Understanding structure-fluorescence correlation is very helpful for the design of fluorescent probes. In this paper, a donor-acceptor-donor (D-A-D) type NIR-II fluorophore with benzobisthiadiazole as the acceptor and triphenyl amine as the donor, and its three derivatives bearing respectively amino, tert-butyloxycarbonyl amino and phenylazo groups in donor moieties, are synthesized. Their electronic structures and optical properties are investigated via theoretical and experimental studies. It is found that all the three types of substituents significantly influence its fluorescent properties and the phenylazo groups dramatically enhance its quantum yield (QY). To achieve biological applications and maintain high QY in aqueous environments, the phenylazo-containing fluorophore is encapsulated in polystyrene-co-poly(ethylene glycol) micelles. The obtained fluorescent micelles have a QY of ≈3.51% in 1000-1500 nm in aqueous medium that is among the highest of the organic NIR-II probes reported so far for biological imaging. The high QY enables the in vivo imaging of the micelle-administered mice to be conducted with high speed and quality. As an application example, ultrafast NIR-II imaging of intravenously injected mice is performed and used to determine their cardiac cycle and heart rate. The micelles also significantly accumulate in tumors after tail-vein injection and exhibit great application potentials in tumor detection.

中文翻译：

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通过苯基偶氮基提高NIR-II染料的量子产率。

了解结构-荧光相关性对于荧光探针的设计非常有帮助。本文以苯并二噻二唑为受体，三苯胺为供体的供体-受体-供体（DAD）型NIR-II荧光团及其在供体部分分别带有氨基，叔丁氧羰基氨基和苯基偶氮基的三个衍生物为合成的。通过理论和实验研究了它们的电子结构和光学性质。发现所有三种类型的取代基均显着影响其荧光性质，并且苯基偶氮基团显着提高其量子产率（QY）。为了实现生物学应用并在水性环境中维持较高的QY，将含苯偶氮基的荧光团封装在聚苯乙烯-共-聚（乙二醇）胶束中。所获得的荧光胶束在水性介质中在1000-1500 nm处的QY约为3.51％，是迄今为止报道的用于生物成像的有机NIR-II探针中最高的。高QY使得能够以高速度和高质量进行给予胶束的小鼠的体内成像。作为一个应用示例，对静脉注射的小鼠进行超快速NIR-II成像，并用于确定其心动周期和心率。尾静脉注射后，胶束也显着积聚在肿瘤中，并在肿瘤检测中显示出巨大的应用潜力。高QY使得能够以高速度和高质量进行给予胶束的小鼠的体内成像。作为一个应用示例，对静脉注射的小鼠进行超快速NIR-II成像，并用于确定其心动周期和心率。尾静脉注射后，胶束也显着积聚在肿瘤中，并在肿瘤检测中显示出巨大的应用潜力。高QY使得能够以高速度和高质量进行给予胶束的小鼠的体内成像。作为一个应用示例，对静脉注射的小鼠进行超快速NIR-II成像，并用于确定其心动周期和心率。尾静脉注射后，胶束也显着积聚在肿瘤中，并在肿瘤检测中显示出巨大的应用潜力。