Lipid-related cancers cause a large number of deaths worldwide. Therefore, development of highly efficient Lipid droplets (LDs) fluorescent imaging probes will be beneficial to our understanding of lipid-related cancers by allowing us to track the metabolic process of LDs. In this work, a LDs-specific NIR (λmax = 698 nm) probe, namely BY1, was rationally designed and synthesized via a one-step reaction by integrating triphenylamine (electron–donor group) unit into the structure of rofecoxib. This integration strategy enabled the target BY1 to form a strong Donor–Acceptor (D-A) system and endowed BY1 with obvious aggregation-induced emission (AIE) effect. Meanwhile, BY1 also showed observable solvent effect and reversible mechanochromatic luminescent property, which could be interpreted clearly via density functional theory (DFT) calculations, differential scanning calorimetry (DSC), powder X-ray diffraction (XPRD), and single crystal X-ray data analysis. More importantly, BY1 exhibited highly specific fluorescent imaging ability (Pearson’s correlation = 0.97) towards lipid droplets in living HeLa cells with low cytotoxicity. These results demonstrated that BY1 is a new promising fluorescent probe for lipid droplets imaging, and it might be beneficial to facilitate biological research of lipid-related cancers.

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Aggregation‐induced emission luminogens (AIEgens) have been widely investigated due to their promising applications in data storage, organic light‐emitting diodes, and deep tissue bioimaging as compared to conventional fluorophores. In this work, we have designed and synthesized two novel rofecoxib analogues functionalized with different terminal groups (−NH2, −Br) on the benzene ring B. Interestingly, the compound 2 a‐3 with −NH2 substituent shows aggregation‐caused quenching effect whereas the compound 1 b‐3 with −Br group displays aggregation‐induced emission (AIE) property which may be caused by the twisted conformation and restricted – stacking of 1 b‐3 according to the X‐ray single crystal diffraction analysis. These opposite results indicated that the terminal groups could have great influence on the photophysical properties of targets. Moreover, the compound 1 b‐3 exhibited multi‐stimuli response luminescence behaviors under various external stimuli including solvatochromism, mechanochromism and acidochromism. Furthermore, lipid droplets imaging investigation proved the compound 1 b‐3 was capable of achieving specific lipid droplets bioimaging. This work not only presents a better understanding of the structure‐fluorescent property relationship based on the scaffold of rofecoxib, but also provides a new avenue for spectral modulation and the development of new MSR materials.