W. Liu et al., Cage effect on stability and molecular dynamics of [(CH3)(3)N](center dot+) and [(CH3)(3)NCH2](center dot+) generated in gamma-irradiated zeolites, PHYS CHEM P, 3(17), 2001, pp. 3532-3535
An EPR study was carried out to elucidate the zeolite cage effect on the st
ability and molecular dynamics of [(CH3)(3)N](.+) and [(CH3)(3)NCH2](.+) ra
dical 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 r
elatively small size cages such as the sodalite cages of SAPO-37 and the be
ta -cages of SAPO-42. On the other hand, the [(CH3)(3)NCH2](.+) radical cat
ion was stable not only in the sodalite cages of SAPO-37, but also in relat
ively large cages such as gmelinite cages or the main channels of Al-offret
ite and the alpha -cages of SAPO-42. Strongly temperature dependent EPR spe
ctra were observed for the [(CH3)(3)NCH2](.+) radical cation stabilized in
Al-offretite and SAPO-42. They were successfully analyzed by a spectral sim
ulation method assuming a three-site exchange for the methyl protons. The e
valuated exchange rates were in the order SAPO-37 (sodalite cages) < Al-off
retite (gmelinite cages or main channels) < SAPO-42 (alpha -cages) in the t
emperature range 110-300 K.