Fig. 2: Characterization of anti-Kasha mechanism in open-form versus Kasha mechanism in closed-form.
a Chemical structure of DCM-IFC in its open form. b Excitation spectra (dotted line, monitored at λem = 520 and 710 nm) and emission spectra (solid line, excited at λex = 480 and 560 nm) of open-form DCM-IFC. c Electron–hole analysis involved during the photoexcitation of the open form, based on the molecular structure at the Franck–Condon state. Femtosecond time-resolved transient absorption spectra (d) and kinetics (e) of open-form DCM-IFC (excited at λex = 480 nm). f Jablonski diagram illustrating the anti-Kasha mechanism. g Chemical structure of DCM-IFC in its closed form. h Excitation spectra (dotted line, monitored at λem = 710 nm) and emission spectra (solid line, excited at λex = 480 and 560 nm) of closed-form DCM-IFC. i Electron–hole analysis involved during the photoexcitation of the closed form, based on the molecular structure at the Franck–Condon state. Femtosecond time-resolved transient absorption spectra (j) and kinetics (k) of closed-form DCM-IFC (excited at λex = 480 nm). Note: open-form DCM-IFC was investigated at pH 11.3 and closed-form DCM-IFC was investigated at pH 2.0. l Two structurally related reference compounds that are locked into open form or closed form. Note: all fluorescence spectra were measured in a mixture solution of acetonitrile (MeCN)/Britton–Robinson buffer.
