氧氟沙星的荧光光谱与质子化作用研究  

Fluorescence Spectra and Protonation of Ofloxacin

作　　者：刘翠格[1] 徐怡庄[1] 魏永巨[2] 齐剑[1] 许振华[1] 叶放 吴瑾光[1] 

机构地区：[1]北京大学化学与分子工程学院,北京100871 [2]河北师范大学化学学院,河北石家庄050016 [3]广州白云山制药厂,广东广州510515

出　　处：《光谱学与光谱分析》2005年第4期584-587,共4页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金 (50 1 0 30 0 1 ;2 0 1 71 0 0 4 ;30 371 60 4 ;39730 1 60 );国家重点基础研究发展规划项目 (2 0 0 2CCA0 1 90 0 )资助

摘　　要：研究了氧氟沙星(Ofloxacin ,OFL)在不同pH条件下的荧光光谱、紫外光谱和质子化作用。在强酸性溶液中,OFL分子可以结合两个质子而以三元酸H3 L2 + 的形式存在,最大荧光发射波长(λmax)为5 0 5nm。随着pH值升高,OFL的荧光光谱发生变化,在激发光谱中35 2nm形成一等荧光点,同时在紫外吸收光谱中出现等色点,这一光谱特征表明H3 L2 + 逐渐失去4位C羰基氧结合的质子。在pH 2 . 5～4范围内,OFL以H2 L+ 形式存在,λmax为4 99nm。当pH >4时,随pH值升高,位于4 99nm的荧光发射峰逐渐蓝移至4 5 5nm ,在4 84nm形成一等荧光发射点,表明C 3位羧基质子的离解。在pH 7左右,OFL以双极离子HL形式存在,λmax为4 5 5nm ,是最强的荧光型体。当pH >8时,随pH值升高,λmax由4 5 5nm红移至约4 75nm ,同时荧光强度下降,表明HL失去哌嗪环N -4上结合的质子。当pH >10时,OFL以阴离子L-形式存在,荧光强度随pH值升高而降低,但λmax基本不变,表明介质环境对OFL的荧光性质有一定影响。Fluorescence spectra, ultraviolet spectra and protonation of Ofloxacin (OFL) at different pH values have been studied. In strong acidic solutions, OFL molecule might accept two protons to exist as ternary acid H3L2+ with a maximum emission wavelength (λ(max)) at 505 nm. Along with the increase in pH value, fluorescence spectrum of(.)OFL changed, an iso-fluorescence point at 352 nm was found in the fluorescence excitation spectra, and at the same time, isosbestic points were found in its LTV absorption spectra. This spectral feature reveals that H3L2+ gradually lost hydrogen ion combined on C-4 keto oxygen. In the range of pH 2.5 to pH 4, OFL exists as H2L+ with λ(max) at 499 m. When pH > 4, the fluorescence emission peak at 499 nm gradually blue-shifted to 455 nm as pH was increasing, and an iso-fluorescence emission point was formed at 484 nm, indicating the dissociation of hydrogen ion of carboxylic acid at C-3. At about pH 7.0, OFL exists in the dipole ion form HL with λ(max) at 455 nm, which is the strongest fluorescence form. When pH > 8, λ(max) red-shift from 455 to 475 nm as pH increases, meanwhile, fluorescence intensity decreases, indicating that HL lost hydrogen ion combined on N-4 of piperazinyl group. When pH > 10, OFL exists in anion ion form L-, and fluorescence intensity decreases with pH increasing, but λ(max) remains essentially constant, indicating that medium environment influences the fluorescence property of OFL.

关 键 词：质子化作用 荧光光谱 氧氟沙星 紫外吸收光谱 荧光发射 荧光强度 pH值 max 紫外光谱 酸性溶液 发射波长 最大荧光 发生变化 激发光谱 荧光性质 介质环境 三元酸 等色点 特征表 pH2 阴离子 分子 羰基 离解 HL 

分 类 号：O626.13[理学—有机化学] O614.33[理学—化学]