不同溶剂中番茄红素的荧光光谱及其特性研究

Flurorescene Spectra of Lycopene in Different Solvents

用970CRT荧光光度计测定了番茄红素在正己烷、乙酸乙酯、四氢呋喃、氯仿、丙酮和苯等6种溶剂中的荧光光谱以及番茄红素在四氢呋喃溶液中不同浓度下的荧光光谱。对所测光谱分析得出:6种溶剂中荧光光谱的最大峰值波长(λmax)分别为542.5 nm5、48.2 nm5、55.0 nm、555.7 nm、556.4 nm和565.7 nm,由于溶剂效应,随溶剂极性由小到大,荧光光谱的最大峰值波长(λmax)逐渐红移,由这些峰值波长计算得出相应的番茄红素分子在6种溶剂中的跃迁能ET分别为220.5 kJ/mol2、18.2 kJ/mol2、15.6 kJ/mol2、15.3 kJ/mol2、14.9 kJ/mol和211.5 kJ/mol,可见跃迁能ET也随溶剂极性增大而降低;当番茄红素在四氢呋喃溶液中的质量浓度低于50μg/ml时,溶液的荧光强度随溶液浓度增加而增大,当质量浓度高于50μg/ml时,由于番茄红素的激发态分子与基态分子相互作用,荧光强度反而减小;在浓度低于80μg/ml的溶液中,番茄红素的荧光光谱除最大峰值外还有三个较小峰值,据此计算得出相应的番茄红素分子的跃迁能分别为E(T1)=278.2 kJ/mol、E(T2)=260.2 kJ/mol和E(T3)=239.3 kJ/mol。

The flurorescecne spectra of terrahydrofuran, chloroform, acetone, lycopene in different solvents including benzene and of lycopene-terrahydrofuran hexane, ethyl acetate, solution with different concentrations are measured by a fluorescence spectrophotometer. It is found that the wavelength of fluorescence spectra maximum （λmax） change along with the variation of the polarity of solvent. The transition energies （ET） of lycopene calculated in different solvents are 220.5 kJ/mol, 218. 2 kJ/mol, 215. 6 kJ/mol, 215. 2 kJ/mol, 214.9 kJ/mol, 211.5 kJ/mol. When the concentration of lycopene-terrahydrofuran solution is lower than 50 μg/ml, the intensity of fluorescence increases with the increase of solution concentration, when the concentration is higher than 50 μg/ml, the intensity of fluorescence decreases with the increase of the concentration, which is caused by the interaction between molecules in the excited state and the ground state. Three weak peaks appear in the fluorescence spectra of solutions when the concentration of which is lower than 80 μg/ml. The corresponding transition energies can be calculated as below： ET^（1）== 278.2 kJ/mol, ET^（2）= = 260.2 kJ/mol and ET^（3）=239.3 kJ/mol.