MODIFICATION OF FLUORESCENCE OF P-N,N-DIMETHYLAMINOBENZONITRILE BY ADSORPTION IN MOLECULAR-SIEVES

The fluorescence of p-N,N-dimethylaminobenzonitrile (DMABN) in molecul ar sieve pores of ZSM-5 shows two maxima. However, these maxima are lo cated at shorter wavelengths compared with DMABN in solutions. In addi tion, the polarizations of both bands are different compared with the fluorescence polarizations in solutions. In molecular sieve pores, the high energy emission is positively, the low energy emission is only w eakly polarized. Therefore, the mechanism explaining the two maxima of the fluorescence cannot be the usual twisted intramolecular charge tr ansfer as in solutions. The proposed explanation assumes that the sorb ed DMABN molecules are not able to be twisted in the narrow molecular sieve channels.