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.