Aggregated Structures of Rhodamine 6G Intercalated in a Fluor-Taeniolite Thin Film

Abstract

To clarify the structure and species of rhodamine 6G (R6G) aggregates formed in taeniolite (TN) interlayer spaces, the oriented thin films of R6G-TN hybrid materials were prepared and analyzed. XRD investigations of these films indicated that the R6G molecules were intercalated in the TN interlayers and that the TN layers were parallel to the glass plate in the thin films. Most of the intercalated R6G molecules were assumed to form various kinds of H-type aggregates in the TN interlayer spaces, since the R6G-TN hybrid films exhibited no emission spectrum by excitation at λ ) 530 nm. The peak-deconvolution results of the UV/vis absorption spectra of the hybrid films indicated that there was one kind of H-type R6G dimer in the thin film. Moreover, polarized UV/vis spectroscopy revealed the existence of high-order aggregates in addition to these dimers. The high-order aggregates, but not the dimers, were found to be aligned perpendicularly to the TN surface in the TN interlayer spaces.

Surface-enhanced Raman scattering (SERS)-active substrates from silver plated-porous silicon for detection of crystal violet

“…The sample that has been stored in air for three weeks still exhibits high and comparable sensitivity to the fresh substrate. For clarity, the spectra are offset along the y-axis.required for an adsorbed CV molecule is taken to be approximately 0.4 nm 2 in case of perpendicular orientation[26] with a long-axis length of about 1.4 nm[27]. The N bulk , under the area of laser spot (∼10 m in diameter and 2 m in penetration depth) can be accordingly calculated to be 2.8 × 10 11 molecules; {N bulk = × 25 × 2 m 3 /(0.4 × 1.4 nm 3 )}.…”

Fluorescence tuning of 2D montmorillonite optically active layers with beta-cyclodextrine/dye supramolecular complexes

“…These spectra showed that the gradient of changes as induced by the polarized light was much higher for polarisation in the x direction than in the y direction. This anisotropy is caused by the orientation of the dye transition moment with respect to the plane surface of montmorillonite upon its adsorption (Sasai et al, 2002). It should be pointed out that when C522 was used for the film modification in the MF-C522 10 −6 sample, no absorbance band for this dye could be detected in the prepared MF sample (Fig.…”

“…2). The technical details were published by Sasai et al (2002). Briefly, the orientation of the slide during measurements was changed around the x-axis at angles α with respect to the y-axis only, with tilt angles α = 0, 40, 50, 60 and 70°.…”

“…Table 1 Values of equilibrium constants K between αCD, βCD and γCD with C522 or PY dyes at 293 K. For xanthene and Coumarine dyes used in the present study, the transition dipole moment is supposed to be parallel to the long molecular axis of heteroaromatic rings ( Fig. 1) (Sasai et al, 2002;Valeur and Berberan-Santos, 2012). The angle between the long molecular axis and the clay surface is therefore expressed as:…”

“…The relative distribution of H-and J-aggregates and monomers can be controlled by the variation of the layer charge of host material (Bujdák et al, 1998;Takagi et al, 2013). Bujdák et al (2003b) and Sasai et al (2002) reported that formation of different dye aggregates on a silicate plane was also directly related to basal spacing. Hence, on the basis of equilibrium between dye molecules in solution and those adsorbed on the surface of the clay mineral, it can be supposed that the relative species distribution can be also controlled by the concentration of dye in solution used for film preparation.…”