Destabilization phenomenon

This model is a polar cross-/ structure with a left-handed twist that complies with the mass-per-unit-length data moreover, it readily accommodates sequence randomization because like residues are still stacked over like residues, regardless of their order, and sequence permutation does not increase the number of charged residues or prolines which would be most likely to destabilize structures of this kind (Fig. 10). The configuration of strands and turns allows some variation without putting charged residues inside the core structure. We envision that structural variations of this kind offer a plausible explanation for the phenomenon of prion variants, as discussed in Section VIII. 

These observations, which prompted a theoretical investigation, have been explained118 by an effect similar to spiroconjugation which is known to be responsible for modifications in the electronic spectra and chemical reactivity of halocyclopentadienes, cyclopenta-diene ketals and 1,1-dioxothiophene122. This spiroconjugation phenomenon could be also involved in the destabilization of spirobisiloles with respect to spirobigermoles and spirobistannoles118. 

P-atom due to an inductive effect, hence destabilizing the HOMO. The LUMO of the chromophore Pd(CNR)2(P) is stabilized, going from a saturated chain P(CI I2) P to P—C=C—P, via coupling of the empty d orbitals located onto P and the empty ir-orbital located onto ethynyl fragment. The emission lifetimes in these polymers were surprisingly short (a few ns). Nevertheless, the quantum yields obtained are larger than expected for such short lifetimes (Table 5). This phenomenon remains unexplained. 

Delocalization energy denotes the energy by which a molecule is stabilized or destabilized compared to a hypothetical reference compound in which electrons (usually ji electrons) are not as mobile. The canonical example is the energy of benzene compared to the hypothetical 1,3,5-cyclohexatriene in which there are three distinct double and three distinct triple bonds. With caveats, one measure of this energy is the heat of hydrogenation of benzene compared to three times the heat of hydrogenation of cyclohexene. As an electronic phenomenon, this lies outside the purview of MM. 

Antiaromaticity [1] is the phenomenon of destabilization of certain molecules by interelectronic interactions, that is, it is the opposite of aromaticity [2], The SHM indicates that when the n-system of butadiene is closed the energy rises, i.e. that cyclobutadiene is antiaromatic with reference to butadiene. In a related approach, the perturbation molecular orbital (PMO) method of Dewar predicts that union of a C3 and a Ci unit to form cyclobutadiene is less favorable than union to form butadiene [3]. 

The destabilization of 4 2 with respect to the parent atomic orbitals is greater than the stabilization of P1, so the stability of the product will depend on the number of its electrons. When the molecule has one or two electrons, the Aufbau principle states that they will occupy XP1, which has a lower energy than the orbitals in the separated atoms. Hence the molecule is stable with respect to the atoms. This analysis explains the phenomenon of covalent bonds ... 

Such a phenomenon could be due to a destabilization action of the acetylenic on the metal-sulfur bond. Such an action has been evidenced some sulfur goes back into the solution (61). 

This phenomenon was also explained by a a -n orbital crossover scheme while the mono- and di-fluoropyridine anions are n radicals, the tetra- and penta-fluoropyridine anions are a radicals. This change has been explained as resulting from combined effects of inductive stabilization of the cr -orbitals and destabilization of the 7i -orbitals by back-donation from fluorine. 

The addition of polymers can also destabilize a colloidal solution for two reasons. Firstly, when polymers adsorb on more than one colloid and this phenomenon is called bridging. Secondly, when polyelectrolytes neutralize oppositely charged colloids and thereby reduce the electrostatic repulsion between the colloids. In some cases both a destabilization and a stabilization of a solution is desired. One example is the manufacturing of paints, where it is required that the paint is easy to apply on the wall and that it stays on the wall. This can be achieved with a solvent which stabilizes the solution but rapidly evaporates when the paint is applied and makes it possible for the colloidal particles to coagulate. 

Carbenes and carbynes can exert both a strong trans influence and trans effect. A trans influence is a ground-state destabilization (thermodynamic) of the trans M-L bond. The trans effect is a kinetic phenomenon wherein the lability of the trans ligand is increased either by ground-state destabilization or transition-state stabilization. 

Franks, F., Hatley, R. H. M and Friedman, H. L The thermodynamics of protein stability. Cold destabilization as a general phenomenon. Biophys. Chem. 31, 307-316 (1988). 

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