N-硝基脲类的合成及其阴离子识别研究

N-nitrourea Derivatives: Synthesis and Anion Recognition Properties

合成了两种新型的阴离子识别受体N-硝基-N-(2,6-二硝基-4-三氟甲基苯基)-N′-(4-氯苯基)脲(受体1)和N-硝基-N-(2,6-二硝基-4-三氟甲基苯基)-N′-(4-甲基苯基)脲(受体2)。利用紫外-可见吸收光谱考察了其与F-、Cl-、Br-、I-、H2PO4-、HPO42-、PO43-阴离子客体的识别作用。结果表明:在受体分子中加入F-、H2PO4-、HPO42-阴离子,其紫外-可见吸收光谱发生明显变化且溶液颜色由黄色变为紫色,而加入其他离子时无此现象。从而实现对这3种阴离子的裸眼检测。测定了结合物的结合比及结合常数。Job工作曲线表明受体与阴离子客体形成了1∶1结合物。结合常数表明:同一受体对不同阴离子的选择性不同,受体分子1选择性HPO42->H2PO4->F-,受体分子2选择性HPO42->F->H2PO4-;受体分子与同一阴离子客体的结合能力呈现规律性,1>2。提出了可能的结合模式。

Two colorimetric anion sensors N-nitro-N-（2,6-dinitro-4-trifluoromethylphenyl）-N′-（4-chlorophenyl）urea（receptor 1） and N-nitro-N-（2,6-dinitro-4-trifluoromethylphenyl）-N′-（4-methylphenyl）urea（receptor 2） were synthe-sized and characterized.The anion recognition properties for the two sensors using anions such as fluoride（F^-） chloride（Cl^-）,bromide（Br^-）,iodide（I^-）,dihydrogen phosphate（H2PO4^-）,hydrogen phosphate（HPO4^2-） and phosphate（PO4^3-） in the form of their corresponding tetrabutylammonium salt in DMSO were evaluated by UV-Vis.Fluoride,dihydrogen phosphate and hydrogen phosphate gave rise to colour changes from yellow to purple,which were visible to the naked eyes.Job plot experiment indicated that 1∶1 stoichiometrical binding compounds were formed between the urea receptors and the anions.The selectivity and sensitivity of receptor 1 and receptor 2 for sensing anions were different,which was in the order of HPO4^2-〉 H2PO4^-〉 F-for receptor 1 and HPO42-〉 F^-〉 H2PO4-for receptor 2,the receptors had no evident binding effect with the other anions.For the same anion,the association constants followed the trend： receptor 1 〉 receptor 2.A possible structure of the binding compound between the receptors and the anions is also proposed.