화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.109, No.9, 3723-3726, 2005
Long-lived radical cation-electron pairs generated by anthracene sorption in non bronsted acidic zeolites
The sorption of anthracene (ANT) in non Bronsted acidic ZSM-5 zeolite through the mere exposure at room temperature of solid ANT and dehydrated zeolite crystals with Li-3.4(AlO2)n(SiO2)(96-n) chemical formulas per unit cell generates spontaneous ionization of ANT (IP 7.44 eV in the gas phase). In contrast, ANT was found to be sorbed as an intact molecule in M(3.4)ZSM-5 with M = Na+, K+, Rb+, and Cs+. The radical cation (ANT(.+)) of the long-lived ANT(.+)@Li(3.4)ZSM-5(.-) pair was characterized by conventional diffuse reflectance UV-visible and resonance Raman spectrometry. In contrast, the X-band continuous wave (CW) EPR signal was found to be typical of a weakly coupled spin correlated ion pair. The two-dimension hyperfine sublevel correlation (2D-HYSCORE) spectra provide a detailed description of the microenvironment of the trapped electron of the ANT(.+)@Li(n)ZSM-5(.-) pair. The trapped electron appears localized in close proximity of occluded ANT(.+), Li+, and the Si-O-Al nearest group of the zeolite framework.