Two Different Thiosemicarbazone Tauto‐Conformers Coordinate to Palladium (II). Stability and Biological Studies of the Final Complexes

Abstract

Thiosemicarbazone moiety is a valuable scaffold for the synthesis of metallic complexes with anticancer purposes, when bearing N‐heterocyclic the final compounds possess diverse biological activities. Using thiazole as bioisosteres, the resulting thiosemicarbazones can afford synthetic drugs with a variety of pharmacological effects. Trying to elucidate, if metal complexes from α‐N‐heterocyclic thiosemicarbazones can achieve more selectivity versus special tumor lines, we have developed new metal complexes with 1H imidazole‐4‐carboxaldehyde 4 N‐p‐tolyl‐ and 4 N‐phenylthiosemicarbazone (HL1 and HL2 respectively). The solution studies of these ligands showed a tautomeric equilibria in solution and their reaction with Li2PdCl4 proved the stability of both forms affording two mononuclear Pd(II) complexes. Both tautomeric forms are clearly coordinated to palladium center acting as two different bidentate ligands. Palladium complexes’ stability in biological buffers was investigated to stablish the optimal conditions for the evaluation of cytotoxicity, that on the triple negative adenocarcinoma cell line showed IC50 values in the low micromolar range. Complexes were also studied with CT DNA (UV‐Visible spectroscopy and viscosity) and with the pBR322 plasmid supercoiled models, indicating non covalent interaction.

Proving the Antimicrobial Therapeutic Activity on a New Copper–Thiosemicarbazone Complex

“…The Cu–N and Cu–S binding distances (Table ) are comparable with those of other reported Cu­(II)–TSCN complexes. The C–S bond distance at the coordinated ligand (∼1.74 Å) is within the expected range for a single bond, confirming the thiolate TSCN’s form. , The C–N and N–N distances are intermediate between single and double bonds, confirming that charge is delocalized along the TSCN skeleton (Figure A). , …”

“…27,28 The C−N and N−N distances are intermediate between single and double bonds, confirming that charge is delocalized along the TSCN skeleton (Figure 2A). 29,30 The crystalline packing of complex 1 is stabilized by intermolecular hydrogen bonds between solvent molecules (dimethyl sulfoxide, DMSO) and N4 of the ligands (N4•••O = 2.794(4) Å) and, in addition, by the existence of a certain π−π stacking between the aromatic rings of adjacent molecules with 3.393 Å (Figure 2B).…”

Novel Thiazole Derivatives Containing Imidazole and Furan Scaffold: Design, Synthesis, Molecular Docking, Antibacterial, and Antioxidant Evaluation

“…Carbothioamide 3a,b was produced by reacting 1-(2-(furan-2-yl)-4-methyl-1H-imidazol-5-yl)ethan-1-one 1 [44] with N-arylhydrazinecarbothioamide [45] in absolute EtOH containing five drops of concentrated HCl (Scheme 1). The structure of thiosemicarbazones 3a and 3b was identified based on elemental analyses and spectral data.…”

Conversion of a double-tetranuclear cluster silver helicate into a dihelicate via a rare desulfurization process

“…8 Thiosemicarbazone ligands have been used for a long time for the preparation of biologically active metal compounds. 9 More recently they have been demonstrated to be suitable precursors of metallosupramolecular architectures due to their great coordinative versatility, with the possibility of obtaining cluster helicates, 5,6 helicates 10 or mesocates 11 with different metal ions and predicting their supramolecular structure. 12 In this work, we present the first case of a double Ag(I) tetranuclear cluster helicate and its conversion into a sulfate dihelicate via a desulfurization process that occurred during recrystallization.…”