Synthesis, spectroscopic, thermal, biological, morphological and molecular docking studies of the different quinolone drugs and their cobalt(II) complexes

Abstract

New six cobalt(II) complexes 1–6 with four generation of quinolone drugs (nalidixic acid (Nal), oxolonic acid (Oxo), pipemidic acid (Pip), lomefloxacin (Lom), pefloxacin mesylate (Pef) and levofloxacin (Lev)) have been synthesized in methanol medium, and the general formula was designed as [Co(L)2(Cl)2(H2O)2]·4H2O (L=Nal (1), Oxo (2), Pip (3), Lom (4), Pef (5), and Lev (6)). The Co(III) complexes were identified using micro–analytical, FT–IR spectroscopy, conductance data, effective magnetic moments, electronic UV–vis spectra, and thermal analyses. The six quinolone drug chelates acts as uni–dentate via nitrogen atom of pyridone/piperazyl moiety. Electronic spectroscopic tools are in agreement with an octahedral geometrical structure. Thermal degradation analyses TG–DTG in nitrogen gas environmental are discussed the number and location of water molecules. The thermal decomposition process is completely in 3–4 steps, that the first step is responsible to loss of four uncoordinated water molecules. The stabilities of Co(II) complex 1–6 were studied dependent on activations of energy E*, entropy ΔS*, enthalpy ΔH* and Gibbs free energy ΔG* that have been estimated using Coats–Redfern and Horowitz–Metzeger non–isothermal methods. Molecular docking was used to predict the binding between some quinolone drugs with the receptor of breast cancer mutant 3hb5-oxidoreductase. The structural view of the synthesized cobalt(II)-quinolone nanoparticles has been documented with the help of transmission electron microscope (TEM). The synthesized metal chelates have been screened in vitro antibacterial activity against bacteria, gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) and two strains of fungus (Aspergillus flavus and Candida albicans). The cobalt(II) chelates were shown to possess more antibacterial activity than the free chelates.