Synthesis And Properties Study Of Actinide Plutonium And Uranium Ligands

The development of civilian energy generation and atomic weapon requires further research on various environment and health issues of actinium,especially Pu^? and U^?.Actinium is introduced into the environment via atomic weapon tests and accidents in nuclear facilities and then is absorbed by humans through ingestion,inhalation,or wounds,which cause acute radiation damage,chemical toxicity and long-term radiation effects,and then induced cancer in the deposition site.The treatment of actinium contaminants is usually achieved by using chelating agents,which formed water-soluble complexes with actinium to accelertate the decorporation rate.Therefore,the development of efficient and low toxicity actinium chelating agents is a research hotspot and also a challenging work.Catecholamines and hydroypyridones as chelating subunits,which have many advantages,such as low toxicity and high chelating ability.The design and synthesis of low toxicity and high efficient chelating agents based on the subunits of siderophore became mainstream research ideas and had received continuous attention.However,the research ideas generally ignored the damage of reactive oxygen species produced by radiation of actinium to the human body.Therefore,the thesis keep up with research ideas of traditional ligands,designed and synthesized ligands which conform to the space structure of actinium based on catecholamine.Meanwhile,bringing catecholamine and hydroxypyridone bonded to[60]fullerene,which was called“free radical sponge”,abtained new type ligands with the ability of chelating and scavenging free radical.Then,the synthesis,structural properties,scavenging free radical properties and chelating properties of target products were investigated.Main conclusions are as follows:?1?In the thesis,twelve new ligands were designed and synthesized based on catecholamine.The structure of intermediates and target product were characterized by NMR,UV-Vis,FTIR,MS,etc.The characterization results are consistent with the expected structure.?2?The antioxidant ability of ligands L^1-3H₂,L^4-6H₆ and L^7-12H₄ were investigated by DPPH free radical method.The results indicated that the antioxidant efficiency?AE?values of the ligand L^1-3H₂ were 181,172,and 160,the AE values of the ligand L^4-6H₆ were 228,256,and 240,and the AE values of the ligand L^7-12H₄ were 446,417,455,450,424,and 442.But the AE values much lower than 4940 of ascorbic acid,remain at a low level,and the antioxidation mechanism of the ligands was discussed.The chelating properties of the ligands L^1-3H₂,L^4-6H₆,and L^7-12H₄ were investigated by potentiometric and spectral titration methods.The results indicated that the average values of log K₄^H,log K₅^H and log K₆^H of ligand L^4-6H₆ were lower than log K₂^H of catechol,that is because the negative inductive effect of the amide group in the ligands and the intramolecular hydrogen bonds of amide group and ortho-position hydroxyl groups,which reduce the electron density of the benzene ring,increase the acidity of the ligands,and facilitate the dissociation of protons.The p Fe^? value of the ligands L^4-6H₆ is significantly lower than that of Me CAM and Enterobactin,which possess a compact molecular scaffold,indicating that the enterobactin analogues ligands with a flexible alkyl chain have a larger coordination cavity and cannot perfectly encapsulated Fe^?.At the same time,the p Fe^? value of the ligand L⁶H₆is lower than that of the ligands L^4-5H₆,indicating that the ligands with longer flexible alkyl chain possess larger coordination cavity and the chelating ability to Fe^? is lower.However,the series of enterobactin analogues ligands with different chain lengths of flexible alkyl backbones can achieve the flexible coordination and possess higher chelating ability for Pu^?,which has larger ionic radius.The average values of the log K₃^H and log K₄^H of the ligand L^7-12H₄ are lower than the log K₂^H of the catechol,which is also because of the negative inductive effect of the amide group in the ligands and the intramolecular hydrogen bonds of amide group and ortho-position hydroxyl groups.The p UO₂^? value of the ligand L^7-12H₄was significantly higher than that of the tetradentate Bis-Me-3,2-HOPO and hexadentate TMA?2Li-1,2-HOPO?₂,which is better than expected results.The higher p UO₂^? value may be attributed to the planar ligand structure which possess well-preorganized ability and well match the UO₂^? coordination environment.At the same time,the p Zn^? value of all ligands were significantly lower than those of chelating agents 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetracarboxylic acid?DOTA?and diethylenetriaminepentaacetic acid?DTPA?,which indicated that catechol derivatives have poor chelating ability for divalent metal ions in vivo and have selective chelating ability for actinium ions.?3?In the thesis,thirteen new ligands were designed and synthesized based on[60]fullerene,and the mechanism of the reaction was also discussed.The structure of intermediates and target product were characterized.The characterization results are consistent with the expected structure.The water-solubility of the ligands?19a-g?reaches a relatively high level of 105-163 mg cm^-3,the water-solubility of[60]fullerene was solved by introducting multiple catecholamines or hydroypyridones.The antioxidant ability of ligands?19a-g?by DPPH free radical method,the results indicate the first-order reactions rate?k₁?value are all about 5.50×10^-2 min^-1,and one order of magnitude higher than the k₁ values of[60]fullerene derivative,which were reported in the literature.The chelating ability of ligands?19a-g?was investigated by fluorescence titration of simulated element Ce^?.The results indicated that the log K_a values of ligands?19a-g?are 5.30?5.82?5.94?5.15?5.74?6.11 and 5.97,respectively.The water-solubility of[60]fullerene was solved by introducting multiple catecholamines or hydroypyridones,and bifunctional[60]fullerene ligands,which possess chelating and antioxidant ability,was convincingly achieved.