Interrupted DNA and Slow Silver Cluster Luminescence

[Image: see text] A DNA–silver cluster conjugate is a hierarchical chromophore with a partly reduced silver core embedded within the DNA nucleobases that are covalently linked by the phosphodiester backbone. Specific sites within a polymeric DNA can be targeted to spectrally tune the silver cluster. Here, the repeated (C(2)A)(6) strand is interrupted with a thymine, and the resulting (C(2)A)(2)-T-(C(2)A)(4) forms only Ag(10)(6+), a chromophore with both prompt (∼1 ns) green and sustained (∼10(2) μs) red luminescence. Thymine is an inert placeholder that can be removed, and the two fragments (C(2)A)(2) and (C(2)A)(4) also produce the same Ag(10)(6+) adduct. In relation to (C(2)A)(2)T(C(2)A)(4), the (C(2)A)(2) + (C(2)A)(4) pair is distinguished because the red Ag(10)(6+) luminescence is ∼6× lower, relaxes ∼30% faster, and is quenched ∼2× faster with O(2). These differences suggest that a specific break in the phosphodiester backbone can regulate how a contiguous vs broken scaffold wraps and better protects its cluster adduct.