摘要
研究了环丙沙星(ciprofloxacin,CIP)在不同pH条件下的荧光光谱、紫外吸收光谱和质子化作用,测量了CIP在中性条件下的荧光量子产率。在H+浓度大于1mol·L-1的HCl介质中,CIP分子(简写为HL)可以结合3个质子而以H4L3+形式存在,有微弱的荧光,最大荧光发射波长(λmax)为456nm。在pH0～2的酸性条件下,CIP主要以H3L2+形式存在,λmax为450nm,荧光较弱,荧光强度随pH的升高而上升。在pH2～4时,CIP主要以H2L+形式存在,具有强荧光,λmax仍为450nm。当pH>4时,λmax逐步蓝移到414nm,荧光强度随pH的升高而稍有降低,同时紫外吸收光谱也有明显变化,表明H2L+随pH升高而失去质子,以双极离子HL形式存在。当pH>8时,荧光强度随pH升高而减弱至消失,表明HL逐步失去质子,转化为无荧光的阴离子L-。在分子形态变化过程中,最大荧光激发波长始终在275nm附近,但最大荧光发射波长有较大变化。在pH7.0的缓冲溶液中,以硫酸奎宁为参比,测得CIP在最大荧光激发波长275nm处的荧光量子产率为0.12。
Fluorescence spectra, ultraviolet absorption spectra, and protonation of Ciprofloxacin （CIP） at different pH values have been studied. Fluorescence quantum yield of CIP under neutral condition has been measured. In HC1 medium with [H^＋ ] 〉1 mol·L^-1 , CIP molecules （simplified as HL） may accept three protons to exist as H4L^3＋ with very weak fluorescence, and its maximum fluorescence emission wavelength （λmax） is 456 nm. In acidic solution of pH 0 to pH 2, CIP mainly exists as H3L^2＋ form with λmax at 450 nm, and fluorescence intensity is relatively weak and increases with increasing of pH. In the range of pH 2 to pH 4, CIP mainly exists as H2^L＋ form with a strong fluorescence, and λmax is still at 450 nm. When pH〉4, λmax gradually blue-shifts to 414 nm, fluorescence intensity slightly decreases as pH increases, and at the same time an evident change in ultraviolet absorption spectruna is observed, indicating that H2^L＋ has lost proton to exist as dipole ion form HL. When pH〉8, the fluorescence intensity decreases until disappearance as pH increases, indicating that HL has lost proton to exist as non-fluorescence anion ion form L^- . In the molecular form changing process, the maximum excitation wavelength of CIP is essentially constant at 275 nm, but the maximum emission wavelength changes obviously. In a buffer solution with pH 7.0, and using quinine bisulphate as a reference, the fluorescence quantum yield of CIP at maximum excitation wavelength 275 nm was measured to be 0.12.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2005年第9期1446-1450,共5页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金(50103001
20171004
30371604和39730160)
国家重点基础研究发展规划项目(2002CCA01900)资助
关键词
环丙沙星
荧光光谱
紫外吸收光谱
质子化作用
荧光量子产率
Ciprofloxacin
Fluorescence spectrum
Ultraviolet absorption spectrum
Protonation
Fluorescence quantum yield
