Materials Science Division, North-East Institute of Science and Technology, CSIR, Jorhat 785006, Assam, India.
J Phys Chem B. 2011 Jul 28;115(29):9040-9. doi: 10.1021/jp201402h. Epub 2011 Jul 6.
In this paper, we explore the effects of the chain length of simple monohydroxy alcohol (C(n)OH, 2 ≤ n ≤ 8) and benzyl alcohol (C(6)H(5)CH(2)OH) upon the fluorescence dynamics of a dipolar solute probe, coumarin 153 (C153), in vesicles formed in aqueous solutions of two oppositely charged (cationic and anionic) surfactants in the presence of 0.05 mol kg(-1) alcohol. The catanionic vesicles are composed of 70 mol % sodium dodecyl sulfate (SDS) and 30 mol % cetyltrimethylammonium bromide (CTAB). The presence of alcohols of different chain length improves the stability of the catanionic vesicles. Dynamic light scattering (DLS) experiments suggest a gentle increase in the hydrodynamic diameter of the catanionic vesicle with alcohol chain length up to n=4 and then an abrupt increase for the rest of the alcohols considered. The polarity and dynamics of the catanionic vesicles, probed by the steady-state and time-resolved fluorescence spectroscopy, indicate a signature of confined water. Quantities measured from fluorescence experiments of these vesicles also show a mild variation for alcohols of chain length n ≤ 4, followed by a sudden variation for alcohols with n > 4. Interestingly, pentanol and benzyl alcohol in catanionic vesicles showed roughly similar effects due to their equivalent chain length. All of these data are remarkably correlated with the recently observed depression of the solubility temperature of catanionics with alcohol chain length (Langmuir2009, 25, 12516-12521).
在本文中，我们研究了简单一元醇（C(n)OH，2 ≤ n ≤ 8）和苄醇（C(6)H(5)CH(2)OH）的链长对偶极体探针香豆素 153（C153）在阳离子和阴离子两种相反电荷的表面活性剂在水溶液中形成的囊泡中的荧光动力学的影响。存在 0.05 mol kg(-1)的醇时，反离子囊泡由 70 mol %的十二烷基硫酸钠（SDS）和 30 mol %的十六烷基三甲基溴化铵（CTAB）组成。不同链长的醇的存在提高了反离子囊泡的稳定性。动态光散射（DLS）实验表明，随着醇链长的增加，反离子囊泡的水动力直径逐渐增加，直到 n=4，然后其余醇的水动力直径突然增加。稳态和时间分辨荧光光谱研究表明，反离子囊泡的极性和动力学表明存在受限水。这些囊泡的荧光实验测量的量也表明，醇链长 n ≤ 4 时略有变化，然后 n > 4 时突然变化。有趣的是，由于它们的等效链长，戊醇和苄醇在反离子囊泡中表现出大致相似的影响。所有这些数据都与最近观察到的醇链长对反离子溶解度温度的降低（Langmuir2009，25，12516-12521）非常相关。
