Study of the photochemical properties of some aromatic compounds on molecular sieves using a picosecond pulse laser system

Abstract

Proton transfer reaction from the excited state of 1-naphthylamine (RNH 2) has been investigated in aqueous solutions of different acidity. Fluorescence from a new species was recorded. The quenching constants of RNH 2*, RNH3+* and the new species and some rate constants are evaluated by means of steady-state fluorescence and picosecond fluorescence decay measurements. The structure of the new emitting species is proposed to be an adduct formed from RNH3+ and an unhydrated ClO4− anion. A theoretical model for the hydration of protons is presented. The formation of the new species is found to be in linear relationship to the presence of unhydrated acid molecules. The results of this study is used to characterize the acidity in zeolite Y and MCM-41 catalysts. Kinetic models For the proton transfer reaction occurring at the catalyst surfaces is proposed and both the fluorescence and deactivation rate constants are determined. Furthermore, the polarity of the surfaces of these catalysts is probed using 2-anilinonaphthalene (2-AN) and rhodamine b lactone (RBL).* (Abstract shortened by UMI.) *Originally published in MAI, Vol 40, No. 2. Reprinted here with corrected school.