Fig. 2. (a) Absorption spectra recorded for 3-benzyl-4-hydroxycoumarin 1a, its deprotonated form Ia (in situ generated from 1a upon addition of Cs2CO3), and their mixture with perfluorohexyl iodide 2a in CH3CN (1 × 10−4 M). (b) Emission of the excited deprotonated intermediate Ia* in CH3CN (in situ generated mixing 1a with Cs2CO3) upon laser irradiation at 314 nm and its intercept at 361 nm with the absorption spectrum, with a 0–0 transition energy (E0,0) determined to be 3.43 eV. (c) Cyclic voltammetry measurement of the deprotonated intermediate Ia carried out in CH3CN vs. Ag/AgCl at a scan rate of 100 and 400 mV s−1. (d) Stern–Volmer luminescence quenching studies of intermediate Ia (1 × 10−4 M in CH3CN) with increasing amounts of perfluorohexyl iodide 2a (excitation at 350 nm; emission was acquired from 360 nm to 440 nm).
