Table 3. Binding Constant (Kb) and Photometric Properties
of Compounds 1−3 in Contact with CT-DNA
with the incremental addition of CT-DNA (Figure S2 in the
Supporting Information (SI)) in fluorescence studies revealed
that they bind to DNA via an intercalative mode.19,20
Competitive binding experiments of compounds 1−3 as
quenchers with DNA-bound EB were also carried out to
confirm the binding of compounds with DNA via intercalation.
The resulting decreases in fluorescence intensity (Figures 2 and
S3 in the SI) of the DNA−EB system with increasing
concentration of compounds indicated that the EB molecules
were displaced by 1−3 from their DNA binding sites. The
quenching data were analyzed using the Stern−Volmer
equation;21 the calculated quenching constant (Kq) and the
apparent binding constant (Kapp) values (Table 4) suggested
st