Photostability of a series of two-photon absorbing fluorene derivatives

The photochemical stability of a series of two-photon absorbing (TPA) fluorene derivatives was investigated in air- and N2-saturated acetonitrile (ACN) at room temperature. The quantum yields of the photoreactions,Φ, were determined at various concentrations of the fluorene derivatives, oxygen concentration of the solvent, and irradiation wavelength. The absorption and fluorescence spectra of the photoproducts, corresponding to different excitation conditions, were analyzed. Photooxidation and electron transfer processes are proposed as photobleaching mechanisms for the fluorene derivatives in ACN. The relatively low photochemical quantum yields (Φ∼10−4) make the derivatives particularly promising for linear and nonlinear optical applications.