Intermediate free wave

Both reacting intermediates, TPrA and Ru(bipy)33 + species, are produced simultaneously during electrochemical oxidation Actual ECL mechanism, however, is somewhat more complicated than expressed by the above reaction pattern with ECL emission from Ru(bipy)32+/TPrA system depending on the applied electrode potential. Usually, the direct oxidation of TPrA at the electrode occurs at more negative potentials than characteristic for the Ru(bipy)32+/Ru(bipy)33 + redox couple. Generally, the ECL emission from Ru(bipy)32+/TPrA system as a function of applied potential consists of two emission waves (both associated with the emission from 3 Ru(bipy)32 + ) attributed to TPrA and Ru(bipy)32 + oxidation, respectively.154 First emission wave corresponds to annihilation of sufficiently stable TPrA + (with half-life of 0.2 ms) and Ru(bipy)3 + species with Ru(bipy)3 + intermediate formed from the reduction of Ru(bipy)32+ by TPrA free radical ... 

Polarography and cyclic voltammetry26 of [V(bipy)3]z (z =2+, 1+, 0, 1-, 2-, 3-) gave Elt2 values of -0.8, -1.01, -1.11, -1.55 and —2.23 V for these five steps, and smaller polarographic waves at -2.10 and -2.6 V were attributed to the reduction of free bipy. From comparison of the Em values for the bipy complexes with those for 4,4 -dimethyl-2,2 -bipy and 5,5 -dimethyl-2,2 -bipy, the electron added (or removed) in the reactions of [V(L)3]Z (z = 2+, 1+, 0) was at t2g orbitals.26 On the other hand, for V(bipy)3/V(bipy)J and V(bipy)J/V(bipy)2-the added electron would occupy orbitals with a predominant n character. However, [V(bipy)3] is diamagnetic, and an intermediate character has been proposed for it. 

The earliest studies investigating the effects of n-3 dietary fatty acid manipulation on vision date back to the early 1970s. Benolken and others (1973) fed rats a fat-free diet, which resulted in a 60% reduction in the retinal DHA content. This was associated with reductions in the amplitudes of the ERG a-wave (and b-wave), reflecting anomalous photoreceptor function. In a later study, the same authors (Wheeler et al., 1975) studied the effects of feeding rats diets free of fat or supplemented with either n-9, n-6, or n-3 precursors. They determined that rats showed increased ERG amplitudes when fed 2% (w/w) linoleic acid (18 2n-6, LA), but an even greater response when 2% (w/w) a-linolenic acid (18 3n-3, ALA) was used. A mixture of 1% (w/w) LA and 1% (w/w) ALA gave an intermediate response, implying that n-3 fatty acids were critical for the development of optimal retinal function. 

Chemical and electrochemical oxidation of these [Pt Me2(a-diimine)] species in MeCN was later studied in more detail in the Tdset group (38). Irreversible electrochemical waves were again observed, and bulk electrolysis revealed consumption of 1.1-1.6 FmoP indicative of a le oxidation process. (Electro)chemical bulk oxidation leads to only marginal formation of methane or ethane, and almost quantitative formation of the species [Pt Me3(a-diimine)(NCMe)] and [Pt Me(a-diimine)(NCMe)] in a 1 1 ratio. It was proposed that the short-lived [Pt Me2(a-diimine)] " " decomposes via a bimolecular methyl transfer from one platinum to another. This explains the product distribution and the lack of products derived from free alkyl radicals. This could either involve a reaction between two [Pt °Me2(a-diimine)] + intermediates or a reaction of [Pt° Me2(a-diimine)] + with the starting material [Pt Me2 (a-diimine)]. 

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