Bujdák Juraj, Iyi Nobuo
National Institute for Materials Science, Namiki 1-1, Tsukuba Ibaraki 305-0044, Japan.
J Phys Chem B. 2006 Feb 9;110(5):2180-6. doi: 10.1021/jp0553378.
The molecular aggregation of six rhodamine dyes (rhodamine 560, B, 3B, 19, 6G, 123) in layered silicate (saponite and fluorohectorite) dispersions was investigated by using visible (vis) spectroscopy. The dye molecular aggregation was influenced by the properties of both the silicates and the dyes themselves. The layer charge of the silicates enhanced the molecular aggregation of the hydrophilic, cationic dyes. The presence of a carboxyl acid group in the dye molecules inhibited adsorption of the dyes on the surface of fluorohectorite, a silicate with a high charge density. A lower or no adsorption could be observed by vis spectroscopy. Strong association of the dyes to the silicate surface led to remarkable changes in the dye spectra, mainly due to the molecular aggregation. Dye assemblies initially formed after mixing the dye solutions with silicate dispersions were unstable. Decomposition of the dye molecular assemblies, and the formation of new species or molecular aggregate rearrangements, were studied on the bases of time-difference spectra. The reaction pathways were specific, not only for the dyes, depending upon their molecular structure and properties, but also on the silicate substrates.
通过可见光谱研究了六种罗丹明染料（罗丹明560、B、3B、19、6G、123）在层状硅酸盐（皂石和氟代锂蒙脱石）分散体中的分子聚集情况。染料的分子聚集受到硅酸盐和染料本身性质的影响。硅酸盐的层电荷增强了亲水性阳离子染料的分子聚集。染料分子中羧酸基团的存在抑制了染料在高电荷密度硅酸盐氟代锂蒙脱石表面的吸附。通过可见光谱可以观察到较低的吸附或无吸附现象。染料与硅酸盐表面的强烈缔合导致染料光谱发生显著变化，这主要是由于分子聚集所致。将染料溶液与硅酸盐分散体混合后最初形成的染料聚集体是不稳定的。基于时间差光谱研究了染料分子聚集体的分解以及新物种的形成或分子聚集体的重排。反应途径不仅对于染料具有特异性，这取决于它们的分子结构和性质，而且还取决于硅酸盐底物。
