Oxalohydrazide‐Based Chemosensor for Detection of Cu²⁺/Fe³⁺ Ions and Its Application in Live Cell Imaging

The N 1 ,N 2 ‐diphenyloxalohydrazide OX(HA) 2 chemosensor was synthesized and used as a colorimetric and fluorescent receptor to detect Cu 2+ and Fe 3+ ions in the presence of other metal ions. A range of physicochemical approaches were utilized to characterize the symmetrical oxalohydrazide‐based receptor, including FT‐IR, 1 H and 13 C NMR, TGA, and mass spectrometry. According to single crystal X‐ray diffraction investigation, OX(HA) 2 crystallizes in monoclinic with space group C2/c . UV‐Vis and fluorescence spectroscopy were used to thoroughly explore OX(HA) 2 ’s sensing capabilities towards diverse cations. Using measurements of fluorescence intensity, the binding constant for OX(HA) 2 with Cu 2+ /Fe 3+ ions was calculated to be 2.78×10 3 M −1 and 1.12×10 3 M −1 with the lower detection limit of 0.43 μM and 0.2 μM respectively. With a 1 : 1 binding mechanism validated by Job's plot, mass spectral analysis, FT‐IR spectra, and density functional theory, the dual‐sensing receptor exhibits remarkable selectivity and sensitivity towards Cu 2+ and Fe 3+ ions. The average fluorescence lifetimes of OX(HA) 2 , OX(HA) 2 +Cu 2+ , and OX(HA) 2 +Fe 3+ were calculated to be 2.19 ns, 1.73 ns, and 1.26 ns, respectively. This fluorescence lifetime measurement results strongly support the complexation of Cu 2+ and Fe 3+ . When Cu 2+ and Fe 3+ ions bind with OX(HA) 2 , they induce the ‘Turn‐Off’ signal. Then, fluorescence imaging of the OX(HA) 2 receptor in MDA‐MB‐231 demonstrated that the receptor holds a lot of promise for usage in bioimaging and their IC 50 value for cytotoxicity is 96.96 μg. Furthermore, fluorescence microscopy experiments demonstrate that OX(HA) 2 can be utilized as a fluorescent probe for detecting Cu 2+ and Fe 3+ ions in living cells, making it potentially helpful as an anticancer medication.