Luminescence of Reichardt's dye in polyelectrolyte-modified saponite colloids

Adsorption of Dye Molecules and Its Potential for the Development of Photoactive Hybrid Materials Based on Layered Silicates

“…This means that while the anionic phenolate group interacts with a cationic group of the adsorbed PDDA, at the same time the pyridinium moiety of the adsorbed dye molecule is attached directly onto a negatively charged surface site of the silicate as shown in Figure . Such an interaction mode dramatically hinders the rotational relaxation and the charge reorganization in the excited states of the adsorbed RD molecule leading to largely enhanced radiative relaxation as well as to photoluminescent colloidal dispersions of saponite particles . In line with these results, another cationic polyelectrolyte, chitosan was also found to improve the adsorption and photophysical properties of various dyes conjugated with montmorillonite …”

“…Our recent studies ,, together with the relevant papers of Takagi and his co-workers have clearly revealed that a similar restriction of excited state conformation together with the RIM mechanism can be possible for adsorbed dye monomers. It is due to the specific environmental effect of the surface confinement of an individual dye molecule on the colloidal particles, which results in enhanced luminescence.…”

“…Very common and effective methods include the functionalization with adsorbed cationic surfactants or polyelectrolytes. In this way, it is possible to achieve the adsorption of even anionic or neutral chromophores. − Using the modification of silicates with oppositely charged polyelectrolyte or surfactant molecules, it is possible to tune the surface charge of silicates . In addition to the regulation of their charge, hydrophilic vs hydrophobic properties of the silicate surfaces can also be controlled by the adsorption of surfactants. , …”

“…Examples for adsorption-induced emission (AdIE). Adsorption of (A) thiacyanine dye monomers on the surface of synthetic saponite Sumecton SA (Reproduced from ref with permission from Elsevier) and (B) conventional Reichardt’s dye on the surface of polycation-modified layered silicate colloidal particles (Reproduced from ref with permission from Elsevier).…”

“…This well-known solvatochromic dye has been considered as a nonluminescent zwitterionic substance with negatively charged phenolate and positively charged pyridinium groups in its aqueous solution. As it was already mentioned earlier, in order to have systems applicable for neutral dyes, it is necessary to modify the surface of the silicate particles through the adsorption of polyelectrolytes , or surfactants . These types of surface functionalization of the silicate substrate can help to achieve such desired properties as the controlled charge density and topography of the surface.…”