Intramolecular forces summary

In summary, intermolecular interactions are of great influence on solvent properties, as indeed are the effects of the intramolecular forces. The strength of the (covalent) bonds which bind the atoms in the molecules together thus determines to a large extent the stability of the products (Table 2.12). 

Baramboim underlined the importance of polymer composition in mechanochemistry [2]. Composition determines the magnitude of inter- and intramolecular forces, the chain flexibility, and packing density. Table 3.1 is a summary of the effects of several factors on the most important reaction parameters. Of course, at higher temperatures, mechanochemistry may be augmented by thermal and oxidative processes. It is unfortunately difficult to compare in detail results of different authors because of the diversity of instruments, conditions and polymers that have been used. It is clear that, especially regarding solvent power and concentration, there is disagreement among authors. Moreover, these two parameters are also interdependent. 

What information does the difference spectrum provide concerning the intramolecular mechanism of the BR to K transition The frequency shifts observed (Fig 6.6-10) between 1300 and 1100 cm characterize an all-trans to 13-cis isomerization of retinal. The unusually strong out-of-plane vibrations at 960 cm and 814 cm indicate considerable distortion of the terminal part of the chromophore. In summary, the BR-K difference spectrum shows that isomerization forces the chromophore and the protein backbone into a strained conformation, generating tension in the protein, which in turn drives the ensuing reactions. 

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