Metallocene–nucleobase conjugates. Synthesis, structure and nucleic acid binding

Abstract

The ferrocenylnucleobase conjugates [Fe(η⁵-C₅H₅){η⁵-C₅H₄CH₂NMe₂CH₂CH₂CH₂[graphic omitted]H}][BF₄]1 and [Fe(η⁵-C₅H₅){η⁵-C₅H₄CH₂[C₅H₂N₄(NH₂)]}]2 of thymine and adenine respectively, have been prepared and their crystal and molecular structures determined. The molecular packing of the two compounds differs markedly in terms of intermolecular hydrogen-bonding interactions. In 1 such interactions are confined to discrete cation ⋯ anion ⋯ solvate units, whereas in 2 the hydrogen-bonding patterns are extensive and involve both the Watson–Crick and Hoogsteen donor and acceptor sites. Electrochemical studies of the interaction of 1 with nucleic acids showed that the incorporation of this single nucleoside base with the metallocene moiety enhances the binding in aqueous solution compared to a cationically charged derivative devoid of this functionality. Moreover, with immobilised nucleic acid, binding was observed exclusively for the conjugate 1.