In this study, we report evidence for emissive aggregates of push–pull phenothiazine and phenothiazine dioxide derivatives produced both in water dispersions and in the solid state, highly promising for applications in both biology and material science. An insightful investigation of the aggregation-induced emission (AIE) mechanism was carried out via time-resolved spectroscopies, with nanosecond and femtosecond temporal resolution, coupled with advanced data analysis. Our steady-state and time-resolved spectroscopic results unambiguously show that a significant AIE behavior is activated by the restriction of intramolecular rotations for the phenothiazine derivatives. Investigation of the nonlinear optical properties also revealed that aggregates exhibit notable emission upon two-photon excitation. In particular, the phenothiazine dioxide-based aggregates exhibit remarkable fluorescence efficiencies and large two-photon absorption cross sections, as well as the capability to be internalized in HeLa cells exerting no cytotoxic effect. These aggregate species thus prove to be promising as novel fluorophores for bioimaging.

中文翻译：

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基于吩噻嗪的荧光团中的聚集诱导发射：对激发态和聚集体形成机制的洞察

在这项研究中，我们报告了以水分散体和固态产生的推拉式吩噻嗪和吩噻嗪二氧化物衍生物的发射聚集体的证据，在生物学和材料科学中的应用前景广阔。通过对聚集诱导发射 (AIE) 机制进行深入研究时间分辨光谱仪，具有纳秒和飞秒时间分辨率，以及高级数据分析。我们的稳态和时间分辨光谱结果明确表明，吩噻嗪衍生物的分子内旋转限制激活了显着的 AIE 行为。对非线性光学特性的研究还表明，聚集体在双光子激发时表现出显着的发射。特别是，吩噻嗪二氧化物基聚集体表现出显着的荧光效率和大的双光子吸收截面，以及在不产生细胞毒性作用的 HeLa 细胞中内化的能力。因此，这些聚集物被证明有希望作为用于生物成像的新型荧光团。