FLUOROMETRIC STUDIES OF PYRENE ADSORPTION ON POROUS CRYSTALLINE CELLULOSE

Pyrene crystals were physically mixed with either porous crystalline c ellulose (PCC) or octa decyl siryl silica-80TM (ODS). Solid-state fluo rescence spectra of pyrene were analyzed to estimate the interaction b etween pyrene and porous materials. Pyrene monomer emission was observ ed at 398 Mn immediately after being mixed with PCC, while pyrene crys tals showed only excimer emission at 475 nm, indicating that the pyren e molecules adsorbed onto the PCC surface in a short period. For the P CC system containing 1.0% pyrene, long-term storage caused an increase in the intensity of excimer-like emission peak at 477 nm accompanied by a decrease in the intensity of monomer emission peak at 398 nm. For the ODS system containing 1.0% pyrene, spectrometric changes were sim ilar to those for the PCC system. In the process of interaction format ion between pyrene and an additive, a two-step mechanism was proposed, i.e., the adsorption of pyrene molecules onto the surface of porous a dditives, and the formation of a ground state dimer of pyrene. The for mation of dimeric pyrene could be associated with the surface polarity of additives. (C) 1998 Academic Press