Mixed pyrazinamide and 4-dimethylaminopyridine nickel(II) complex: Characterization, DFT, and biological potentials

Abstract

Ni(II) complex of pyrazinamide with 4-Dimethylaminopyridine formulated as [Ni(PZA)2(DMAMP)2](H2O) [PZA=pyrazinamide, DMAMP = 4-Dimethylaminopyridine] has been prepared and structurally elucidated using spectroscopic techniques and single crystal x-ray diffraction. The [Ni(PZA)2(DMAMP)2](H2O)X-ray structural refinement showed the PZA coordinates with the metal center Ni2+ ion as a neutral ligand in chelating with two nitrogen and two nitrogen atoms from the bidentate PZA ligand, along with two nitrogen atoms from the monodentate DMAMP moiety in a slightly distorted octahedral configuration. The findings of the X-ray analysis indicate that the product crystallizes in the tetragonal system with a=b=13.2738(5), c = 14.8262(8) Å, and space group P41212 with (α = β = γ = 90o). Thermogravimetric analysis was achieved on the sample to ascertain the thermal stability, method of thermal degradation of the complex, the existence of lattice water molecules, and the formation of the metal oxide. Additionally, antibacterial efficacy of the complex was evaluated in-vitro against 5 bacteria isolates (3 Gram + and 2 Gram -) using the agar disk diffusion method and antimycobacterial activities against three spp. of Mycobacterium tuberculosis to compare the potencies of the metal complex with the parent drug. The results revealed that the complex exhibited improved action by showing promising broad-range anti-bacterial potential compared to the ligands. The DFT studies showed that the Ni complex has an energy gap (ΔE) value of 3.025 eV in methanol, which is lower than that of the free ligands; 4.968 eV and 5.034 eV for pyrazinamide and 4-Dimethylaminopyridine respectively.