Functionalized α‐Cyanostilbene Derivatives for Detection of Hypoxia or Proteostasis Imbalance in Live Cells

α-Cyanostilbene represents one of the easily functionalized aggregation-induced emission (AIE) scaffolds. It has been widely adopted for the construction of fluorescent materials for broad applications. Here, we further expanded the utilization of α-cyanostilbene derivatives for the detection of hypoxia or proteostasis imbalance in live cells. Four different amine containing donors were introduced to construct α-cyanostilbene derivatives (R-ASC) with donor-acceptor scaffolds. Equipped with the cysteine (Cys) reactive group, maleimide (MI), R-ASC-MI shows fluorescence turn-on property upon binding with unfolded proteins in vitro and in live cells under proteostatic stress. By virtue of R-ASC-MI, the level of unfolded protein loads in cells can be quantified by flow cytometry, or visualized under microscope. Furthermore, we also characterized the performance of R-ASC-NO