Strategies for modulating the luminescence properties of pyronin Y dye–clay films: an experimental and theoretical study

Abstract

The aggregation process, particularly the type and extent of pyronin Y (PY) laser dye intercalated into supported thin films of two different trioctahedral clay minerals, LAPONITE® (Lap) and saponite (Sap), at different dye loadings is studied: (i) experimentally by means of electronic absorption and fluorescence spectroscopy and (ii) theoretically by modeling the distribution of the dye into the interlayer space of these layered silicates. According to the results, H-type aggregates of the PY dye are favoured in Lap even at very low dye loading while a much lower molecular aggregation tendency in J-type geometry is found in Sap films. The aggregation state of PY in each clay mineral is likely attributed to different strengths of the electrostatic interactions between the dye and the layered silicate in the interlayer space due to their distinctive charge localization on the TOT clay layer (i.e. net negative charge in octahedral layers for Lap vs. in tetrahedral layers for Sap), as well as the interlaminar water distribution in each clay mineral, although other factors such as their CEC and particle size cannot be discarded. To reduce the huge aggregation processes of PY dye into Lap films, surfactant molecules (DDTAB) are co-adsorbed in the interlayer space of the clay. At an optimized surfactant concentration, the aggregation tendency of PY dye in Lap is considerably reduced enormously improving the fluorescence efficiency of the PY/Lap films. Finally, by means of anisotropic response from the hybrid films to the plane of the polarized light, the orientation of the PY molecules with respect to the normal axis of the clay layer is determined for all films (with and without surfactant) at different dye loadings.

Supramolecular Organization in Confined Nanospaces

“…Indeed inclusion compounds of engineered clays are beginning to show actual potential as eco‐friendly functional materials . Such progress was also fostered by modeling studies – that suggested, for example, to contrast the worsening in the mechanical properties of a clay (caused by the incorporation of dyes) via the co‐adsorption of surfactants in the interlayer space of the clay . Taking inspiration from Blue Maya, the indigo molecule was recently encapsulated into zeolite L microcrystals yielding an exceptionally robust colorant: the insight from simulations was instrumental for the successful blockage of the crystal terminations.…”

“…[773][774][775][776][777][778] Such progress was also fostered by modeling studies -that suggested, for example, to contrast the worsening in the mechanical properties of a clay (caused by the incorporation of dyes) via the co-adsorption of surfactants in the interlayer space of the clay. [779][780][781] Taking inspiration from Blue Maya, the indigo molecule was recently encapsulated into zeolite L microcrystals yielding an exceptionally robust colorant: [782] the insight from simulations [191] was instrumental for the successful blockage of the crystal terminations. An atomistic knowledge of natural host matrices is also important for their use in environmental 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 protection (e. g., absorption of organic pollutants by layered hydroxides, [783,784] sequestration of trace uranium in multiphase iron minerals [785] ) and in the realization of new materials via sustainable fabrication approaches; for instance, using a vaporinduced approach, a direct synthesis of zeolites starting from clay minerals has been recently performed.…”

Modification, hybridization and applications of saponite: An overview

“…Saponite has a rigid structure and can provide a confined microenvironment to luminescent molecules on a nanoscale. Hence, in the interlayer space of Sap, J-aggregates with a more open geometry in which the luminescent dye molecules better contact with the surface of Sap become favorable (Epelde-Elezcano et al, 2016). A good dye distribution in the interlayer space of Sap can be achieved reducing molecular aggregation.…”

“…These interactions are conducive to suppressing dye molecule aggregation. They can also increase luminous intensity of the dye molecules and extend the fluorescence lifetime Epelde-Elezcano et al, 2016;Boháč et l., 2016;Bujdák et al, 2016). In addition, in a confined microenvironment of the interlayer space of Sap, the dye molecules have to occur in a parallel orientation with respect to the surface of the Sap nanoparticles (Tominaga et al, 2017) (Fig.…”

Spectroscopic Studies of Synthetic and Natural Saponites: A Review

“…Among the clay minerals of interest is saponite, which has applications as: adsorbent for the removal of heavy metal ions [1,2] and carcinogenic compounds [3]; control agent of the aggregation of luminescent dyes [4,5]; matrix for controlled release of drugs [6]; catalysts for industrially important reactions [7][8][9] and for prebiotic chemistry [10,11] ; immobilization support for various catalysts [12][13][14][15] and many more. These applications would be dependent on properties such as size, cation-exchange capacity, plasticity, catalytic activity, swelling behavior, permeability, and substitutions in the saponite structure.…”