Exciplex Ensemble Modulated by Excitation Mode in Intramolecular Charge-Transfer Dyad: Effects of Temperature, Solvent Polarity, and Wavelength on Photochemistry and Photophysics of Tethered Naphthalene–Dicyanoethene System

Solvent, temperature, and excitation
wavelength significantly affected
the photochemical outcomes of a naphthalene–dicyanoethene system
tethered by different number (n) of methylene groups
(1–3). The effect of irradiation
wavelength was almost negligible for 2a but pronounced
for 3a. The temperature dependence and theoretical calculations
indicated the diversity of exciplex conformations, an ensemble of
which can be effectively altered by changing excitation wavelength
to eventually switch the regioselectivity of photoreactions.