Elaborated 1H NMR study for the ligitional behavior of two thiosemicarbazide derivatives towards some heavy metals (Sn(II), Sb(III), Pb(II) and Bi(III)), thermal, antibacterial and antifungal studies

A new series of heavy metal complexes are prepared. Sn(II), Sb(III), Pb(II) and Bi(III) are the metal ions used in complexation with two thiosemicarbazide ligands. The IR and 1H NMR spectra of the free ligands display their presence in thiole–thione forms coincide with each other. The IR spectra of the complexes support the presence of 2:2 molar ratio (M:HL) with HL1 ligand and 1:1 beside 1:2 with HL2. The ligand coordinates as bi molecules in some complexes and displays two tautomer forms at the same complex molecule 1H NMR spectra of Sn(II) and Sb(III) complexes were done and comes coincide with IR data. The electronic spectral analysis displays a lower shift appearance in n → π* charge transfer band in most isolated complexes. As well as, a new band is shinned in visible region with Sb(III), Bi(III) complexes and Sn(II)–HL2. This band is pointed to its use in spectrophotometric analysis for these metal ions. The TG analysis for all isolated compounds was briefly discussed. The molecular modeling parameters support the stability of thiole form of the free ligands in comparing with their thiones by a small difference. The antibacterial and antifungal activities were studied against some organisms and reveal the priority of most investigated complexes.

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• A new series of heavy metal complexes are prepared.
• Sn(II), Sb(III), Pb(II) and Bi(III) are the metal ions used in complexation with two thiosemicarbazide ligands.
• The IR and 1H NMR spectra of the free ligands display their presence in thiole–thione forms coincide with each other.
• The IR spectra of the complexes support the presence of 2:2 molar ratio with HL1 ligand and 1:1 beside 1:2 with HL2.
• The antibacterial and antifungal activities were studied.