Figure 5.

Spectrofluorimetric titration of 8 b with ct DNA (A, c _L=10 μm, c _DNA=1.49 mm; c _DNA in base pairs) in BPE buffer (c _Na+=16 mm, pH 7.0; with 5 % v/v DMSO), 22AG (B, c _L=5 μm, c _22AG=285 μm; c _22AG in oligonucleotide) in K‐phosphate buffer (c _K+=73 mm, pH 7.0; with 5 % v/v DMSO) and PSS (C, c _L=10 μm, c _PSS=195 μm) in BPE buffer (c _Na+=16 mm, pH 7.0; with 2.5 % v/v DMSO); λ _ex=515 nm. Red: Spectra of the pure ligand solutions; blue: spectra at the end of the titrations. The arrows indicate the changes in emission intensity upon addition of the host molecule. Insets: Plot of the relative fluorescence intensity I/I ₀ (corrected with regard to the change of the absorption at the excitation wavelength) versus c _DNA/c _L or c _PSS/c _L. Inset pictures in A: Fluorescence colors of 8 b in the absence and in the presence of ct DNA; λ _ex=366 nm. The contrast and brightness were enhanced by 30 % without changing the true colors (cf. Figure S5).