A conjugated polymer with ethyl 2-(2-(pyridin-2-yl)-1H-benzo[d]imidazol-1-yl) acetate units as a novel fluorescent chemosensor for silver(I) detection

A novel conjugated polymer (P1) containing fluorene and ethyl 2-(2-(pyridin-2-yl)-1H-benzo[d]imidazol-1-yl)acetate (PBMA) was designed and successfully synthesized through the Sonogashira coupling reaction. P1 shows high sensitivity and selectivity for Ag+ detection in comparison to other metal cations. Upon addition of Ag+, the fluorescent emission of the polymer solution in THF was quenched dramatically, accompanying the color changed from blue to green. The detection limit for Ag+ was 5 × 10−8 mol L−1. However, the similar copolymers P2 and P3 containing 2-(pyridin-2-yl)-1H-benzo[d]imidazole and 2-(thiophen-2-yl)-1H-benzo[d]imidazole, respectively, did not show such a selectivity for Ag+ detection. The 1H NMR measurements confirmed that the PBMA units play a key role for the selective recognition of Ag+.