Hydrogen bonding, cooperative effect

Hydrogen bond cooperativity is treated in the work of Sear and Jackson, by including in the association energy a three-body term which either increases or decreases the strength of the bonds in chains of three or more molecules. Their model (in essence, an association model) is able to account for the effect of density on the degree of association and, thus, it can describe vapor-liquid equilibria. 

K. Stokely, M.G. Mazza, H.E. Stanley, G. Franzese, Effect of hydrogen bond cooperativity on the behavior of water. Proc. Natl. Acad. Sci. USA 107(4), 1301-1306 (2010)... 

Beyond the concept of combined acid catalysis, there are also many other bifunctional acid catalysts interacting with nucleophiles and electrophiles simultaneously, and thus benefiting through such cooperative effect. Selected examples on Lewis acid/hydrogen bonding cooperative catalysis and Lewis acid/transition-metal... 

Fig. 5. Protein folding. The unfolded polypeptide chain coUapses and assembles to form simple stmctural motifs such as -sheets and a-hehces by nucleation-condensation mechanisms involving the formation of hydrogen bonds and van der Waal s interactions. Small proteins (eg, chymotrypsin inhibitor 2) attain their final (tertiary) stmcture in this way. Larger proteins and multiple protein assembhes aggregate by recognition and docking of multiple domains (eg, -barrels, a-helix bundles), often displaying positive cooperativity. Many noncovalent interactions, including hydrogen bonding, van der Waal s and electrostatic interactions, and the hydrophobic effect are exploited to create the final, compact protein assembly. Further stmctural...

It has been pointed out321-324 that the two groups of solvents differ by some definite structural features. In particular, ED, 1,2-BD, and 1,3-BD possess vicinal OH groups that can form intramolecular hydrogen bonds. For these solvents, the ability of the organic molecule to interact with neighboring molecules is reduced. This results in the possibility of a different orientation at the interface because of different interactions of the OH groups with the Hg surface.323 The different molecular structure leads to different dipolar cooperative effects. As a result, the dependence of C on the bulk permittivity follows two different linear dependencies. 

Theoretically, the problem has been attacked by various approaches and on different levels. Simple derivations are connected with the theory of extrathermodynamic relationships and consider a single and simple mechanism of interaction to be a sufficient condition (2, 120). Alternative simple derivations depend on a plurality of mechanisms (4, 121, 122) or a complex mechanism of so called cooperative processes (113), or a particular form of temperature dependence (123). Fundamental studies in the framework of statistical mechanics have been done by Riietschi (96), Ritchie and Sager (124), and Thorn (125). Theories of more limited range of application have been advanced for heterogeneous catalysis (4, 5, 46-48, 122) and for solution enthalpies and entropies (126). However, most theories are concerned with reactions in the condensed phase (6, 127) and assume the controlling factors to be solvent effects (13, 21, 56, 109, 116, 128-130), hydrogen bonding (131), steric (13, 116, 132) and electrostatic (37, 133) effects, and the tunnel effect (4,... 

Guo, H., and M. Karplus. 1994. Solvent Influence on the Stability of the Peptide Hydrogen Bond A Supramolecular Cooperative Effect. J. Phys. Chem. 98, 7104-7105. 

There is also the possibility of Davydov coupling, which is likely to appear when there are double or multiple H-bond systems [7,21-23]. It is responsible for cooperative effects between neighboring hydrogen bonds in cyclic hydrogen bonded dimers, or more generally in hydrogen-bonded chains in solids [ 10,24—34]. 

---