Synthesis and fluorescence behavior of 3-methacryamide-9-carbazole and its polymer

Abstract

A novel acrylic monomer-bearing carbazole chromophore, 3-methacrylamide-9-ethyl-carbazole and its model compound 3-isobutyramide-9-ethylcarbazole were synthesized by reaction of 3-amino-9-ethyl carbazole and the corresponding acyl chloride in the presence of triethylamine. It can be polymerized easily by using azo-bisisobutyronitrile as an initiator or photopolymerized without any sensitizer. The photochemical behavior of 3-methacrylamide-9-ethyl-carbazole, its polymer and 3-isobutyramide-9-ethylcarbazole were investigated by recording the fluorescence spectra in N,N-dimethylformamide. It was found that the fluorescence intensity of the monomer is dramatically lower than those of its polymer and the model compound in the same chromophore concentration. This phenomenon, termed as the ‘structural self-quenching effect’, was commonly observed for acrylic monomers bearing chromophore moieties and ascribed to the coexistence of the electron-donating chromophore and the electron-accepting double bond within one molecule. The strong fluorescence of the polymer can be quenched by adding electron-deficient monomers having no chromophore moieties such as methyl methacrylate and acrylonitrile, and the Stern–Volmer constants were determined. It is observed that the higher the electron deficiencies of the quenchers, the higher the Stern–Volmer constants, implying a stronger quenching effect.Copyright © 2000 John Wiley & Sons, Ltd.