Manganese (II), ferric (III), cobalt (II) and copper (II) thiosemicarbazone Schiff base complexes: Synthesis, spectroscopic, molecular docking and biological discussions

Abstract

Mn(II), Fe(III), Co(II) and Cu(II) Schiff base complexes with general formula ML−2 .nH2O (where M is a respected metal ions and L−2 is the Schiff base). The Schiff base (L = TSCPA) was formed by the condensation of thiosemicarbazide and phthalic anhydride in acetic acid. The microanalytical analysis confirmed the 1:1 (metal: ligand) molar ratio. Magnetic susceptibility and electronic absorption spectra were suggested that the Fe(III) and Co(II) complexes were octahedral structure but the Mn(II) and Cu(II) complexes were tetrahedral geometry. FTIR spectra reveal that the ligand exists, predominantly, as keto form in a solid state but as enol form in the alkaline medium. The coordination between TSCPA chelate and central metal ions take place through nitrogen –NH, sulphur C=S and oxygen –OH groups. Based on the molar conductance measurements the complexes may be formulated as [Mn(L)(H2O)] · 4H2O, [Fe(L)(Cl)(H2O)2] · 2H2O, [Co(L)(H2O)3] · 3H2O and [Cu(L)(H2O)] · 4H2O due to their non-electrolytic behavior. The Schiff base ligand and their metal complexes were screened in vitro against G(+Ve) and G(−Ve) bacteria. This study came after proactive step, which concerning with docking study against pathogen proteins corresponding to microorganisms for bacteria and fungi, which will be scanned in vitro study. Thermogravimetry (TGA) and differential thermogravimetry (DTG) were discussed.