Bio-active mixed ligand Cu(II) and Zn(II) complexes of pyrimidine derivative Schiff base: DFT calculation, antimicrobial, antioxidant, DNA binding, anticancer and molecular docking studies

Abstract

A new series of bio active Cu(II) and Zn(II) complexes [CuL(phen)](OOCCH₃) (1), [ZnL(phen)](OOCCH₃) (2), [CuL(bpy)](OOCCH₃) (3), [ZnL(bpy)](OOCCH₃) (4) have been synthesized using the pyrimidine derivative Schiff base (HL) [HL = 2-(4,6-dimethylpyrimidin-2-ylimino)methyl)-4-nitrophenol], 1,10-phenanthroline (phen), 2,2’-bipyridine (bpy) and acetate salts of Cu(II) and Zn(II). UV-Visible, FT-IR, ¹H-NMR, ESR, elemental analysis, molar conductance and EI-MS spectral techniques have been used to endorse the square planar geometry for the complexes 1–4. The optimized molecular structure and the harmonic vibrational frequencies have been scrutinized by DFT methods. The antibacterial and antifungal activity of Schiff base (HL) and complexes 1–4 indicates that complex 1 acts as good antimicrobial agent against microbial strains than HL, complexes 2–4 and standard drugs streptomycin and nystatin. DNA cleavage study of the complexes 1–4 exposes that complexes 1 and 3 spectacle good cleaving agent than complexes 2 and 4. The interaction of complexes 1–4 with CT DNA using absorption, emission and viscometric measurements signifies that complexes 1–4 bind via an intercalation mode. The highest binding constants (K_b) for the complex 1 is confirmed as 7.83 × 10³ M⁻¹ and 2.98 × 10⁴ M⁻¹ by absorption and emission spectrum respectively. These experimental observations were found to be close to the theoretical observations investigated by the molecular docking technique. Antioxidant property of the complexes 1–4 using DPPH assay clinches that complex 1 produces significant scavenging effect than other compounds. The result of in vitro cytotoxicity of the Schiff base (HL) and complexes 1–4 shows that complex 1 shows better ability to inhibit the growth of cancer cells.

Communicated by Ramaswamy H. Sarma

GRAPHICAL ABSTRACT

Highlights

• All synthesized complexes are good inhibitive nature.

• DFT are compassionate to reconnoitre the enhanced structure and chemical reactivity of the complexes.

• Complex 1 has strong DNA binding/cleaving efficacy through intercalation binding mode.

• DNA binding effect has also been proved by molecular docking studies.

• Complex 1 may be an appreciated material in cancer chemotherapy mediators in imminent years.

Keywords:

• Bioactive
• DFT
• antimicrobial
• cleavage
• binding
• docking
• anticancer

Acknowledgements

The authors express their honest thanks to the Management of the Department of Chemistry, The American College, Madurai, Tamil Nadu, India for their inspiration. Also, they thank the Management of the Ramco Institute of Technology, Rajapalayam to encourage completing the research work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors thank the DST-SERB (Ref. No.: SR/FT/CS-117/2011 dated 29.06.2012), Government of India, New Delhi for the financial assistance.