The role of aromatic rings as hydrogen-bond acceptors in molecular recognition

Abstract

Observations of phenol-benzene and ammonia-benzene complexes in the gas phase show that hydrogen bonds link their proton donors to the $\pi $ electrons of the benzene with a bond energy of between 2 and 4 kcal mol$^{-1}$, large enough to be biologically significant. Intramolecular hydrogen bonds between OH and NH donors and aromatic acceptors have also been found in crystal structures of organic compounds. NH-aromatic interactions stabilize $\alpha $-helices if donors and acceptors occur at successive turns of the helix. these interactions also contribute to the stability of several proteins and play an important part in cellular and synaptic signal transmission.