Bujdák Juraj, Iyi Nobuo, Hrobáriková Jana, Fujita Taketoshi
Institute of Inorganic Chemistry, Slovak Academy of Sciences, Bratislava, SK-84236, Slovak Republic.
J Colloid Interface Sci. 2002 Mar 15;247(2):494-503. doi: 10.1006/jcis.2001.8140.
The optical properties of reaction systems composed from a pseudoisocyanine (PIC) solution and dispersed layered silicates were studied using visible spectroscopy. Two series of reduced-charge montmorillonites were used as the silicate materials. Each series consisted of eight samples with different layer charges, which were prepared from one parent material. Observed trends were verified with another series of dioctahedral and trioctahedral smectites of different layer charges, structure, and origin. The layer charge density of the silicates significantly affected the aggregation of PIC cations. In addition to the formation of J-aggregates, dye spectral bleaching was also observed. Silicates with very low charge densities induced neither significant aggregation nor spectral bleaching of the dye. The highest levels of PIC J-aggregate formation were found in dispersions of the layered silicates with a medium surface charge. However, reversible spectral bleaching was also observed in some cases. PIC dye cations probably change their conformations during the adsorption process, due to the tension resulting from the large size of the cations and the relatively high charge density at the silicate surface. The bleached dye recovers, at least partially, with the rearrangement and redistribution of the dye cations over the time. In contrast, the presence of silicates with very high charge densities (synthetic taeniolite and fluorohectorite) led to the very fast and irreversible decomposition of the PIC. Perhaps, the tension in adsorbed dye cations, induced by the high charge density at the silicate surface, resulted in significant destabilization and a decomposition reaction of the chromophore.
利用可见光谱研究了由假异氰蓝（PIC）溶液和分散的层状硅酸盐组成的反应体系的光学性质。使用了两个系列的低电荷蒙脱石作为硅酸盐材料。每个系列由八个具有不同层电荷的样品组成，这些样品由一种母体材料制备而成。用另一系列不同层电荷、结构和来源的二八面体和三八面体蒙脱石验证了观察到的趋势。硅酸盐的层电荷密度显著影响PIC阳离子的聚集。除了形成J-聚集体外，还观察到染料光谱漂白现象。电荷密度极低的硅酸盐既不会引起染料的显著聚集，也不会导致光谱漂白。在具有中等表面电荷的层状硅酸盐分散体中发现了最高水平的PIC J-聚集体形成。然而，在某些情况下也观察到了可逆的光谱漂白现象。由于阳离子尺寸较大以及硅酸盐表面相对较高的电荷密度所产生的张力，PIC染料阳离子在吸附过程中可能会改变其构象。随着时间的推移，漂白的染料会随着染料阳离子的重新排列和重新分布至少部分恢复。相比之下，具有非常高电荷密度的硅酸盐（合成锂蒙脱石和氟锂蒙脱石）的存在导致PIC非常快速且不可逆的分解。也许，硅酸盐表面的高电荷密度引起的吸附染料阳离子中的张力导致了显著的不稳定和发色团的分解反应。
