Selective quinizarin-linked bis-1,2,3-triazoles as probes for Fe(II)/(III): Characterization, metal ion binding, DFT, and antiallergy activity via docking studies

Herein, two new molecular probes of quinizarin-linked bis-1,2,3-triazoles have been synthesized via CuAAC reaction to detect transition metal(s), such as iron (Fe). FTIR, 1H & 13C-NMR, and HRMS spectroscopy fully characterized the synthesized probes. Absorption spectroscopy showed selective binding of probes with Fe(II) and Fe(III) ions. Job's plot suggested a 1:1 stoichiometric ratio of ligand and metal ion. Both probes 3a and 3b showed association constant of 4.42 x 103 M- 1 and 4.35 x 103M-1 for Fe(II) and 4.35 x 103 M- 1 and 4.59 x 103 M-1 for Fe(III), through Benesi-Hildebrand (B-H) plots. The DFT was performed for geometrical optimization of probes and their complexes, supported by Mulliken charges and Molecular electrostatic potential. Above and beyond, probes and their complexes were also docked with human histamine H1 receptor (PDB ID: 3RZE) protein, providing foretastes of its anti-allergic activity.