THE PHOTOREDUCTION OF METHYLVIOLOGEN VIA ELECTRON TRANSFER FROM ALUMINOSILICATE ZEOLITES

摘要

The photoreduction yields of methylviologen and various alkylated homologues in zeolite-X, Y and A were determined at 77 K. in the absence of any reducing counteranion. Upon irradiation at 77 K, dehydrated samples turned light blue and a single line ESR spectrum was observed with a g-factor identical to that of the methylviologen radical cation. Samples that were not dehydrated produced ESR spectra about 10% as intense as those that had the water removed. The photoreduction yield was largest in zeolite Y, less in zeolite X which has more cations and hence more crowding in the cages, and very small in zeolite A which has much smaller cages. The electron donor in these systems is believed to be the anionic aluminosilicate framework of the host zeolite.