Novel optically active copolyacrylates synthesized by conventional radical polymerization of R/S-(+/−)-α-ethylbenzylacrylamide (R/S-EBzA) or R/S-(+/−)N-methacryloyloxyehtyl-N′-α-ethylbenzyl(urea) (R/S-MEBzU) and the vinyl acetate (VAc) in the presence of 1,1′-azobis (cyclohexanecarbonitrile) as the initiator showed optical rotation values ([α] D 23 ) of +45°/−50°for R/S-EBzA-co-VAc and of −40°in the case of S-MEBzU-co-VAc. Next, the hydrolysis reaction of the synthesized copolymers was accompanied of their chemical modification with dansyl chloride in order to obtain novel photopolymers. The structure, some physical and chemical properties of these polymers were investigated through spectral and thermal analysis ( 1 H-NMR, FTIR, UV/vis and fluorescence, and DSC), gel permeation chromatography, and optical measurements. The sensing capacity of the above photopolymers was examined by fluorescence spectroscopy in parallel with quenching studies using various acids (1-S-camphorsulfonic acid, p-toluenesulfonic acid, HCl) and metal ions (Cu 2+ , Hg 2+ , Fe 2+ ). The results revealed that the dansyl fluorophore could be useful in sensor applications for detection of some metal ions and in monitoring the protons in organic medium, the most efficient quencher being Fe 2+ and HCl for all dansyl-labeled polyacrylates.
An optically active copolyacrylate, poly(N-acryloyl-L-alanine-co-N-acryloyl-L-histidine), is prepared by classical radical copolymerization of N-acryloyl-L-alanine and N-acryloyl-L-histidine, and further chemically modified with 1-pyrene-methanol. The structures of the synthesized compounds are confirmed by spectral analysis (FTIR, 1 H/ 13 C-NMR, UV, fluorescence spectroscopy), thermal methods, and molecular weight measurements. Also, their optical activity is studied using circular dichroism (CD) spectroscopy and optical rotation measurements. The specific rotation values reveal that the direction of rotation of the parent copolymer is dictated by the monomer containing L-alanine. CD data suggest negative and positive Cotton effects regarding the monomers with amino acids. In the case of the unmodified copolymer it is noted the changes of ellipticity values with increasing pH while the random-coil conformation is preserved, which makes it suitable as a pH-responsive system. Photochemical and photophysical investigations reveal that the pyrene-functionalized chiroptical copolyacrylate can be used as a fluorescent chemosensor for the detection of nitro-derivatives in organic media.
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