Intramolecular DNA Coiling Mediated by a Metallo‐Supramolecular Cylinder

: In the groove! A tetracationic supramolecular cylinder, [Fe2 L3 ]4+ (L=C25 H20 N4 ), with a triple-helical architecture is just the right size to fit into the major groove of DNA and too big to fit into the minor groove. NMR spectroscopic data confirm that the cylinder binds in the major groove. Linear dichroism shows that very low loadings of [Fe2 L3 ]4+ have a dramatic bending effect on the DNA and atomic force microscopy images show that this is an intramolecular effect resulting in coils of DNA.