A novel ratiometric fluorescent Fe3+ sensor based on a phenanthroimidazole chromophore

Phenanthroimidazole derivative 1 has been developed as a rare example of ratiometric fluorescent sensors for Fe3+. Interestingly, upon treatment with Fe3+, the sensor displayed a ratiometric fluorescent response with an enhancement of the ratios of emission intensities at 440 and 500 nm from 0.36 to 3.24. The detection range of the sensor for Fe3+ is in the 1.0 × 10−5–1.5 × 10−4 M concentration range and the detection limit is 5.26 × 10−6 M. In addition, the sensor showed good selectivity to Fe3+ with the selectivity coefficients (KFe3+=SFe3+/S0)(KFe3+=SFe3+/S0) of Fe3+ over other metal ions tested in the range of 5–68.