Fluorescence-switching dyes serve as important tools for bioimaging and environment sensing. Herein, we report a new type of molecule, tetrakis(benzo[b]furyl)ethene (TBFE), that undergoes two-wavelength ON–OFF–ON three-stage fluorescence switching triggered by aggregation. This compound features a sterically hindered tetrasubstituted ethene, made available by a hafnium-mediated McMurry coupling reaction. A fluorescent band of TBFE at 360 nm in THF disappears upon dilution with water towards 40% water in THF, giving way to a new peak at 510 nm. This switching behaviour is attributed to the combination of THF/H₂O ratio-dependent aggregation-caused quenching and aggregation-induced emission, as supported by the change of size distribution measured by dynamic light scattering and scanning electron microscopy.

中文翻译：

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聚合响应ON-OFF-ON扭曲四（苯并[荧光切换行为b ]呋喃基）乙烯由铪介导的McMurry偶联制成†

荧光转换染料是生物成像和环境传感的重要工具。在本文中，我们报道了一种新型分子，四（苯并[ b ]呋喃基）乙烯（TBFE），该分子经历了由聚集触发的两波长ON-OFF-ON三阶段荧光转换。该化合物的特征是通过hind介导的McMurry偶联反应可获得的位阻四取代乙烯。用水稀释至THF中40％的水稀释后，TBFE在THF中在360 nm处的荧光带消失，并在510 nm处出现新的峰。该转换行为归因于THF / H ₂的组合O比率依赖的聚集引起的猝灭和聚集诱导的发射，由动态光散射和扫描电子显微镜测量的尺寸分布的变化所支持。