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Abstract: 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. [Copyright &y& Elsevier]

Abstract: A novel 2-(pyridin-2-yl)-1H-benzo[d]imidazole based conjugated polymer (P1) was synthesized and characterized. The binding and recognition behavior of P1 toward the metal ions and amino acids were investigated. The fluorescence of P1 can be completely quenched by Cu2+ and Ni2+ through a photoinduced electron transfer process, resulting in the formation of metal complexes with polymer ([P1-Cu2+] and [P1-Ni2+]), which indicates that P1 is a selective chemosensor for Cu2+ and Ni2+. Moreover, in situ formed [P1-Cu2+] complex showed excellent fluorescence “turn on” properties with high selectivity toward Cys, while [P1-Ni2+] complex with high selectivity toward His and Tryp. These complexes are promising chemosensors for amino acids due to fast response time (less than 5min), high selectivity and high sensitivity (detection limit concentration is 0.1ppm for Tryp). Hence, a facile method to tune the detection selectivity of conjugated polymeric chemosensor with metal ions has been developed. [Copyright &y& Elsevier]

Abstract: 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 molL−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+. [Copyright &y& Elsevier]