基于脲/石墨烯氧化物的四面体阴离子荧光传感器的研究

The most important challenge in the arena of anion recognition at present is to develop fluorescent sensors for binding of specific tetrahedral anions in supramolecular chemistry. More efficiently sensitivity and selectivity binding of tetrahedral anions is the key to develop fluorescence sensors. In this project, a novel tetrahedral anion fluorescent sensor based on urea/graphene oxide nanocomposite will be developed. Owing to graphene oxide characterized high specific surface area and abundant functional groups on the surface, fluorescent urea-based receptor can be easily adsorbed onto the surface of graphene oxide nanaosheets through π-π and other non-covalent interactions. Based on this, a novel platform for tetrahedral anion detection based on fluorescence resonance energy transfer(FRET) from urea-based receptor to graphene oxide (GO) was constructed, which quenched the fluorescence of urea-based receptor because of the FRET. The recognition ability of urea/graphene oxide fluorescent sensor towards tetrahedral anions is detected by means of fluorescence and nuclear magnetic characterization. When tetrahedral anions were added, the strong hydrogen binding between fluorescence urea-based receptor and anion weakened the interaction between fluorescence urea-based receptor and GO, which led to the release of fluorescence urea-based receptor from GO, and thus, the recovery of urea-based receptor fluorescence. Quantification of the tetrahedral anion is obtained through analysis of the changes of fluorescence emission intensity. Meanwhile graphene oxide can greatly reduce background interference signal to improve the detection capability of tetrahedral anion. We systematically investigate the anion recognition and detection to discuss the recognition mechanism, and summarize new phenomenon or properties in the sensing process. It is great significance to develop high efficient fluorescence sensor for detection of harmful anion pollutants in the environment monitoring and medical diagnosis in future.

构建特异性识别四面体阴离子荧光传感器成为超分子化学的重要挑战。高灵敏度，高选择性是发展荧光传感器的关键。本项目拟以具有高的比表面积和丰富官能团的石墨烯氧化物纳米片为平台，通过π-π堆积等非共价键作用使具有荧光的脲类受体组装在石墨烯氧化物表面，基于石墨烯氧化物荧光共振能量转移原理，构建新型光响应型脲/石墨烯氧化物四面体阴离子荧光传感器。利用脲与四面体阴离子的强氢键作用，采用光谱、核磁等分析检测手段，表征该传感在识别过程中荧光强度等功能信号的改变，实现对四面体阴离子有效识别检测。力求解决传统有机脲类阴离子荧光传感器背景干扰大，灵敏度低的问题，提高脲类荧光传感器对四面体阴离子的检测能力。探讨阐述其识别作用机理，并对该复合受体在传感过程中出现的一些新现象或性质进行系统研究，对开发在环境阴离子污染物监控和有害阴离子的医疗诊断分析等方面的阴离子荧光化学传感器具有重要意义。

开展水系含氧酸类阴离子识别检仍是超分子化学研究的重要挑战。本项目提出利用结合芘基在荧光传感器应用上的优势以及脲基团在阴离子识别键合方面的优点，设计合成了单脲、二脲及三脲等一系列基于芘基的脲类受体，成功研究了芘基脲类受体在含水体系中对各种类型阴离子客体的分子键合行为，并总结了芘基脲类受体对阴离子型客体在水溶液中的键合规律及作用机制。本项目研究发现芘基单脲受体可以实现对PPi快速比色响应，芘基二脲类受体可实现含水体系内选择性键合硫酸根和PPi。在项目进行过程中，我们还发现经过简单的微调受体骨架基团，受体的荧光大大增强。通过π-π堆积等非共价键作用使具有荧光的脲类受体组装在石墨烯氧化物表面，制备出新型光响应型脲/石墨烯氧化物比率型识别四面体硫酸根阴离子荧光传感器，并初步探讨了其识别作用机理。这些研究结果对于丰富芘基脲类受体在阴离子识别检测中的应用，对开发在环境阴离子污染物监控和有害阴离子的医疗诊断分析等方面的阴离子荧光化学传感器具有重要意义。