Experimental study and ab initio molecular orbital calculation on the photolysis of n-butyrophenone included within the alkali metal cation-exchanged ZSM-5 zeolite

Effects of ion-exchanged alkali metal cations on the adsorption and the photolysis (Norrish type I and type II reactions) of n-butyrophenone included within the alkali metal cation-exchanged ZSM-5 zeolite have been investigated by experimental and theoretical approaches. The yields of the photolysis decreased and the ratio of the type I/type II reactions increased, respectively, by changing the ion-exchanged cations from Cs+ to Li+. The observed IR spectra of the adsorbed n-butyrophenone and the ab initio molecular orbital calculations of this host–guest system indicate that the n-butyrophenone mainly interacts with alkali metal cation, while the electrostatic interaction between the n-butyrophenone and cation increases by changing the cations from Cs+ to Li+. These results indicate that the smaller cation has the stronger electrostatic interaction between n-butyrophenone and promotes the Norrish type I reaction in the photolysis of n-butyrophenone.