CH-X hydrogen bonding

Abstract The history of weak CH X hydrogen bonds is discussed, beginning with early hints of their existence, to our current understanding of their widespread occurrence. While the presence of such bonds is no longer contested, there is a great deal of uncertainty regarding whether, and to what degree, these weak interactions may contribute to the structure of biomolecules. The ability of quantum calculations to address this issue, and their success to date, are discussed in detail. 

Vishveshwara, S. (1978) Ab-initio molecular orbital studies on CH -X hydrogen bonded systems, Chem. Phys. Lett. 59, 26-29. 

As an alternative to the more usual hydrogen-bonding groups such as urea, amides, and guanidinium, it is possible to use imidazolium groups to create CH" "- X hydrogen bonds as in receptor The charged nature of this... 

Fig. 1 (a) Synthesis of 1,2,3-triazole by copper(l)-catalyzed azide-alkyne cycloaddition (CuAAC) and the CH X hydrogen bonds that form with neutral triazole and positively charged triazolium moieties, (b) Synthesis of iodotriazolium with halogen bonds... 

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