A STUDY ON THE PHOTOPHYSICAL PROPERTIES OF ANTHRACENE IN ZEOLITE

Abstract

The photophysical behaviours of anthracene in zeolite Y were investigated using various steady state spectroscopic methods and a picosecond time-resolved fluorescence spectroscopic technique. A Xe-129 nuclear magnetic resonance (NMR) study shows that anthracene molecules can be optimally intercalated into the supercages of Na+- and Cu2+-exchanged zeolite Y at 570 and 520 K respectively. Anthracene introduced into the supercage of Na+- exchanged zeolite Y shows excimeric fluorescence with a lifetime of several nanoseconds, as well as monomeric fluorescence with a lifetime of 300 ps. The excimer forms immediately on absorption of a photon. Cu2+-exchanged zeolite Y with anthracene intercalation shows electron spin resonance (ESR) signals and absorption bands attributable to the stable, ground state anthracene cation radical, the Cu+ ion and the trapped electron in the copper ion cluster, indicating charge transfer from anthracene to the Cu2+ ion or copper ion cluster. The excitation energy of anthracene is quenched rapidly by the presence of copper ion.