Hydrogen bonding fields

Finally, since besides the inductive effect of the sulfoxide and the sulfone functional groups, hydrogen bonding, field effects and steric effects to solvation may or may not work in the same direction, the pKx values can be useful in assigning configurations of suitable pairs of stereoisomeric sulfoxide and sulfone carboxylic acids291. 

Finally, the use of a u-polarity field instead of different and more empirical electrostatic, hydrophobic, and hydrogen-bonding fields should lead to considerable advantages in molecular field analysis (MFA) techniques such as ComFA. On the one hand, a includes all three aspects of interactions in a single field, and on the other hand, this interaction picture meanwhile is much better validated quantitatively than the empirical fields presently used in MFA. The only problem here is that a is a surface property and thus less a field in space. With some effort it should be possible to develop reasonable functions for the extension of a perpendicular to the molecular surface and thus to generate a kind of 3D a-filed as required for MFA. 

In the CoMFA method developed by Cramer et a molecule is described using electrostatic, steric, and, sometimes, hydrogen bonding fields calculated at the... 

Using CoMFA,currently one of the most popular 3D-QSAR techniques, Kim examined the relationships between lipophilicity indices (log P and log k) and various molecular fields (i.e., steric, electrostatic, and hydrogen bond fields). Because the complex nature of lipophilicity was largely... 

The CoMSIA analysis using steric, electrostatic, and lipophilic fields as descriptors gave a model with (f of 0.873 and of 0.954. The CoMSIA steric, electrostatic, and lipophilic fields explained the variance of 8.8, 40.9 and 50.2 %, respectively. This indicated that the hydrophobic interaction was a major factor to explain the field properties of the alkylphosphonates lo. Further attempts to combine the hydrogen bond fields with the standard steric, electrostatic, and lipophilic fields did not lead to any significant improvement = 0.869, = 0.952). Indeed,... 

---