Fig. 4. Steady-state absorption and emission spectra.

Absorption spectra of 2-MeTHF solutions and drop-cast films on a quartz substrate of (A) 1 (5.0 μM) and (B) 2 (10 μM) at 25°C under air. Fluorescence spectra of 2-MeTHF solutions and drop-cast films of (C) 1 and (D) 2 at 25°C under air. The absorption spectra of 1 at a wavelength region from 300 to 800 nm are shown in fig. S27.