Kohno Yoshiumi, Totsuka Koichi, Ikoma Shuji, Yoda Keiko, Shibata Masashi, Matsushima Ryoka, Tomita Yasumasa, Maeda Yasuhisa, Kobayashi Kenkichiro
Department of Materials Science and Chemical Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8561, Japan.
J Colloid Interface Sci. 2009 Sep 1;337(1):117-21. doi: 10.1016/j.jcis.2009.04.065. Epub 2009 May 3.
The aim of this study is the improvement of the photostability of several natural anionic dyes, carmine (CM), carthamus yellow (CY), and annatto dye (ANA), by complexation with hydrotalcite. The composite of the dyes and hydrotalcite is prepared by the coprecipitation method. CM is successfully intercalated in the hydrotalcite layer when the amount of introduced CM is large. The photostability of CM in CM/HT composites is superior to the CM adsorbed on silica surface. The effect of the stability enhancement is larger when the amount of introduced CM exceeds 0.23 g/g-host, or when the layer charge density of the hydrotalcite is larger. CY is also stabilized by complexation with hydrotalcite, whereas ANA is not stabilized by complexation with hydrotalcite. The photostability of an anionic natural dye can be improved by intercalation into the hydrotalcite layer, if the dye has a hydrophilic nature and a rather planar structure. The intercalated dye is stabilized by the protection from the attack of the atmospheric oxygen. In addition, contribution of the electrostatic interaction between the positively charged hydrotalcite layer and the intercalated anionic dye is also proposed.
本研究的目的是通过与水滑石络合来提高几种天然阴离子染料（胭脂红（CM）、红花黄（CY）和胭脂树橙染料（ANA））的光稳定性。染料与水滑石的复合材料通过共沉淀法制备。当引入的CM量较大时，CM成功地插层到水滑石层中。CM/HT复合材料中CM的光稳定性优于吸附在二氧化硅表面的CM。当引入的CM量超过0.23 g/g主体，或水滑石的层电荷密度较大时，稳定性增强的效果更大。CY也通过与水滑石络合而得到稳定，而ANA则未通过与水滑石络合而得到稳定。如果阴离子天然染料具有亲水性和相当平面的结构，则通过插层到水滑石层中可以提高其光稳定性。插层染料通过免受大气氧的攻击而得到稳定。此外，还提出了带正电的水滑石层与插层阴离子染料之间静电相互作用的贡献。
