METALLOCENE-NUCLEOBASE CONJUGATES - SYNTHESIS, STRUCTURE AND NUCLEIC-ACID BINDING

The ferrocenylnucleobase conjugates CH(2)NMe(2)CH(2)CH(2)CH(2)-NC(O)NH C(O)CMeCH}][BF4] 1 and [Fe(eta(5)-C5H5){eta(5)-C5H4CH2[C5H2N4(NH2)]}] 2 of thymine and adenine respectively, have been prepared and their cr ystal and molecular structures determined. The molecular packing of th e two compounds differs markedly in terms of intermolecular hydrogen-b onding interactions. In 1 such interactions are confined to discrete c ation ... anion ... solvate units, whereas in 2 the hydrogen-bonding p atterns are extensive and involve both the Watson-Crick and Hoogsteen donor and acceptor sites. Electrochemical studies of the interaction o f 1 with nucleic acids showed that the incorporation of this single nu cleoside base with the metallocene moiety enhances the binding in aque ous solution compared to a cationically charged derivative devoid of t his functionality. Moreover, with immobilised nucleic acid, binding wa s observed exclusively for the conjugate 1.