198 Topics in Current Chemistry Editorial Board: A. de Meijere KN ...

Directional Aspects of Intermolecular Interactions 49
b
a
Fig. 38 a, b. Minor groove binding of netropsin in DNA [100]: a chemical formula of netropsin;
b binding of netropsin by way of N-H◊◊◊O bonds (dotted lines) and C-H◊◊◊C interactions. The
latter define the specificity of the drug
duplex DNA, as illustrated in Fig. 38. These compounds are relatively cytotoxic.
In the crystal structure of netropsin bound to a dodecamer with four A◊ T
base pairs in the middle, the four base pairs have high propeller twists [99, 100].
As a result, the amino group of adenine is located half-way between the carbonyl
groups of two adjacent thymine residues and some three-center hydrogen bonds