Spectral Characteristics of Sulfa Drugs: Effect of Solvents, pH and β-Cyclodextrin
作者:A. Antony Muthu Prabhu、G. Venkatesh、N. Rajendiran
DOI:10.1007/s10953-010-9559-0
日期:2010.7
The absorption and fluorescence spectra of sulfamethoxazole (SMO), sulfisoxazole (SFO), sulfathiazole (STO) and sulfanilamide (SAM) in different solvents, pH and β-cyclodextrin (β-CD) have been analyzed. The inclusion complexes of the above sulfa drugs with β-CD were investigated by UV-visible spectroscopy, fluorometry, DFT, SEM, FT-IR and 1H NMR. The solvent study indicates that the position of the substituent (oxazole or thiazole group) in the SAM molecule (R–SO2–NH-group) is not the key factor to change the absorption and emission behavior of these sulpha drug molecules. In aqueous solution, a single fluorescence band (340 nm) was observed whereas in solutions of β-CD dual emission (430 nm) was noticed in sulpha drug compounds. Formation of the inclusion complex in SMO, SFO and STO should result dual emission which is due to a Twisted Intramolecular Charge Transfer band (TICT). The β-CD study indicates that (i) sulpha drugs form 1:1 inclusion complexes with β-CD and (ii) the red shift and the presence of TICT in the β-CD medium confirms heterocyclic ring encapsulated in the β-CD cavity with the aniline ring present on the out side of the β-CD cavity.
分析了磺胺甲噁唑(SMO)、磺胺异噁唑(SFO)、磺胺噻唑(STO)和磺胺(SAM)在不同溶剂、pH 值和β-环糊精(β-CD)中的吸收光谱和荧光光谱。通过紫外可见光谱、荧光测定法、DFT、扫描电镜、傅立叶变换红外光谱和 1H NMR 对上述磺胺类药物与 β-CD 的包合物进行了研究。溶剂研究表明,SAM 分子(R-SO2-NH-基团)中取代基(噁唑或噻唑基团)的位置并不是改变这些磺胺药物分子吸收和发射行为的关键因素。在水溶液中观察到的是单一荧光带(340 nm),而在β-CD溶液中观察到的是α-药物化合物的双发射(430 nm)。在 SMO、SFO 和 STO 中形成的包合物应导致双发射,这是由于分子内电荷转移扭曲带(TICT)造成的。β-CD 研究表明:(i) α-药物与 β-CD 形成 1:1 的包合复合物;(ii) β-CD 介质中的红移和 TICT 的存在证实了杂环封装在 β-CD 空腔中,苯胺环存在于 β-CD 空腔的外侧。