Directionality in hydrogen bonds

Vedani A, Dunitz JD (1985) Lone-pair directionality in hydrogen bond potential functions for molecular mechanics calculations. The inhibition of human carbonic anhydrase II by sulfonamides. J Am Chem Soc 107 7653-7658... 

A. Vedani and J. D. Dunitz,/. Am. Chem. Soc., 107, 7653 (1985). Lone-Pair Directionality in Hydrogen Bond Potential Functions for Molecular Mechanics Calculations The Inhibition of Human Carbonic Anhydra.se II by Sulfonamides. 

Each of the pharmacophore queries consisted of one donor, one acceptor and one of the two hydrophobic points indicated in Figure 1.16. The directionality of hydrogen bonds was inferred from the X-ray structure and reasonably loose tolerances of 1.5 A were used for donor-acceptor distances and 2-2.5 A to the hydrophobe were chosen to allow for the flexibility seen across kinase structures and to maximise the diversity amongst the identified fragments. Four pharmacophore queries were completed and the results were combined. The chosen fragments were further filtered by molecular weight (between 150 and 250), 51og P (between 2.5 and —2.5) and the presence of... 

There are other examples in which the directionality of hydrogen bonds follows more stringently from the NMR spectra. Aminomethylation of resorcarenes leads to 118, which was found in a C4-symmetrical conformation in the crystalline state. 

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