Two phenanthro[9,10-d]imidazole-based fluorescence probes for distinguishable detection of Cys and Fe3+ and their applications in food and water as well as living cells monitoring

Accurately designing and developing the dual responsive fluorescence probe with simultaneous recognition of intracellular biothiols and metal ions is of great significance. Here, we reported two phenanthrene[9,10-d]imidazole derivatives (PIP-CHO and NO2-PIP-CHO) modified with aldehyde fragment as chemosensor for synchronous detection of Cys and Fe3+. PIP-CHO and NO2-PIP-CHO performed the hydrophilic nature despite the fact that they possessed the distinct aggregation behavior with the increasing of water contents. In aqueous medium (water/DMF), PIP-CHO predominantly exhibited high sensitivity and selectivity for “on–off” fluorescent recognition of Fe3+ with a limit of detection (LOD) of 213.74 nmol·L–1, and Cys with a LOD of 116.66 nmol·L–1, respectively. Correspondingly, the detection limits of NO2-PIP-CHO toward Fe3+ and Cys were calculated in DMF as 347.68 and 215.64 nmol·L–1, respectively. The fluorescent recognition mechanism of cycloaddition and coordination for PIP-CHO with Cys and Fe3+ was rationally explained by SEM, 1H NMR and ESI-MS, respectively. Noteworthy, the naked-eye strips encompassing PIP-CHO enabled distinguishable visualization of Cys and Fe3+ with the color change under visible or UV light. In addition, PIP-CHO can be successfully applied to detect Cys and Fe3+ in food and water samples by fluorescence method, as well as the living Yeast cells via fluorescence dual channel.