Polypyridyl complex

Elliott C M, Derr D L, Matyushov D V and Newton M D 1998 Direct experimental comparison of the theories of thermal and optical electron-transfer studies of a mixed-valence dinuclear iron polypyridyl complex J. Am. Chem. 

Covalent hydration and pseudobase formation in transition metal polypyridyl complexes reality or myth N. Serpone, G. Ponterini, M. A. Jamieson, F. Bolletta and M. Maestri, Coord. Chem. Rev.,... 

Nasr C, Hotchandani S, Kim WY, Schmehl RH, Kamat PV (1997) Photoelectrochemistry of composite semiconductor thin films. Photosensitization of Sn02/CdS coupled nanocrystal-Utes with a ruthenium polypyridyl complex. J Phys Chem B 101 7480-7487... 

Palanichamy, K., and Ontko, A.C. (2006) Synthesis, characterization, and aqueous chemistry of cytotoxic Au(III) polypyridyl complexes. Inorganica Chimica Acta, 359, 44. 

Alkyl, allyl, and aryl bromides are dehalogenated mainly with the formation of R R dimers in the presence of polypyridyl complexes of the metals of Group VIII. It has been demonstrated that the complexes [Co(bpy)3] + 203-204 [Ni(bpy)3]2+,205 and [Ni(phen)3]2+206 catalyze the reductive dimerization of allyl and alkyl bromides in organic 203 205 206 and aqueous micellar 204 solution. 

Run(Hedta)(NO+)]° and [Fen(Hedta)(NO )] have been shown to be effective electrocatalysts for the reduction of N02 in acidic aqueous media, to yield N20, N2, NH3OH+, or NH4 339,340 An element of selectivity is available by control of pH and applied potential. Steps involved in the typical six-electron reduction of nitrite to ammonia catalyzed by [Run(Hedta)(NO+)]° are summarized in Equations (67)-(69). The mechanisms by which nitrite is reduced appeared to be similar to those identified for Fe-porphyrin331 and Ru or Os-polypyridyl complexes.337... 

Cyclic voltammetry is an excellent tool to explore electrochemical reactions and to extract thermodynamic as well as kinetic information. Cyclic voltammetric data of complexes in solution show waves corresponding to successive oxidation and reduction processes. In the localized orbital approximation of ruthenium(II) polypyridyl complexes, these processes are viewed as MC and LC, respectively. Electrochemical and luminescence data are useful for calculating excited state redox potentials of sensitizers, an important piece of information from the point of view of determining whether charge injection into Ti02 is favorable. 

The sensor for the measurement of high levels of CO2 in gas phase was developed, as well90. It was based on fluorescence resonance energy transfer between 0 long-lifetime ruthenium polypyridyl complex and the pH-active disazo dye Sudan III. The donor luminophore and the acceptor dye were both immobilized in a hydrophobic silica sol-gel/ethyl cellulose hybrid matrix. The sensor exhibited a fast and reversible response to carbon dioxide over a wide range of concentrations. 

With the aim of mimicking, on a basic level, the photoinduced electron-transfer process from WOC to P680+ in the reaction center of PSII, ruthenium polypyridyl complexes were used (182-187) as photosensitizers as shown in Fig. 19. These compounds are particularly suitable since their photophysical and photochemical properties are well known. For example, the reduction potential [Rum(bpy)3]3+/-[Run(bpy)3]2+ (bpy = 2,2 -bipyridine) of 1.26 V vs NHE is sufficiently positive to affect the oxidation of phenols (tyrosine). As traps for the photochemically mobilized electron, viologens or [Co(NH3)5C1]2+ were used. 

The ruthenium(II) polypyridyl complexes are also popular but the brightnesses do not exceed 15,000 and thermal quenching is rather significant. This property can be utilized to design temperature-sensitive probes providing that the dyes are effectively shielded from oxygen (e.g., in polyacrylonitrile beads). Despite often very high emission quantum yields the visible absorption of cyclometallated complexes of iridium(III) and platinum(II) is usually poor (e < 10,000 M-1cm-1), thus,... 

All the three polypyridyl complexes display the reversible reduction sequence 2 + / + /0. The relative potential values are reported in Table 7. As far as the nature of such redox changes is concerned, it is important to recall the ambiguity that exists in attributing metal-centred or ligand-centred redox processes for metal-polypyridine complexes. 

Table 7 Formal electrode potentials (V vs. SCE) for the redox processes exhibited by polypyridyl complexes in acetonitrile solution...

A. Kirsch-De Mesmaeker, G. Orellano, J. K. Barton, and N. J.Turro, Light-dependent interactions of ruthenium(II) polypyridyl complexes with DNA probed by emission spectroscopy, Photochem. Photobiol. 52,461 (1990). 

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