Binuclear Copper Complexes Research Articles

A hybrid silicotungstate based on tri-coordination copper complex and Keggin type cluster with reactive oxygen species catalytic ability

A hybrid polyoxometalate based on binuclear copper complex and α-Keggin-type silicotungstate [Cu2(4,4′-bpy) (Phen)2][SiW12O40] (abbreviated as CSW) (4,4′-bpy = 4,4′-bipyridine; Phen = 1,10-phenanthroline) has been synthesized and structurally characterized by elemental analyses, X-ray powder diffraction (XRPD), IR spectrum, X-ray photoelectron spectrum (XPS) and single-crystal X-ray diffraction. Structural analysis shows that CSW is an ionic compound, in which the cation is a binuclear copper complex [Cu2(4,4′-bpy) (Phen)2]4+ and the anion is a α-Keggin-type silicotungstate [SiW12O40]4– cluster. Notably, the Cu ions in the [Cu2(4,4′-bpy) (Phen)2] exist in the form of tri-coordination, which the phenomenon is very rare in polyoxometalates. Moreover, CSW can catalyze the production of reactive oxygen species efficiently.

Ditopic binuclear copper(II) complexes for DNA cleavage

Herein we present the synthesis of two ligands containing two di(2-picolyl)amine (DPA) units linked by either a 1,1′-(pyridine-2,6-diyl)bis(3-ethylurea) (L1) or a 1,1′-(1,3-phenylene)bis(3-ethylurea) (L2) spacer. The corresponding binuclear CuII and ZnII complexes were prepared and isolated. The X-ray structures of the L1 ligand and the [Cu2L1Cl2]2+ complex evidence an unusual cis/trans conformation of one of the urea groups stabilized by an intramolecular hydrogen bond with the nitrogen atom of the pyridyl spacer. The CuII complexes form rather strong ternary complexes with phosphorylated anions. The [Cu2L1]4+ complex presents a rather high affinity for pyrophosphate (logK11 = 8.19 at pH 7, 25 °C), while [Cu2L2]4+ stands out because of its strong binding to AMP2− (logK11 = 9.3 at pH 7, 25 °C). The interaction of the CuII complexes with deoxyribonucleic acid from calf thymus (ct-DNA) was monitored using circular dichroism (CD) and luminescence spectroscopies. These studies revealed a quite strong interaction of the complexes with ct-DNA (Kb = (6.4 ± 0.7) × 103 for [Cu2L1]4+ and Kb = (6.3 ± 1.0) × 103 for [Cu2L2]4+). Competition experiments carried out in the presence of methyl green and BAPPA (N1,N3-Bis(4-amidinophenyl)propane-1,3-diamine) as major and minor groove competitors, respectively, confirm that the interaction of both complexes with DNA takes place through the minor groove, in agreement with docking studies. The [Cu2L2]4+ complex is quite efficient in promoting the cleavage of the double-stranded pUC19 plasmid DNA, by favoring the conversion of the supercoiled form to the nicked form following a hydrolytic mechanism.

КАТАЛІТИЧНА АКТИВНІСТЬ БІЯДЕРНОГО КОМПЛЕКСУ МІДІ(ІІ) НА ОСНОВІ 2-(5-(1,2,4)ТРИАЗОЛ-1-ІЛМЕТИЛ-1Н-(1,2,4)-ТРИАЗОЛ-3-ІЛ)-ПІРИДИНУ В РЕАКЦІЯХ ОКИСНЕННЯ КАТЕХОЛІВ

Methods of the synthesis of 2-(5-(1,2,4)triazol-1-ylmethyl-1H-(1,2,4)-triazol-3-yl)-pyridine and a binuclear copper complex are described. The structure of the complex is established by X-ray structural analysis. The complex is a centrosymmetric [Cu2(L)2(NO3)2·2H2O]·H2O dimer. The Cu-Cu distance is 4.0408 (3) Å. In the complex the ligand is in a deprotonated state. Due to this, the triazole fragment acts as a bridge between the two metal centers. Copper ions are in an octahedral environment. The equatorial plane is formed by three triazole nitrogen atoms and one pyridyl nitrogen atom. The axial positions are occupied by a water molecule and a nitrate ion. Isotropic patterns corresponding to binuclear copper particles of the [Cu2L2-H]+ composition were registered in the ESI mass spectra of the solution of the [Cu2(L)2(NO3)2(H2O)2]·H2O complex. These data confirm the presence of a binuclear complex in solution. The catecholoxidase activity of the binuclear copper (II) complex based on 2-(5-(1,2,4)triazol-1-ylmethyl-1H-(1,2,4)-triazol-3-yl)-pyridine was studied. The kinetics of model reactions of the catecholase type were investigated by the method of initial velocities using a model substrate of 3,5-di-tert-butyl catechol (3,5-DTBK). At low concentrations of 3,5-DTBK, the dependence of the initial oxidation rate on the concentration of the substrate is linear, which corresponds to the first order of the reaction on the substrate. However, the dependence graph at higher concentrations of 3,5-DTBK is nonlinear and indicates the saturation of the catalyst with the substrate. The form of the dependence of the initial reaction rate on the substrate concentration is explained within the framework of the Michaelis-Menten model, which well describes the behavior of natural metaloenzymes.

