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Product analyses and nanosecond time-resolved spectroscopy on laser flash photolysis were studied for the photoinduced electron-transfer reaction of 3,4-di(α-styryl)furan (6a). A combination of these results, kinetic, density functional theoretical (DFT), and time-dependent DFT analyses enabled assignment of the absorption to the tetramethyleneethane (TME)-type radical cation (7a·+, λmax = 392 nm) and the corresponding singlet biradical (17a**, λmax = 661 nm). These two intermediates were mechanistically linked to each other with a facile back electron-transfer reaction. The present studies provide a new method for the generation of aryl-substituted TME-type intermediates. [ABSTRACT FROM AUTHOR]

Solvent, temperature, and excitationwavelength significantly affectedthe photochemical outcomes of a naphthalene–dicyanoethene systemtethered by different number (n) of methylene groups(1–3). The effect of irradiationwavelength was almost negligible for 2abut pronouncedfor 3a. The temperature dependence and theoretical calculationsindicated the diversity of exciplex conformations, an ensemble ofwhich can be effectively altered by changing excitation wavelengthto eventually switch the regioselectivity of photoreactions. [ABSTRACT FROM AUTHOR]