新型胶束自组装荧光探针及其检测重金属离子的性能与机制

Fluorescent chemosensors have become a research hot spot in the field of heavy metal ion detection for their capability in rapid and efficient detection of matter. The self-organized chemosensors based on micelle template have attracted much attentions because they have many advantages, such as simple structure,convenience in improvement of measuring capability,etc. However, it is difficult to improve the measuring capacity and achieve versatilization of analytes of these fluorescent chemosensors because the modification capability of those used receptors are not satisfied. In this applying project thiacalix[4]arenes will be chosen as the receptors to prepare novel micellar self-assembled fluorescent chemosensors because of their excellent recognition for heavy metal ions and ease of modification. More efforts will be put on the investigation of capability and influence factors of heavy metal ion detection by these novel fluorescent chemosensors, the relationship between structure and measuring capability of the fluorescent chemosensors, the fluorescent signal responding mechanism of the fluorescent chemosensors, and the methods and solutions for the elimination of interferences in measurement.The kinetic, thermodynamic properties and the fluorescence-quenched mechanism of novel micellar self-organized fluorescent chemosensor will also be investigated by quantum chemistry calculation. It is expected that this research will provide new materials, methods and theories for the heavy metal ion detection based on the fluorescent spectrophotometric method.

荧光探针由于能实现对待测物质的快速高效检测，一直是水体重金属检测领域的研究热点。其中胶束自组装型荧光探针由于具有结构简单、性能改进便捷等诸多优点，近年来逐步受到重视。但目前该类探针所用受体的化学修饰性较弱，制约了其检测对象的多样化和检测性能的改进。本项目拟选用具有优秀重金属离子识别特性和较强化学修饰性的硫杂杯[4]芳烃类分子受体，设计制备针对重金属离子的新型胶束自组装荧光探针，重点考察新型胶束自组装荧光探针对重金属离子的选择性检测性能，阐明新型荧光探针的组成结构与重金属检测性能之间的构效关系和规律，揭示各条件因素对检测性能的影响规律，探索降低和消除检测干扰的有效方法和手段，采用量子化学计算方法，研究新型胶束自组装荧光探针检测重金属离子过程中的动力学和热力学性质及探针荧光淬灭的光物理机制，并探讨新型荧光探针的荧光信号响应微观机制，以期为基于荧光分析法的水体重金属检测提供新的材料、方法和理论。

荧光探针由于能实现对待测物质的快速高效检测，一直是水体重金属检测领域的研究热点。其中胶束自组装型荧光探针由于具有结构简单、性能改进便捷等诸多优点，近年来逐步受到重视。但目前该类探针所用受体的化学修饰性较弱，制约了其检测对象的多样化和检测性能的改进。本项目选用具有优秀重金属离子识别特性和较强化学修饰性的硫杂杯[4]芳烃和杯[4]芳烃类分子受体，设计制备针对重金属离子的新型胶束自组装荧光探针。通过分子设计共制备出25种硫杂杯芳烃和杯芳烃类分子受体化合物，分别筛选出针对Cu2+离子的对叔丁基硫杂杯[4]芳烃（简称TCA）、针对Pb2+离子的氨基噻二唑杯[4]芳烃衍生物（简称AMT-CA）和针对Cd 2+离子的杯[4]芳烃哌啶衍生物（简称PD-CA）三种优秀分子受体，并分别制成以苝为荧光体的Cu2+离子胶束自组装荧光探针，以蒽为荧光体的Pb2+离子胶束自组装荧光探针，以苝为荧光体的Cd 2+离子胶束自组装荧光探针。利用稳态荧光分析法测算了探针体系的胶束聚集数，研究表明受体加入能显著减小表面活性剂胶束的胶束聚集数。利用参比法测算探针体系中荧光体的荧光量子产率，发现表面活性剂胶束可以显著提高荧光体的荧光量子产率并降低荧光体所处微环境的极性。采用化学计量学方法研究分析受体络合重金属的紫外可见光谱数据，解析得到受体对重金属的络合常数。通过荧光猝灭实验考察了溶液的pH值、共存干扰离子等因素对胶束自组装荧光探针检测重金属离子性能的影响，同时研究了受体、荧光体和表面活性剂三者之间的构效关系。采用密度泛函（DFT）理论计算方法，深入地研究了探针分子受体与金属离子络合的热力学性质和激发态性质，发现受体与金属结合后，由于d轨道的存在使络合物在能量较低处产生新的吸收峰，该吸收峰的能量与荧光团的发射峰能量相同或相近，从而发生分子间荧光共振能量转移，导致荧光淬灭产生信号响应。本项目研究成果为针对重金属离子的胶束自组装荧光探针的研制提供了有价值的理论、方法和数据参考。