In short: A weak hydrogen-bond occurring between soft acids and soft bases.
Nature: Largely of dispersion and partly from charge-transfer and electrostatic forces.
Characteristics: ca. 1.5-2.5 kcal/mol; orientation dependent; additive in enthalpy; entropically favored; cooperative; effective in water as well as in nonpolar media.
Implication:
The CH/pi interaction makes an important contribution to the understanding of weak intermolecular forces and their potential value to the physical, chemical, and biochemical sciences.
Conformation
Chiroptical property
Reaction selectivity
Chiral recognition
Crystal packing
Clathrate (inclusion compound, host/guest complex)
Crystal engineering
Self-assembly
Solid-state reaction
Liquid crystal
Chromatography
Polymer science
Coordination chemistry, Organometallic chemistry
3D Structure of proteins
3D Structure of DNA
Specificity of proteins and nucleic acids
Cluster, LB membrane, Electron transfer, etc.
For further information, see our books, The CH/pi Interaction, Wiley-VCH, New York, 1998 and Introduction to Intermolecular Forces in Organic Chemistry, Kodansha, 2000 (in Japanese), chapter 5, and New edition, Introduction to Intermolecular Forces in Organic Chemistry, Kodansha, 2008, chapter 6.
Key words: CH/p, CH-p, CH/pi, CH-pi, alkyl/pi, alkyl-pi, hydrogen bond, weak interaction, intermolecular force, soft acid/soft base interaction