title: Novel methodology to control the adsorption structure of cationic porphyrins on the clay surface using the "size-matching rule".
abstract: Saponite-type clays that have different cation exchange capacities were successfully synthesized by hydrothermal synthesis. The structure and properties were analyzed by X-ray diffraction, X-ray fluorescence, (27)Al NMR, FT-IR, thermogravimetric and differential thermal analysis, atomic force microscopy, and cation exchange capacity measurement. The intercharge distances on the synthetic saponite (SS) surfaces were calculated to be 0.8-1.9 nm on the basis of a hexagonal array. The complex formation behavior between SS and cationic porphyrins was examined. It turns out that the average intermolecular distance between porphyrin molecules on the SS surface can be controlled, depending on the charge density of the SS. In the case of tetrakis(1-methylpyridinium-4-yl)porphyrin (H(2)TMPyP(4+)), the average intermolecular distances on the SS surface can be controlled from 2.3 to 3.0 nm on the basis of a hexagonal array. It was also found that absorption maxima of porphyrins depend on the charge density of the SS. The adsorption behavior of porphyrin on the SS surface can be rationally understood by the previously reported "size-matching rule". This methodology using host-guest interaction can realize a unique adsorption structure control of the porphyrin molecule on the SS surface, where the gap distance between guest porphyrin molecules is rather large. These findings will be highly valuable to construct photochemical reaction systems such as energy transfer in the complexes.
authors.affiliation: Department of Applied Chemistry, Graduate Course of Urban Environmental Sciences, Tokyo Metropolitan University, Minami-ohsawa 1-1, Hachiohji, Tokyo 192-0397 Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Egawa
authors.forename: Hajime
authors.initials: H
authors.lastname: Watanabe
authors.forename: Takuya
authors.initials: T
authors.lastname: Fujimura
authors.forename: Yohei
authors.initials: Y
authors.lastname: Ishida
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yamato
authors.forename: Dai
authors.initials: D
authors.lastname: Masui
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Shimada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tachibana
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Yoshida
authors.forename: Haruo
authors.initials: H
authors.lastname: Inoue
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Takagi
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000138:chemical synthesis / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D000077215:Clay; D015394:Molecular Structure; D010316:Particle Size; D011166:Porphyrins / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; D002412:Cations; D011166:Porphyrins; C099453:saponite; D000077215:Clay