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 Cu2+ and Fe3+ 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, H-1 and C-13 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 Cu2+/Fe3+ ions was calculated to be 2.78x10(3) M-1 and 1.12x10(3) M-1 with the lower detection limit of 0.43 mu M and 0.2 mu M 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 Cu2+ and Fe3+ ions. The average fluorescence lifetimes of OX(HA)(2), OX(HA)(2)+Cu2+, and OX(HA)(2)+Fe3+ 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 Cu2+ and Fe3+. When Cu2+ and Fe3+ 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 IC50 value for cytotoxicity is 96.96 mu g. Furthermore, fluorescence microscopy experiments demonstrate that OX(HA)(2) can be utilized as a fluorescent probe for detecting Cu2+ and Fe3+ ions in living cells, making it potentially helpful as an anticancer medication.