Spectroscopic and thermal degradation behavior of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes with thiopental sodium anesthesia drug

A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized with thiopental sodium anesthesia drug. The elemental analyses of the complexes are confined to stoichiometry of the formulas [M(TPL)3]⋅nH2O (M = Cr(III) or Fe(III); n = 6 or 5), [M(TPL)2(H2O)2]⋅nH2O (M = Mn(II), Co(II) or Ni(II); n = 0 or 4), and [M(TPL)2] (M = Cu(II) or Zn(II); n = 2 or 0) respectively, where TPL is thiopental chelating agent. Structures have been discussed and suggested upon elemental analyses, infrared, Raman, electronic, electron spin resonance, 1H NMR spectral data and magnetic studies. The X-ray powder diffraction (XRD) was performed of metal complexes. The XRD patterns indicate crystalline nature for the complexes. The measured low molar conductance values in dimethylsulfoxide indicate that the complexes are non-electrolyte nature. Spectroscopic discussion refer that coordination take place through three types: CN (pyrimidine moiety) nitrogen and C2S (2-thiolate group) for Cr(III), Mn(II) and Fe(III), C6O (amido group) oxygen and C2S (2-thiolate group) for Co(II) and Ni(II), and Cu(II) and Zn(II) ions coordinated via CN (pyrimidine moiety) nitrogen, C2S (2-thiolate group) and C6O (amido group) oxygen, respectively. The thermal behavior (TG/DTG/DTA) of the complexes was studied and kinetic parameters were determined by Horowitz–Metzger and Coats–Redfern methods. The thiopental and its complexes have been screened for their antimicrobial (G+ and G−) bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa) and fungi (Aspergillus flavus and Candida albicans) activities by minimum inhibitory concentration (MIC) method.

► The novel Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of thiopental have synthesized.
► The compounds containing pyrimidine ring play an important role in many biological systems.
► Thiopental is capable of existing in tautomeric forms (thione–thiol).
► The Cr(III) and Fe(III) complexes have crystalline particles in nano-scale range.