title: Sequential energy and electron transfer in a three-component system aligned on a clay nanosheet.
abstract: To achieve the goal of energy transfer and subsequent electron transfer across three molecules, a phenomenon often utilized in artificial light harvesting systems, we have assembled a light absorber (that also serves as an energy donor), an energy acceptor (that also serves as an electron donor) and an electron acceptor on the surface of an anionic clay nanosheet. Since neutral organic molecules have no tendency to adsorb onto the anionic surface of clay, a positively charged water-soluble organic capsule was used to hold neutral light absorbers on the above surface. A three-component assembly was prepared by the co-adsorption of a cationic bipyridinium derivative, cationic zinc porphyrin and cationic octaamine encapsulated 2-acetylanthracene on an exfoliated anionic clay surface in water. Energy and electron transfer phenomena were monitored by steady state fluorescence and picosecond time resolved fluorescence decay. The excitation of 2-acetylanthracene in the three-component system resulted in energy transfer from 2-acetylanthracene to zinc porphyrin with 71% efficiency. Very little loss due to electron transfer from 2-acetylanthracene in the cavitand to the bipyridinium derivative was noticed. Energy transfer was followed by electron transfer from the zinc porphyrin to the cationic bipyridinium derivative with 81% efficiency. Analyses of fluorescence decay profiles confirmed the occurrence of energy transfer and subsequent electron transfer. Merging the concepts of supramolecular chemistry and surface chemistry we realized sequential energy and electron transfer between three hydrophobic molecules in water. Exfoliated transparent saponite clay served as a matrix to align the three photoactive molecules at a close distance in aqueous solutions.
authors.affiliation: Department of Physics and Materials Science, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishi-kawatsu-cho, Matsue, Shimane 690-8504, Japan and Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, Tokyo 192-0397, Japan. takagi-shinsuke@tmu.ac.jp.
authors.forename: Takuya
authors.initials: T
authors.lastname: Fujimura
authors.affiliation: Department of Chemistry, University of Miami, Coral Gables, Florida 33146-0431, USA. murthy1@miami.edu.
authors.forename: Elamparuthi
authors.initials: E
authors.lastname: Ramasamy
authors.affiliation: Division of Material Science and Engineering, Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Ishida
authors.affiliation: Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, Tokyo 192-0397, Japan. takagi-shinsuke@tmu.ac.jp and Center for Artificial Photosynthesis, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Shimada
authors.affiliation: Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, Tokyo 192-0397, Japan. takagi-shinsuke@tmu.ac.jp and Center for Artificial Photosynthesis, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Takagi
authors.affiliation: Department of Chemistry, University of Miami, Coral Gables, Florida 33146-0431, USA. murthy1@miami.edu.
authors.forename: Vaidhyanathan
authors.initials: V
authors.lastname: Ramamurthy