Intercalation characteristics of rhodamine 6G in fluor-taeniolite: Orientation in the gallery

The orientation of rhodamine 6G (R6G) in the 22-Angstrom 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 Angstrom. 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.