Intercalation Characteristics of Rhodamine 6G in Fluor-Taeniolite: Orientation in the Gallery

Abstract

Abstract--The orientation of rhodamine 6G (R6G) in the 22-,~ basal-spaced complex with Li-fluortaeniolite has been studied using X-ray powder diffraction, 1-dimensional Fourier analysis, polarized infrared (IR) spectroscopy, carbon analysis and thermal analysis. The R6G was adsorbed by cation exchange in aqueous solution. In the range of 0.086 to 0.46 molar ratio of R6G to taeniolite, the basal spacings of the complex were nearly constant at 21.7 to 22.2 ,~. From X-ray diffraction (XRD) data, it was confirmed that R6G in the complex orients with its longest xanthene ring axis perpendicular to the ab plane of the host. The pleochroism of IR absorption bands at 1331, 1517, 1537 and 1621 cm -1 supports the vertical orientation. The wide stability range of the vertical configuration is consistent with the strong coulombic force between the highly negatively charged silicate layer of the host [cation exchange capacity (CEC) = 157 _+ 9 meq/100 g] and the positively charged nitrogen bonded to both sides of the R6G xanthene ring.

Molecular orientation of methylene blue cations adsorbed on clay surfaces

“…In fact, this type of orientation has been determined directly by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy for MB/mica films (Hähner et al, 1996). Recently, there have been a few works on successful analysis of the molecular orientation of other dyes, such as rhodamines and oxazines, by indirect methods (Fujita et al, 1997;Yamaoka et al, 2000;Sasai et al, 2000;Chen et al, 2002;Iyi et al, 2002). Most of them involved the use of polarized spectroscopy.…”

Molecular Orientation of Intercalants Stabilized in the Interlayer Space of Layered Ceramics: 1-D Electron Density Simulation

“…Organic/Inorganic 2-D Nanohybrids There have been several reports of 1-D electron density mapping for organic-inorganic 2-D nanohybrids, for example layered ceramic materials intercalated with organic molecules, in an effort to determine the orientation and arrangement of organic molecules stabilized in the interlayer space. [65][66][67][68] For example, Marangoni et al synthesized Zn 2 Al-LDH nanohybrids intercalated with a series of blue dye molecules such as Evans blue (EB), Chicago sky blue (CB) and Niagara blue (NB) via a coprecipitation method, where interlayer structures of dye molecules were proposed by 1-D electron density mapping. Due to the relatively large number of (00l) diffraction peaks (up to 7 (00l) peaks), they were able to suggest interlayer structures of those dye molecules projected on the c-axis via Fourier transform analysis.…”

“…As an another example of 1-D electron density mapping for an organic/inorganic 2-D nanohybrid, Fujita et al proposed an appropriate molecular orientation of rhodamine 6G (R6G) in the interlayer space of Li-fluortaeniolite, 66) a smectite-type clay, by calculating 1-D electron density along the z-direction from ten well-ordered (00l) XRD peaks as well as from the possible model structures. Based on the expansion of basal spacing and the molecular dimension of R6G, they proposed two possible orientation models of R6G in the interlayer for Fourier transformation; one is a vertical model with a perpendicular monolayer orientation where the longest axis of xanthene ring in R6G is perpendicular to the basal plane of clay, and the other is a parallel model where the longest axis of xanthene ring is parallel to the basal plane, that is, R6G molecules are oriented with a bilayer stacking arrangement.…”

Fluorescence Anisotropy to Study the Preferential Orientation of Fluorophores in Ordered Bi-Dimensional Systems: Rhodamine 6G/Laponite Layered Films

“…Indeed, pure R6G thermodegradates at around 330ºC, whereas the degradation of R6G in Lap films starts in the 390-420ºC temperature range [57,[105][106][107]. Consequently, the clay matrix protects dye molecules against thermal degradations, improving the operative lifetime in optoelectronic devices based on the photoresponse of R6G.…”