Study of the chemical structure and the microbial effect of iron(III) metal ions with four consecutive generations of quinolones in a nanometric form for the purpose of increasing the efficacy of antibacterial and antifungal drugs

Abstract

A new series of iron(III) complexes with different fourth generation of quinolone drugs of the type [Fe(L)n(Cl)x]⋅yH2O ((1) L: nalidixic acid, n = 3, x = 3, y = 3; (2) L: oxolonic acid, n = 3, x = 3, y = 0; (3) L: pipemidic acid, n = 3, x = 3, y = 2; (4) L: lomefloxacin, n = 3, x = 3, y = 0; (5) L: pefloxacin mesylate, n = 3, x = 3, y = 2; (6) L: levofloxacin, n = 3, x = 3, y = 6) were synthesized and identified using microanalysis, Fourier transform infrared spectroscopy, conductance data, effective magnetic moments and electronic UV–visible spectra. In these six complexes, the quinolone drug chelates act in a unidentate manner via nitrogen atom of pyridone/piperazyl moiety. Electronic spectroscopic data are in agreement with an octahedral geometrical structure. Thermal degradation analyses in nitrogen gas were used to investigate the number and location of water molecules. The thermal decomposition process is completed in 3−5 steps, the first step being responsible for loss of uncoordinated water molecules and the steady state of all complexes occurs at around 500 °C with oxide forms as residual products. The stabilities of iron(III) complexes 1–6 were studied in terms of activation energy E*, entropy ΔS*, enthalpy ΔH* and Gibbs free energy ΔG* that were estimated using Coats–Redfern and Horowitz–Metzger non‐isothermal methods. Molecular docking was used to predict the binding between some of the quinolone drugs and the receptor of prostate cancer 2q7k hormone.