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 (C2A)6strand
is interrupted with a thymine, and the resulting (C2A)2-T-(C2A)4forms only Ag106+, a chromophore with both prompt (∼1 ns) green
and sustained (∼102μs) red luminescence.
Thymine is an inert placeholder that can be removed, and the two fragments
(C2A)2and (C2A)4also
produce the same Ag106+adduct. In relation
to (C2A)2T(C2A)4, the
(C2A)2+ (C2A)4pair is
distinguished because the red Ag106+luminescence
is ∼6× lower, relaxes ∼30% faster, and is quenched
∼2× faster with O2. 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.