Chemical Control of Photoinduced Charges under Confinement in Zeolites

Abstract

The organized internal porous void of dehydrated zeolites provides a suitable environment to promote long-lived photoinduced charge separation. Herein we have conducted time-resolved UV–visible absorption spectroscopy experiments from nanosecond to day time scale following nanosecond UV (266 nm) pulsed laser irradiation of trans-stilbene (t-St) occluded in channels of nonacidic M–FER, M–MFI, and M–MOR zeolites with various pore diameters, with differing framework aluminum content, and with different extraframework cations (M = Na+, K+, Rb+, and Cs+). The cation radical of trans-stilbene (t-St•+) and trapped electron (AlO4•–) have been generated directly by means of laser-induced electron transfer within the channels of medium pore zeolites. We have highlighted that the general back electron transfer processes include direct charge recombination (CR), hole transfer (HT), and finally electron–hole recombination to re-form the occluded t-St ground state without any isomerization or oligomerization. It was de...