Oligonucleotides metal-modified base pairing

Terpyridine (tpy) forms [M(tpy)2] complexes, which are not good candidates for metal-mediated base pairs within a nucleic acid duplex because of their octahedral geometry, in which the two tpy ligands are situated in reciprocally perpendicular planes. ThCTefore, they have been used instead to connect the ends of terminally modified oligonucleotides. The tpy-modified ssDNA, which did not... 

The rich coordination chemistry of transition metal ions has been used not only to create metal-ligand complexes that play the role of alternative nucleo-base pairs within nucleic acid duplexes, but also to influence the secondary structure adopted by the nucleic acid, for example, hairpin, duplex, or triplex, and to create connectors for such nucleic acid structures. In this context, oligonucleotides that contain terminal ligands can lead to structures distinct from those accessible by using centrally-modified oligonucleotides, such as cyclic structures or hairpins (Fig. 3). 

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