Multiple coordination modes of a new ditopic bis(pyrazolyl)methane-based ligand

Copper-Based Complexes with Adamantane Ring-Conjugated bis(3,5-Dimethyl-pyrazol-1-yl)acetate Ligand as Promising Agents for the Treatment of Glioblastoma

The new ligand L2Ad, obtained by conjugating the bifunctional species bis(3,5-dimethylpyrazol-1-yl)-acetate and the drug amantadine, was used as a chelator for the synthesis of new Cu complexes 1-5. Their structures were investigated by synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and by combining X-ray absorption fine structure (XAFS) spectroscopy techniques and DFT modeling. The structure of complex 3 was determined by single-crystal X-ray diffraction analysis. Tested on U87, T98, and U251 glioma cells, Cu(II) complex 3 and Cu(I) complex 5 decreased cell viability with IC50 values significantly lower than cisplatin, affecting cell growth, proliferation, and death. Their effects were prevented by treatment with the Cu chelator tetrathiomolybdate, suggesting the involvement of copper in their cytotoxic activity. Both complexes were able to increase ROS production, leading to DNA damage and death. Interestingly, nontoxic doses of 3 or 5 enhanced the chemosensitivity to Temozolomide.

Supramolecular topology design of silver(i) and copper(ii) coordination polymers through a new semi-rigid sulfonyl ligand with different anion templates

A series of metal organic coordination polymers (MOCPs) of silver(i) and copper(ii) coordinated with a novel multifunctional semi-rigid sulfonyl ligand with different anion templates and oxidation states were designed for the first time. In addition, their atomically precise molecular structure was determined by single crystal X-ray diffraction analysis. In comparison, the topology of silver(i)-based MOCPs is affected significantly by different anion templates. The coordination modes are quite different with the anions varying: linear for ClO4-, trilateral for CO2CF3-, and tetrahedral for CO2C2F5-. Due to the difference of electron configurations between Ag(i) and Cu(ii), the coordinated configuration of the metal center is also different. While the coordinated configuration of Cu(ii) center tends to be placed in an octahedron. Furthermore, for the copper(ii) MOCPs, the oxidation state of the L ligand also plays an important role. When the N atoms in L were oxidized, the coordination mode of Cu(ii) became tetrahedral with Cu(ii) stuck on the bottom of the conventional octahedral mode. In general, it is an effective and controllable strategy to mediate the coordination mode and aggregation of supramolecular assembly-based MOCPs through the combination of a multifunctional organic ligand and its corresponding oxidation state design; elaborate metallic species and electron configuration selection; and suitable anion template introduction to generate multiform and hierarchical non-covalent bond interactions including π-π interactions and hydrogen bond formation that afford their coordination mode diversity.