2. Experiment
The two compounds were both synthesized in our laboratory by the method of Pd-catalyzed Heck coupling reactions [10]. The chemical structures of the two fluorine-based molecules are shown in the top-right corner in Fig. 1(A) and (B), respectively. The only difference between the two compounds is the electron donor groups (amino group and methoxyl group, respectively). The linear absorption spectra of the two compounds in DMF at a concentration of 2.0 × 10−4 mol/L were measured using a UV–vis-NIR Cary5000 spectrophotometer. The influences from the quartz liquid cell and the solvent have been subtracted.