Synthesis and Metal‐Ion Binding Properties of Duplexes Containing Thymine Analogs with 1,2‐Diamine Groups

Thymidine analogue with a 1,2-diamino side chain at the 3N position is synthesized and converted into an amidite unit for oligonucleotide synthesis. It is used for preparing oligonucleotides containing a 1,2-diamino side chain as X residue. Thermal denaturation studies are performed on a duplex containing an X-X pair in the presence and absence of metal ions. Among various metal ions used in this research, Cd(II), Co(II), Cu(II), Ni(II), and Zn(II) ions increased the duplex stability. The results prove the new strategy to design metallo-base pairs containing various metal ions.