The CH/π Interaction. Implications in Molecular Recognition

Abstract

The CH/π interaction is a weak hydrogen bond occurring between CH groups and π-electron systems. Evidence for such a weak attractive molecular force has been presented. These include data from IR, NMR, CD spectroscopies, and X-ray crystallography. The conclusion has been supported by ab initio MO calculations. An important point is that CH- and π-groups are arranged generally in chemical structures and have many chance to interact each other. Unlike ordinary hydrogen bondings, the CH/π interaction may occur in protic media as well as in nonpolar atmosphere. Consequences in supramolecular chemistry, selectivities in chemical reactions, as well as the substrate specificities of proteins were discussed in the light of the CH/π interaction hypothesis.