Chromogenic anion receptors based on 4-nitrophenylhydrazone and phenylhydrazone have been designed and synthesized. UV–Vis and 1H NMR titration showed that receptor 1 responded to anions according to their basicity. Although the nature of hydrogen bonds in hydrazone N–H and vinylic C–H is weak, receptor 1 bound weakly basic anions such as chloride, bromide, iodide and hydrogen sulfate utilizing only hydrogen bond in CH3CN. No color change was observed with these anions. However, for more basic anions such as acetate dihydrogen phosphate and fluoride, color change due to deprotonation observed. Furthermore, the solution color of 1 changed to deep blue with fluoride. Fluoride could be distinguished from acetate and dihydrogen phosphate with naked eye. However, phenylhydrazone based receptor 2 showed only hydrogen bonding association with all anions investigated except fluoride. Due to low deprotonation tendency and its structure, color change of solution 2 was not observed.
我们设计并合成了基于 4-
硝基苯腙和苯基腙的致色阴离子受体。紫外-可见光和 1H NMR 滴定显示,受体 1 根据阴离子的碱性对其做出反应。虽然腙的 N-H 和
乙烯基 C-H 中的氢键性质很弱,但受体 1 只利用 CH3CN 中的氢键与
氯化物、
溴化物、
碘化物和
硫酸氢盐等弱碱性阴离子结合。这些阴离子不会产生颜色变化。但是,对于
醋酸盐磷酸二氢盐和
氟化物等碱性较强的阴离子,则观察到由于去质子化而引起的颜色变化。此外,1 的溶液颜色在
氟化物的作用下变为深蓝色。肉眼可以将
氟化物与
醋酸盐和
磷酸二氢盐区分开来。然而,基于苯腙的受体 2 只显示出与除
氟化物以外的所有阴离子的氢键联系。由于其低去质子化倾向及其结构,溶液 2 没有发生颜色变化。