Paras Nath Yadav

Platinum(II) and palladium(II) complexes with 2-acetyl pyridine 4N-ethyl thiosemicarbazone able to overcome the cis-platin resistance. Structure, antibacterial activity and DNA strand breakage.

The reactions of Pd(II) and Pt(II) with 2-Acetyl Pyridine N(4)-Ethyl-Thiosemicarbazones, HAc4Et and 2-Acetyl Pyridine N(4)-1-(2-pyridyl)-piperazinyl Thiosemicarbazone, HAc4PiPiz and 2-Formyl Pyridine N(4)-1-(2-pyridyl)-piperazinyl Thiosemicarbazone, HFo4PiPiz afforded the complexes, [Pd(Ac4Et)], 1, [Pd(HAc4Et)2]Cl2, 2 and [Pd(Ac4Et)2], 3[Pt(Ac4Et)], 4, [Pt(HAc4Et)2]Cl2, 5, [Pt(Ac4Et)2], 6 and [Pd(Fo4PipePiz)Cl], 7, [Pd(Fo4PipePiz)2], 8, [Pd(Ac4PipePiz)Cl], 9 and [Pd(Ac4PipePiz)2], 10. The crystal structure of the complex [Pt(Ac4Et)2], 6 has been solved. The platinum(II) atom is in a square planar environment surrounded by two cis nitrogen atoms and two cis sulfur atoms. The ligands are not equivalent, one being tridentate with (N,N,S) donation, the other being monodentate using only the sulfur atom to coordinate to the metal. The tridentate ligand shows a Z, E, Z configuration while the monodentate ligand shows an E, E, Z. Inter-molecular hydrogen bonds stabilize the structure, while the crystal packing is determined by π−π, and Pt – C interactions. The antibacterial effect of Pd(II) and Pt(II) complexes were studied in vitro. The complexes were found to have effect on Gram(+) bacteria, while the same complexes showed no bactericidal effect on Gram(−) bacteria. The effect of the Pd(II) and Pt(II) complexes on the in vitro DNA strand breakage was studied by agarose gel electrophoresis. The complexesxa01-6 were found to exhibit a cytotoxic potency in a very low micromolar range and to be able to overcome the cisplatin resistance of A2780/Cp8 cells (Kovala-Demertzi etxa0al. 2000).

Synthesis, crystal structure, spectral properties and cytotoxic activity of platinum(II) complexes of 2-acetyl pyridine and pyridine-2-carbaldehyde N(4)-ethyl-thiosemicarbazones

The reactions of Na2PtCl4 with pyridine-2-carbaldehyde and 2-acetyl pyridine N(4)-ethyl-thiosemicarbazones, HFo4Et and HAc4Et respectively, afforded the complexes [Pt(Fo4Et)Cl], [Pt(HFo4Et)2]Cl2, [Pt(Fo4Et)2] and [Pt(Ac4Et)Cl], [Pt(HAc4Et)2]Cl2 x 2H2O, [Pt(Ac4Et)2]. The new complexes have been characterized by elemental analyses and spectroscopic studies. The crystal structure of the complex [Pt(Ac4Et)Cl] has been solved. The anion of Ac4E coordinates in a planar conformation to the central platinum(II) through the pyridyl N, azomethine N and thiolato S atoms. Intermolecular hydrogen, non-hydrogen bonds, pi-pi and weak Pt-pi contacts lead to aggregation and a supramolecular assembly. The cytotoxic activity for the platinum(II) complexes in comparison to that of cisplatin and thiosemicarbazones was evaluated in a pair of cisplatin-sensitive and -resistant ovarian cancer cell lines A2780 and A2780/Cp8. The platinum(II) complexes showed a cytotoxic potency in a very low micromolar range and were found able to overcome the cisplatin resistance of A2780/Cp8 cells.

Palladium(II) complexes of 4-formylantipyrine N(3)-substituted thiosemicarbazones: first example of X-ray crystal structure and description of bonding properties

Abstract Reaction of 4-formylantipyrine with thiosemicarbazide, N(3)-methylthiosemicarbazide and N(3)-ethylthiosemicarbazide produced the expected thiosemicarbazones, 1, 2 and 3. The three thiosemicarbazones were then reacted with K2PdCl4 to produce [Pd(NS)2] complexes, 4, 5, and 6, respectively, with coordination by the imine nitrogen and thiolate sulfur of the anionic thiosemicarbazone moiety. The thiosemicarbazones and their palladium complexes have been characterized by spectral IR, UV–Vis and 1H, 13C NMR and electrochemical techniques. The crystal structure of 6 has been obtained and found to be highly symmetrical with a trans arrangement of the two bidentate ligands.

Preparation, spectral and structural characterization of (2-benzoylpyridine N(4)-methyl-N(4)-phenylthiosemicarbazonato) chloropalladium(II)

The synthesis, as well as spectral and structural characterization, of (2-benzoylpyridine-N(4)-methyl-N(4)-phenylthiosemicarbazonato)chloropalladium(II), [Pd(Bz4MePh)Cl], is described. The unit cell contains two crystallographically independent molecules [Pd(1)(Bz4MePh)Cl], (1), and [Pd(2)(Bz4MePh)Cl], (2), stabilized by intra- and intermolecular hydrogen bonding. The distance between the Pd(1) and Pd(2) centres is 3.5038(11) Å. The spectroscopic techniques used in this study are the following: u.v.-visible, i.r. and 1H n.m.r. The protonation constants, determined spectrophotometrically, of the uncoordinated HBz4MePh are pKa1 = 10.82 ± 0.03 and pKa2 = 4.09 ± 0.02.

Synthesis, solution and spectral studies of palladium(II) complexes with 2-hydroxyacetophenone N(3)-propylthiosemicarbazone. Crystal structure of a tripalladium complex

Abstract The reactions of palladium(II) salts with 2-hydroxyacetophenone N(3)-propylthiosemicarbazone, H 2 Ap3Pr, are described. The synthesis and spectral characterization of a new triangular , trinuclear palladium(II) complex with the dianion, Ap3Pr 2− , are reported. The X-ray crystal structure determination of [Pd(Ap3Pr 2 )] 3 ·DMF shows it to contain a chair-form hexagon of alternating Pd and S atoms to form a molecular bowl. The spectrophotometric characterization of H 2 Ap3Pr is also reported.