Electron intra-molecular

Many suitable molecules can be designed, with end-groups chosen for SAM formation with dissimilar metal electrodes. For instance, two Au and one A1 electrode could be used. The molecule 0 2A would have two -SH terminations to bond to Au, and one -COOH end group (on D2) to bond to Al. The electron path between the two Au electrodes would traverse a donor moiety Dj with low IPD and an acceptor moiety A, while the path from the Al electrode to the second Au electrode would traverse a weaker donor moiety D2 (with larger IPd) and the common acceptor moiety A. The larger electron current would flow between the two Au electrodes, because the intra-molecular electron mobility would be larger Dj —> A, while the smaller electron current would flow D2 —> A. The smaller... 

Berlin YA, Ratner MA (2005) Intra-molecular electron transfer and electric conductance via sequential hopping unified theoretical description. Radiat Phys Chem 74 124—131... 

In (1), Hq yields the total energy of system in which the molecules and the lattice are excited, yet there are no interactions between molecules and the lattice. The transfer of an electron from site m to site n is given by //j. Polaronic effects, i.e., effects due to the interaction of the electronic excitation and the lattice, are given by H2 and H. hi H2, the energy of the site is reduced by the interaction with the lattice vibration. In H, the lattice vibration alters the transition probability amplitude from site m to n. The term lattice vibration may refer to inter-molecular or intra-molecular vibrations. Static disorder effects are considered in H4, which describes the changes to the site energy or transition probabihty amplitude by variations in the structure of the molecular sohd. 

A distinctive feature of the O2 and S2 luminescence spectra in minerals is a quasi-linear vibrational structure of the broad luminescence band (Tarash-chan 1978). The O2 and S2 molecular ions are isoelectronic. From the molecular orbital diagram describing their electron structure the emission transition Eg- n l2 is determined. When observing luminescence spectra at 77 K, a fine structure associated with the frequency of intra-molecular vibrations of O2 and S2 is detected. This frequency depends on the type of the molecular ion, on inter-nuclear distance and upon the particular position of the molecular ion in the structures. For S2 the maximum of the emission band lies within the range of 600-700 nm with a mean vibration frequency of 500-600 cm , while for O2 the respective maximum is 450-550 nm with a frequency in the 800-1,200 cm range. 

As a hydride ion, that is with the pair of electrons from the C-H bond. This type of reaction is called a hydride transfer. You may have noticed that the transfer was done intra-molecularly within a six-membered ring and therefore has a six-membered transition state. Draw it. 

If definite stoichiometry is maintained in the exciplex formation, an isoemissive point similar to isosbestic point in absorption miy be observed. An interesting example of intra-molecular exciplex formation has been reported foi 9-methoxy-10-phenanthrenecarboxanil. The aniline group is not necessarily coplanar with the phenanthrene moiety but is oriented perpendicular to it. The u-elcctron located on its N-atom interacts with the excited -electron system and an intramolecular exciplex with T-bone type structure is formed in rigid glassy medium where rotation is restricted. Temperature dependence of fluorescence of this compound in methylcyclohexane-isopentane (3 1) solvent shows a definite isoemissive point (Figure 6.8). As the solvent melts and movement is restored to the molecule, structured fluorescence reappears. 

A review on die inter- and intra-molecular cycloaddition of oxidopyridiniums and pyridinium ylides has appealed.117 The known 1,3-dipolar cycloaddition of 1 -methyl-4-phenyl-3-oxidopyridinium with electron-deficient dipolarophiles has been used to produce tropenones which can be transformed into 6- and 7-substituted 3-phenyltropanes, analogues of cocaine.118... 

Various nucleophiles, such as alcohols, fluoride ion, amides, allylsilane, and electron-rich aromatic rings, have been successfully used in this reaction in either an inter- or intra-molecular mode. A recent example of a new C-C bond formation in this reaction in the inter-molecular mode includes the preparation of derivatives 17 by the oxidation of 2-alkoxynaphthols 16 in the presence of an allylsilane or a silyl enol ether as a carbon-based nucleophile (Scheme 7) [22]. 

But if we examine the localized near the donor or the acceptor crystal vibrations or intra-molecular vibrations, the electron transition may induce much larger changes in such modes. It may be the substantial shifts of the equilibrium positions, the frequencies, or at last, the change of the set of normal modes due to violation of the space structure of the centers. The local vibrations at electron transitions between the atomic centers in the polar medium are the oscillations of the rigid solvation spheres near the centers. Such vibrations are denoted by the inner-sphere vibrations in contrast to the outer-sphere vibrations of the medium. The expressions for the rate constant cited above are based on the smallness of the shift of the equilibrium position or the frequency in each mode (see Eqs. (11) and (13)). They may be useless for the case of local vibrations that are, as a rule, high-frequency ones. The general formal approach to the description of the electron transitions in such systems based on the method of density function was developed by Kubo and Toyozawa [7] within the bounds of the conception of the harmonic vibrations in the initial and final states. 

Brittain T (2008) Intra-molecular electron transfer in proteins. Protein Pept Lett 15 556-561... 

The most spectacular member of this group is the poly(p-phenylene-terephthalamide), better known under its commercial names Kevlar and Twaron. Here we have the combined effects of intra-molecular 7i-electron conjugation between aromatic rings and CONH-groups and the inter-molecular hydrogen-bonding of the CONH-groups. The increment of the latter is, hence, elevated from 15.0 to 30.0 (Table 6.1B). 

Non-tetrahedral structures of organic derivatives of the silicon subgroup elements are often caused by inter- or intra-molecular coordination interaction X M. This takes place in compounds where there is a nucleophilic substituent at the central M atom. An electronegative X atom, which has at least one unshared electron pair (X = N, P, O, S, halogen) and is directly bonded to M, can be such a substituent. Compounds of this kind tend to be involved in inter-molecular coordination. There can be also a heteroatom X as part of the organic substituent at M in this case an intra-molecular coordination usually occurs . Such compounds, which contain five- or six-membered coordination rings, include, for example, draconoides (4) , their analogues (5) , metalloatranes (6) and others. The stability of a coordination bond X —> M increases with the atomic number of M Si < Ge < Sn < Pb. 

Electron flow through flavocytochrome bz has been extensively studied in both the S. cerevisiae (Tegoni et al., 1998 Daff et al., 1996a Chapman et al., 1994 Pompon, 1980) and H. anomala (CapeillEre-Blandin et al., 1975) enzymes. The catalytic cycle is shown in Figure 3. Firstly, the flavin is reduced by L-lactate a carbanion mechanism has been proposed for this redox step (Lederer, 1991). Complete (two-electron) reduction of the flavin is followed by intra-molecular electron transfer from fully-reduced flavin to heme, generating flavin semiquinone and reduced heme (Daff et al.. 

However, the studies on the hinge and Tyrl43 provided no information on the electron transfer from flavin-semiqumone to b 2-heme, the step which rate limits the catalytic cycle. In some elegant experiments, Tegoni et al. (1998) showed that the variation of the rate constant (In et) for this step correlates well with variations in the driving force (AG). Thus, this slow intra-molecular electron transfer is almost certainly controlled by thermodynamics. Tegoni et al. (1998) also provided some evidence that the faster, flavohydroquinone - b 2-heme, electron transfer may also be under thermodynamic control although this remains to be conclusively demonstrated. 

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