Interactions of diaryl-polyamines with nucleic acids. Allosteric effects with dinuclear copper complexes

A series of α,ω-diarylamines with a variable number of ethylenediamine units between terminal naphthylrings shows dramatic affinity changes towards double-stranded nucleic acids, particularly upon complexation with Cu(II) ions. Metal salts alone have under the applied conditions only a negligible effect. The affinity of the metal-free ligands towards nucleic acids shows significant differences to those of the underlying polyamines, with a reversed stabilization of DNA instead of the usually observed preference for RNA. The affinity changes and preliminary NMR studies are in line with intercalation of naphthylrings into the double-stranded nucleic acid, which is hampered by complex formation with Cu(II).