【作者】 杨莲莲；

【导师】 李村；

【作者基本信息】 安徽大学 ， 应用化学， 2013， 硕士

【摘要】 近年来,随着化学传感器的迅速发展,荧光探针研究在化学、生物、医学和环境等诸多领域受到了人们越来越多的关注,成为目前的一大研究热点。金属离子是化学、环境科学、生命科学和医学等诸多学科领域的研究对象,因此溶液中金属离子的识别和检测也成为了分析化学研究的热点问题。荧光分子／离子探针技术因具有选择性好、灵敏度高、简单快速且不需要借助昂贵仪器的优点而被广泛地应用于各种金属离子的检测。利用荧光强度与离子浓度的关系可以对离子进行定量或定性的分析,方便、快捷且具有较高的选择性和灵敏性,非常适用于重金属离子的实时或原位检测。本文基于C=N异构化和激发态分子内质子转移机理,设计合成了六种席夫碱化合物L1-L6,并利用紫外-吸收光谱法和荧光光谱法研究了他们对金属离子的选择性识别性能。作为多功能荧光传感器,新型咔唑-席夫碱L1被设计、合成和表征。通过紫外吸收光谱法和荧光光谱法,L1都能选择性识别Fe3+离子和Cu2+离子。利用Job曲线法测得L1与Fe3+离子和Cu2+离子的络合比分别是2：1和1：1。L1与Fe3+离子和Cu2+离子的检出限分别是4.23×10-6M和5.67x10-6M。加入Fe3+/Cu2+离子后,L1的荧光增强,其可归因于C=N异构化和ESIPT。同时L1跟其他离子的相互作用也被研究,其紫外和荧光光谱并没有明显的变化。因此L1是一种高选择性和高灵敏性的新型Fe3+／Cu2+离子化学传感器。L2分子是咔唑基团与4-氨基安替比林缩合的产物,它与Cr3+和Cu2+离子结合后溶液由无色分别变为黄色和淡黄色,便于可视检测,是一种检测Cr3+和Cu2+离子的比色探针。同时,L2中加入Cr3+和Cu2+离子后其紫外吸收发生明显蓝移,其与Cr3+离子和Cu2+离子的结合常数Ka分别为2.20x104M-1和1.75x104M-1；结合比分别为1：1和2：1；检测下限分别为logClim为-5.54M-1和-5.56M-1,即Clim分别为2.86x10-6M和2.75x10-6M。将噻吩引入到咔唑母体上,设计合成了L3和L4。探针L3分子是咔唑-噻吩基团与4-硝基-2-羟基苯胺缩合反应得到的产物,加入Fe3+离子后,313nm处出现新的吸收峰,溶液由黄绿色变为无色,肉眼即可观察出,因此L3可以作为裸眼识别Fe3+离子的比色探针,与Fe3+离子的结合常数K。为4.21×104M-1,对Fe3+离子的检测限为6.16x10-7M。荧光光谱研究显示：加入Fe3+后L3的荧光峰强度增加了13倍；加入Cr3+后荧光增强11倍。因而L3可作为Fe3+和Cr3+离子荧光探针,其与Fe3+和Cr3+离子的结合常数Ka分别为4.67x104M-1和5.97x104M-1,结合比都为2：1,检测限分别为3.74x10-6M和2.56x10-6M。L4分子是比L3分子少一个羟基的噻吩类席夫碱。对其进行紫外吸收光谱研究和荧光发射光谱研究,结果显示L4对金属离子没有选择性识别,表明羟基是与金属离子配位的结合位点。将水杨醛基团引入咔唑母体合成了席夫碱探针L5和L6,在结构上L5比L6少一个硝基。L5在乙腈溶液中选择性识别Fe3+离子,加入Fe3+离子后,其紫外吸收在432nm处出现一个新的吸收峰,检测限为9.21×10-7M,络合比为1：1。在(乙腈/水=3/1)混合溶剂中,Fe3+/Cr3+离子对L5具有明显的荧光增强响应,其检出限分别为8.16x10-7mol/L和1.15×10-6mol/L,络合比分别为1：1和2：1,结合常数Ka分别为3.21×104M-1和2.21×104M-1。经荧光光谱法研究发现,L6可作为选择性识别Cu2+/Cr3+离子的比率荧光探针,结合常数Ka分别为1.53x106M-1和5.37x105M-1,络合比都为2：1,且识别过程是可逆的,其检出限分别为2.01×10-7M和2.440x10-7M。更多还原

