Cage effect on stability and molecular dynamics of [(CH3)(3)N](center dot+) and [(CH3)(3)NCH2](center dot+) generated in gamma-irradiated zeolites

• An EPR study was carried out to elucidate the zeolite cage effect on the stability and molecular dynamics of [(CH3)(3)N](.+) and [(CH3)(3)NCH2](.+) radical cations generated in gamma -irradiated Al-offretite, SAPO-37 and SAPO-42, which contained (CH3)(4)N+ ions as organic template. The [(CH3)(3)N](.+) radical cation was stable at room temperature when it was generated in relatively small size cages such as the sodalite cages of SAPO-37 and the beta -cages of SAPO-42. On the other hand, the [(CH3)(3)NCH2](.+) radical cation was stable not only in the sodalite cages of SAPO-37, but also in relatively large cages such as gmelinite cages or the main channels of Al-offretite and the alpha -cages of SAPO-42. Strongly temperature dependent EPR spectra were observed for the [(CH3)(3)NCH2](.+) radical cation stabilized in Al-offretite and SAPO-42. They were successfully analyzed by a spectral simulation method assuming a three-site exchange for the methyl protons. The evaluated exchange rates were in the order SAPO-37 (sodalite cages) < Al-offretite (gmelinite cages or main channels) < SAPO-42 (alpha -cages) in the temperature range 110-300 K.

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