Structures and esterolytic reactivity of novel binuclear copper(ii) complexes with reduced l-serine Schiff bases as mimic carboxylesterases

Three novel binuclear copper(ii) complexes with reduced l-serine Schiff bases were synthesized and their structures were analyzed with single-crystal X-ray diffraction and DFT calculations. The crystal data revealed that all of these binuclear complexes are chiral. Both 5-halogenated (bromo- and chloro-) binuclear complexes exhibit right-handed helix structural character. Interestingly, the 5-methyl-containing analogue has a two-dimensional pore structure. In this paper, the esterolysis reactivity of the as-prepared complexes shows that in the hydrolysis of p-nitrophenyl acetate (PNPA) these three complexes provide 26, 18, 40-fold rate acceleration as compared to the spontaneous hydrolysis of PNPA at pH 7.0, respectively. Under selected conditions, in excess buffered aqueous solution a rate enhancement by three orders of magnitude was observed for the catalytic hydrolysis of another carboxylic ester, p-nitrophenyl picolinate (PNPP). These complexes efficiently promoted PNPP hydrolysis in a micellar solution of cetyltrimethylammonium bromide (CTAB), giving rise to a rate enhancement in excess of four orders of magnitude, which is approximately 2.0-3.2 times higher than that in the buffer.

Synthesis, X-ray structure, antiproliferative activity, interaction with HSA and docking studies of three novel mono and binuclear copper complexes containing the maltol ligand

The present study aims at synthesizing three new copper(ii) complexes of maltol in the presence of 1,10-phenanthroline-, 2,2′-bipyridine- and 4,4-dibromo-2,2′-bipyridine ligands.

Binuclear copper(II) complexes: Synthesis, structural characterization, DNA binding and in silico studies

Two new binuclear Cu(II) complexes represented by the general formula {(dmso)Cu(?-L)4Cu(dmso)} (1) and {(Phen)(L)Cu(?-L)2Cu(L)(Phen)} (2) where dmso = dimethyl sulphoxide, L = 2-bromophenyl acetate and Phen = = 1,10-phenanthroline have been synthesized, isolated quantitatively and characterized by UV/Vis and FT-IR spectroscopic techniques, thermogravimetry/ /differential thermal analysis and X-ray single crystal XRD studies. Complex 1 is paddlewheel with 1,2-O,O-bridging while 2 has 1,1-O-bridging. The values of the intrinsic binding constants with DNA were found out to be 2.0?103 and 1.1?103 M-1, respectively for compound 1 and 2. The mode of interaction of complexes with DNA was also evaluated through computational study by molecular docking (in silico) study using molecular operating environment (MOE) software. The synthesized complexes are structurally as well as biologically important.

Triple-bridged helical binuclear copper(i) complexes: Head-to-head and head-to-tail isomerism and the solid-state luminescence.

A family of helical dinuclear copper(i) pyridylphospholane complexes [Cu2L3X]X (X = BF4-, Cl- and Br-) was prepared. The family includes the first examples of this type of complex based on copper(i) chloride and copper(i) bromide. The two isomers typical of this class of compounds, namely head-to-head and head-to-tail complexes, were studied in solution by spectroscopic and optical methods, and in the solid state by X-ray diffraction. Furthermore, the solid-state luminescence of the complexes at different temperatures was studied, and the results were interpreted using quantum-chemical calculations. It was shown that the luminescence of the complexes is attributed to the 3(M + X)LCT transitions.

Структурные особенности биядерных комплексов меди(I) с 10-м-(арил)феноксарсинами

Структурно охарактеризованы новые биядерные комплексы меди(I) с 10-м-(арил)фено­ксарсинами.

