Synthesis, Structure, and Antiproliferative Activities of Complexes of Some Transition Metals with 5,7-Dichloro-8-Hydroxyquinoline-2-Carboxaldehyde-4-Phenyl-3-Thiosemicarbazone

A new quinoline–thiosemicarbazone derivative, 5,7-dichloro-8-hydroxyquinoline-2-carboxaldehyde-4-phenyl-3-thiosemicarbazone (QPS) and seven complexes of QPS with d-transition metals (Mn, Fe, Co, Ni, Cu, Zn, Cd) were successfully synthesized. Spectrometry methods such as IR, ESI-MS, and ¹H NMR were utilized to determine the structure of complexes that almost all complexes form the metal:ligand ratio of 1:1, except for FeQPS, which forms a 1:2 ratio. The center metals bond to QPS through O, N_quinoline and N_{thiosemicarbazone}. Four tested complexes (MnQPS, CoQPS, NiQPS, CuQPS) show medium inhibition to KB and Hep-G2 cancer cell lines. ZnQPS has the high activity against KB and Hep-G2 (IC₅₀ = 13.51 and 10.28 μg/mL) and a high impact against the LU cancer cell line (IC₅₀ = 2.0 μg/mL). CdQPS complexes showed excellent activity on both KB and Hep-G2 with IC₅₀ very low, IC₅₀ = 3.12 and 3.06 μg/mL, which is much lower than cisplatin.