Mechanism of rhodamine 6G molecular aggregation in montmorillonite colloid
Mechanism of rhodamine 6G molecular aggregation in montmorillonite colloid
复制标题
蒙脱石胶体中罗丹明6G分子聚集机制
DOI：
--
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
J. Bujdák
中科院分区：
文献类型：
--
作者：
Marcel Lofaj;I. Valent;J. Bujdák
摘要采用阻流混合装置和可见吸收光谱分析了染料罗丹明6G(R6G)在钠饱和蒙脱石胶体中的分子聚集。确定了反应的两个阶段：第一阶段很短，只需几秒钟，涉及R6G阳离子的吸附和它们在胶体颗粒表面的初始聚集。最初形成的J-聚集体表现出与R6G单体形式相似的光谱性质。在第二阶段，最初形成的聚集体转变为夹心型H-聚集体，吸收波长明显较低的光和吸附的单体。总的重新安排花了几个小时。通过主成分分析(PCA)和多元曲线分辨(MCR)，确定了光谱性质与R6G溶液相同的单体也是复杂光谱中的一个成分。染料的部分漂白也得到了证实。聚集体重排反应动力学遵循考虑分子聚集复杂机理的模型。用拉伸指数函数进行数据拟合，得到了反应速率常数，其范围为10−3−4×10−3s−1。
AbstractStopped-flow mixing device and visible absorption spectroscopy were used for the analysis of dye rhodamine 6G (R6G) molecular aggregation in the colloids based on Na-saturated montmorillonite. Two stages of the reaction were identified: The first stage was very short and taking only several seconds, involving the adsorption of R6G cations and their initial aggregation on the surface of colloid particles. The initially formed J-aggregates exhibited similar spectral properties as monomeric form of R6G. In the second stage, initially formed aggregates converted to sandwich-type H-aggregates absorbing light at significantly lower wavelengths and adsorbed monomers. The aggregate rearrangement took several hours. Monomers, with the spectral properties identical to R6G solution, were also identified as a component in complex spectra using principal component analysis (PCA) and multivariate curve resolution (MCR). Partial bleaching of the dye was also proven. Reaction kinetics of the rearrangement of the aggregates followed the model considering a complex mechanism of the molecular aggregation. Data fits using stretched-exponential function led to the determination of rate constants, which had been in the range 10−3−4×10−3s−1.