将喹啉和丹磺酰胺两种荧光基团同时引入配体L1, 利用L1与锌离子自组装构筑三核锌有机-金属大环化合物H-1(比率荧光探针), 实现了对生物分子谷胱甘肽(GSH)的有效识别。利用紫外光谱、荧光光谱、1H NMR、ESI-MS等表征方法研究了H-1对生物分子谷胱甘肽(GSH)的光谱识别作用。紫外滴定光谱表明, 当向H-1中加入谷胱甘肽分子后, 425 nm处的吸收峰强度降低, 320 nm处的吸收峰强度增大, 等吸收点为355 nm。利用320 nm处的吸光度值模拟计算平衡常数, lgK为4.03±0.11, 说明H-1与GSH形成了1∶1的包合物。荧光光谱分析表明, 当向H-1中加入GSH后, 以340 nm光激发, 波长为513 nm处丹磺酰胺的荧光强度下降, 并且发生红移, 而396 nm处喹啉基团的荧光强度增大。利用喹啉基团与丹磺酰胺基团荧光发射峰强度变化的比值可以精准检测谷胱甘肽分子, 检测限可达到2.5×10-6 mol·L-1。

Two fluorescent groups of quinoline and dansylamide were introduced into ligand L1 together, and a trinuclear zinc metal-organic compound H-1 as a ratiometric fluorescent probe was self-assembled by L1 and zinc ion, and the sensitive recognition of γ-glutamyl-cysteinyl-glycine (GSH) was realized by H-1. The recognition process was studied by UV-Vis, fluorescence spectra, 1H NMR and ESI-MS. UV-Vis adsorption titration results show that the addition of GSH to the solution of H-1 causes a significant absorbance decrease at 425 nm and an obvious absorbance increase at 320 nm. The isobestic point is 355 nm. The equilibrium constant lgK of 4.03 ± 0.11 is obtained with the absorbance value at 320 nm. This indicates that 1∶1 stoichiometric host-guest complexation of H-1 for GSH is formed. The fluorescence spectra show that the addition of GSH to the solution of H-1 causes an obvious dansyl-based fluorescence decrease at 513 nm upon excitation at 340 nm with a significant red-shift, and an increase of quinoline-based fluorescence at 396 nm. The ratio of dansyl-based fluorescence to quinoline-based fluorescence can be used to detect GSH and the detection limit is up to 2.5 × 10-6 mol·L-1.