Singlet-Triplet Energy Gaps in Binuclear Copper Complexes and Organic Diradicals by Approximate Spin Projected Spin-unrestricted Coupled Cluster Method

The performance of the approximate spin projected (AP) coupled cluster singles and doubles (CCSD) methods based on the spin-unrestricted Hartree-Fock and Brueckner determinants, namely AP-UCCSD and AP-UBD, is benchmarked for singlet-triplet energy gaps in various open-shell species. The test set includes the TS12 set, organic diradicals, and two binuclear copper complexes. We demonstrate that chemical accuracy (1 kcal/mol) can be reached for small open-shell molecules. These methods also provide highly accurate results for larger systems, in good agreement with the established equation of motion spin-flip CCSD (EOM-SF-CCSD) results.

Binuclear Schiff base copper(II) complexes: Syntheses, crystal structures, HSA interaction and anti-cancer properties

Three binuclear Schiff base copper(II) complexes: [Cu2(HL1)2(CH3OH)(NO3)]·NO3 (1), [Cu2(HL2)2(CH3OH)2]·2NO3 (2), and [Cu2(HL3)2(C2H5OH)2]·2NO3 (3) [HL1 = (E)-N′-(5-fluoro-2-hydroxybenzylidene)benzohydrazide, HL2 = (E)-N′-(5-chloro-2-hydroxybenzylidene)benzohydrazide, and HL3 = (E)-N′-(5-bromo-2-hydroxybenzylidene)benzohydrazide], were synthesized and characterized employing various spectroscopic techniques. X-ray crystallography analysis revealed complexes 1–3 to have similar molecular structures. Results from the MTT assay revealed that all copper complexes displayed greater cytotoxicity toward several tumor cell types than cisplatin or the Schiff-base ligands. Further investigations revealed that complex 1 can induce mitochondrion-mediated apoptotic cell death. In addition, the interaction between these Cu(II) complexes and human serum albumin (HSA) was also investigated.

Synthesis and Structure of Mononuclear Copper(II) Complexes with Azaheterocyclic Ligands L (L = Bipy, BPA, and Phen) and Dodecahydro-closo-Dodecaborate Anion [B12H12]2–

A systematic study of copper(I)/copper(II) complexation with azaheterocyclic ligands and the boron cluster anions [BnHn]2– (n = 10, 12) shows the possibility of synthesizing mononuclear, binuclear, trinuclear, tetranuclear, and polymeric copper(II) complexes. Here, we have studied copper(I) complexation with the [B12H12]2– anion and azaheterocyclic ligands L (L = Bipy, BPA). The reaction have been carried out in air in organic solvents (CH3CN and DMF). Under these conditions, copper(I) is oxidized, and mononuclear copper(II) complexes with ligands L and the [B12H12]2– anion of different composition and structure are formed as final products. In addition, copper(II) complexes have been synthesized in the copper(I)/silver(I) system. The effects of the reaction conditions (the nature of the starting closo-dodecaborate, the source of copper(I), the presence of silver(I) compounds in the reaction solution) on the composition and structure of the final products have been shown. Reaction products have been identified by elemental analysis, IR spectroscopy, and X-ray diffraction. The structures of complexes [Ag(Bipy)2]NO3, [Cu(BPA)2Cl]Cl · DMF, [Cu(BPA)2Cl]2 · 2DMF, [Cu(BPA)2(DMF)2][B12H12] · DMF, [Cu(BPA)2][B12H12]]n, and [Cu(Bipy)(DMF)4][B12H12] have been determined by X-ray diffraction (CCDС nos. 1899332–1899337, respectively).

Synthesis, Structure and Magnetic Properties of Copper(II) Complexes of Diphenyl‐(1‐propylbenzimidazol‐2‐yl)methanol

AbstractTwo types of binuclear copper complexes [LCuN3]2 and [LCuNO3]2.of bidentate ligand ‐ diphenyl‐(1‐propylbenzimidazol‐2‐yl)methanol (HL) in the 4:1 ratio were synthesized. The crystal structure of copper complexes shows a centrosymmetric dimeric binuclear complex with two Cu2+ cations bridged by two oxygen atoms from two organic ligands. In the complexes, a very strong antiferromagnetic exchange interaction between copper atoms is observed.

