Intercalation Characteristics of 1,1′-Diethyl-2,2′-Cyanine and Other Cationic Dyes in Synthetic Saponite: Orientation in the Interlayer

Masashi Iwasaki1, Masaki Kita1, Kengo Ito2, Atsuya Kohno1 and Koushi Fukunishi1
1 Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
2 Sony Corporation, Atsugi Tec. No. 2, Atsugi-shi, Kanagawa 243-0021, Japan
E-mail of corresponding author: fuku@ipc.kit.ac.jp

Abstract: The basal spacings of complexes of saponite with five cationic dyes, 1,1′-diethyl-2,2′-cyanine, crystal violet, methylene blue, 1,1′-diethyl-2,2′-carbocyanine, and 1,1′-diethyl-2,2′-dicarbocyanine, varied with degree of saturation of each dye. At low loading of dye to saponite, each cationic dye showed nearly the same absorption spectrum in the UV-visible region as that of its dilute aqueous solution, whereas the spectrum changed distinctly at high loading. With increasing degree of dye loading, the absorption band shifted to longer wavelength for 1,1′-diethyl-2,2′-cyanine (J band) and to shorter wavelength for the others (D, H bands). On the basis of the basal spacing of each respective dye-clay complex, the orientation of the intercalated dye molecules is proposed as follows: the major plane of the cationic dye lies horizontal to the 2:1 layer surface at low loading. With increasing loading, the dye molecules interact with adjacent dye molecules and orient vertically to the 2:1 layer at high loading near the cation-exchange capacity.

Key Words: Clay-Dye Complex • Crystal Violet • Cyanine Dyes • Methylene Blue • Orientation of Dye Molecules • Saponite • Visible Spectroscopy

Clays and Clay Minerals; June 2000 v. 48; no. 3; p. 392-399; DOI: 10.1346/CCMN.2000.0480310
© 2000, The Clay Minerals Society
Clay Minerals Society (www.clays.org)