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

摘要

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 Hg~(2+) 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 Hg ~(2+). Around 77% of photoluminescence intensity of P-3 was quenched when the concentration of Hg~(2+) reached 7.7 × 10~(-4) M and with a detection limit in the range of about 4.8 μM. A comparison experiment suggested that a synergic effect of the tethered T and S atoms interrelated with Hg~(2+) existed in P-3. Most of the fluorescence intensity of P-3 was recovered upon the addition of iodide anions to the P-3/Hg~(2+) complex; this suggested that P-3 could be used as a potential reversible optical Hg~(2+) probe.