Pyrene-functional star polymers as fluorescent probes for nitrophenolic compounds

Novel tetra-armed star-shaped styrenic copolymers with pyrene side groups [(S1-S3)-Pyr] were prepared and employed as fluorescence sensing probe for fast and sensitive determination of nitroaromatic compounds. (S1-S3)-Pyr depicted characteristic pyrene monomer emission signals as well as broad excimer bands in their fluorescence emission spectra due to close proximity of the pyrene groups on the polymer chains and the ratio of monomer to excimer emission intensities gradually decreased as the pyrene content of the star polymers were increased from S1-Pyr to S3-Pyr. The highest quenching efficiency in the presence of 25 equivalent nitroaromatics was observed for 2,4,6-trinitrophenol/picric acid (99.4%) followed by 2,4-dinitrophenol (84.2%), 4-nitrophenol (82.6%), 2,4,6-trinitrotoluene (44.0%), 2,4-dinitrotolunene (32.6%), and 4-nitrotoluene (28.8%). Superior quenching efficiencies of nitrophenolic compounds were ascribed to their strong binding affinity for (S1-S3)-Pyr due to the acidity of phenolic hydroxyl units. Besides, quenching ratios of S1-Pyr, S2-Pyr, and S3-Pyr were measured to be very close to each other. Thus, (S1-S3)-Pyr are considered to be highly selective and sensitive fluorescence probes for phenolic nitroaromatic compounds. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46310.