Photoactive Pt-Ii And Pd-Ii Complexes Of N,N-Diethyl-N '-3,4,5-Trimethoxybenzoylthiourea: Synthesis, Crystal Structures, Dft And Cytotoxicity Studies

Photo-chemical isomerism of the cis-[Pd-II/Pt-II(L-kappa S,O)(2)] complexes of N,N-di-ethyl-N '-3,4,5-trimethoxy-benzoylthiourea (HL) in acetonitrile reversibly produces geometric trans-[Pd-II/Pt-II(L-kappa S,O)(2)] isomers in solution after irradiation with visible light, as determined by H-1 NMR, UV-vis and reverse phase chromatography (RP-HPLC). Single-crystal X-ray diffraction studies reveal that the new trans-[Pd-II/Pt-II(L-kappa S,O kappa S,O)(2)] complexes crystallize in a triclinic P1 space group, with the sulfur and oxygen donor atoms arranged trans to each other in the six-membered chelate. Structural analysis of the cis- and trans-[Pd-II/Pt-II(L-kappa S,O)(2)] complexes performed using time-dependent DFT at the B3LYP/CEP31-G level of theory reveals that the cis-[Pd-II/Pt-II(L-kappa S,O)(2)] complexes are more stable than their trans-[Pd-II/Pt-II(L-kappa S,O)(2)] counterparts. The cytotoxicity of the HL ligand and its corresponding cis-[Pd-II/Pt-II(L-kappa S,O)(2)] and trans-[Pd-II(L-kappa S,O)(2)] complexes was investigated against the human prostate cancer cell line (DUI45) and the normal embryonic kidney cell line (HEK-293). Cytotoxicity was evident after complexation with the HL ligand. In particular trans-[Pd-II(L-kappa S,O)(2)] and cis-[Pt-II(L-kappa S,O)(2)] complexes produced a significant dose-dependent decrease in cell viability of both cell lines. cis-[Pt-II(L-kappa S,O)(2)] presented the most cytotoxic activity against DUI45 and comparable selectivity to doxorubicin, a commonly used anticancer drug, indicating its potential as a Pt-based anticancer compound.