Low-dimensional compounds containing cyanido groups. XXIX. Crystal structures, spectral and magnetic properties of five [Cu(L)2X]C(CN)3 complexes (L = 2,2′-bipyridine or 1,10-phenanthroline; X = Cl−, Br− or CH3COO−)

Copper Complexes with 1,10-Phenanthroline Derivatives: Underlying Factors Affecting Their Cytotoxicity

The interpretation of in vitro cytotoxicity data of Cu(II)-1,10-phenanthroline (phen) complexes normally does not take into account the speciation that complexes undergo in cell incubation media and its implications in cellular uptake and mechanisms of action. We synthesize and test the activity of several distinct Cu(II)-phen compounds; up to 24 h of incubation, the cytotoxic activity differs for the Cu complexes and the corresponding free ligands, but for longer incubation times (e.g., 72 h), all compounds display similar activity. Combining the use of several spectroscopic, spectrometric, and electrochemical techniques, the speciation of Cu-phen compounds in cell incubation media is evaluated, indicating that the originally added complex almost totally decomposed and that Cu(II) and phen are mainly bound to bovine serum albumin. Several methods are used to disclose relationships between structure, activity, speciation in incubation media, cellular uptake, distribution of Cu in cells, and cytotoxicity. Contrary to what is reported in most studies, we conclude that interaction with cell components and cell death involves the separate action of Cu ions and phen molecules, not [Cu(phen)_n] species. This conclusion should similarly apply to many other Cu-ligand systems reported to date.

Low-dimensional compounds containing cyanido groups. Part XXXV. Structure, spectral, thermal and magnetic properties of a binuclear CuII-biquinoline complex with bridging and terminal dicyanamide ligands

From the system CuCl₂-biq-NaN(CN)₂ (biq is 2,2'-biquinoline), the binuclear molecular complex bis(μ-dicyanamido-κ²N¹:N⁵)bis[(2,2'-biquinoline-κ²N,N')(dicyanamido-κN¹)copper(II)], [Cu₂(C₂N₃)₄(C₁₈H₁₂N₂)₂] or [Cu₂(biq)₂(dca)₂(μ_1,5-dca)₂] (1) [dca is dicyanamide, N(CN)₂^-] was isolated and characterized by crystal structure analysis, and spectral, thermal and magnetic measurements. IR spectroscopy confirmed the presence of the biq and dca ligands in 1. Its solid-state structure consists of discrete centrosymmetric binuclear copper(II) units with double end-to-end dca bridges. Each Cu^II atom is in a distorted square-pyramidal environment with the equatorial plane formed by two nitrile N atoms from bridging dca groups, one of the two N atoms of the chelate biq molecule and one nitrile N atom from a terminal dca ligand, whereas the second biq N atom occupies the axial position. Thermal decomposition of 1 in an air atmosphere proceeds gradually, with copper(I) cyanide being the final decomposition product. Magnetic measurements revealed the formation of alternating spin chains and a relatively strong exchange interaction within the binuclear units was also confirmed by Broken Symmetry DFT (density functional theory) calculations.

Low-dimensional compounds containing cyanido groups. Part XXXIV. Structure, spectral and magnetic properties of the first complex with pyridylbenzimidazole and nonlinear pseudohalide anion

From the system CuCl2 – pbi – NaN(CN)2 −, polymeric [CuCl(μ1,5-dca)(pbi)]n·nH2O (1) complex (dca=dicyanamide, pbi=2-(2-pyridyl)benzimidazole) was isolated and characterized by structure analysis, spectral and magnetic measurements. Infrared spectroscopy confirmed the presence of pbi, dca and water molecules in 1. Its solid-state structure is formed by infinite chains running along the b axis. In the chain, the Cu(II) atom is penta-coordinated by two nitrogen atoms of chelate pbi ligand, by two nitrile nitrogen atoms of bridging μ1,5-dca and by chloride ligand which occupies the apical position of tetragonal pyramid around the Cu(II) atom. Asymmetric unit is supplemented by one molecule of solvated water, which along with chlorine atom serves as acceptors in intermolecular hydrogen bonds and along with π–π interactions create a 3D supramolecular structure. Magnetic measurements revealed the presence of a weak ferromagnetic exchange interaction J/kB =0.11 K.

A CuII complex with an carbamoylcyanonitrosomethanide ligand formed in situ by the nucleophilic addition of water to dicyanonitrosomethanide: structure, spectral and magnetic properties

The complex (2,2'-biquinoline-κ²N,N')(carbamoylcyanonitrosomethanide-κ²N,O)chloridocopper(II) acetonitrile monosolvate, [Cu(C₃H₂N₃O₂)Cl(C₁₈H₁₂N₂)]·CH₃CN or [Cu(ccnm)Cl(biq)]·acn (acn is acetonitrile, biq is 2,2'-biquinoline and ccnm is carbamoylcyanonitrosomethanide), (I), was prepared as a result of nucleophilic addition of water to the dicyanonitrosomethanide ion in the presence of Cu^II and biq. IR spectroscopy confirmed the presence of ccnm, biq and acn in (I). The solid-state structure consists of the neutral complex containing ccnm and biq ligands, coordinated to the Cu^II atom in a bidendate chelating manner, and a chloride ligand, resulting in a distorted tetragonal pyramidal coordination of Cu^II. The asymmetric unit is supplemented by one molecule of solvated acn which, along with the nitrile group of ccnm, serves as an acceptor in intermolecular hydrogen bonding, creating infinite chains along the b axis. Magnetic measurements revealed a paramagnetic behaviour with a very small Weiss temperature Θ = -0.32 K and high anisotropy of the g tensor (g_x = 2.036, g_y = 2.120 and g_z = 2.205).