12: The CH⋯π Hydrogen Bond

Weak interactions between functional groups such as CH⋯O, CH⋯N and CH⋯π hydrogen bonds (H-bonds) are ubiquitous in organic compounds and play an important role in conformation, molecular orientation, crystal packing, and molecular recognition. In this chapter, we focus on the CH⋯π H-bond in crystals. A definition of the CH⋯π H-bond is introduced first. Then, evidence from crystallographic database and spectroscopic studies is presented. Finally, computational study is described. This is important to elucidate the nature of weak H-bonds, i.e., to allow quantitative estimation of weak interaction energy and cooperative effects.