【作者】 孟伟； 羡蕾； 刘翠格； 魏永巨；

【Author】 MENG Wei,XIAN Lei,LIU Cui-ge and WEI Yong-ju~*(College of Chemistry and Material Science,Hebei Normal University,Shijiazhuang 050016)

【机构】 河北师范大学化学与材料科学学院；

【摘要】 研究了东莨菪内酯的荧光光谱和荧光量子产率。在pH<6.2的弱酸性条件下,东莨菪内酯有荧光,最大激发波长λ_ex和发射波长λ_em分别为343 nm和458nm。随pH升高,荧光增强,λ_ex红移至388 nm,λ_em红移至462 nm,表明7-羟基质子电离。测得电离常数pK_a为7.32。在pH 9～11时,东莨菪内酯有稳定的强荧光。当pH>12时,内酯环水解导致荧光强度下降并消失。在甲醇和乙醇介质中,东莨菪内酯的荧光比在水中减弱,发射波长蓝移至420 nm。以硫酸奎宁为参比,测得东莨菪内酯水溶液的荧光量子产率为0.71。更多还原

【Abstract】 Fluorescence spectra and fluorescence quantum yield of scopoletin have been studied.Under weak acidic conditions of pH<6.2,scopoletin has fluorescence,with maximum excitation wavelengthλ_ex at 343 nm and emission wavelengthλ_em at 458 nm.Along with the increase in pH,fluorescence intensity increases,λ_ex red-shifts to 388 nm,λ_em red-shifts to 462 nm,indicating the ionization of 7-OH proton.Ionization constant pK_a is determined to be 7.32. In the range of pH 9～11,scopoletin has strong and steady fluorescence.When pH>12,fluorescence gradually decreases and finally disappear,due to the hydrolysis of lactonic ring of scopoletin.In the media of methanol and ethanol, fluorescence of scopoletin was weaker than in water,andλ_em blue-shifts to 420 nm.Using quinine bisulphate as a reference,fluorescence quantum yield of scopoletin aqueous solution is measured to be 0.71.更多还原