Three benzimidazole based tridentate ligands (L1–L3) and their mononuclear complexes with the general formula of [M(L)Cl2] (where M: Mn(II), Cu(II), and Zn(II), L: ligand) were prepared. The solid state structures of the ligands and [Cu(L1)Cl2], [Mn(L3)Cl2], and [Zn(L3)Cl2] complexes were determined by single crystal X‐ray diffraction studies. The X‐ray crystallographic data confirmed the tautomeric conversion of alkyne groups in L2 to allene isomer L3. In the structures of the complexes, each metal ion is five‐coordinate binding to three nitrogen atoms from the ligands and two chloride ions. The ligands and their metal complexes were studied for their DNA binding properties (Dsfs‐DNA, double‐stranded fish sperm DNA). DNA binding studies were performed by UV–Vis and fluorescence techniques and experimental observations revealed strong binding of ligands and order of DNA binding was found to be L2 > L3 > L1. The DNA binding ability of the metal complexes is higher than free ligands. Finally, molecular dockings were performed to investigate the possible interaction sites of the DNA with the synthesized molecules. Molecular dockings results showed that the ligands bind into the minor groove of DNA.
In the current study, four new phenolic oxime ligands (HL1ox-HL4ox) containing diazo groups (-N = N-) were synthesized and used for liquid-liquid extraction of heavy metal ions [Cu(II), Ni(II), and Zn(II)]. The new compounds were characterized by analytical and spectroscopic methods. Solid-state structures of HL1ox-HL3ox were determined by single-crystal X-ray diffraction studies. Hirshfeld surface analysis of the compounds was performed to determine the contribution of different intermolecular contacts to the stability of the structures. The HL1ox-HL4ox ligands showed higher extraction performance for Cu(II) ion than Ni(II) and Zn(II) ions. The effect of pH on extraction capacity was investigated and the oxime compounds showed high extraction capacity at low pH values. The effects of the substitute groups (at the meta position of the phenol ring) on the extraction were investigated. Within the oxime ligands, the HL3ox compound exhibited higher extraction capacity for Cu(II) ions. The better extraction value of HL3ox is attributed to the weak hydrogen bond type interactions, which result in more stable complexes.
A tridentate bisbenzimidazole‐pyridine ligand (L‐C5) with two pentyl side‐units and its metal complexes with Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ metal ions were synthesized and characterized. The structures of the ligand (L‐C5) and its five coordinate [Mn(L‐C5)Cl2] were elucidated by single crystal X‐ray diffraction studies. The absorption and photoluminescence properties of the compounds were studied in solution media. The ligand is highly fluorescent, and binding of the metal ions to the ligand has caused significant changes in the emission band (shift or quenching). Moreover, the effect of aggregation on UV–Vis. absorption and emission properties was examined in MeOH‐water mixtures. The ligand was found to show aggregation‐induced quenching in the MeOH‐water mixture. The ligand was also screened for its colorimetric and fluorometric sensing ability of several metal ions [Na+, K+, Mg2+, Al3+, Ca2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Hg2+, Pb2+]. The ligand showed selective sensing ability towards Zn2+, and the limit of detection was calculated as 3.09 × 10−7 m. The ligand also showed a distinguishable color change in the presence of Fe2+ under daylight.
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