Excited states redox properties

Ground- and Excited-State Redox Properties of Pt(diimine)(dithiolate) Complexes 17-29 ... 

It follows from the discussion in the Section 5.4.1 that excited state redox properties can be controlled through ground-state redox potentials (Sections 5.3.2. and 5.3.3.) and excited state energy bo- The excited state energy is dependent on the molecular structure, but in a way that is interrelated with the structural dependence of the redox potentials. In Section 5.3.1 it was mentioned that the MLCT excitation energy, hv, (Figme 2) depends linearly on the difference between oxidation and reduction potentials. This dependence stems from the intramolecular charge separation that occurs in MLCT excited states ... 

Finally, it should be noted that an enormous research effort have been spent on the development of photo-redox active polypyridine complexes and optimization of their excited state redox properties. The vast literature on this topic offers discussions and theories of the relations between molecular structure, medium and excited state redox properties and lifetimes, as well as a broad choice of polypyridine complexes suitable as photosensitizers, especially those based on Ru [9, 14, 28, 74, 95, 98, 151-153, 205, 217, 222, 224, 226, 287, 289, 290, 295, 297]. 

The luminescent properties of [Os (N)(NH3)4]X3 (X = C1, CF3S03) and (Ph4As)2[Os -(N)(CN)5] have also been reported (Table 3). The complexes are emissive and have long excited state lifetimes both in the solid state and in fluid solutions at room temperature (Aen,= 550nm in MeCN). [Os(N)(NH3)4]Cl3 is a powerful one-electron oxidant in the excited state, with an excited state redox potential of 2.1 V vs. NHE. The emitting state has been suggested to be d y) dj f] in origin. 

Selective production of enzymatically active NADH by visible light and without formation of dimers has been achieved by the photoreduction of NAD using [Ru(bipy>3]S04 and [Ru(bipy)3]2(S04)3 as sensitizers, and triethanolamine as electron donor.The synthesis, photophysical properties, and excited-state redox behaviour of [(CN)(bipy)2Ru(CN)Pt(dien)X 104 and [(dien)PtNC Ru(bipy)2 CNPt(dien)]C104 (dien = diethylenetriamine) have been reported, as have the light-induced electron-transfer reactions between [Ru(bipy) (thpy)3 f [where thpy = 2-(thiazol-2 -yl)pyridine, n=2,1, or 0] and methyl viologen. ... 

Ruthenium, tris(2,2 -bipyridyl)-chemical actinometer, 409 excited electronic states redox properties, 490 structure, 64... 

Ru(bpy)2(N-N)] complexes, where N-N is a bidentate polypyridyl ligand (see Fig. 6) exhibit photophysical properties strongly dependent on the substitution of this ligand. Variations in N-N have a systematic effect on ground and excited state redox potentials, absorption spectra, emission energies, and excited state lifetimes. 

Table 4.6). From these quenching data, the complex is found to be a strong photoreductant, having a value for [Au2(dppm)2 ] of-1.6 0.1V versus SCE. The excited and ground state redox properties of the complex are shown in Fig. 4.13. 

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