Hydrogen-bonding capacity

Fig. 10. Possible collagen-linke structure depending on the hydrogen-bonding capacity of certain polypeptides based on their proline content...

As a consequence, the overall penetrant uptake cannot be used to get direct informations on the degree of plasticization, due to the multiplicity of the polymer-diluent interactions. The same amount of sorbed water may differently depress the glass transition temperature of systems having different thermal expansion coefficients, hydrogen bond capacity or characterized by a nodular structure that can be easily crazed in presence of sorbed water. The sorption modes, the models used to describe them and the mechanisms of plasticization are presented in the following discussion. 

Van de Waterbeemd, H., Kansy, M. Hydrogen-bonding capacity and brain penetration. Chimia 1992, 46, 299-303. 

The solubility properties of a compound are determined by the fundamental interactions of the compound in the solid state and by its interactions with aqueous solution [64]. Chemical properties that can be manipulated to impact solubility include ionization state, lipophilicity, hydrogen bonding capacity, and the three-dimensional shape of compounds. 

Not surprisingly, the diacid 13 and its diamide are waterlogged with 2-4 molecules of HzO from which they are difficult to liberate. Binding experiments in CHC13, a non-competing solvent, revealed that stoichiometric complexes, e.g. 48 were formed with diketopiperazines 40) (Kh 104) and amides such as malonamide. With structures of inadequate hydrogen bonding capacity, such as sarcosine anhydride, com-plexation does not occur. 

Some phosphines are easily soluble in water due to their strong hydrogen-bonding capacity. Representatives of these ligands are l,3,5-triaza-7-phosphaadaman-tane (pta), the polyoxyethylene-substituted and the carbohydrate-derived phosphines. A detailed compilation of water-soluble phosphines (together with the known solubilities) can be found in [4],... 

El Tayar, N., Mark, A. E., Vallat, P., Bmnne, R. A., Testa, B. and van Gunsteren, W. E. Solvent-dependent conformation and hydrogen-bonding capacity of cyclosporin A evidence from partition coefficients and molecular dynamics simulations, J.Kled. Chem., 36 (1993), 3757-3764... 

In summary, rj(r) turns out to be a key index in connecting the electrostatic component of the stacking interaction energy with the hydrogen bonding capacity of cytosine as schematically represented is Figure 27.6. 

It should be kept in mind that the terms acidity and basicity of the solvent have to be intended not only according to the Lewis concept (electrophilic vs. nucleophilic properties), but also according to the Bronsted concept (proton donor vs. proton acceptors), or to the hydrogen bonding capacity (hydrogen bond donor vs. hydrogen bond acceptor). 

This hydrogen bonding capacity expressed by the polar selectivity is not limited to an increase in retention for phenols. Packings with embedded polar groups that excel in this feature also exhibit increased retention for analytes with other functional groups. Specifically, carboxylic acids at acidic pH and with acetonitrile as the organic modifier and compounds with sulfonamide functions at acidic and neutral pH exhibit significant... 

Both Ser and Thr are commonly considered to be hydrophilic due to the hydrogen bonding capacity of the hydroxyl group and play a dynamic role in the functioning of cellular processes. Thr has been observed to have an effect on the eating patterns of mammals. 

---