title: Spectroscopic characterization of supramolecular chiral porphyrin homoassociates at the air-water interface.
abstract: The water-soluble 4-sulfonatophenyl meso-substituted porphyrin (TPPS) dye exhibits a transformation to a chiral self-aggregate from the non-aggregated species (diprotonated H4TPPS(2-)) at low concentration (no more than 1 × 10(-5) M). Immobilization of supramolecular chiral porphyrin homoassociates was mediated by the electrostatic interaction between the anionic TPPS molecule and cationic surfactant monolayer at the air-water interface. With the immobilization, a reversible transformation from monomeric TPPS to J-aggregate (M↔J) could be changed into an irreversible (M→J), which is desirable for stabilization of aggregation structure for a long period. The novel finding was achieved using a fine-tuned specialized solid-state circular dichroism (CD) spectrophotometer and derived analytical procedure to obtain artifact-free CD signals. To our knowledge, this is the first report achieving the chiral control of a homoassociate induced by a chiral surfactant at the air-water interface, indicating that the handedness of the formed homoassociate could be determined.
authors.affiliation: Department of Chemical Engineering, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan.
authors.forename: Takunori
authors.initials: T
authors.lastname: Harada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Moriyama
authors.forename: Hiromi
authors.initials: H
authors.lastname: Takahashi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Umemura
authors.forename: Haruo
authors.initials: H
authors.lastname: Yokota
authors.forename: Ryo
authors.initials: R
authors.lastname: Kawakami
authors.forename: Kenji
authors.initials: K
authors.lastname: Mishima