A Phenazine based colorimetric and fluorescent chemosensor for sequential detection of Ag+ and I- in aqueous media.

A new colorimetric and fluorescent probe MNTPZ based on 1H-imidazo[4,5-b]phenazine derivative has been designed and synthesized for successive detection of Ag+ and I- . The probe MNTPZ shows selective colorimetric response by a change in color from yellow to orange and "turn-off" fluorometric response upon binding with Ag+ in DMSO: Water (pH = 7, 1:1, v/v) over other cations. The binding mode of probe MNTPZ to Ag+ was studied by Job's plot, 1 H NMR studies, FT-IR spectroscopy and DFT calculations. Moreover, the situ generated probe MNTPZ+ Ag+ complex acted as an efficient fluorometric "turn-on" probe for I- via Ag+ displacement approach. The detection limit of probe MNTPZ for Ag+ and the resultant complex probe MNTPZ+ Ag+ for I- were determined to be 1.36 μmol/L and 1.03 μmol/L respectively. Notably, the developed probe was successfully used for quantitative determination of I- in real samples with satisfactory results.