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

Research involving coordination chemistry with Schiff
base hydrazones
finds applications in various areas, particularly in bioinorganic
chemistry and biomedicine. This work aims to contribute to this field
by employing the ligand (E)-2-((2-(benzothiazol-2-yl)hydrazone)methyl)phenol
(H2L), synthesized via a condensation reaction with salicylic
aldehyde. The ligand was isolated, characterized, and subsequently
complexed with nickel(II) chloride and copper(II) nitrate, yielding
three new crystalline complexes: [Ni(HL)2] (1), [Ni2(L)2(Py)2(EtOH)]·DMF·0.5H2O (2), and [Cu3(L#)2(DMF)2] (3) (where Py = pyridine).
The metal complexes were structurally characterized using IR, UV–vis,
TGA-DSC, and SCXRD techniques. These analyses confirmed the coordination
of the ligand to the metal center via nitrogen and oxygen donor atoms,
establishing the formation of mono-, bi-, and trinuclear complexes,
respectively. DNA interaction studies were performed through spectroscopic
titration and viscosity measurements, indicating that the complexes
interact via an intercalative mode, with the interaction order being 3 > 2> 1. Partition coefficient
analysis revealed that complexes 1 and 3 have a greater tendency to partition into the organic phase, suggesting
their potential to cross lipid membranes, while complex 2 and the ligand are more hydrophilic. Fluorescence-based BSA binding
studies demonstrated interactions between the complexes and the biomolecule,
following the same order as observed in the DNA interaction. Biological
tests showed that the ligand lacked antimicrobial and antiyeast activity,
while the metal complexes are biologically active. Notably, the copper
complex displayed the strongest antibacterial effect, likely due to
copper’s essential biological role.