Fluorene-based conjugated polymer with tethered thymines: click postpolymerization synthesis and optical response to mercury(II).

A kind of fluorene-based conjugated polymer with tethered thymine (T) groups {poly[(9,9-dioctyl)-2,7-fluorene-{9,9-dioctyl-4-1,2,3-triazol-[5-(hydroxymethyl)tetrahydrofuran-2-yl]-5-methylpyrimidine-2,4(1H,3H)-dione}-2,7-fluorene]- co-[(9,9-dioctyl)-2,7-fluorene-4,7-bis(5-thiophen-2-yl)benzo-2,1,3-thiadiazole] ( P-3)} was successfully synthesized by a Cu(I)-catalyzed click reaction between the acetylene-substituted polymer precursor {poly[(9,9-dioctyl)-2,7-fluorene-(9,9-dioctyl-4-phenylacetylene fluorene)]- co-[(9,9-dioctyl)-2,7-fluorene-4,7-bis(5-thiophen-2-yl)benzo-2,1,3-thiadiazole]} and 3′-azido-3′-deoxythymidine. The chemical structures of the intermediates and target polymer were verified by Fourier transform infrared spectroscopy and ¹H-NMR analyses. The specific binding with Hg²⁺ of P-3 was corroborated by ultraviolet-visible spectroscopy and photoluminescence analyses against other metal ions. The results show that P-3 possessed selectivity and sensitivity toward Hg²⁺. Around 77% of photoluminescence intensity of P-3 was quenched when the concentration of Hg²⁺ reached 7.7 × 10⁻⁴ M and with a detection limit in the range of about 4.8 μ M. A comparison experiment suggested that a synergic effect of the tethered T and S atoms interrelated with Hg²⁺ existed in P-3. Most of the fluorescence intensity of P-3 was recovered upon the addition of iodide anions to the P-3/Hg²⁺ complex; this suggested that P-3 could be used as a potential reversible optical Hg²⁺ probe. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]