HYDROGEN-BOND PATTERNS. Raymond E. Davis. Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712-1167, USA.

Our study of hydrogen-bond patterns has the following broad aims:

1. identify and describe hydrogen-bond patterns (HBPs) that persist across traditional boundaries of chemical functionality;

2. investigate the possibility of hydrogen-bond pattern functionalities by which molecules "recognize" each other;

3. characterize each hydrogen-bond pattern with respect to the range, frequencies, and metrical aspects of chemical functional groups that display that pattern;

4. provide and elaborate protocols, including the graph-set methodology originated by Etter, to facilitate the recognition, characterization, and cataloguing of common hydrogen-bond patterns.

Current work is focused in these areas:

* Diversity of chemical functionalities. Which chemical functional groups are observed to display a particular hydrogen-bond pattern?

* Frequency of occurrence of chemical functionalities. For a given chemical functional group, how common or how unusual is a particular hydrogen-bond pattern? Can structural features be identified -- in terms of chemical groupings, metrical aspects, or accompanying HBPs -- that correlate with the frequency of occurrence of a particular HBP for a given chemical functional group?

* Variability of metrical aspects. Over what range of geometric constraints does a particular HBP vary?

* Pattern cofunctionality. Do certain patterns often occur together? Could such pairs of patterns be considered to be cofunctional?

We will discuss our recent work in these areas, including an introduction to the graph-set methodology for describing hydrogen-bond patterns.

Supported in part by the Robert A. Welch Foundation, Grant F-233