THE RELATION BETWEEN THE STRUCTURE OF NITROBENZENE DERIVATIVES AND FLUORESCENCE QUENCHING EFFICIENCY TO THE POLY(2,5-DIPENTYLOXY-<I>para</I>-PHENYLENE ETHYNYLENE)

The poly(2,5-dipentyloxy-para-phenylene ethynylene) (P) was synthesized by Pd-catalyzed Sonogashira coupling reaction. Due to causing energy transfer between the nitrobenzene's quenchers and the polymer chains through the charge-transfer interaction, the fluorescence quenched properties of P varied obviously with the parasubstituting group's structure in the nitrobenzene derivatives. The fluorescence quenching efficiency of quenchers improved with increasing of electron repulsion capability of the para-substituting group. The fluorescence quenching efficiency increased nonlinearly with the concentration of the quenchers and had, however, no relation with the quenching time.