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Unlocking Light-Up Effect of Push-Pull Hemicyanine Dyes in Hybrid Silicate Dispersions: Impact of the Terminal
Viktória Planetová1, Peter Boháč1,2, Juraj Bujdák1,3
1Department of Hydrosilicates, Institute of Inorganic Chemistry, Slovak Academy of Sciences, Bratislava SK-845 36, Slovak Republic.
Abstract:
Emission enhancement of cationic dipolar hemicyanines was observed upon their adsorption onto the layered silicate saponite. The extent of the light-up effect depends on the type of the terminal arylamine group and the concentration on the silicate surface. Dye-structure modification included gradual rigidification of the triarylamine moiety in the molecules, progressing from the nonplanar, propeller-shaped triphenylamine via the semirigidified carbazole to the fully rigidified azatriangulene. In addition, we explored the photoluminescence properties of corresponding cyanine dyes with planar, sterically less demanding N,N-dialkylaminoaryl groups, which, unlike derivatives with the triarylamine moiety, preferentially formed dye aggregates even at low concentrations. The resulting spectral properties were attributed to a combination of surface fixation-induced emission, concentration quenching, aggregation-caused quenching, and aggregation-induced emission. These phenomena existed in dynamic equilibrium, and their impact was influenced by the structure of the terminal arylamine group.
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