氧化吩噻嗪衍生物的室温磷光性质研究及其生物成像应用

Room temperature phosphorescence (RTP), an afterglow that could be observed at room temperature even after stopping the UV-irradiation, has drawn increasing attention for its great potential in the applications of display, anti-counterfeiting, bioimaging and so on. Particularly, in bioimaging, the common fluorescence imaging would suffer the interference of background fluorescence from organisms, while phosphorescence one was not. As the RTP materials with ultralong emission lifetime could filter the background fluorescence by collecting phosphorescence signal after stopping the excitation light, thus to largely improve the imaging result with high signal-to-noise ratio. However, most RTP systems contain noble metals, which would lead to a series of problems, such as high cost and potential toxicity, etc. The alternative metal-free phosphors were seldom reported, especially those with persistent RTP effect. In previous work, we have successfully realized RTP effect in a series of phenothiazine 5,5-dioxide derivatives, and found it could act as a good building block to construct RTP luminogens. Therefore, in this project, we will continue to optimize the structure of these compounds, and explore the internal mechanism behind their RTP phenomena. With the deep understanding of them, could the purely organic materials with outstanding RTP performance be obtained, thus to realize the biological phosphorescence imaging.

室温磷光是一种在室温条件下缓慢发光的光致发光现象，当激发光停止后，发光现象能持续存在，其由于在显示、防伪以及生物成像等方面具有广阔的应用前景而备受关注。特别是在生物成像中，生物体的背景荧光会对普通的荧光成像结果造成干扰，而室温磷光材料由于具有超长的发光寿命，可以通过停止激发光后收集磷光信号的方法过滤背景荧光，从而实现超高对比度的生物成像。然而，目前大多数的室温磷光体系都含有贵金属，这将会导致一系列的问题，例如高的成本和潜在的毒性等，而关于纯有机室温磷光化合物的报导还很少，特别是那些具有超长寿命的磷光化合物。申请人在以前的工作中发现氧化吩噻嗪是一种优良的室温磷光化合物构造单元，因此，在本项目中将继续优化此类化合物的结构，深入探讨其产生室温磷光的内部机理，以期获得性质突出的纯有机室温磷光材料，并探索其在生物磷光成像方面的应用。

纯有机室温磷光材料因其广阔应用前景一直备受关注，但是目前的相关报道还相对较少，主要是其内部机制不够清晰，阻碍了相关材料体系的发展。项目负责人在本项目的资助下设计合成了一系列的纯有机室温磷光化合物，深入研究了其中的内部机制，揭示了化学结构、分子构象及其相应晶体堆积对其室温磷光性质的影响，并基于对机理的深入理解进一步优化分子结构，成功开发了一系列构筑刺激响应型磷光材料的新策略，获得了具有良好室温磷光性能的纯有机体系，探索了其在防伪、信息加密、生物成像等方面的应用。基于此，在Sci. Adv.、Nat. Commun.、Adv. Mater.、Angew. Chem.和Matter等国际权威期刊发表论文15篇，申请专利7项。其中，通过将同时具有室温磷光性能的氧化吩噻嗪和吩噻嗪衍生物集成在一个掺杂系统中形成三重态激基复合物，极大地提高了有机材料的磷光性能，获得了一批性能出色的纯有机室温磷光材料，在大气环境中能够兼具高效率(> 20%)和长寿命(> 10 s)。当将其制备成纳米晶时，在水溶液中的余辉最长能持续约25分钟。基于这类材料的超长发光寿命，首次实现了小鼠肝肿瘤的磷光标记，成像信噪比高达158，是目前已报道的肝脏肿瘤光学成像最优结果之一。