Formation of the Long-Lived Charge-Separated State of the 9-Mesityl-10-methylacridinium Cation Incorporated into Mesoporous Aluminosilicate at High Temperatures

The 9-mesityl-10-methylacidinium cation (Acr(+)-Mes) was incorporated into Na+-exchanged mesoporous aluminosilicate (AlMCM-41) by cation exchange. Incorporation of Acr(+)-Mes into AlMCM-41 has made the lifetime of the electron-transfer (ET) state (Acr(center dot)-Mes(center dot+)) produced upon photoexcitation of Acr(+)-Mes extremely long (e.g., 10 s) even at high temperatures (e.g., 373 K). The formation and decay of the ET state can be repeated by on off photoirradiation cycles. Both intra- and intermolecular back electron-transfer processes of the ET state of Acr(+)-Mes were observed by electron spin resonance (ESR) and time-resolved nanosecond diffuse reflectance absorption spectra, respectively. The ET state has both strong oxidizing and reducing abilities to be able to oxidize neighboring 1-pyrenemethylammonium and reduce the hexyl viologen dication incorporated into AlMCM-41 by cation exchange, respectively.