Binuclear Cu(I) and Mn(0) Complexes with a Tridentate Pyridine‐NHC‐Phosphane Ligand in a µ‐κ2Ĉ,N‐M;κ1P‐M Coordination Mode

The reaction of a non‐symmetrical pyridine‐NHC‐phosphane (NĈP) ligand – generated in situ upon the deprotonation of the corresponding imidazolium salt – with equimolar amount of [Cu(NCMe)4](BF4) or Mn2(CO)10 leads to the formation of bimetallic complexes [Cu2(NĈP)2(NCMe)](BF4)2 and [Mn2(CO)7(NĈP)], respectively, in which the tridentate ligand exhibits an unusual µ‐κ2Ĉ,N‐M;κ1P‐M coordination mode. According to NMR spectroscopy and mass spectrometry, the binuclear copper complex is in equilibrium in MeCN solution with two mononuclear species, namely [Cu(κ2Ĉ,P‐NĈP)2](BF4) and [Cu(κ3‐N,Ĉ,P‐NĈP)(NCMe)](BF4).

Binuclear copper(II) complex with 2-imidazolylbenzothiazole and bridged chloride ligands

Dimeric chloro-bridged copper(II) complex of L2Cu2Cl4 composition [L stands for 2-(1H-imidazol-4-yl)-1,3-benzothiazole ligand] was obtained from CuCl2·2H2O and ligand L in ethanol. According to X-ray diffraction studies, the complex is a dimer with two bridged chloride ligands and two chloride ions coordinated with only copper atom. Cyclic voltammetry demonstrated the stability of dimeric structure of the complex in DMF solution.

Mixed ligand Cu(II) complexes: Square pyramidal vs trigonal bipyramidal with the pyrrole-based dipodal ligand having hydrogen bond acceptors

The condensation between N,N-di(α-formylpyrrolyl-α-methyl)-N-methylamine LH2 and ethanolamine or picolylamine afforded the [1 + 2] acyclic Schiff base in an excellent yield. The reaction between LH2 and [Cu(OAc)2·H2O] yielded a bis(aqua)-bridged binuclear copper(II) complex [Cu{MeN(CH2–C4H2N–CHO)2-κN,N,N)}(μ-H2O)]21. The same product was obtained from the reaction between acyclic, cyclic or bicyclic Schiff base of LH2 and [Cu(OAc)2·H2O] or [CuCl2·2H2O] via hydrolysis of the Schiff-bases. Complex 1 readily reacts with diimines such as 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen) and 2,9-dimethyl-1,10-phenanthroline (dmp) to give mixed ligand mononuclear Cu(II) complexes [Cu{MeN(CH2–C4H2N–CHO)2-κN,N,N)}(bipy)] 2, [Cu{MeN(CH2–C4H2N–CHO)2-κN,N,N)}(phen)] 3, and [Cu{MeN(CH2–C4H2N–CHO)2-κN,N,N)}(dmp)] 4 in very high yields. In all structures, L2− retains its original coordination mode and the geometry around the copper atom in 1, 2 or 3 is best described as a distorted square pyramidal (sp); on the other hand, the copper atom assumes a distorted trigonal bipyramidal (tbp) geometry with dmp in 4 owing to the steric bulk of methyl groups. DFT calculations gave the energy difference between sp and tbp geometries of different copper(II) complexes containing bipy and phen ligands bearing sterically encumbered substituents. As the steric bulk increases, tbp becomes the preferred geometry.

Interactions of binuclear copper(II) complexes with S-substituted thiosalicylate derivatives with some relevant biomolecules

Interactions of copper(II) complexes which contain S-alkyl derivatives of thiosalicylic acid (alkyl = methyl, ethyl, propyl and butyl; aryl = benzyl), marked as 1–5, with guanosine-5′-monophosphate (5′-GMP) and calf thymus DNA (CT-DNA) were studied. Kinetics of substitution reactions of 1–5 with 5′-GMP and CT-DNA were investigated under pseudo-first-order conditions at 310 K and pH = 7.2 in 25 mM Hepes buffer using stopped-flow method. All complexes have high affinity toward studied bio-molecules. Additionally, interactions with CT-DNA were followed by absorption spectroscopy and fluorescence quenching measurements. The results indicate that complexes bind to DNA exhibiting high binding constants (Kb = 104 M−1). During the examination of competitive reactions with ethidium bromide (EB), results showed that complexes can replace EB-bound DNA. In addition, a new crystal structure of the binuclear Cu(II) complex with S-substituted thiosalicylate derivative has been reported. In the present series of Cu(II) complexes the crystal structure is the first example of a complex comprising an S-aryl derivative of thiosalicylate ligand. Through comparative study of structural properties of six molecules from four crystal structures we examined the structural variations, potentially important for biological activity of these complexes.

