Synthesis, characterization, molecular docking, biological activity and density functional theory studies of novel 1,4‐naphthoquinone derivatives and Pd(II), Ni(II) and Co(II) complexes

Abstract

Two novel heterocyclic ligands, 2-[(5-fluoro-1,3-benzothiazol-2-yl)amino]naphthalene-1,4-dione (HL 1 ) and 2-[(5-methyl-1,3-benzothiazol-2-yl)amino]naphthalene-1,4-dione (HL 2 ), and their Pd(II), Ni(II) and Co(II) complexes were prepared and characterized using 1 H NMR, 13 C NMR, infrared and UV-visible spectroscopic techniques, elemental analysis, magnetic susceptibility, thermogravimetry and molar conductance measurements. The infrared spectral data showed that the chelation behaviours of the ligands towards the transition metal ions were through one of the carbonyl oxygen and deprotonated nitrogen atom of the secondary amine group. Molar conductance results confirmed that the complexes are non-electrolytes in dimethylsulfoxide. The geometries of the complexes were deduced from magnetic susceptibility and UV-visible spectroscopic results. Second-order perturbation analysis using density functional theory calculation revealed a stronger intermolecular charge transfer between ligand and metal ion in [NiL 1 (H 2 O) 2 (CH 3 COO-)] and CoL 1 compared to the other complexes. The in vitro antibacterial activity of the compounds against some clinically isolated bacteria strains showed varied activities. [NiL 1 (H 2 O) 2 (CH 3 COO-)] exhibited the best antibacterial results with a minimum inhibitory concentration of 50 μg mL −1 . The molecular interactions of the compounds with various drug targets of some bacterial organisms were established in a bid to predict the possible mode of antibacterial action of the compounds. The ferrous ion chelating ability of the

Novel 3‐Hydroxy‐2‐naphthoic hydrazone and Ni(II), Co(II) and Cu(II) Complexes: Synthesis, Spectroscopic Characterization, Antimicrobial, DNA Cleavage and Computational Studies

“…The DFT‐optimized geometries, with the key interatomic distances, in Angstrom, of [CuLCl 2 ], [CoLCl 2 ] and [NiLCl 2 ] complexes are shown in Figure . The metal–ligand distances obtained were similar to literature‐reported metal–ligand distances …”

“…The enthalpy (∆H), Gibb's free energy (∆G) and entropy (∆S) were calculated, according to following expression: M(II) represents the Cu(II), Co(II) and Ni(II) ; L i , L j are the coordinated ligands; m and n are the numbers of moles of the ligands.…”

“…HOMO and LUMO are also regarded as the frontier molecular orbitals . The electron‐donating ability of a complex is associated with the E HOMO ; the higher the E HOMO energies (less negative), the more energy, implying more ability to donate electrons . The distribution of electrons of the HOMO (Figure ) is prominent in the [CuLCl 2 ] complex, compared to Co and Ni complexes.…”

“…The thermodynamic properties of the complexes are shown in Table . Entropy is the degree of disorderliness of a system . Positive entropy designates increase in randomness in a system, and aids favorable formation of the complex .…”

Synthesis, Spectroscopic, Antimicrobial Activity and Computational Studies of Some Homoleptic and Heteroleptic Metal(II) Complexes of 2‐Furoic Acid Hydrazone

“…All the optimized complexes and the key interatomic distances of [Cu(L) 2 ], [Co(L) 2 ], [Ni(L) 2 ] etc are presented in Å (Figure ). The calculated metal‐ligand interatomic distances are similar to previously reported metal‐ligand distances …”