Fluorescent Sensing of Cesium Ions by an Amide‐Linked BODIPY Dye: Synthesis and Photophysical Properties

In this study, a new fluorescent sensor for Cs + ion was designed and synthesized from the combination of pyridine‐2,6‐dicarboxamide and 4,4‐difluoro‐4‐borata‐3a,4a‐diaza‐s‐indacene (BODIPY) scaffolds. The sensing capability of the target compound against a variety of ions was investigated. The structure of the target compound was proved by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, and 1 H and 13 C NMR spectroscopies. Photophysical properties of the amide‐linked BODIPY compound were studied by utilizing fluorescence spectroscopies in DMSO/water (9:1, v/v) solution. It was found that the final amide‐linked BODIPY compound showed exclusively selective and sensitive turn‐off sensor behavior for Cs + ion over other metal ions (Li + , Na + , K + , Cs + , Mg 2+ , Ca 2+ , Ba 2+ , Hg 2+ , Pb 2+ , Mn 2+ , Cd 2+ , Ag + , Ni 2+ , Cu 2+ , Zn 2+ , Co 2+ , Cr 3+ and Fe 3+ ). The addition of Cs + resulted in quenching of fluorescence intensity and the detection limit was calculated to be 0.273 μM. According to Job's Plot, binding stoichiometry ratio of the target compound with Cs + was 1:1.