THEORETICAL STUDIES, SYNTHESIS AND CHARACTERIZATION OF PALLADIUM (II) AND PLATINUM (II) COMPLEXES WITH LIGANDS DERIVED FROM PYRENE AND THIOSEMICARBAZONES

Coordination complexes with metals have been investigated with the aim of developing new chemotherapeutic agents with lower toxicity, fewer side effects, improved bioavailability, and greater stability. This work consists of theoretical studies of Molecular Docking and interaction energy calculations in order to better guide the experimental phase and to understand the interaction with the DNA–complex. The DNA structure was obtained from the Protein Data Bank under the code 1FQ2. The ligand used for the formation of Pd(II) and Pt(II) complexes was synthesized through condensation reactions between pyrenecarboxaldehyde and thiosemicarbazide. The synthesis was carried out starting from the ligand with the HPrCh substituent, which was then used in reactions for the formation of complexes with Pd(II) and Pt(II), where Ch = cyclohexyl. After synthesis, the complexes were characterized by FTIR and UV–Vis spectroscopy, followed by preliminary biological assays.

The Molecular Docking results showed that both the Pd(II) and Pt(II) complexes displayed good interaction when compared to camptothecin, which is known for its strong interaction within the grooves of this DNA. Interaction energy values indicated that both complexes exhibited more favorable binding energies than camptothecin. FTIR spectroscopy was used to investigate the interactions of the HPrCh ligand with Pt(II) and Pd(II) ions, confirming the formation of the [Pt(HPrCh)₂] and [Pd(HPrCh)₂] complexes. Spectroscopic assignments revealed the presence of a broad ν(N–H) band with a slight shift upon complex formation, suggesting coordination. The ν(C–H) bands confirmed the integrity of the aromatic structure, indicating no disruption of the aromatic rings. A slight shift to lower frequency observed in ν(C=N) supported coordination through the azolic nitrogen atom v(C=N). The appearance of new bands attributed to metal–ligand bonds v(Pd–N, Pt–N, Pd–S, and Pt–S) provided further evidence of complex formation. Preliminary results proved to be very promising, indicating that these complexes are potential prototypes for cancer therapy.