Metal complex of polymer with 2-(pyridin-2-yl)-1H-benzo[d]imidazole unit as a selectivity-tunable chemosensor for amino acids

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 5 min), high selectivity and high sensitivity (detection limit concentration is 0.1 ppm for Tryp). Hence, a facile method to tune the detection selectivity of conjugated polymeric chemosensor with metal ions has been developed.