Stationary electron donor

Finally, stereoregularity of the initial PAN also affects the disposition of a CTC obtained from this polymer to the formation of photoinduced states with complete charge transfer. Both the values of the stationary concentration of these states and the rate of growth to this level, are considerably higher for a PCS obtained from the polymer with elevated stereoregularity. All this characterizes the effect of PCS stereoregularity on their reactivity in the formation of a CTC. The semi-conductive properties of PCS complexes of various classes with electron donors have been studied267, 268 ... 

The adsorption of particles of various type results in the change in electric conductivity of such bridges mainly due to local chemical interaction of adsorbed particles with electrically active defects which are electron donors and resulting, thereby, in decrease of their concentration or, on the contrary, in increase due to creation of new defects of this type. In both cases as it has been shown above there are substantially straightforward and easily verified relationships linking both the initial rates in the change of electric conductivity and the stationary values reflecting concentration of adsorbed particles in ambient volume. 

A characteristic increase of 90 after the horizontal section is apparently more pronounced when the potassium oxalate K2C2O4 is used as the electron donor instead of the sulfide ions (Fig. 2.25). A qualitative similarity of the adsorption isotherms and the MO concentration dependence on the initial quantum yield indicates that the adsorbed dye molecules take part in the reaction. Note that all kinetic curves attain the same value of the stationary quantum yield ratio depends on the nature of polymeric surfactant used for stabilization of CdS colloid. With PAA, this ratio equals ca. 0.5, and 0.6 with PVS. 

For example, supported TiCl4/MgCl2 catalysts show a short period of acceleration, followed by a prolonged steady period 92,93). However, in the presence of electron donors, they may show the typical decay rate kinetics observed during propylene polymerization 93). Bulk catalysts prepared by interaction of TiCU with Mg(OR)2 show either a stationary rate, or a non-stationary rate, according to the titanium content 88,94). Bulk catalysts prepared by reduction of TiCl4 with organomagnesium compounds show a decay type rate 92-95>. 

Table 6.6 [46] gives experimental results for the complexing constant together with values determined by other methods. In Table 6.7 [129] a comparison between chromatographic and static values of the partition coefficient is given for acetylene, methylacet-ylene and vinylacetylene, which form hydrogen bonds with various electron-donor stationary phases. The agreement between the GC and static values is reasonable. 

Hi) n-electron acceptor/yc-electron donor stationary phases l-(3,5-Dinitrobenzamido)-l,2,3,4-tetrahydrophenanthrene W-(3,5-Dinitrobenzoyl)-l,2-diphenyl-1.2-diaminoethane yV-(3,5-Dinitrobenzoyl)-l,2-diaminocyclohexane yV-(3,5-DinitrobenzoyI)-(l-naphthyl)glycine amide Whelk-O 1 ULMO DACH DNB CHIREX 3005... 

The reactivity of ylides is influenced not only by the substituents R and R, but also by the character of the so-called stationary substituents on the phosphorus atom. If the phenyl groups normally used are replaced by electron donors such as alkyl groups, the electron density on the phosphorus and thus the nucleophilicity of the ylide are increased. The structure of the stationary substituents on the phosphorus has a considerable influence on the stereochemistry of Wittig reactions. These effects are discussed in Section C.2. 

Metal ions can act as electron-pair acceptors, reacting with electron donors to form coordination compounds or complexes with either the stationary phase... 

It is possible to achieve good separation of drugs, environmental pollutants, and components of biological liquids having electron donor properties on liquid-crystalline complexes with ions of transition metals. In recent years, remarkable progress in research on the use of liquid-crystalline compounds as stationary phases, in both gas... 

The interaction between a solvated peptide or protein and a chemically modified RPC and HIC stationary phase in a fully or partially aqueous solvent environment can be discussed in terms of the interplay of weak physical forces. The main types of physical interactions that are involved in order of relevance and dominance for the establishment of the selective recognition and binding between a peptide or protein and RPC and HIC ligates are (I) hydrophobic interactions and related phenomena mediated by polarized electron donor or electron acceptor processes, (2) Lifshitz-London forces and van der Waals and associated weak dipolar interactions, (3) tt 7t and n ->dipole interactions, (4) hydrogen bond interactions, (5) electrostatic interactions, (6) metal ion coordination interactions, and (7) secondary macromolecular interactions involving force field effects. 

Accordingly, the excited sensitizer was reduced by an electron donor before the electron transfer occurred. This process competes with the recombination given by Eq. (10.10). Such a supersensitization was never really proved. It is assumed that the increase of the stationary photocurrent upon addition of a reducing agent is entirely due to the regeneration of the adsorbed dye (Figure 10.20). 

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