A 'simple' donor–acceptor AIEgen with multi-stimuli responsive behavior

There is still an urgent demand for novel smart materials that can achieve a diverse range of practical applications in the synthetic material area. Herein, we developed a simple but versatile aggregation-induced emission luminogen (AIEgen, 1). Compound 1 was sensitive to an electric stimulus and displayed reversibly three-color switched electrochromism and on-to-off electroluminochromism. Such properties allowed the fabrication of high-performance non-doped OLEDs with a high external quantum efficiency of 5.22%. Due to its AIE property and remarkable sensitive color change in response to polarity change, it can serve as a unique imaging probe for detecting environmental polarity in cells and selective visualization of lipid droplets in live tissues. More impressively, compound 1 exhibited a wide range of thermoresponsive behaviors with a ratiometric luminescence change and noticeable fluorescence color switching. As another remarkable feature, it can respond to anisotropic shearing force and isotropic hydrostatic pressure with prominent and contrasting luminescence conversion due to the distinct disturbance of the weak intermolecular interactions and charge transfer process. The present results may offer an important guideline for multifunctional molecular design and provide an important step forward to expand the real-life applications of smart materials.