Synthesis, structure and biological activities of mixed ligand copper(II) and nickel(II) complexes of N′-(1E)-[(5-bromo-2-hydroxyphenyl)methylidene]benzoylhydrazone

We have made an effort to synthesize ternary complexes [Cu2(L)2(Him)2]·CH3OH 1, [Cu(L)(bipy)] 2 and [Ni(HL)(PMDT)]BF43 (H2L = N′-(1E)-[(5-bromo-2-hydroxyphenyl)methylidene]benzoylhydrazone; Him = imidazole; bipy = 2,2′-bipyridine and PMDT = N,N,N′,N″,N″-pentamethyldiethylenetriamine). Their crystal structures were determined by X-ray diffraction method. Single crystal X-ray of 1 revealed the geometry of phenoxo bridged copper center and the distance between the two Cu(II) ion is 3.245 Å. The two copper ions are penta coordinated with distorted square pyramidal geometries. Magnetic measurements of dicopper complex 1 exhibited the presence of antiferromagnetic exchange interaction. The observed trend in the spin Hamiltonian parameters in complexes 1 and 2g|| > g⊥ > 2.0023 and |A⊥| ≪ |A||| ≈ 163–173 × 10−4 cm−1) indicates dx2-y2dx2-y2 band ground state with tetragonal site symmetry for copper(II). Complex 3 was crystallized in orthorhombic crystal system having six coordination numbers. Superoxide dismutase activities of all these complexes have been revealed to catalyze the dismutation of superoxide (O2-) and IC50 values were evaluated. DNA cleavage properties and antibacterial activity have been measured and discussed.

Graphical abstractThree new mixed ligand complexes [Cu2(L)2(Him)2]·CH3OH 1, [Cu(L)(bipy)] 2 and [Ni(HL)(PMDT)](BF4) 3 (H2L = N′-(1E)-[(5-bromo-2-hydroxyphenyl)methylidene]benzoylhydrazone; Him = imidazole; bipy = 2,2′ bipyridine and PMDT = N,N,N′,N″,N″-pentamethyldiethylenetriamine) have been synthesize and characterized. Their crystal structures were determined by single crystal X-ray diffraction method.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Design of new ligand and metal complexes. ► Single crystal X-ray structure. ► Superoxide dismutase activity determination. ► π⋯π-interaction. ► Antibacterial and DNA cleavage activity.