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利用核磁共振波谱技术研究了不同浓度硫酸溶液中氧氟沙星(OFL)的1H,19F和13C核磁共振谱,对不同硫酸浓度引起的δH,δF,δC和JFC耦合常数的变化进行比较分析,由此推测其结构状态.综合1H,19F和13C核磁共振谱特点及其变化,提出OFL分子在强酸性环境中N1’被进一步质子化的结构模型.在浓硫酸溶液中,N1’被进一步质子化,并与F9形成氢键(N1’—H+┈F9),该结构使分子的共轭程度大幅降低,导致其荧光发射波长、荧光激发波长及紫外吸收波长均发生蓝移.硫酸溶液中氧氟酸和甲基氧氟沙星的荧光光谱行为进一步证明了OFL分子在浓硫酸溶液中质子化模型的合理性.
The 1H, 19F and 13C nuclear magnetic resonance spectra of ofloxacin (OFL) in different concentrations of sulfuric acid solutions were studied by using nuclear magnetic resonance spectroscopy. The changes of the coupling constants of δH, δF, δC and JFC induced by different sulfuric acid concentrations were compared. The structural states of N1 ’were further protonated by OFL in a strongly acidic environment by comprehensively analyzing the characteristics and their changes of 1H, 19F and 13C NMR spectra. In concentrated sulfuric acid solution, N1’ was further protonated (N1’-H + ┈F9). This structure greatly reduces the degree of conjugation of the molecule, resulting in a blue shift of the fluorescence emission wavelength, the fluorescence excitation wavelength and the UV absorption wavelength. The concentration of oxygen in the sulfuric acid solution Fluorescence spectroscopy of hydrofluoric acid and ofloxacin further proves the rationality of the protonation model of OFL molecule in concentrated sulfuric acid solution.