Synthesis Of Novel Cholesterol NBD Derivatives And Their Applications In The Detection Of Hg 2+ And Phosphorus-containing Pesticides

Organophosphate pesticides?OPs? have provide a useful tool for biological protection from pests, which increase crop production and promotes economic development. But it also causes serious threat to environment and human health, due to inappropriate use and toxicity of refractory OPs. Long-term intake of food with excessive amounts of pesticides will probably result in the disorder of the nervous system, digestive system dysfunctions, cardiovascular, cancer and malformation. What's more, accumulation in soil of OPs result in soil structure changes and leanness. The pesticide residue in soil got into the coastal waters may near shore by rainfall or irrigation, but if it exceeds the self-purification capability of natural system it will lead to poisoning or even death for sea creature. In conclusion, the accurate detection of OPs is extremely urgent.Heavy metal Hg has been widely used in electronic and electroplating industry, which has made outstanding contribution to the progress of human civilization. But it can't be ignored that mercury wastewater and exhaust has posed serious threat to global ecological environment. Heavy metal ions cannot self-degradation in a natural environment, which pass to the breathing system and food chain into the human body. Its continuously accumulation in animal and human body, could lead to hepatitis, nephritis, brain tissue damage and so on. Therefore, control the heavy metal waste water and exhaust, and develop high sensitivity and rapid identification sensor are significant measures for security of human being.At present, there are many detection methods for OPs, which mainly uses traditional inspection method such as GC, GC-MS, HPLC, immunization techniques and biosensor technology of combined modern detector method, but there are still some shortages and deficiencies, such as complex for sample pre-preparation, poor repeatability, long time-consuming and expensive apparatuses and so on, which make it difficult to achieve a sensitive and rapid determination of OPs. Fluorescence methods possess a number of advantages, such as high sensitivity, great selectivity, abundant signals and simple equipment, etc, in contrast with other detection methods. So it has received the researchers'?extensive concern in recent years. Furthermore, homogeneous fluorescence sensors were also widely used to detect Hg²⁺ in situ. In the recent ten years, our research group has long been committed to design and fabricate of sensors of hazardous chemicals. In general, polycyclic aromatic hydrocarbons, such as perylene and pyrene, were mainly used as sensing fluorophore, besides, NBD was also widely used in fluorescence sensing, due to it possesses a great deal of advantage, such as high quantum yield, sensitive to solvent polarity, fast-response, etc. NBD-based fluorescence chemosensors have been widely applied in environment monitoring and soft materials and other fields.Based on the discussions above and research background in our lab, NBD-appended cholesteryl derivatives were designed and fabricated, whose fluorescence behaviors and sensing performances were systematically studied. Four chapters were listed in this dissertation.Chapter one of this dissertation mainly describes the progress in the study of various OPs fluorescent sensors, with emphasis on the fluorescence biosensors and fluorescence chemosensors.Chapter two describes the progress in the study of various Hg²⁺ fluorescent sensors, including "turn-off" and "turn-on" type sensors. Also, NBD-based fluorescent sensors were summarized.Chapter three, a new fluorescent ligand CTN containing one NBD unit, two Chol residues, and two triazoles in the linkers was designed and synthesized. Studies of the fluorescence behaviors of the CTN in solution revealed that not only the polarity of solvent can cause the changing of the fluorescence emission, but also the concentration of CTN also lead to the changing of aggregation. Based on the structure of CTN, its sensing performances to Hg²⁺?were studied, and the study result shows that CTN is supersensitive to the presence of Hg²⁺?Detection Limit:0.08 ?M?, and forms a 1:1 non-fluorescent complex. Furthermore, the non-fluorescent CTN-Hg²⁺ complex was used as a sensing platform for detection of OPs. It is anticipated that the compound and the detection methods as developed pave the way for efficient sensing of Hg²⁺ and organophosphorus pesticides in real-life applications.Chapter four, two NBD derivatives modified with calix[4]pyrrole, ?,?-CPN and ?, ?-CPN were designed and synthesized, respectively. In the design, calix[4]pyrrole was specially chosen as a molecular recognition group. Fluorescence study showed that the two compounds behavior similarity. Studies of sensing performances to metal ions revealed that ?, ?-CPN and ?, ?-CPN have no response to metal ions, which demonstrate that there is no interaction between CPN and metal ions. Furthermore, ?,?-CPN and ?, ?-CPN were also used to detect OPs, and it was showed that ?, ?-CPN is supersensitive to the presence of glyphosate, however, as for ?, ?-CPN, it didn't produce the same results. Unlike the method described in former chapter, this method does not need Hg²⁺, avoiding second contamination from the heavy metal ion. Therefore, the study of this work offers great opportunity to design new fluorescence chemosensor for OPs detection.