Charge transfer degree

Kawamoto T, Mori T, Konoike T, Enomoto K, Terashima T, Uji S, Kitagawa H, Takimiya K, Otsubo T (2006) Charge transfer degree and superconductivity of the incommensurate organic superconductor (MDT-TSF)(l3)o.422- Phys Rev B 73 094513/1-8... 

The most prospective donors are those with ionization potentials of ID < 6.6 eV. Acceptors with electron affinities of EA > 2.6 eV are suitable. When / EA < 4 eV, donor-acceptor interaction leads to strong molecular complexes with a charge-transfer degree >0.5. Donor-acceptor charge transfer often results in the formation of ion radical salts having metallic conductivity. In terms of charge-transfer degree, ion radical salts have values >0.7. 

Electronic and IR spectra of the bithiopyrylium 13 (Z = S, R = Ph), bithiopyranylidene 14 (Z = S, R = Ph), and polyiodide complexes of the latter have been analyzed as a function of charge-transfer degree and temperature (90MI2). 

The Franck-Condon principle reflected in tire connection between optical and tliennal ET also relates to tire participation of high-frequency vibrational degrees of freedom. Charge transfer and resonance Raman intensity bandshape analysis has been used to detennine effective vibrational and solvation parameters [42,43]. 

MEH-PPV and P3MBET, were used. As a measure of the efficiency of the photo-induced charge transfer, the degree of luminescence quenching and the ratio of the charged photoexcitation bands to the neutral photoexcitation bands were taken. These two numbers are plotted in Figure 15-15 versus the electrochemical reduction potential. A maximum in the photoinduced electron transfer was determined for Cbo. 

It should be noted that the properties of a CTC depend to a considerable degree on the conditions of their preparation. Temperature increase, in particular, favors the accumulation of complete charge transfer states in a CTC. In the case of a CTC obtained in solution, the increase of dielectric constant of the solvent has the same effect. The method of preparation of a CTC also affects the kinetic curves of the accumulation and depletion of complete transfer states arising at protoirradiation. 

The products of the thermal transformation of PAN were used for the examination of the effect of stereoregularity of the initial polymer on the CTC properties. At equal transformation degrees, the concentration of complete charge transfer states in a bromine-complexed PCS, obtained on the basis of PAN-c (t e., a polymer with elevated content of isotactic sequences), exceeds by two orders of magnitude this parameter in the polymer obtained on the basis of PAN-r. 

The composition of the electrical effect in the case of the 1,4-benzo-quinones seems to depend upon the degree of substitution. The association constants and charge transfer absorption energies of the 2-substituted-l,4-benzo-quinone-hexamethylbenzene complexes (sets 15-2 and 154) show values of pj of 55 and 44 respectively. Values of p are set forth in Table XVII. 

Ketenes are especially reactive in [2 + 2] cycloadditions and an important reason is that they offer a low degree of steric interaction in the TS. Another reason is the electrophilic character of the ketene LUMO. As discussed in Section 10.4 of Part A, there is a large net charge transfer from the alkene to the ketene, with bond formation at the ketene sp carbon mnning ahead of that at the sp2 carbon. The stereoselectivity of ketene cycloadditions is the result of steric effects in the TS. Minimization of interaction between the substituents R and R leads to a cyclobutanone in which these substituents are cis, which is the stereochemistry usually observed in these reactions. 

Bases stacked rather than hydrogen bonded have also been studied with quantum chemical methods [182, 244-247]. The nature of excited states in these systems has been debated and theoretical calculations are called to decide on the degree of excited state localization or delocalization, as well as the presence and energy of charge transfer states. The experimentally observed hypochromism of DNA compared to its individual bases has been known for decades [248], Accurate quantum chemical calculations are limited in these systems because of their increased size. Many of the reported studies have used TDDFT to calculate excited states of bases stacked with other bases [182, 244, 246, 247], However, one has to be cautious when us-... 

Fig. 4.4. Potential dependence of (a) the coverage degree of platinum by tin and (b) charge transferred during tin adsorption on platinum (according to Eq. 4.1). Tin was adsorbed from Sn(S04)2 ( ) and from SnS04 (O).

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