Evidences for electron transfer from

Evidences for electron transfer from surface tg bulk. According to the nature of the clay, variable amounts of Fe are present in the lattice. Glauconite, which is an iron rich member of the dioctahedral smectite family, reacts at pH 7 with sodium... 

The parent cyclopropane system does not, in fact, readily undergo electron transfer in solution apparently, the excited state reduction potentials of most sensitizers are too low (Table 3). However, introducing simple alkyl substituents increases the donor capacity of the cyclopropane system. This is aptly shown by the (gas-phase) ionization potential of 1,1-dimethylcyclopropane (9.0 eV) compared with that of cyclopropane (9.87 eV). PET from a series of methyl-substituted cyclopropanes to photoexcited chloranil was probed in solution. These experiments failed to provide evidence for electron transfer from cis- or rrans-1,2-dimethylcyclopropane. On the other hand, 1,1,2-trimethyl- and 1,1,2,2-tetramethylcyclopropane were oxidized [108, 109]. 

Note that experimental data of Shopes et al. on electron transfer from Cyt c559 to P960 was earlier shown in Fig. 4 as evidence for electron transfer from reduced Cyt c559 to the photooxidized primary donor P960. ... 

R.F. Bartholomew, R.S. Davidson, P.F. Famheth, J.F. McKeUar, and P.H. Turner, The photo reaction of aromatic carhonyl compounds with amines evidence for electron transfer from tertiary aromatic amines to triplet henzophenone, J. Chem. Soc. Perkin 2, 577 (1972). 

Moser, J.E. and M. Gratzel (1998). Excitation-wavelength dependence of photo-induced charge injection at the semiconductor-dye interface Evidence for electron transfer from vibrationally hot excited states. Chimia 52, 160-162. 

These reactions are relevant to this review in that they may be photoinduced, but as radical chain processes many of them can be initiated in other ways. Radical chain dehalogenation of aryl halides has been reviewed previously.The chain propagation sequence for the deiodination of aryl iodides with CH5O-/CH3OH is shown in Scheme 1. The species (Arl) is very short lived and deiodinates efficiently. Reactivity diminishes in the order Arl > ArBr > ArCl and is enhanced in cases where there is relief of steric strain. Photochemical dehalogenations of aryl halides with AIH4 and BH4 have been proposed to follow similar radical chain mechanisms. Evidence for electron transfer from BH4 to ArCl has been present by Freeman and Ramnath. ... 

Binding at the remote site has also been detected in studies on the quenching of the excited states [Cr(phen)3] and [Ru(bipy)3] by French bean plastocyanin [103]. The model adopted allows for electron transfer from the remote and adjacent sites, where at low protein concentrations the adjacent pathway is 10 times faster. At the higher concentrations of protein, up to 4 X 10 M, an interesting feature is the evidence for an adduct in which two PCu(I) molecules are associated with one inorganic complex. The oxidant is believed to be sandwiched between two PCu(I) s. 

The substrate half-reactions are displayed in Tables I and II. In each case, a two-electron process seems to be involved. Only in nitro-genase are greater numbers of electrons transferred, and the discussion earlier in this paper summarizes the evidence that these processes occur in two-electron steps. The two-electron reaction of the molybdenum site never appears to be simply an electron transfer reaction. In the case of nitrogenase, each substrate takes up an equal (or greater) number of protons to form the product. In the other molybdenum enzymes, proton transfer and addition or removal of H20 are also required. In each case, however, there is at least one proton transferred in the same direction as the pair of electrons. These data, taken in conjunction with the EPR evidence for proton transfer from the substrate to the active site in xanthine oxidase, suggest that the molybdenum site in all the enzymes... 

Evidence from pulse radiolysis experiments for electron transfer from the type 1 to the type 2 copper site in A. cycloclastes NiR has been... 

Raney niekel can be used for the ehemoselective reduction of a,y9-unsaturated ketones, esters, acids, nitriles, and nitroalkenes to give the corresponding saturated carbonyl compounds and carbonyl analogs in excellent yields. From trapping experiments it became evident that electron transfer from nickel to give the enone radical anion initiates the reaction which then proceeds via proton transfer and second electron-proton transfer cycle (Scheme 8) [37]. 

Alteration of the reaction mechanism from direct oxygen transfer to electron transfer becomes more evident in the reduction of His64Ser Mb compound I by DTCO, because rapid formation of compound II was clearly observed this was followed by the slow conversion of compound II to the ferric state [108]. The Aobs value for electron transfer from DTCO to His64Ser Mb compound I agrees with a linear correlation for reactions of [(TMP)Fe =0] + with DMA via electron transfer (see Figure 3) [108]. 

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