Research Article

Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases with 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation

Volume: 2026 Number: 2 October 3, 2026

Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases with 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation

Abstract

In this study, two azo-Schiff base ligands were synthesized via condensation of vanillin and 4-(dimethylamino)benzaldehyde with 4-aminoazobenzene. Mixed-ligand complexes of Co(II), Ni(II), and Cu(II) were synthesized using 1,10-phenanthroline (Phen) and metformin (Met), affording twelve complexes with a metal-to-ligand ratio of 1:2. The synthesized ligands and their complexes were characterized using FT-IR, 1H-NMR, UV-Vis spectroscopy, atomic absorption spectroscopy (AAS), elemental analysis (C, H, N), molar conductivity, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). XRD analysis revealed an average crystallite size of 56 nm using Scherrer's equation. Spectral data confirmed coordination through the azomethine and azo nitrogen atoms, while electronic spectra and magnetic measurements supported octahedral geometry around the metal ion. The effective magnetic moments were 3.91-4.25 B.M. for Co(II), 2.654-2.899 B.M. for Ni(II), and 1.65-1.721 B.M. for Cu(II) complexes. Molar conductivity values (135-170 Ω-1cm2mol-1) indicated that complexes behave as 1:2 electrolytes. TGA confirmed the presence of water of crystallization, whereas SEM revealed aggregated nanostructures with particle sizes of 130-270 nm. Molecular docking studies against the bacterial protein (1JIK) and acetylcholinesterase (1B41) showed favorable binding affinities, with ligand L2 exhibiting the highest affinity toward the acetylcholinesterase target (-9.494 kcal/mol). Antibacterial evaluation against Escherichia coli and Staphylococcus aureus demonstrated enhanced activity of the complexes compared with the free ligand, with complex 5 showing the highest inhibition zones (22 and 20 mm, respectively). The combined experimental and molecular docking results highlight the potential of these mixed-ligand complexes as promising bioactive coordination compounds.

Keywords

Supporting Institution

Department of Chemistry, College of Education for Pure Sciences, University of Mosul, Mosul, Iraq.

Project Number

N/A

Ethical Statement

The authors declare that this study does not involve human participants or animals. All experimental procedures were conducted in accordance with accepted scientific and ethical standards.

Thanks

The authors gratefully acknowledge the Department of Chemistry at the College of Education for Pure Sciences, University of Mosul, for the facilities and resources provided that contributed to the completion of this research. They also express their appreciation to the laboratories and technical staff for their support and assistance during the experimental procedures.

References

  1. 1. Shivhare R, Danao K, Nandurkar D, Rokde V, Ingole A, Warokar A, et al. Schiff base as multifaceted bioactive core. In: Schiff Base in Organic, Inorganic and Physical Chemistry. IntechOpen; 2023. Available from: .
  2. 2. Singh HL, Khaturia S, Solanki VS, Sharma N. Synthesis of coordination compounds of dibutyltin(IV) with schiff bases having nitrogen donor atoms. J Indian Chem Soc. 2023 Mar;100(3):100945. Available from: .
  3. 3. Wang R, Lee CS, Lu Z. Recent development of three-coordinated boron-doped aromatics for optoelectronic applications. J Organomet Chem. 2023 Jan;984:122564. Available from: .
  4. 4. Katouah H, Hameed AM, Alharbi A, Alkhatib F, Shah R, Alzahrani S, et al. Green synthesis strategy for new schiff‐base complexes: Characterization, conductometry, in vitro assay confirmed by in silico approach. ChemistrySelect. 2020 Sep 7;5(33):10256–68. Available from: .
  5. 5. Al-Abbasy O, Alsarraf Z, Mahdi N, Al-Barwari A. Ascorbic acid: Rationale and applications in inhibiting enzymatic browning of fruits and vegetables-A comprehensive review. Iran Food Sci Technol Res J. 21(6):697–715. Available from: .
  6. 6. Pang X, Lv J, Zhu C, Qin L, Yu Y. Photodeformable azobenzene‐containing liquid crystal polymers and soft actuators. Adv Mater. 2019 Dec 9;31(52):1904224. Available from: .
  7. 7. Saleh MY, Al-barwari ASMO, Ayoob AI. Synthesis of some novel 1,8-naphthyridine chalcones as antibacterial agents. J Nanostructures. 2022 Jul 1;12(3):598–606. Available from: .
  8. 8. Derafa W, A.A. Elkanzi N, M. Ali A, Abdou A. Three Co(II), Ni(II) and Cu(II) schiff base complexes incorporating 2-[(4-{[(4-methylphenyl)sulfonothioyl]oxy}phenyl)methylene] amino}benzoic acid: Synthesis, structural, dft, biological and molecular docking investigation. Bull Chem Soc Ethiop. 2024 Jan 23;38(2):325–46. Available from: .

Details

Primary Language

English

Subjects

Transition Metal Chemistry

Journal Section

Research Article

Publication Date

October 3, 2026

Submission Date

May 31, 2026

Acceptance Date

August 3, 2026

Published in Issue

Year 2026 Volume: 2026 Number: 2

APA
Abbas, Z., & Al-Barwari, A. (2026). Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases with 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation. Journal of the Turkish Chemical Society Section A: Chemistry, 2026(2), 1-17. https://doi.org/10.18596/jotcsa.1960619
AMA
1.Abbas Z, Al-Barwari A. Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases with 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation. JOTCSA. 2026;2026(2):1-17. doi:10.18596/jotcsa.1960619
Chicago
Abbas, Zainab, and Alyaa Al-Barwari. 2026. “Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases With 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation”. Journal of the Turkish Chemical Society Section A: Chemistry 2026 (2): 1-17. https://doi.org/10.18596/jotcsa.1960619.
EndNote
Abbas Z, Al-Barwari A (October 1, 2026) Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases with 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation. Journal of the Turkish Chemical Society Section A: Chemistry 2026 2 1–17.
IEEE
[1]Z. Abbas and A. Al-Barwari, “Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases with 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation”, JOTCSA, vol. 2026, no. 2, pp. 1–17, Oct. 2026, doi: 10.18596/jotcsa.1960619.
ISNAD
Abbas, Zainab - Al-Barwari, Alyaa. “Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases With 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation”. Journal of the Turkish Chemical Society Section A: Chemistry 2026/2 (October 1, 2026): 1-17. https://doi.org/10.18596/jotcsa.1960619.
JAMA
1.Abbas Z, Al-Barwari A. Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases with 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation. JOTCSA. 2026;2026:1–17.
MLA
Abbas, Zainab, and Alyaa Al-Barwari. “Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases With 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation”. Journal of the Turkish Chemical Society Section A: Chemistry, vol. 2026, no. 2, Oct. 2026, pp. 1-17, doi:10.18596/jotcsa.1960619.
Vancouver
1.Zainab Abbas, Alyaa Al-Barwari. Novel Mixed-Ligand Co(II), Ni(II), and Cu(II) Complexes of Azo-Schiff Bases with 1,10-Phenanthroline and Metformin: Synthesis, Characterization, Molecular Docking, and Antibacterial Evaluation. JOTCSA. 2026 Oct. 1;2026(2):1-17. doi:10.18596/jotcsa.1960619