实验观测了3-羟基黄酮(3-HF)在不同极性溶剂中的吸收光谱和荧光光谱, 发现在吸收光谱中有3个吸收带, 峰值位于300和345 nm的两个吸收带较强, 位于415 nm处的吸收带较弱。 用345 nm作为激发光, 观测到两个荧光带, 其中峰值位于400 nm的荧光带为3-HF稀醇式构型的发射, 随着溶剂极性的增大其强度增强, 峰值位于526 nm的荧光带为3-HF互变异构体的发射, 随着溶剂极性的增大其强度减弱, 这表明溶剂极性阻碍质子转移的发生。 用415 nm的光激发样品, 在荧光光谱中发现了3个新荧光谱带, 峰值分别位于440, 471和515 nm, 这３个荧光谱带归属至今未见报道。 为了指认这３个荧光谱带, 分别观测了3-HF在不同酸碱度溶液的荧光光谱及其吸收光谱, 通过对这些光谱的分析研究, 指认出荧光峰位于440和471 nm的荧光谱带为3-HF的两种阳离子的发射, 峰值位于515 nm的荧光谱带为3-HF的阴离子的发射。

The absorption and fluorescence spectra of 3-hydroxyflavone (3-HF) in different polar solvents were observed with UV-Vis spectrometer and fluorescence spectrometer, respectively. There are three absorption bands in the absorption spectra, wherein two absorption bands with absorption peak at 300 and 345 nm, respectively, are strong, and the other one with absorption peak at 415 nm is weak. When the samples in different polar solvents were excited by 345 nm light, there appeared two new fluorescence bands peaked at 400 and 526 nm, respectively. The fluorescence band at 400 nm is attributable to the emission from enol structure and its intensity increases with increasing the polarity of protic solvents; that at 526 nm is attributable to the emission from the isomer structure and its intensity decreases with increasing the polarity of protic solvents. The results show that the increase in the polarity of protic solvents prevents the formation of isomer. When the samples in different polar solvents were excited by 415 nm light, three new fluorescence bands peaked at 440, 471 and 515 nm have not been reported so far. In order to identify the three new fluorescence bands, we prepared the samples with pH value of 5.0, 4.0 and 3.0 through incorporating the different amounts of acetic acid into 3-HF solution. The fluorescence spectra in different pH value solution were observed under excitation of 415 nm light, and it was found that the intensity of two fluorescence bands in the region of shorter wavelength changes with pH values changing. For identifying the fluorescence band of 515 nm peak wavelength, we put sodium hydroxide into 3-HF in ethanol solution and prepared 3-HF samples with pH values of 8.0, 8.5, 9.0, and 10.0. When the samples were excited by the 415 nm light, it was found that two fluorescence bands in the region of shorter wavelength disappeared and the intensity of the fluorescence band of 515 nm was enhanced. Since in sodium hydroxide solution 3-HF forms anion easily, we ascribed the fluorescence band with 515 nm peak wavelength to the emission from the 3-HF anion.