A fluorescent and colorimetric chemosensor for dihydrogen phosphate ions based on 2-pyridine-1H-imidazo[4,5-b]phenazine–zinc ensemble

A long wavelength emission fluorescent (600 nm) and colorimetric (from pink to yellow) chemosensor with high selectivity for H2PO4− ions was designed and synthesized according to the twisted intramolecular charge transfer (TICT) mechanism. The sensor was bearing a 2-pyridine-1H-imidazo[4,5-b]phenazine and Zn2+ metal complex (S2–Zn), which shown brilliant fluorescent and colorimetric response for H2PO4− anions in aqueous solution. The detection limit of the sensor toward H2PO4− is 2.4 × 10−6 M, and other anions, including F−, Cl−, Br−, I−, AcO−, HSO4−, ClO4− and CN− had nearly no influence on the probing behavior. The test strips based on 2-pyridine-1H-imidazo[4,5-b]phenazine and Zn2+ metal complex (S2–Zn) were fabricated, which could act as a convenient and efficient H2PO4− test kits.