高选择性氟离子识别受体的设计与识别机理

Design of a Fluoride-Selective Colorimetric Receptor and Its Fluoride Recognition Mechanism

将酰胺识别基团耦合至基态具有分子内电荷转移特征的对硝基苯基偶氮苯胺分子中 ,设计合成了受体分子N 苯甲酰基 4 ( 4′ 硝基苯基偶氮基 )苯胺 ( 3 ) ,对氟离子表现出极高的识别选择性 .乙腈中该受体 3的最大吸收峰位于 3 80nm ,加入氟离子后 ,该吸收峰强度逐渐减弱 ,同时在 5 3 0nm处出现新的吸收峰 ,后者为受体分子与氟离子形成的 1∶1配合物的吸收峰 .溶剂极性效应实验表明 ,该吸收峰具有电荷转移特征 .引入氟离子后受体 3溶液的颜色由浅黄色转变为紫红色 ,可实现氟离子的裸眼检测 .质子溶剂效应 ,1HNMR滴定为受体分子 3与阴离子间的氢键作用本质提供了直接证据 .

This paper will report the design and synthesis of a fluoride-selective colorimetric receptor, N-benzoyl-4-(4'-nitrophenylazo) aniline, 3, in which amide as recognition group was coupled to 4-(4-nitrophenylazo) aniline (2) of ground-state intramolecular charge transfer character. It was found that 3 had an absorption maximum at 380 nm in acetonitrile, which decreased gradually upon addition of F-. A new band peaked at 530 nm appeared, which turned the solution from light yellow to purplish red. The new band due to the hydrogen bonding complex of 3 with F- was shown to be of charge transfer character by the observation of a substantial red shift with increasing solvent polarity. H-1 NMR titrations confirmed hydrogen bonding interaction between 3 and F-.