Ruthenium bipyridyl

This photoinitiator (or photocatalyst) is composed of an electron relay system in which ruthenium bipyridyl... 

Fig. 10.34. Sensors based on acyclic, macrocyclic and calixarene ruthenium—bipyridyl (from Beer, P. D. (1996) Chem. Commun. 689).

The anion coordination properties of receptors such as compound [93] (Fig. 51) are currently under investigation. This molecule contains both a redox-active ruthenium bipyridyl moiety and also a cobaltocenium unit. This type of host has already been shown by 1H nmr and fluorescence emission spectroscopy to exhibit remarkable selectivity for the chloride anion in preference to dihydrogenphosphate (Beer and Szemes, 1995). 

The dye sensitised semi-conductor electrode is a transparent conducting sheet of glass coated (5 pm) with nanocrystalline TiOj (diameter 20 nm) doped with a ruthenium bipyridyl complex. The dye absorbs light, becomes excited and injects electrons into the TiOj electrode. The electrons travel into the transparent WO3 hhn and then, to balance the charge, lithium ions from the electrolyte solution insert into the WO3 and in so doing create the coloured species as described above. If the light source is removed then the cell is bleached back to its original colour. However, if the... 

Other workers have employed different sensitiser systems, e.g. duel sensitisation by a zinc porphyrin and copper phthalocyanine on TiOj, Eosin Y or tetrabro-mophenol blue on ZnO, and a ZnO/SnOj mixture with a ruthenium bipyridyl complex, to produce good energy conversion factors. 

Ruthenium bipyridyl complexes are suitable photosensitizers because then-excited states have a long lifetime and the oxidized Ru(III) center has a longterm chemical stability. Therefore, Ru bipyridyl complexes have been studied intensively as photosensitizers for homogeneous photocatalytic reactions and dye-sensitization systems. The Ru bipyridyl complex, bis(2,2 -bipyridine)(2,2 -bipyri-dine-4, 4,-dicarboxylate)ruthenium(II), having carboxyl groups as anchors to the semiconductor surface was synthesized and single-crystal Ti02 photoelectrodes sensitized by this Ru complex were studied in 1979 and 1980 [5,6]. 

The use of transition or rare earth metal complexes as emitting materials for OLED has attracted much attention recently because of the enhancement in EL efficiency from triplet excited state.16 Chan and co-workers demonstrated that incorporation of ruthenium bipyridyl complexes into conjugated polymers would enhance the charge carrier mobilities.17 Through attachment of different transition metal complexes onto polymer chains, tuning of light-emitting properties could be achieved.18... 

Similarly in the case of organic solar cells, the low optical absorbance in the red/near-infrared region of the dyes commonly used in DSSCs such as ruthenium bipyridyl [276] has prompted the incorporation of Pcs in these devices [277,278],... 

PHOTO-INDUCED ELECTRON TRANSFER REACTIONS IN POLYMER-BOUND RUTHENIUM BIPYRIDYL COMPLEXES... 

Fig. 8 Oxidation of benzene to phenol using a ruthenium-bipyridyl-Schiff s base type complex as a catalyst and ferf-BuOOH as the oxidant...

Visible light soaking alone is not a dominant stress factor, which means that the dye (a ruthenium bipyridyl complex) used in these tests is surprisingly stable [7,18,19]. 

The theme of photosensitizing semiconductor electrodes introduced in Section 57.3.2.5(iii) may be developed with an example from ruthenium—bipyridyl chemistry. The sequence (40) is well known. The effectiveness of the photosensitization should be increased by the covalent attachment of the tris(bipyridyl)ruthenium(II) entity to the semiconductor surface, for example to Sn02. This has been achieved using the versatile halosilane chemistry shown in equation (41). The coimter anion was PFg . Cyclic voltammetry showed that the behaviour of the sjretems Sn02/aqueous [Ru(bipy)3] " and Sn02(Alm)/electroly te were very similar but with a -1-0.05 V shift in E°. The coated electrode gives a photocurrent with a red shift of 10 nm which is twice as large as for the non-coated electrode. Unfortunately the current falls off due to promotion of the hydrolysis of the Aim. 

We recently incorporated the ruthenium(II) bipyridyl moiety into acyclic, macrocyclic, and lower rim caUx[4Jarene structural frameworks to produce a new class of anion receptor capable of optical and electrochemical sensing (226, 253. 254). Stability constant determinations in DMSO using H NMR titration techniques demonstrated that these acyclic receptors (131 and 132) form strong complexes with chloride and dihydrogen phosphate anions (stronger than with analogous monopositive cobaltocenium based receptors). The ruthenium ion is dipositive and hence the electrostatic interactions are particularly favorable. The 4,4 -substituted ruthenium bipyridyls were observed to bind anions more... 

Tennakone K., Kumara G. R. R., Kottegoda I. R. M., Wijayantha K. G. U. and Perera V. P. S. (1998). A solid-state photo voltaic cell sensitized with a ruthenium bipyridyl complex , /. Phys. D Appl. Phys. 31, 1492-1496. 

Tachibana Y., Hague S. A., Mercer I. P., Durrant J. R. and Klug D. R. (2000), Electron injection and recombination in dye-sensitized nanocrystalline titanium dioxide fdms a comparison of ruthenium bipyridyl and porphyrin sensitizer dyes , J. Phys. Ghent. B 104, 1198-1205. 

Adams, C.J., Bowen, L.E., Humphrey, M.G., Morrall, J.P.L., Samoc, M., Yellowlees, L.J. Ruthenium bipyridyl compounds with two terminal alkynyl hgands. Dalton Trans. 4130-4138 (2004)... 

Photocurrent generation is one of the most interesting direct applications of photosynthetic studies. The adsorption of sensitizers onto semiconductor surfaces has been found to be an efficient way to generate photocurrents and has been studied extensively. Ruthenium bipyridyl complexes, in particular, have been the focus of recent research [137-139]. In these cases, only the first layer of molecules, which is in direct contact with the surface, is active. A highly porous semiconductor material was therefore employed to compensate for the low level of absorption of the single molecular layer. Other varieties of chromophores, semiconductor materials, and electron carriers for totally solid systems have been the subjects of extensive studies. The present... 

For coordinating and sensing luminescent lanthanide ions, a luminescent ruthenium bipyridyl complex has been covalently linked to one, two or six lower rim acid-amide modified caUx[4]arene moieties in receptors 155-157. All these complexes coordinated with lanthanide ions, Nd , Eu and Tb, with the formation of adducts of variable stoichiometries. The adduct formation affected the Ru luminescence, which was strongly quenched by Nd ion, increased by the Tb ion and moderately quenched or increased by Eu ion (2004IC3965). 

Professor Wang, Dr Jia and Dr Li have written about the Electro-chemiluminesence of a set of particular Ruthenium (bipyridyl) complexes. Dr Viswanatha and Dr Pandey have described the study of semiconducting quantum dots using optical spectroscopy in both frequency and time domains. 

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