对一种简单结构的喹哪啶衍生物作为离子荧光探针的性能进行了研究。 探针由8-羟基喹哪啶的2-位引入水杨醛构成, 通过双键连接喹啉环与苯环以及推-拉电子基团构成大共轭结构, 使其发光量子产率提高; 探针分子中的氮、 氧原子提供了良好的配位作用点, 能选择性与离子配合而使荧光性质发生变化。 在乙腈/水溶液中, Fe3+与探针形成1∶1的配合物而使其荧光猝灭, 配合为自发的熵驱动放热过程。 红外光谱和1H NMR滴定推测探针分子中的两个羰基氧和氮的孤对电子参与Fe3+络合, 光诱导引发电子转移过程导致荧光猝灭。 在乙腈溶液中, F-使探针在415 nm处的荧光峰降低, 在560 nm处出现新荧光峰, 形成比率荧光, 荧光由蓝色变为黄色至橙红色。 同时, F-使探针在280和340 nm处的紫外吸收峰降低, 在455 nm处出现新的吸收峰, 形成比率吸收, 颜色由无色变为黄色至橙色。 1H NMR滴定推测探针分子与F-是通过氢键作用。 为一种同时检测阴、 阳离子的双功能探针, 荧光法对Fe3+和F-的检出限分别低至13.6 nmol·L-1和1.6 μmol·L-1, 紫外法对F-的检出限低至16.5 μmol·L-1。 利用探针对F-识别时明显的颜色变化, 建立了可视性, 快速度, 易操作的目视检测微量F-的方法。

A simple quinaldine derivative probe for cation and anion was investigated with spectroscopy. In probe molecular structure, the conjugate aromatic ring group was introduced at 2- of 8-hydroxyquinaldine to form a large conjugate structure, which enhances the photoluminescence quantum yield. N and O atoms of probe provide good coordination point, which can cooperate with ion selectivity and change its fluorescence properties. In CH3CN/H2O solution, probe emits blue fluorescence at 415 nm, however, Fe3+ led the fluorescence quenching. The 1∶1 stoichiometry of probe with Fe3+ was confirmed. IR spectrum and 1H NMR titration spectra speculated that the nitrogen of quinaldine group and the two carboxylate oxygen are involved in the complexation, inducing photoinduced electron transfer transfer process cause the fluorescence quenching. The complexation was an exothermic reaction driven by entropy processes. In CH3CN solution, the emission intensity of probe at 415 nm reduced when a new emission appeared at around 560 nm with the addition of F-, blue fluorescence changed to yellow, exhibited a ratio fluorescence emission. The absorption bands at 280 and 340 nm reduced while a new absorption appeared around at 455 nm with the addition of F-, exhibited a ratiometric absorbance, and the color changed from colorless to orange, which could be observed by the naked eye. It is noteworthy that the ratio fluorescence/absorbance change could be potentially useful for the quantitative determination of F-. 1H NMR titration spectra speculated that the reaction of probe and F- through hydrogen bonding effect. The probe can monitor Fe3+ and F- simultaneously as a dual-function chemsensor, and the limit of detection are 13.6 nmol·L-1 and 1.6 μmol·L-1 by fluorescence spectroscopy, and the limit of detection is 16.5 μmol·L-1 to F- by absorption spectroscopy. Making use of the obvious color change of probe with F- for both visible light and fluorescence could be readily distinguished by the naked eyes. A method of visual detection of trace F- was established with intuitionistic, rapid, sensitive and easy operability.