A reversible fluorescent chemosensor for mercury ions based on 1H-imidazo[4,5-b]phenazine derivatives

A series of non-sulfur, fluorescent sensors (S6, S6-1 or S6-2) for mercury ions bearing 1H-imidazo[4,5-b]phenazine derivatives have been designed and synthesized. Among these sensors, a furan group into the sensor S6 molecule was as the functional group, compound S6-1 containing the 5-(4-Nitrophenyl)-2-furan group was synthesized, and in order to establish the furan groupʹs contribution to the sensorʹs fluorescent sensing abilities, compound S6-2, which without containing the furan group was also synthesized. S6 showed excellent fluorescent specific selectivity and high sensitivity for Hg2+ in aqueous solution. The detection limit of the sensor towards Hg2+ is 1.6×10−7 M, and other ions, including Fe3+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ had nearly no influence on the probing behavior. Notably, this sensor serves as a recyclable component in sensing materials. The test strips based on S6 were fabricated, which could act as a convenient and efficient Hg2+ test kits.