香豆素衍生物的光谱性质研究及痕量Fe^(3+)的测定

Study on Fluorescent Properties of Coumarin Derivatives and Determination of Trace Iron

对比考查了水与乙醇溶液中不同浓度下丁二酸(7-羟基香豆素)单酯(SCE)的荧光光谱特性,基于溶剂本身的性质及SCE在氢键溶剂中的二聚作用对其光谱进行了讨论。同时基于不同pH值水溶液中荧光光谱的变化,计算得到该试剂激发态分子的酸离解常数pKa*=2.03。研究发现在pH3.3盐酸介质中,Fe3+可使SCE的荧光猝灭,且其荧光猝灭程度与Fe3+的加入量呈线性关系。该方法线性范围为0.66~6.59μg·L-1,方法检测限为51ng·L-1,对比母体7-羟基香豆素对Fe3+的检测,SCE测定的灵敏度提高了104倍,从而建立了荧光猝灭法测定痕量Fe3+的新方法。

The fluorescence spectra of the succinic acid （7-hydroxy-coumarin） ester （SCE） of different concentration in water and ethanol solvents were studied. It was found that the peak wavelength changes not only with solvent, but also with the concentration. These phenomena of spectra have been discussed on the basis of solvent properties and dimerisation of SCE in hydrogen bonding solvents. The author thought that there are dimerisation phenomena in the SCE solutions at high concentration. The formation of dimer was caused by the aid of hydrogen bonding between SCE and solvent or between SCE themselves. Its acidic dissociation constant at excited state was determined based on the changes of the fluorescence spectra in water. And a simple and sensitive fluorescence quenching method for the determination of trace iron was developed. The method is based on the reaction of SCE with iron in hydrochloric acid medium. The fluorescence intensity was measured with excitation and emission wavelengths of 347 and 457 nm, respectively. The linear range for the determination of iron was 0.66-6.59 μg·L^-1. The detection limit was 51 ng·L^-1. The author contrasted SCE with 7-hydroxy-coumarin to determine Fe^3＋, and found the sensitivity of SCE is 104 higher than that of 7-hydroxy-coumarin. To our thinking there is a carboylate group in SCE, whose coordinate force with iron is stronger than hydroxide radical in 7-hydroxy-coumarin.