Synthesis and Characterization of Novel Hydrazone Complexes: Exploring DNA/BSA Binding and Antimicrobial Potential

Area of Science:

• Coordination Chemistry
• Bioinorganic Chemistry
• Medicinal Chemistry

Background:

• Schiff base hydrazones are valuable ligands in coordination chemistry.
• These ligands and their metal complexes have diverse applications, especially in bioinorganic and biomedical fields.

Purpose of the Study:

• To synthesize and characterize a new Schiff base hydrazone ligand, (E)-2-((2-(benzothiazol-2-yl)hydrazone)methyl)phenol (H₂L).
• To prepare and structurally elucidate novel nickel(II) and copper(II) complexes derived from H₂L.
• To investigate the DNA and bovine serum albumin (BSA) binding interactions and biological activities of the synthesized complexes.

Main Methods:

• Ligand synthesis via condensation reaction.
• Complex formation with nickel(II) chloride and copper(II) nitrate.
• Structural characterization using IR, UV-vis, TGA-DSC, and single-crystal X-ray diffraction (SCXRD).
• DNA interaction studies via spectroscopic titration and viscosity measurements.
• Partition coefficient analysis.
• Bovine serum albumin (BSA) binding studies using fluorescence spectroscopy.
• Biological activity testing (antimicrobial, antiyeast).

Main Results:

• Three new crystalline complexes were synthesized: [Ni(HL)₂] (1), [Ni₂(L)₂(Py)₂(EtOH)]·DMF·0.5H₂O (2), and [Cu₃(L^#)₂(DMF)₂] (3).
• Structural analyses confirmed mono-, bi-, and trinuclear complex formations with N and O donor atoms.
• Complexes interact with DNA via intercalation, with the order of interaction strength: 3 > 2 > 1.
• Complexes 1 and 3 show higher lipophilicity, suggesting potential membrane permeability.
• Complexes bind to BSA, following the same interaction order as DNA.
• The ligand showed no antimicrobial or antiyeast activity, while the metal complexes are biologically active.
• The copper complex demonstrated the most potent antibacterial activity.

Conclusions:

• The synthesized Schiff base hydrazone ligand forms stable mono-, bi-, and trinuclear complexes with Ni(II) and Cu(II).
• The metal complexes exhibit significant DNA and BSA binding capabilities, with potential for membrane interaction.
• The copper complex displays promising antibacterial properties, highlighting its potential therapeutic applications.