A novel Cu(II) distorted cubane complex containing Cu4O4 core as the first tetranuclear catalyst for temperature dependent oxidation of 3,5-di-tert-butyl catechol and in interaction with DNA & protein (BSA)

A novel palladium(II) antitumor agent: Synthesis, characterization, DFT perspective, CT-DNA and BSA interaction studies via in-vitro and in-silico approaches

Since numerous people annually pass away due to cancer, research in this field is essential. Thus a newly made and water like palladium(II) complex of formula [Pd(phen)(acac)]NO₃, where phen is 1,10-phenanthroline and acac is acetylacetonato ligand, has been synthesized by the reaction between [Pd(phen)(H₂O)₂](NO₃)₂ and sodium salt of acetylacetone in the molar ratio of 1:1. It has been structurally characterized via the methods such as conductivity measurement, elemental analysis and spectroscopic methods (FT-IR, UV-Vis and ¹H NMR). The geometry optimization of this complex at the DFT level of theory reveals that Pd(II) atom is situated in a square-planar geometry. The complex has been screened for its antitumor activity against K562 cancer cells which demonstrated efficacious activity. The interaction of above palladium(II) complex with CT-DNA as a target molecule for antitumor agents and BSA as a transport protein was studies by a variety of techniques. The results of UV-Vis absorption and fluorescence emission indicated that the Pd(II) complex interacts with EB + CT-DNA through hydrophobic and with BSA by hydrogen bonding and van der Waals forces at very low concentrations. In these processes, the fluorescence quenching mechanism of both the macromolecules seems to be the combined dynamic and static. The interaction was further supported for CT-DNA by carrying out the gel electrophoresis and viscosity measurement and for BSA by the circular dichroism and Förster resonance energy transfer experiments. Furthermore, results of partition coefficient determination showed that the [Pd(phen)(acac)]NO₃ complex is more lipophilic than that of cisplatin. Moreover, molecular docking simulation confirms the obtained results from experimental tests and reveals that the complex tends to be located at the intercalation site of DNA and Sudlow's site I of BSA.

Synthesis of Novel Tetra(µ3-Methoxo) Bridged with [Cu(II)-O-Cd(II)] Double-Open-Cubane Cluster: XRD/HSA-Interactions, Spectral and Oxidizing Properties

A new double-open-cubane core Cd(II)-O-Cu(II) bimetallic ligand mixed cluster of type [Cl2Cu4Cd2(NNO)6(NN)2(NO3)2].CH3CN was made available in EtOH/CH3CN solution. The 1-hydroxymethyl-3,5-dimethylpyrazole (NNOH) and 3,5-dimethylpyrazole (NNH) act as N,O-polydentate anion ligands in coordinating the Cu(II) and Cd(II) centers. The structure of the cluster in the solid state was proved by XRD study and confirmed in the liquid state by UV-vis analysis. The XRD result supported the construction of two octahedral and one square pyramid geometries types around the four Cu(II) centers and only octahedral geometry around Cd(II) two centers. Interestingly, NNOH ligand acts as a tetra-µ3-oxo and tri-µ2-oxo ligand; meanwhile, the N-N in NNH acts as classical bidentate anion/neutral ligands. The interactions in the lattice were detected experimentally by the XRD-packing result and computed via Hirschfeld surface analysis (HSA). The UV-vis., FT-IR and Energy Dispersive X-ray (EDX), supported the desired double-open cubane cluster composition. The oxidation potential of the desired cluster was evaluated using a 3,5-DTB-catechol 3,5-DTB-quinone as a catecholase model reaction.

Dinuclear copper(II) complexes with derivative triazine ligands as biomimetic models for catechol oxidases and nucleases

The research reported herein focuses on the synthesis of two new Cu(II) complexes {[Cu₂(2-X-4,6-bis(di-2-picolylamino)-1,3,5-triazine], with X = butane-1,4-diamine (2) or N-methylpyrenylbutane-1,4-diamine (3)}, the latter with a pyrene group as a possible DNA intercalating agent. The structure of complex (3) was determined by X-ray crystallography and shows the dinuclear {Cu^II(μ-OCH₃)₂Cu^II} unit in which the Cu^II···Cu^II distance of 3.040 Å is similar to that of 2.97 Å previously found for 1, which contains a {Cu^II(μ-OH)₂Cu^II} structural unit. Complexes (2) and (3) were also characterized in spectroscopic and electrochemical studies, and catecholase-like activity were performed for both complexes. The kinetic parameters obtained for the oxidation of the model substrate 3,5-di-tert-butylcatechol revealed that the insertion of the spacer butane-1,4-diamine and the pyrene group strongly contributes to increasing the catalytic efficiency of these systems. In fact, K_ass becomes significantly higher, indicating that these groups influence the interaction between the complex and the substrate. These complexes also show DNA cleavage under mild conditions with moderate reaction times. The rate of cleavage (k_cat) indicated that the presence of butane-1,4-diamine and pyrene increased the activity of both complexes. The reaction mechanism seems to have oxidative and hydrolytic features and the effect of DNA groove binding compounds and circular dichroism indicate that all complexes interact with plasmid DNA through the minor groove. High-resolution DNA cleavage assays provide information on the interaction mechanism and for complex (2) a specificity for the unpaired hairpin region containing thymine bases was observed, in contrast to (3).