Construction of heterometallic and mixed-valence copper(I/II) chloride π-complexes with 1,2,4-triazole allyl-derivative

An engineered POSS drug delivery system for copper(II) anticancer metallodrugs in a selective application toward melanoma cells

In this work, a polyhedral silsesquioxane (POSS) was used as an engineered drug delivery system for two oxindolimine-copper(II) anticancer complexes, [Cu(isaepy)]+ and [Cu(isapn)]+. The interest in hybrid POSS comes from the necessity of developing materials that can act as adjuvants to improve the cytotoxicity of non-soluble metallodrugs. Functionalization of POSS with a triazole ligand (POSS-atzac) permitted the anchorage of such copper complexes, producing hybrid materials with efficient cytotoxic effects. Structural and morphological characterizations of these copper-POSS systems were performed by using different techniques (IR, NMR, thermogravimetric analysis). A combination of continuous-wave (CW) and pulsed EPR (HYSCORE) spectroscopies conducted at the X-band have enabled the complete characterization of the coordination environment of the copper ion in the POSS-atzac matrix. Additionally, the cytotoxic effects of the loaded materials, [Cu(isapn)]@POSS-atzac and [Cu(isaepy)]@POSS-atzac, were assessed toward melanomas (SK-MEL), in comparison to non-tumorigenic cells (fibroblast P4). Evaluation of their nuclease activity or ability to facilitate cleavage of DNA indicated concentrations as low as 0.6 μg mL-1, while complete DNA fragmentation was observed at 25 μg mL-1. By using adequate scavengers, investigations on active intermediates responsible for their cytotoxicity were performed, both in the absence and in the presence of ascorbate as a reducing agent. Based on the observed selective cytotoxicity of these materials toward melanomas, investigations on the reactivity of these complexes and corresponding POSS-materials with melanin, a molecule that contributes to melanoma resistance to chemotherapy, were carried out. Results indicated the main role of the binuclear copper species, formed at the surface of the silica matrix, in the observed reactivity and selectivity of these copper-POSS systems.

Bromine versus chlorine substituent in breathing crystals of a copper(I) coordination compound with a triazolamine Schiff base

It is known that N-[4-(chlorobenzylidene)-4H-1,2,4-triazol-4-amine in reaction with copper(I) perchlorate(VII) forms metastable breathing crystals built up of X-shaped binuclear units containing copper(I) ions in a trigonal coordination sphere. Using trifluoromethanesulfonate instead of perchlorate(VII) affects the self-assembly of the X-shaped units and the breathing function of the resulting crystals. The latter are not breathing crystals. Copper(I) trifluoromethanesulfonate with N-[4-(bromobenzylidene)-4H-1,2,4-triazol-4-amine crystallizes in two forms: open (with the presence of 1D channels) and closed (without 1D channels). Both are characterized by the presence of X-shaped binuclear cationic units and the trigonal coordination sphere of copper(I) ions. The open form has the ability to engage in reversible sorption. The desorption process is associated with the large reorientation of the binuclear units and the reorganization of the intermolecular interactions leading to the closure of the channels. The post-synthetically obtained channel-less form differs from the channel-less form obtained by direct crystallization, the latter being incapable of sorption. The mechanism of the desorption process of the open form is governed by the general principle of dense packing, and the main reason for the sorption process is the formation of directional halogen-halogen interactions. The halogen atom in the para position of the ligands influences the formation of different crystalline forms and also a different mechanism for the desorption process.

3-Phenyl-4-(prop-2-en-1-yl)-5-[(prop-2-en-1-yl)sulfanyl]-4H-1,2,4-triazole

1,2,4-Triazoles appear to be attractive substances due to their wide range of applications. Previously 3-phenyl-4-(prop-2-en-1-yl)-5-[(prop-2-en-1-yl)sulfanyl]-4H-1,2,4-triazole (Atr) has proven to be an effective precursor for us to prepare Cu(I)-π,σ-coordination compounds with nonlinear optical and magnetic properties. In this study, we present the structural characterization of Atr by a single-crystal X-ray diffraction method. The crystals are monoclinic, Sp.gr. P21, Z = 2, unit cell dimensions: a = 5.6967(3), b = 7.8045(3), c = 14.9327(7) Å, β = 91.113(4)°, V = 663.78(5) Å3 at 150 K. To analyze the intermolecular interactions in the crystal structure of Atr, a DFT computational study was also performed.

