Article ID Journal Published Year Pages File Type
1694348 Applied Clay Science 2015 11 Pages PDF
Abstract

•Dye molecules in supramolecular complexes were investigated at montmorillonite surfaces.•Equilibrium constants for supramolecular complex formation were determined.•Both ionic and non-ionic dyes were incorporated in 2D hybrid films.•Orientation of dye molecules in 2D films was determined using UV-Vis spectroscopy.•Non-ionic dye retained its fluorescence properties in 2D montmorillonite film.

Montmorillonite 2D-optically active layers were investigated using non-ionic Coumarine and cationic Pyronine dyes. The modification of thin montmorillonite films (MF) was done by single dye species and/or with β-cyclodextrine (CD) supramolecular complexes (SC). Equilibrium constants for SC formation were determined in the range 0.1·103 − 6.0·103 for temperatures 283–323 K. Thus amounts of dye incorporated in the SC with CD prepared at temperature 293 K is more than 96% for Coumarine and more than 81% for Pyronine dye. Adsorption of SC in MF was proved by detection of increased first basal reflections using X-ray diffraction. The molecular transition moments for monomeric dye species in 2D MF of SC for Pyronine absorbing at 560 nm were inclined 60° and co-adsorbed dimers or higher aggregates of molecules tilted around 33° towards montmorillonite surface. Coumarine absorption in the whole investigated spectral range indicated average molecule inclination around 28°. The angle of the Coumarine dye is favourable for the formation of J-aggregates with sufficient fluorescence intensity detected at 478 nm for solid state applications.

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