ABSTRACT
The reaction between 5-acetylbarbituric acid and 4-dimethylthiosemicarbazide or 4-hexamethyleneiminyl thiosemicarbazide produces 5-acetylbarbituric-4-dimethylthiosemicarbazone (H2AcbDM) and 5-acetylbarbituric-4N-hexamethyleneiminyl thiosemicarbazone (H2Acbhexim). Eight new complexes with different copper(II) salts have been prepared and characterized using elemental analysis, molar conductance, UV-Vis, ESI-HRMS, FT-IR, magnetic moment, EPR, and cyclic voltammetry. In addition, three-dimensional molecular structures of [Cu(HAcbDM)(H2O)2](NO3)·H2O (3a), [Cu(HAcbDM)(H2O)2]ClO4 (4), and [Cu(HAcbHexim)Cl] (6) were determined by single crystal X-ray crystallography, and an analysis of their supramolecular structure was carried out. The H-bonded assemblies were further studied energetically using DFT calculations and MEP surface and QTAIM analyses. In these complexes, the thiosemicarbazone coordinates to the metal ion in an ONS-tridentate manner, in the O-enolate/S-thione form. The electrochemical behavior of the thiosemicarbazones and their copper(II) complexes has been investigated at room temperature using the cyclic voltammetry technique in DMFA. The Cu(II)/Cu(I) redox system was found to be consistent with the quasi-reversible diffusion-controlled process.
ABSTRACT
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Subject(s)
Humans , Female , Middle Aged , Graves Ophthalmopathy/drug therapy , Orbital Diseases/drug therapy , Antibodies, Monoclonal/therapeutic use , Thyroid Diseases/complications , Adrenal Cortex Hormones/therapeutic useABSTRACT
Octahedral 1:1 Ni(II) and square-planar 1:1 Pd(II) and Pt(II) complexes of formulae [Ni(HAcb4DM)(AcO)(H2O)2]·H2O (1), [Pd(HAcb4DM)Cl]·5H2O (2) and [Pt(HAcb4DM)Cl]·3H2O (3), where H2Acb4DM = 5-acetylbarbituric-4N-dimethylthiosemicarbazone (H2 denoting its two dissociable protons, one enolic and one thiolic), have been synthesized and characterized by elemental analysis and by 1H and 13C NMR, UV-vis, and IR spectroscopy. Crystallisation of compounds 13 from DMSO afforded complexes of formulae [Ni(HAcb4DM)2]·2H2O (1a), [Pd(Acb4DM)(DMSO)]·DMSO (2a) and [Pt(Acb4DM)(DMSO)]·DMSO (3a), the molecular and crystal structures of which were determined by X-ray diffractometry. The thiosemicarbazone in 1a coordinates to the metal ions in an ONS-tridentate manner in the O-enolate/S-thione form, but in complexes 2a and 3a the thiosemicarbazone binds Pd(II) or Pt(II) as an ONS-pincer ligand in the O-enolate/S-thiolate form. The 195Pt NMR spectrum of 3 shows a signal at −2950 ppm along with two new signals at −3348 and −2731 ppm, indicating the presence of solvolysis products. The catalytic activity of complex 2a has been explored in arylaryl Suzuki cross-coupling reactions. H2Acb4DM and complexes 2 and 3 were screened for in vitro cytotoxicity against a human tumour cell line (HeLa-229), with the clinically employed drug cisplatin as a reference.
