Concomitant Site-Specific Incorporation of Silver(I) and Mercury(II) Ions into a DNA Duplex.

A GNA (glycol nucleic acid)-based nucleoside analogue containing 1 H-imidazo[4,5-f][1,10]phenanthroline (P) as an artificial nucleobase was used to form a stable mercury(II)-mediated P-HgII -T-H base pair within a parallel-stranded DNA duplex. The nucleobase P shows an affinity towards silver(I) and mercury(II), tuneable through the acidity of the medium when the canonical nucleobase thymine is located in its complementary position. This extraordinary behavior was exploited to enable the concomitant site-specific incorporation of silver(I) and mercury(II) into a DNA scaffold for the first time. This achievement is all the more remarkable because it was made possible by the involvement of only one type of artificial nucleobase. The simultaneous incorporation of two different soft metal ions with a precise control of their respective positions within the nucleic acid scaffold significantly reduces the complexity in the formation of a heterometallic array of metal ions in DNA and thereby facilitates new applications of metal-functionalized nucleic acids.