silica, C-2 silica and C-18 silica at two pH values are shown in Figure 14. The data shows that... 

Small hydrophobic cations derived from naphthalene, anthracene, and pyrene and larger molecules such as rhodamine and fluorescein can be readily intercalated into the a-ZrP galleries. Inorganic complexes, ruthenium tris bipyridine derivatives, and others can also be intercalated into the galleries of a-ZrP. This list has... 

This type of receptor is represented by compounds 16a,b bearing ruthenium ) bipyridine moieties. Both calixarenes [18] exhibit 1 1 binding of chloride and bromide anions (DMSO-d6), and they are especially suitable for the complexation of H2POj (X16a=2.8-104 M-1 K16b=5.2 103 M"1). On the other hand, if we compare these results with those for similar non-calixarene receptors, where the bipyridine unit is substituted by alkyl, aryl or ethylene glycol substituents, the introduction of calixarene does not bring any substantially new features into the complexation abilities of these derivatives. As shown by X-ray analysis, the anion is encapsulated within the cavity formed by amidic functions with the contributions of CH...anion interactions from the bipyridine unit. 

A keen recent interest in polyimine ruthenium(II) complexes (tris-bipyridinates, tris-phenanthrolinates, and their analogues) has largely been evoked by the ample scope they offer as selective DNA-cleaving agents and probes in biochemistry. Such ruthenium(II) complexes, as well as their photophysics, are of particular interest in creating the devices for molecular electronics (e.g., systems of the light-switch type) and in analytical detection of metal ions as well. 

Bilirubin and bilirubin oxidase were used for cathodic oxygen reduction, while Ru(bpy)3 " /Ru(bpy)3 [Ru(bpy)3 + and Ru(bpy)3 are complex tris (bipyridine)ruthenium(III) and tris(bipyridine)ruthenium(II) cations] was the mediator redox system. In the electrodes, these enzymes were immobilized with Nafion solution treated with quaternary ammonium salts, and put on a support of carbonized cloth, serving as the current collector. The treated Nafion solution helped to maintain enzyme activity for a long time. 

A photoactive metal center is introduced in these systems. The ruthenium bipyridyl complexes are coordinated to the emeraldine base to form the corresponding polymer complexes as described above." The incorporation of the ruthenium centers to the pyridyl backbone has been also reported to give the ruthenium complexes Conjugated ruthenium bipyridine complexes thus obtained are evaluated to be photorefractive materials. Other transition metal complexes can be employed to form the corresponding polymer complexes. The pyridine unit is replaced by bithienyl, 1,4-diazabutadiene, ethylene, benzimidazole or thiazole. ... 

Photochemical Reduction of CO2 to HCOO Catalyzed by Ruthenium Bipyridine or Phenanthroline Complexes... 

Srimani D, BalaramanE, HuP, Ben-David Y, Milstein D (2013) Formation of tertiary amides and dihydrogen by dehydrogenative coupling of primary alcohols with secondary amines catalyzed by ruthenium bipyridine-based pincer complexes. Adv Synth Catal 355 2525... 

In another approach, implemented with nanofibers based on ionic transition metal complexes [ruthenium(II) tris(bipyridine)] embedded in PEO, inter-digitated electrodes are used instead of sandwich geometries. Fibers are deposited across the gap between electrodes, and injected carriers recombine yielding luminescence from a point source that has sub-wavelength dimensions ( 0.2 x 0.3 pm, Figure 5.11). ... 

Maggini M, Done A, Scorrano G and Prato M 1995 Synthesis of a [60]fullerene derivative covalently linked to a ruthenium (II) tris(bipyridine) complex J. Chem. Soc., Chem. Commun. 845-6... 

Tris(2,2 -bipyridine)ruthenium(II) complex (Ru(bpy)3+) has been most commonly employed as a chromophore in the studies of photoinduced ET. Electrostatic effects on the quenching of the emission from the Ru(II) complex covalently bound to polyeletrolytes have been studied by several groups [79-82]. 

Complexation via amidinate units was found in ruthenium complexes containing tri- and pentacyclic trifluoromethylaryl-substituted quinoxalines. The complex fragment [(tbbpy)2Ru] (tbbpy = bis(4,4 -di-ferf-butyl-2,2 -bipyridine) has been employed in these compounds which have all been structurally characterized by X-ray diffraction. ... 

Vinyl substituted bipyridine complexes of ruthenium 9 and osmium 10 can be electropolymerized directly onto electrode surfaces The polymerization is initiated and controlled by stepping or cycling the electrode potential between positive and negative values and it is more successful when the number of vinyl groups in the complexes is increased, as in 77 A series of new vinyl substituted terpyridinyl ligands have recently been synthesized whose iron, cobalt and ruthenium complexes 72 are also susceptible to electropolymerization... 

There are more examples of a second type in which the chirality of the metal center is the result of the coordination of polydentate ligands. The easiest case is that of octahedral complexes with at least two achiral bidentate ligands coordinated to the metal ion. The prototype complex with chirality exclusively at the metal site is the octahedral tris-diimine ruthenium complex [Ru(diimine)3 with diimine = bipyridine or phenanthroline. As shown in Fig. 2 such a complex can exist in two enantiomeric forms named A and A [6,7]. The bidentate ligands are achiral and the stereoisomery results from the hehcal chirality of the coordination and the propeller shape of the complex. The absolute configuration is related to the handness of the hehx formed by the hgands when rotated... 

We report here studies on a polymer fi1m which is formed by the thermal polymerization of a monomeric complex tris(5,5 -bis[(3-acrylvl-l-propoxy)carbonyll-2,2 -bipyridine)ruthenium(11) as its tosylate salt,I (4). Polymer films formed from I (poly-I) are insoluble in all solvents tested and possess extremely good chemical and electrochemical stability. Depending on the formal oxidation state of the ruthenium sites in poly-I the material can either act as a redox conductor or as an electronic (ohmic) conductor having a specific conductivity which is semiconductorlike in magnitude. 

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