2-Pyridine-1H-benzo[d]imidazole based conjugated polymers: A selective fluorescent chemosensor for Ni2+ or Ag+ depending on the molecular linkage sites

Three conjugated polymers comprised of 9,9-didodecyl-2,7-diethynyl-9H-fluorene and 2-pyridine-1H-benzo[d]imidazole units, which are alternatively linked to 4,7-position (P1) and 5,5′-position (P2, P3), respectively, have been synthesized via Sonogashira reaction. P2 and P3 with the twisted conjugated backbones were proved to show selectivity for nickel ion. By contrast, P1 with the linear conjugated backbone exhibited highly selectivity for silver ion. The results suggest that the metal ion recognition feature of the chemosensors based on the conjugated polymers can be adjusted by fine-tuning the linkage pattern between the recognition group and the conjugated backbone. Thus, a selective chemosensor for detection of nickel ion was developed.