Laser flash photolysis study of anthracene/viologen charge transfer complex in non-polar, dealuminated zeolites

Abstract

A charge-transfer anthracene/viologen complex has been assembled within two purposely-prepared, non-polar Beta zeolite samples devoid of framework negative charge and positive cations. IR spectroscopy (absence of silanol groups), vapor adsorption (preferent n-hexane adsorption over water) and powder X ray diffraction (high crystallinity with minimum structural defects) indicate the “hydrophobic”, low-polarity characteristics of the Beta zeolite samples used. Laser flash photolysis upon 532 nm selective excitation of the charge-transfer band shows that the photogenerated radical ions live hundreds of μs. This is the same time scale as for conventional, polar faujasites with high Al content. We suggest that in our non-polar zeolite the compartmentalized space and the ability of zeolites to participate in electron transfer processes are the main factors contributing to the remarkable lifetime increase of radical ions.