Fig. 4. Changes in the fluorescence spectra of: (a) 2 (c = 5 × 10⁻⁷ M) and (b) 3 (c = 1 × 10⁻⁶ M), upon titration with GMP (c = 1 × 10⁻³ M) at λ_exc = 350 nm. (Insets) Dependence of 2 and 3 emission intensity at 475 nm on c(GMP). Done at pH 7.0, sodium cacodylate buffer, I = 0.05 M.