Cu(I)‐catalyzed azide–alkyne cycloaddition synthesis and fluorescent ion sensor behavior of carbazole‐triazole‐fluorene conjugated polymers

Abstract

Abstract 1,8‐Carbazole‐based conjugated polymers were synthesized by the Cu(I)‐catalyzed azide–alkyne cycloaddition between 1,8‐diethynylcarbazole monomers and 2,7‐diazidofluorene counter comonomers. Successful polymer formation was revealed by conventional techniques, such as gel permeation chromatography and 1 H NMR spectroscopy, and the bathochromically shifted absorption with respect to the model monomer. The resulting polymer displayed selective metal ion recognition in terms of fluorescence quenching or the appearance of a new emission peak. The fluorescence chemosensor behavior could be achieved only when the 9 H position of the carbazole was unsubstituted. Of the studied metal cations, Sn 2+ ions were the most strongly bound to the polymer. The degree of fluorescence quenching was more significant than that of the model monomer, a fact that highlights the use of polymeric chemosensors. Moreover, CN − anion recognition was also demonstrated by the fluorescence recovery of the polymer–Sn 2+ ion complex. Overall, this is the first click polymerization of 1,8‐carbazole‐based monomers, and the selective ion sensor behavior was achieved by the characteristic 1,8‐di(triazolyl)carbazole unit. © 2020 Society of Chemical Industry