Theoretical Modeling of the Structure of N-[2-[(Hydroxyalkylimino)Methyl]Phenyl]-4-Methylbenzene-Sulfamides and Their Mono- and Binuclear Copper(II) Complexes

The paper presents a theoretical DFT UB3LYP/6-311++G(d,p) modeling of the structure and magnetic properties of Cu(II) coordination compounds with tridentate Schiff bases derived from 2-tosylaminobenzaldehyde and amino alcohols. It is shown that the elongation of the aliphatic chain in the amine part of ligand systems prevents the formation of binuclear metal-chelate structures. At the same time, mononuclear bis-chelate complexes, as well as mono-adducts containing a coordinated solvent molecule and a tridentate azomethine compound, are formed regardless of the number of methylene units.

Controlled Synthesis of Two Pyrazole-3-Carboxylic Acid Mononuclear- and Binuclear-Copper Complexes and Their Highly Selective Oxidation of Benzylic sp3 C–H Bonds

Controlled Synthesis of Two Pyrazole-3-Carboxylic Acid Mononuclear- and Binuclear-Copper Complexes and Their Highly Selective Oxidation of Benzylic <i>sp</i>³ C–H Bonds

DNA cleavage, DNA/HSA binding study, and antiproliferative activity of a phenolate-bridged binuclear copper(II) complex.

A novel phenolate-bridged binuclear copper(II) complex, [Cu 2II (L-3H)Cl] (1, where L = 2,6-bis[((2-hydroxybenzyl)(2-pyridylmethyl)amino)methyl]-4-methylphenol), have been synthesized and characterized. The antiproliferative activity of the complex has been tested in vitro against the human cervical cancer cell line HeLa, human non-small-cell lung cancer cell line A-549, the human breast cancer cell line MCF-7, and the human hepatic cell line LO2. The results show the complex has the low micromolar range (9.4-11.2µM) of IC50 values towards the three cancer cell lines, which is markedly comparable to those of cisplatin. However 1 exhibited 10.6-fold less toxicity than cisplatin toward normal cells LO2, suggesting that complex 1 had high selectivity between tumor cells and normal cells. The interactions with DNA were investigated by UV-Vis absorption, fluorescence, circular dichroism, and gel electrophoresis. The results show that the copper(II) complex could strongly bind to DNA mainly by the groove binding mode and efficiently cleave the pBR322 plasmid DNA into its nicked and linear forms in the presence of excessive ascorbic acid. In addition, the evaluation of the protein binding ability shows that complex 1 could bind to human serum albumin (HSA) with a moderate binding affinity and quench the intrinsic fluorescence of HSA.

Synthesis and photoluminescence properties of different structural cuprous complexes regulated by benzoxazole ligands and halogen/pseudohalide ions

Reaction of 2-(2′-pyridyl)benzoxazole (2-PBO), 2-(4′-pyridyl)benzoxazole (4-PBO) and 2,2-(1,4-butanediyl)bis-1,3-benzoxazole (BBO) ligands with CuX (X = I, Br, SCN) afforded a binuclear copper(I) complex [Cu(2-PBO)(μ2-I)]2 (1) and three copper(I) coordination polymers [Cu4(4-PBO)4(μ3-I)4]n (2), {[Cu(4-PBO)(μ3-SCN)]2}n (3) and {[Cu(BBO)(μ2-Br)]2}n (4). The structural analysis revealed that the all copper(I) ions are four-coordinated and the geometric structure around the central copper(I) atom possessing slightly distorted tetrahedral geometry in complexes 1–4. Halogen or pseudohalide ions can not only act as counter anions, but also as ligands participation in coordination when the cuprous ion coordination sites are not saturated. Due to the different coordination modes of the benzoxazole ligands, in order to satisfy the tetra-coordination of cuprous ions, halogen or pseudohalide ions adopt μ2 and/or μ3-bridging modes to synergistically complete coordination. Photoluminescence investigation show that complexes 1, 3 and 4 have two emission peaks, the high energy band peak is attributed to MLCT[d10(Cu)→π*] and XMCT, the low energy band peak is caused by the 3CC emission. This may be due to the presence of μ2-X (X = I, Br, S) in these complexes. However complex 2 only had one emission peak, which may be attributed to MLCT[d10(Cu)→π*] and XMCT.