【Abstract】 With the rapid development of chemosensors, the study on fluorescent probes has become one of the hottest research fields including chemistry, biology, medical science, and environment, and drew more and more attention of people in recent years. The analysis and detection of metal ions are important for its implications in such fields:chemistry, biology, medicine and environment. There are lots of advantages for fluorescence chemosensors such as high selectivity, sensitivity, simplicity and without resorting to any expensive instruments, which was successfully applied in the detection of many metal ions in aqueous solution. Using the relationship between the fluorescence property and the ions concentration, fluorescent probes is fit for the heavy metal detection in real time or in situ for its characteristics of convenience, shortcut, high sensitivity and selectivity. Based on the principle of C=N isomerization and the obstructed excited state intramolecular proton transfer (ESIPT), six compounds L1-L6were designed and synthesized. By using UV-vis and fluorescence spectrometry methods, we studied their selectively recognition for the metal ions.A new carbazole-based Schiff-base fluorescent chemosensor (L1) was designed, synthesized by condensation reaction between2-amino-4-nitrophenol and3-formyl-9H-hexylcarbazole, which can selectively recognized Fe3+and Cu2+ions over a number of other metal ions. Compound L1could detect Fe3+and Cu2+by UV-Vis and fluorescence spectrometry method. The stoichiometry ratio of L1-Fe3+and L1-Cu2+determined by the method of Job’s plot are2:1and1:1, respectively. Moreover, the detection limits were calculated to be4.23×10-6mol/L for Fe3+ion and5.67×10-6mol/L for Cu2+ion. In the presence of Fe3+/Cu2+ions, the fluorescence enhancement was attributed to the inhibited C=N isomerization and the obstructed excited state intramolecular proton transfer (ESIPT) of compound L1. At the same time, the interactions of compounds L1with other ions were also investigated and no obvious changes of UV-vis absorption and fluorescence were observed. Thus a new kind of chemosensor with high sensitivity and selectivity for Fe3+/Cu2+detection was introduced.The compound L2was synthesized by condensation of4-amino antipyrine with3-formyl-9H-hexylcarbazole. When it bonds Cr3+and Cu2+ions, the color of L2in CH3CN solution alters from colorless to yellow and light yellow, respectively. L2can be used as colorimetric probe for Cr3+and Cu2+ions recognization by simple visual inspection. Addition of Cr3+/Cu2+ions to solution, the UV-vis absorption band occur obvious blue shift. The Ka of L1-Cr3+and L1-Cu2+are2.20×104M-1and1.75×104M-1, respectively. The stoichiometry ratio of L1-Cr3+and L1-Cu2+calculated by the Job’s plot method are2:1and1:1, respectively. The calculated detection limits are2.86×10-6M for Cr3+ion and2.75×10-6M for Cu2+ion.L3and L4were designed by introduced thiophene to the carbazole group. Compound L3was synthesized by condensation of2-amino-4-nitro phenol with3-thienyl-hexylcarbazole. Addition of Fe3+ion to L3solution, there is a new UV-vis absorbance band at313nm and the solution color changes from yellowish green to colorless. So L3can be used as colorimetric probe for Fe3+ion recognization observed by unaided eye. The Kais4.21×104M-1and the detection limit is6.16×10-7M. The experiment results show that the intensity of fluorescence peak enhanced13-fold and11-fold with addition of Fe3+/Cr3+ions, respectively. Thus L3could be used as fluorescence probe for detection of Fe3+/Cr3+ions. The Ka of L3-Fe3+and L3-Cr3+are4.67×104M-1and5.97×104M-1, respectively. Both the stoichiometry ratio of L3-Fe3+and L3-Cr3+are2:1. The detection limits are calculated to be3.74×10-6M for Fe3+ion and2.56x10-6M for Cr3+ion. L4was a Schiff base without-OH group comparing with L3. It could not selectively detect metal ions by UV-Vis and fluorescence spectroscopy method. The results show that the phenolic hydroxy is one important bond site of compound for binding to metal ions.The L5and L6were synthesized by introducing salicylaldehyde to the carbazole group and L5had no-NO2group on salicylaldehyde comparing with L6. In CH3CN solution, L5could selectively recognize for Fe3+ion. Addition of Fe3+ion, a new UV-vis absorbance peak located at432nm. The calculated detection limit is9.21×10-7M and the stoichiometry ratio of L5-Fe+is1:1. In the mixed solvent of acetonitrile and water (volume ratio=3:1), the fluorescence intensity enhancement is observed for reaction of L5and Fe3+/Cr3+ion. The detection limits are8.16×10-7M for Fe3+ion and1.15×10-6M for Cr3+ion. The stoichiometry ratio and the Ka of L5-Fe3+/L5-Cr3+are1:1/2:1and4.67x104M-1/5.97×104M-1, respectively. By fluorescence spectrometry studies, we found L6could be used as a ratio fluorescent probe for Cu2+/Cr3+ions detection in CH3CN solution. The Ka of L6-Cu2+and L6-Cr3+are1.53x106M-1and5.37×105M-1, respectively. Both the stoichiometry ratio of L6-Cu2+and L6-Cr3+are2:1. Moreover, the reaction of L6bonding to Cu2+/Cr3+ions is reversible and the detection limits are2.01x10-7M for Cu2+ion and2.440×10-7M for Cr3+ion.更多还原