Phosphorescence and photochemical properties of benzophenone included within alkali metal cation-exchanged ZSM-5 zeolites

The phosphorescence properties of benzophenone included within alkali metal cationexchanged ZSM-5 zeolites were investigated to clarify the effects of the micro-environment of hostadsorbents on the electronic excited states of guest-molecules included within the restricted void spaces. Benzophenone included within such cation-exchanged ZSM-5 zeolites was found to exist in both a protonated and hydrogen-bonded form. It was found that exchanging the cations dramatically affects the ratio of their contents. Photolysis of these systems revealed that both benzhydrol and benzpinacol were the main products, their yields strongly depending on the kind of the cations exchanged. Especially, the protonated species was found to play a significant role in the photoreactions observed with benzophenone included within zeolite cavities.