A Novel Fluorescent Probe Based on Pyrazole-Pyrazoline for Fe (III) Ions Recognition

Firstly, a novel pyrazole-pyrazoline fluorescent probe was developed and synthesized. The probe can be used to determine Fe³⁺ ions in a series of cations in tetrahydrofuran aqueous solution with high selectivity and high sensitivity. After the addition of iron ions, the fluorescence intensity is significantly reduced, Its structure was characterized by ¹H NMR, ¹³C NMR and HR-ESI-MS. UV absorption spectra and Fluorescence spectroscopy were used to study the selective recognition of probe M on metal ions. The probe M can selectivity and sensitivity to distinguish the target ion from other ions through different fluorescence phenomena. In addition, the binding modes of M with Fe³⁺ were proved to be 1:1 stoichiometry in the complexes by Job's plot, IR results. The combination of probe M and iron ions is 1:1, and the detection limit is 3.9 × 10^-10 M. The binding mode and sensing mechanism of M with Fe³⁺ was verified by theoretical calculations using Gaussian 09 based on B3LYP/6-31G(d) basis.