Here we describe the synthesis of eight benzothiadiazole-based D–π–A–π–D materials and evaluate their potential as imaging agents for two-photon excited fluorescence (2PEF). These compounds exhibit fluorescent emission with λ_max ranging from 529 to 674 nm in toluene and quantum yields as high as 99%. Emission from the aggregated state is also examined with all species exhibiting emission from the aggregated state. Finally, three of these compounds are encapsulated within an amphiphilic water-soluble polymer and explored as imaging agents. The use of benzothiadiazole functionalized with two locked-planarity hexamethylazatriangulene (HMAT) donors was found to give red fluorescence with the highest two-photon cross-section σ₂ of 230 GM, while also exhibiting the highest photostability of the series.

中文翻译：

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可调谐的基于苯并噻二唑的供体-受体材料，用于双光子激发荧光

在这里，我们描述了八种基于苯并噻二唑的D–π–A–π–D材料的合成，并评估了它们作为双光子激发荧光（2PEF）成像剂的潜力。这些化合物在甲苯中的荧光发射波长为_λmax，范围为529 nm至674 nm，量子产率高达99％。还检查了聚集态的排放，所有物种均表现出聚集态的排放。最后，将其中的三种化合物封装在两亲水溶性聚合物中，并作为显像剂进行研究。带有两个锁定平面hexamethylazatriangulene（HMAT）供体官能化的苯并噻二唑使用的发现，得到的红色荧光具有最高双光子截面σ ₂ 拥有230 GM的光稳定性，同时还展现了该系列中最高的光稳定性。