Efficient optical photoswitching of benzyloxy-substituted TCF-based D–π–A molecules

Molecules exhibiting photo-switching behavior are essential for the development of various photonic and optoelectronic devices. In this study, we report the synthesis of five novel donor–π–acceptor organic dyes, in which a stilbene moiety serves as a π-linker between the electron-donating and electron-withdrawing units. To address the challenge of developing photo-switchable molecules responsive to visible light, we performed fundamental optical characterization in both solution and solid state. The photoisomerization capability was confirmed for all compounds through real-time absorption measurements, enabling the calculation of E → Z isomerization kinetics. The presence of both isomeric forms was further validated by ¹H NMR spectroscopy. These experimental findings were supported by quantum chemical calculations, which identified the most stable conformers and accurately predicted their spectral properties. Moreover, pump–probe experiments demonstrated that irradiation with linearly polarized light efficiently triggers photo-induced birefringence in dye-doped polymer systems, with a notable “memory effect” observed for all studied compounds. Remarkably, the dyes are highly sensitive to light, and the birefringence saturation can be achieved at light intensities comparable to natural daylight, highlighting their broad potential application in optoelectronic devices.