Synthesis, characterization, crystal structures, in vitro and in vivo antitumor activity of palladium(II) and zinc(II) complexes with 2-formyl and 2-acetyl pyridine N(4)-1-(2-pyridyl)-piperazinyl thiosemicarbazone

Synthesis and Characterization of Novel Cu(II), Pd(II) and Pt(II) Complexes with 8-Ethyl-2-hydroxytricyclo(7.3.1.02,7)tridecan-13-one-thiosemicarbazone: Antimicrobial and in Vitro Antiproliferative Activity

“…The very intense bands at about 22,220 cm´1 and 23,250 cm´1, respectively, are assignable to a combination of metal-ligand charge transfer and d-d bands (Table 1) [44]. The values of µ eff , for complexes 1-5 suggest the presence of an unpaired electron.…”

Palladium(II) Complex of the 5-Hydroxypyridine-2-carbaldehyde N(4)-ethylthiosemicarbazone: Synthesis and Characterization

“…The shift of N(4)C 2 H 5 proton resonance were not significant as the aldehyde hydrogen because of their greater distance from the coordinating thion sulphur 13 . 1 H-NMR signals in the complex were essentially shifted upfield compare to that of free thiosemicarbazone and the affected proton resonance were C(6)H, C(7)H and S=C-N(4)H. These upfield shifts support coordination of the pyridinyl nitrogen, azomethine nitrogen and thionyl sulphur to Pd(II) forming two five membered chelate rings around Pd(II) centre which contribute to the stability of the complex a structural motive that seems to be stable both in the solid state and in DMSO solution 11,12 . A comparison of these bands with bands of free ligands revealed that there is decrease in intensity and increase in the frequency that is attributed to coordination of ligand 11,12,14,15 .…”

“…In the 1 H-NMR spectra of the complex, C(6)H in the free ligand (8.09 ppm) was shifted up field in the complex (7.88 ppm) upon coordination, in accord with an increased electron density at this site in the complex due to π-back bonding from Pd(II) 11 . Absence of the N(3)H signal in the complex, implies that anionic ligand was involved in coordination 9,11 .…”

“…Absence of the N(3)H signal in the complex, implies that anionic ligand was involved in coordination 9,11 . On coordination of the sulphur and imine nitrogen atoms the electron density would be expected to be lost from the H-C=N function, as has been observed for many complexes of thiosemicarbazones.…”

“…Free ligand did not show any peak attributed to S-H proton indicating that it exist in thione form. The broad peak in the 10.39 ppm region was identified as C(5)OH signal and it was not detected in the complex may be because of excessive hydrogen bonding or exchange of -OH proton with the water molecule 6,11,12 .…”