Synthesis, X-ray crystallography and electrochemistry of three novel copper complexes with imidazole-containing hydantoin and thiohydantoins

Three types of copper derivatives formed by CuCl2·2H2O interaction with (Z)-3-aryl-2-(methylthio)-5-(pyridine-2-ylmethylene)-3,5-dihydro-4H-imidazol-4-ones

The reactions of (Z)-3-aryl-2-(methylthio)-5-(pyridine-2-ylmethylene)-3,5-dihydro-4H-imidazol-4-ones (3) with CuCl2·2H2O in the presence of a reducing solvent (alcohol or dimethylformamide (DMF)) produce three types of Cu-containing compounds: two Cu complexes with a composition of CuII(3)Cl2 (4) and CuI(3)Cl (5) as well as a salt (3 + H)+CuICl2- (6) in a 4 : 5 : 6 ratio depending on the substituent at the N(3) nitrogen atom of the ligand moiety. In non-reducing solvents (dimethyl sulfoxide (DMSO) and CHCl3/acetone), only complexes 4 were formed, All three Cu derivatives (4, 5, and 6) were characterized by single-crystal X-ray diffraction, UV/vis spectroscopy, and electrochemistry data. Convenient electrochemical and UV-vis spectral criteria were recorded, which made it possible to distinguish between the different Cu-containing compounds. Based on the electron spectroscopy and electron paramagnetic resonance (EPR) data, a possible scheme for the formation of compounds 4-6 was proposed, including the initial coordination of copper(ii) chloride with an organic ligand, the subsequent reduction of the resulting complex 4 by DMF with the formation of salt 6, and the further transition of salt 6 into the complex 5.

Novel Copper-Containing Cytotoxic Agents Based on 2-Thioxoimidazolones

A series of 73 ligands and 73 of their Cu⁺² and Cu⁺¹ copper complexes with different geometries, oxidation states of the metal, and redox activities were synthesized and characterized. The aim of the study was to establish the structure-activity relationship within a series of analogues with different substituents at the N(3) position, which govern the redox potentials of the Cu⁺²/Cu⁺¹ redox couples, ROS generation ability, and intracellular accumulation. Possible cytotoxicity mechanisms, such as DNA damage, DNA intercalation, telomerase inhibition, and apoptosis induction, have been investigated. ROS formation in MCF-7 cells and three-dimensional (3D) spheroids was proven using the Pt-nanoelectrode. Drug accumulation and ROS formation at 40-60 μm spheroid depths were found to be the key factors for the drug efficacy in the 3D tumor model, governed by the Cu⁺²/Cu⁺¹ redox potential. A nontoxic in vivo single-dose evaluation for two binuclear mixed-valence Cu⁺¹/Cu⁺² redox-active coordination compounds, 72k and 61k, was conducted.