TCNE-decorated triphenylamine-based conjugated polymer: Click synthesis and efficient turn-on fluorescent probing for Hg~(2+)

摘要

A type of triphenylamine-based conjugated polymer with cyano-containing chromophore in side chain, poly[(9,9-dioctyl)-2,7-fluorene-co-N-4-(1,1,4,4-tetracyanobuta-1,3-dienyl)-4,4'-triphenylamine] (P3)was successfully synthesized by catalyst-free and efficient click reaction between poIy((9,9-dioctyl)-2,7-fluorene-co-N-4-ethynyl-4,4'-triphenylamine] (P2) and tetracyanoethylene (TCNE). Chemical structures of intermediates and target polymer were verified by FT-IR and ~1H NMR analyses. Fluorescence of P3's THF solution was specifically quenched by the introduction of I", accompanied by the change of its apparent color from pale brown to light yellow. With the introduction of Hg~(2+), fluorescence of P3/I~-complex recovered quickly and even exceeded the initial intensity of pristine P3 (when the concentration of Hg~(2+) above ~6.65 x 10~(-5) M). Other common cations brought very slight interference for P3/I~-complex's response of Hg~(2+), and the detection limit of Hg~(2+) reached ~6.9 nM for such probing system.