A discrete self-assembled metal array in artificial DNA

DNA has a structural basis to array functionalized building blocks. Here we report the synthesis of a series of artificial oligonucleotides, d(5'-GH(n)C-3') (n = 1 to 5), with hydroxypyridone nucleobases (H) as flat bidentate ligands. Right-handed double helices of the oligonucleotides, nCu(2+).d(5'-GHnC-3'), (n = 1 to 5), were quantitatively formed through copper ion (Cu2+)-mediated alternative base pairing (H-Cu2+-H), where the Cu2+ ions incorporated into each complex were aligned along the helix axes inside the duplexes with the Cu2+-Cu2+ distance of 3.7 +/- 0.1 angstroms. The Cu2+ ions were coupled ferromagnetically with one another through unpaired d electrons to form magnetic chains.