J Porous Mater (2006) 13: 157–161 DOI 10.1007/s10934-006-7025-6 Preparation and properties of trans-2-butene-1,4-bis (triphenylphosphonium)-saponite Yusuke Tanaka · Tomohiko Okada · Makoto Ogawa Received: June 29, 2005 / Revised: November 16, 2005 C  Springer Science + Business Media, LLC 2006 Abstract Intercalation of trans-2-butene-1,4-bis(triphenyl phosphonium) into synthetic saponite (Sumecton SA; cation exchange capacity of 71 meq (100 g clay) −1 ) was con- ducted by the cation exchange reaction in aqueous solu- tion. The sample was obtained as powder and thin supported film. Quantitative cation exchange was shown by the chem- ical composition of the product as well as the amount of the trans-2-butene-1,4-bis(triphenylphosphonium) remain- ing in the solution. The intercalation compound adsorbed styrene from aqueous solution and exhibited thermal sta- bility (decomposes at higher than 400 ◦ C) as shown by the TG-DTA curves recorded in air. Keywords Adsorption . Intercalation compound . Synthetic saponite . Trans-2-butene-1,4-bis (triphenylphosphonium) 1. Introduction Intercalation of organic molecular species into smectites has long been recognized as a way to prepare inorganic-organic hybrid materials with unique nanostructures controlled by the host-guest and guest-guest interactions. Besides the ba- sic scientific interests to the detailed structures of result- ing intercalation compounds and the mechanism of the re- action, [1] intercalation compounds have been investigated Y. Tanaka . M. Ogawa Graduate School of Science and Engineering, Waseda University, Nishiwaseda 1-6-1, Shinjuku-ku, Tokyo 169-8050, Japan. T. Okada () . M. Ogawa Department of Earth Sciences, Waseda University, Nishiwaseda 1-6-1, Shinjuku-ku, Tokyo 169-8050, Japan. e-mail: makoto@waseda.jp for such materials applications as adsorbents, sensors, and photo/electrofunctional materials [2, 3]. In order to optimize the performance of the functional hybrids as well as to gen- erate novel functions, the selection of guest species is one of the most importance issues [4–7]. There are so many reports on the intercalation of organoammonium ions into smectites for such purposes as determining the cation exchange capacity [4] and mod- ifying the surface properties [3, 5, 8, 9]. However, pa- pers on organophosphonium-clays are limited. Boyd et al. reported the adsorption of series of aromatic compounds and hydrocarbons onto tetramethylammonium(TMA)-and tetramethylphosphonium(TMP)-montmorillonites from va- por and aqueous solutions [10, 11]. TMP-montmorillonite is reported to be superior adsorbents to TMA-montmorillonite for aromatics from water as a result of lower hy- dration of TMP ions. The superior thermal stability of organophosphonium-smectites to organoammonium- smetcites was also reported [12]. In the study on clay- polymer nanocomposites, the improvement of the thermal stability has been a topic of interests [13]. These reports mo- tivated us to study the intercalation of other organophospho- nium ions into smectites. In this paper, we report the prepa- ration of a new intercalation compound, trans-2-butene-1,4- bis(triphenylphosphonium)(abbreviated as t -BPP)-saponite, and its some properties. The molecular structure of t -BPP is shown in Scheme 1. 2. Experimental Materials Synthetic Na + -saponite (Sumecton SA, obtained from Ku- nimine Ind. Co., synthesized by a hydrothermal reaction, cation exchange capacity (CEC) = 71 meq (100 g of host) −1 Springer