硫杂蒽酮类延时荧光探针的设计及其用于荧光寿命成像的研究

Thioxanthone, Cu(I) complex, and eosin derivatives can produce distinct delayed fluorescence because of their small singlet-triplet energy gap and high reverse intersystem crossing. Since the velocity constant of reverse intersystem crossing in the delayed fluorescence process is much larger than the quenching constant of active oxygen, the disturbance from active oxygen can be eliminated in the process of delayed fluorescence, which can theoretically overcome the most disadvantageous of phosphorescent probes. Delayed fluorescence-based probes are also expected to show longer lifetime, and fluorescence intensity / lifetime dual mode for detection, and higher selectivity and sensitivity, etc. Therefore, delayed fluorescence-based probes are very suitable for fluorescence lifetime imaging (FLIM). However, delayed fluorescence, as a normal photophysical phenomenon, has not been used for the design of fluorescent probes and fluorescence lifetime imaging till now. In view of the catalysis reaction of glutathione reductase, in this project, a series of delayed fluorescence probes based on thioxanthone, Cu(I) complex, and eosin derivatives have been developed on the basis of photophysical principles. The decay processes in the excited state and the interaction with the guest species will be studied in detail. We are expected to find some universal rules that affect the selectivity and sensitivity of delayed fluorescence-based probes, which will instruct us to further design more useful delayed fluorescence-based probes.

硫杂蒽酮、一价铜配合物、以及曙红类化合物具有较小的单重态-三重态能差和较高的反向系间穿越速率，能产生明显的延时荧光。由于产生延时荧光的反向系间窜越速率常数远大于磷光速率常数和活性氧淬灭常数，因此延时荧光可以消除活性氧干扰，从理论上克服了磷光传感器的最大缺陷。延时荧光探针还具有较长的荧光寿命、可用荧光和寿命双重检测模式，基于延时荧光为传感机制的荧光探针可能具有更高的选择性和灵敏度，因此特别适合于荧光寿命成像技术。然而，延时荧光过程还未被用作新的光物理传感机制来设计荧光探针，也未用于荧光寿命成像。本项目拟针对谷胱甘肽还原酶催化反应的特点，结合光物理的基本原理，设计出一系列硫杂蒽酮、一价铜配合物、以及曙红类延时荧光传感分子，并利用光物理原理对其激发态衰变以及与谷胱甘肽还原酶的相互作用过程的机制进行详细的研究。这不仅有利于揭示这些过程的本质，也为更有效地设计该类延时荧光探针提供必要的理论指导。

苯并噻二唑-芴基衍生物、一价铜双膦配合物具有较小的单重态-三重态能差和较高的反向系间穿越速率，能产生明显的延时荧光。由于产生延时荧光的反向系间窜越速率常数远大于磷光速率常数和活性氧淬灭常数，因此延时荧光可以消除活性氧干扰，从理论上克服了磷光传感器的最大缺陷。延时荧光探针还具有较长的荧光寿命、可用荧光和寿命双重检测模式，基于延时荧光为传感机制的荧光探针可能具有更高的选择性和灵敏度，因此特别适合于荧光寿命成像技术。然而，延时荧光过程还未被用作新的光物理传感机制来设计荧光探针，也未用于荧光寿命成像。本项目拟针对针延时荧光分子的特点，结合光物理的基本原理，设计出一系列苯并噻二唑-芴基衍生物DAD电子转移化合物、一价铜配合物等延时荧光传感分子，用于荧光探针和荧光寿命成像。利用光物理原理对其激发态衰变以及与客体分子互作用过程的机制进行详细的研究，并在以下工作取得进展：1）基于一价铜双膦配合物的延时荧光材料；2）苯并噻二唑-芴基DAD分子内电子转移化合物用于延时荧光探针的设计及其时间分辨荧光成像；3）苯并噻二唑类延时荧光分子用于靶向特定细胞器的研究。本工作所设计合成的一系列苯并噻二唑-芴基D-A类型的分子内电荷转移化合物，分别连接生物相容性较好的功能基团，如：线粒体靶向基团三苯基磷，溶酶体靶向基团吗啉，修饰后的分子仍然表现出具有较好的延时荧光性质，溶液中具有较长的荧光寿命，并能产生很好的时间分辨的荧光成像。通过对各种不同结构的延时荧光分子的光物理性质研究，本质上了解延时荧光分子探针分子设计的基本要求与规律。