Tang Yao-Ji, Chen Ying, Yao Min-Na, Zou Zhe-Xiang, Han Guo-Bin, Li Yao-Qun
Department of Chemistry and The Key Laboratory of Analytical Sciences of the Ministry of Education, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China.
J Fluoresc. 2008 Mar;18(2):261-7. doi: 10.1007/s10895-007-0248-3. Epub 2007 Sep 25.
Total internal reflection fluorescence (TIRF) spectroscopy was used to investigate the adsorption behavior of meso-tetrakis(p-sulfonatophenyl)porphyrin (TPPS) at the glass/water interface in the presence of a cationic surfactant (cetyltrimethylammonium bromide, CTAB) far below the critical micelle concentration. The adsorption model of TPPS at the glass/water interface in the presence of low concentration of CTAB was proposed, which was different from the adsorption of TPPS in the presence of micelles of CTAB at the glass/water interface. TPPS and CTAB did not form stable complex at the interface in dilute system. The interfacial species of TPPS were analyzed by comparing the spectra of TPPS at the glass/water interface and in the aqueous phase. The influences of the TPPS concentration, the CTAB concentration, and the pH values on the interfacial fluorescence spectra and intensities were studied. It was demonstrated that electrostatic interaction and hydrophobicity performed an important role on the adsorption of TPPS in the presence of CTAB. The different effects of TPPS concentration on the adsorption behaviour of TPPS at different pH were observed for the first time. It was found that the adsorption isotherms of TPPS at glass/water interface could fit Freundlich equation at pH 7.1.
全内反射荧光（TIRF）光谱法被用于研究在远低于临界胶束浓度的阳离子表面活性剂（十六烷基三甲基溴化铵，CTAB）存在下，中位四（对磺基苯基）卟啉（TPPS）在玻璃/水界面的吸附行为。提出了低浓度CTAB存在下TPPS在玻璃/水界面的吸附模型，该模型不同于CTAB胶束存在时TPPS在玻璃/水界面的吸附。在稀体系中，TPPS和CTAB在界面处未形成稳定的络合物。通过比较TPPS在玻璃/水界面和水相中的光谱，分析了TPPS的界面物种。研究了TPPS浓度、CTAB浓度和pH值对界面荧光光谱和强度的影响。结果表明，静电相互作用和疏水性在CTAB存在下对TPPS的吸附起着重要作用。首次观察到TPPS浓度在不同pH下对TPPS吸附行为的不同影响。发现在pH 7.1时，TPPS在玻璃/水界面的吸附等温线符合Freundlich方程。
