Development of a Benzimidazole-Based Fluorescent Probe for the Sensitive and Selective Detection of Mercury(II) Ions

In this work, we have synthesized and characterized a new benzimidazole appended Schiffbase-based fluorescent chemosensor 2-((1H-benzo[d]imidazol-2-yl)thio)-N-(4-(2-(2-(2-hydroxy-3-methoxybenzylidene)hydrazinyl)phenyl)acetamide (MBIA) for sensitive and selective detection of Hg2+ ions. In the presence of Hg2+ ions, MBIA shows an immediate turn off response of blue fluorescence and a color change from colorless to pale yellow in DMF-Water (1:4 v/v) medium. MBIA forms a strong complex with Hg2+ having binding constant 2.19 +/- 0.55 x 10(7) M-1. From the results of Job's plot, NMR titration, Mass spectrometric studies and DFT studies we reveal the stoichiometry of MBIA-Hg2+ system is 2:1. The Limit of detection (LOD) for MBIA towards Hg2+ ions is 2.80 x 10(-7) M. The practical utility of MBIA in real sample analysis is examined by spiking Hg2+ in water samples collected from various sources such as tap water and drinking water. Furthermore, MBIA and its Hg2+ complex (MBIA-Hg2+) possesses significant anticancer activity against HeLa (Human cervical cancer cell line) and A549 (Human lung adenocarcinoma cell line) cancer cell lines with encouraging outcomes. This dual functionality such as sensing activity and anticancer nature of this probe makes it as the stand alone work in the fields of both environmental and biological chemistry.