Harada Takunori, Moriyama Hiroshi, Takahashi Hiromi, Umemura Kazuo, Yokota Haruo, Kawakami Ryo, Mishima Kenji
Department of Chemical Engineering, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan.
Appl Spectrosc. 2014;68(11):1235-40. doi: 10.1366/13-07432. Epub 2014 Oct 1.
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.
