Syntheses of nucleic acid mimics designed for metal-induced strand formation on DNA

This paper describes design and syntheses of a new class of chelator-type nucleic acid mimics. Four nucleic acid mimics , , , possess a nucleobase and two ethylenediamine moieties for intermolecular metal coordination. We expected that chelator-type nucleic acid mimics formed a strand in the presence of metal ion and then interacted with a single-stranded DNA. Efficient synthetic routes leading to the four nucleic acid analogues have been achieved via the key intermediate compound which was derived from 3,5-dimethylphenol in five steps. Compound was treated with zinc nitrate and Zn complex was isolated as crystals. 1H NMR study of Zn complex in D2O showed the single-strand formation. Job plots showed that mixture of (dT)70 with Zn complex at 5°C reached a minimum absorbance at a mole ratio of 2:1, and the hypochromic effect showed the π–π stacking interaction between the nucleobases. Thermal denaturation study at 2:1 mole ratio of complexes between (dT)70 and Zn complex showed melting point at 27°C.