6-Amino-3-(prop-2-en-1-yl)-9H-purin-3-ium Tetracopper(I) Hexabromide: Synthesis and X-ray Structure Determination

6-Amino-3-(prop-2-en-1-yl)-9H-purin-3-ium tetracopper(I) hexabromide [(C5H5N5(C3H5))2Cu4Br6] (1) is synthesized in this paper. The title compound is characterized by Raman spectroscopy and single crystal X-ray diffraction: monoclinic, Sp.gr. P21/c, Z = 2, unit cell dimensions: a = 8.6870(3), b = 9.7447(2), c = 16.4418(4) Å, β = 100.681(3)°, V = 1367.72(7) Å3 at 150 K. The peculiarities of the metal coordination and distribution of weak interactions are analyzed. The significant role of hydrogen bonds in the construction of 1 crystal structure is shown.

Syntheses and crystal structures of two copper(I)-halide π,σ-coordination compounds based on 2-[(prop-2-en-1-yl)sulfan-yl]pyridine

The title compounds, di-μ-chlorido-bis-({2-[(η-2,3)-(prop-2-en-1-yl)sulfan-yl]pyridine-κN}copper(I)), [Cu2Cl2(C8H9NS)2], and di-μ-bromido-bis-({2-[(η-2,3)-(prop-2-en-1-yl)sulfan-yl]pyridine-κN}copper(I)), [Cu2Br2(C8H9NS)2], were obtained by alternating-current electrochemical synthesis starting from an ethano-lic solution of 2-[(prop-2-en-1-yl)sulfan-yl]pyridine (Psup) and the copper(II) halide. The isostructural crystals are built up from centrosymmetric [Cu2 Hal 2(Psup)2] dimers, which are formed due to the π,σ-chelating behavior of the organic ligand. In the crystals, the dimers are linked by C-H⋯Hal hydrogen bonds as well as by aromatic π-π stacking inter-actions into a three-dimensional network.

Synthesis, structure and computational study of 5-[(prop-2-en-1-yl)sulfanyl]-1,3,4-thiadiazol-2-amine (Pesta) and its heterometallic π,σ-complex [Cu2FeCl2(Pesta)4][FeCl4]

Copper(I) π-coordination compounds with allyl derivatives of azoles are an interesting subject of current research, but Cu^I π-complexes with other transition-metal ions incorporated in the structure have been virtually uninvestigated. The present work is directed toward the synthesis and structural characterization of the novel heterometallic Cu^I/Fe^II π-complex di-μ₂-chlorido-1:2κ²Cl;2:3κ²Cl-tetrakis[μ₂-5-(prop-2-en-1-ylsulfanyl)-1,3,4-thiadiazol-2-amine]-1:2κ²N⁴:N³;1(η²),κN⁴:2κN³;2:3κ²N³:N⁴;2κN³:3(η²),κN⁴-dicopper(I)iron(II) tetrachloridoferrate(II), [Cu₂FeCl₂(C₅H₇N₃S₂)₄][FeCl₄] (1). The structure of the 5-[(prop-2-en-1-yl)sulfanyl]-1,3,4-thiadiazol-2-amine (Pesta, C₅H₇N₃S₂) ligand is also presented. The cationic substructure in 1 consists of one Fe^II and two Cu^I ions bridged by two chloride ions along with two σ,σ- and two π,σ-coordinated ligands, whereas the anionic part is built of isolated tetrahedral [FeCl₄]^2- ions. π-Coordination of the Pesta allyl group to the Cu^I ions prevents agglomeration of the inorganic Cu-Cl-Fe-Cl-Cu part into infinate chains. An energy framework computational analysis was performed for Pesta.

Crystal structure and enantiomeric layer disorder of a copper(I) nitrate π-coordination compound

The novel π-coordination compound [CuI(m-dmphast)NO3], where m-dmphast = 5-(allylthio)-1-(3,5-dimethylphenyl)-1H-tetrazole, is characterized using single-crystal X-ray diffraction and crystallizes in a noncentrosymmetric space group. Additionally, for the first time in this group of materials, the streaks of X-ray diffuse scattering in the reciprocal space sections were observed and described. This gave the possibility for a deeper insight into the local structure of the title compound. The conjecture about the origin of diffuse scattering was derived from average structure solution. It was then confirmed using the local structure modelling. The extended [Cu(m-dmphast)NO3]∞ chains, connected by weak interactions, produce layers which can exist in two enantiomeric forms, one of which predominates.