Complexes photoinduced electron transfer

Walker G 0, Barbara P F, Doom S K, Dong Y and Hupp J T 1991 Ultrafast measurements on direct photoinduced electron transfer in a mixed-valence complex J. Rhys. Chem. 95 5712-15... 

Aminopyridines can be perfluoroalkylated in a photoinduced electron transfer process. A charge transfer complex between the heterocycle and polyfluoroalkyl iodide, observable by NMR, is photolytically stimulated... 

Photoinduced electron-transfer reactions of metal complexes in solution. D. G. Whitten, Acc. Chem. Res., 1980,13, 83-90 (105). 

Photoinduced Electron Transfer Reactions of Gold Complexes 273... 

Fig. 4 Coupling of the redox participants to the DNA w-stack is requisite to DNA-mediated charge transport. Rapid (>109 s 1) photoinduced electron transfer occurs between the metallointercalators, [Ru(phen)2dppz]2+ and [Rh(phi) 2phen]3+, when they are tethered to opposite ends of a DNA duplex over 40 A apart. Conversely, electron transfer does not occur between non-intercalated Ru(II) and Rh(III) complexes tethered to DNA...

The ability to switch a molecular unit on and off is a key component of an efficient molecular device, since it allows modulation of the physical response of such a device by external physical or chemical triggers. A molecular device, based on a trinuclear metal complex, shown in Figure 59, functions as an electroswitchable-photoinduced-electron-transfer (ESPET) device.616 Electrochemical switching of the redox state of a spacer intervening between a donor-acceptor pair can dictate the type of the observable charge separation and the lifetime of the resulting ion pair.616... 

Figure 59 A trinuclear metal complex that functions as an electroswitchable-photoinduced-electron-transfer...

The first photophysical investigation performed on stereochemically pure metal-based dendrimers having a metal complex as the core is that concerning the tetranuclear species based on a [Ru(tpphz)3]2+ core (tpphz=tetrapyrido[3,2-a 2, 3 -c 3",2"-h 2",3"j]phenazine) [67]. Dendrimer 45 is an example of this family. In this compound, two different types of MLCT excited states, coupled by a medium- and temperature-dependent photoinduced electron transfer, are responsible for the luminescence behavior. However, the properties of all the optical isomers of this family of compounds are very similar. This finding is also in... 

SCHEME 42. Preparation of photoinducible electron-transfer Ru(II)-complexes.279... 

Electron-transfer activation. The photoinduced electron-transfer activation of the [DBC, TCNE] complex generates the DBC+ cation radical, which undergoes a fast electrocyclic ring opening, i.e.,... 

Cationic ions and polyelectrolytes can stabilize the formation of the PS I monolayers at the air-water interface. These complex monolayers can be transferred onto the hydrophobic substrate surfaces by horizontal lifting method. The PS I/polyelectrolyte complex film may be used for the development of a biosystem for the studies on photoinduced electron transfer and for hydrogen evolution. 

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. 

In classical kinetic theory the activity of a catalyst is explained by the reduction in the energy barrier of the intermediate, formed on the surface of the catalyst. The rate constant of the formation of that complex is written as k = k0 cxp(-AG/RT). Photocatalysts can also be used in order to selectively promote one of many possible parallel reactions. One example of photocatalysis is the photochemical synthesis in which a semiconductor surface mediates the photoinduced electron transfer. The surface of the semiconductor is restored to the initial state, provided it resists decomposition. Nanoparticles have been successfully used as photocatalysts, and the selectivity of these reactions can be further influenced by the applied electrical potential. Absorption chemistry and the current flow play an important role as well. The kinetics of photocatalysis are dominated by the Langmuir-Hinshelwood adsorption curve [4], where the surface coverage PHY = KC/( 1 + PC) (K is the adsorption coefficient and C the initial reactant concentration). Diffusion and mass transfer to and from the photocatalyst are important and are influenced by the substrate surface preparation. 

Sabbatini N, Dellonte S, Bonazzi A et al (1986) Photoinduced electron-transfer reactions of poly(pyridine)ruthenium(II) complexes with europium(III/II) cryptates. Inorg Chem 25 1738-1742... 

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