Synthesis, X-ray structure and anti-corrosion activity of two silver(I) pyrazino complexes

Two new silver(I) pyrazine complexes [Ag₂(ampyz)(NO₃)₂]_n, 1 and {[Ag(2,3-pyzdic)](NO₃)}_n, 2 (where ampyz = aminopyrazine, and 2,3-pyzdic = 2,3-pyrazinedicarboxamide) were synthesized and structurally characterized by X-ray single crystal structure analysis. Complex 1 has a 2D sheet structure through both bridging μ_O,O′-(NO₃) groups and μ_N,N′-pyrazine moieties. A 3D structure with a characteristic (10,3)-d or 10³-utp net is formed through extensive hydrogen bonding. Complex 2 has a 1D chain structure through bridging μ_N,N′-pyrazine moieties. Strong hydrogen bonds further connect these chains to extend the dimensionality to a 3D network structure. The complexes were tested as corrosion inhibitors for mild steel in 0.1 M nitric acid medium using potentiodynamic polarization technique. Both complexes are of mixed type corrosion inhibitors with dominant anodic effect. The inhibition efficiencies are 68% and 50% for complexes 1 and 2, respectively. The inhibition mechanisms of both inhibitors are mainly due to adsorption of the inhibitor molecules on the surface of mild steel. All data were compared and fitted to the kinetic-thermodynamic model. The binding constants K are 3263 and 1147 for complexes 1 and 2, respectively.     

Synthesis, crystal structure and in vitro antibacterial activity of two novel silver(I) complexes

Two silver(I) complexes [Ag₂(dppm)₂(L¹)₂(CH₂Cl₂)₂] (1) and [Ag₄(dppm)₂(L²)₂(NO₃)₂] (2) have been prepared by the reactions of [Ag₂(dppm)₂(NO₃)₂] with HL¹ and HL² [dppm = bis(diphenylphosphino)methane, HL¹ = 2-(9H-carbazol-9-yl) acetic acid and HL² = (E)-3-(4-(9H-carbazole-9-yl) phenyl) acrylic acid], respectively. Both complexes have been structurally characterized by X-ray crystallography, confirming that 1 is a binuclear complex whereas 2 is a tetranuclear one. Both complexes were assayed for antibacterial activity against two Gram-positive bacterial strains (Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 6538) and two Gram-negative bacterial strains (Pseudomonas aeruginosa ATCC 13525 and Escherichia coli ATCC 35218) by MTT method. Complex 2 exhibited powerful antibacterial activities against B. subtilis ATCC 6633 with MIC of 0.78 μg/mL, which was superior to the positive controls penicillin G. On the basis of the biological results, structure-activity relationships were discussed.     

Synthesis,crystal structure,and Helicobacter pylori urease inhibition of a dicyanoamide bridged Cu(I/II) complex

A dicyanoamide-bridged polymeric copper(I/II) complex, [Cu^II(sal)(bipy)Cu^I(dca)₂]_n, was prepared by reaction of 5-methylchlorosalicylaldehyde (Hsal), 2,2′-bipyridine (bipy), sodium dicyanoamide (Nadca), and copper perchlorate in methanol. The complex was characterized by elemental analyses, infrared and electronic spectroscopy, and single-crystal X-ray determination. Cu^II has a square pyramidal coordination, and Cu^I has triangular coordination. The complex showed high urease inhibitory activity with IC₅₀ value of 0.16 ± 0.23 μM.     

Synthesis, structure and characterization of binuclear silver(I) complexes

Summary Two binuclear Ag^I complexes, [{Ag(dppp)}₂](NO₃)₂ (1) and [{Ag(dppb)}₂(NO₃)]₂ (2) (dppp = Ph₂P(CH₂)₃PPh₂, dppb = Ph₂P(CH₂)₄PPh₂], were synthesized and characterized by elemental analysis, t.g., i.r. and ³¹P-n.m.r. spectra. Single crystals of complex (2) were obtained from MeOH-CHCl₃. The X-ray crystal structure shows that the dppb ligand is bidentate, with two ligands bridging two metal ions to form a centrosymmetric dimer.     

Synthesis, structure, DNA-binding properties and antioxidant activity of silver(I) complexes containing V-shaped bis-benzimidazole ligands

A V-shaped ligand bis(2-benzimidazol-2-ylmethyl)benzylamine L(1) with its two derivatives bis(N-methylbenzimidazol-2-ylmethyl)benzylamine L(2) and bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine L(3) have been prepared. Reaction of these shape-specific designed ligands with Ag(pic) (pic = picrate) afforded three novel complexes, namely, [Ag(2)L(1)(2)](pic)(2)1, [Ag(2)L(2)(2)](pic)(2)·2DMF 2 and [AgL(3)(pic)] 3. The ligands and complexes were characterized on the basis of elemental analysis, UV-Vis, IR, NMR spectroscopy and X-ray crystallography. Complex 1 is a dinuclear metallacycle with a 2-fold rotational symmetry in which two syn-conformational L(1) ligands are connected by two linearly coordinated Ag(I) atoms. Due to the strong interaction between two adjacent Ag(I) atoms, the coordination mode of the central Ag(I) atom can be described as T-shaped. Complex 2 consists of a centrosymmetric dinuclear pore canal structure assembled from two nearly linearly coordinated Ag(I) atoms and two L(2) ligands. The structure of complex 3 adopts a four-coordinate environment for AgN(2)O(2), with the counterion participating in an eight-shaped geometry. In order to explore the relationship between the structure and biological properties, the DNA-binding properties have been investigated by viscosity measurements, electronic absorption, and fluorescence. The results suggest that the ligands and complexes bind to DNA in an intercalation mode, and their binding affinities for DNA are also different. Moreover, the three Ag(I) complexes also exhibited potential antioxidant properties in vitro studies.     

Synthesis,characterization, and urease inhibitory activity of two copper(II) complexes of cyclohexanecarboxylate

The crystal structures of two copper(II) complexes of the cyclohexanecarboxylate ligand, namely [Cu(C₆H₁₁CO₂)₂(H₂O)₂]·H₂O (1) and [Cu(dpyam)₂(C₆H₁₁CO₂)](NO₃)·H₂O (2) (C₆H₁₁CO₂H = cyclohexanecarboxylic acid; dpyam = di-2-pyridylamine), have been determined by single-crystal X-ray analysis. Complex 1 contains the square-planar trans-CuO₄ chromophore, while 2 shows the square pyramidal cis-distorted octahedral CuN₄OO′ chromophore. Both complexes were found to show strong inhibitory activity against jack bean urease (IC₅₀ = 1.75 and 8.57 μM for 1 and 2, respectively), when compared with acetohydroxamic acid (IC₅₀ = 63.12 μM).     

Synthesis,characterization, and antimicrobial activity of two Schiff base silver(I) complexes derived from 4-carboxybenzaldehyde

Two new Schiff base silver(I) complexes, {[Ag(L¹)][H₂O]}_∞ (1) and {[Ag(L²)][H₂O]}_∞ (2), where L¹ = 4-((2-diethylaminoethylimino)methyl)phenecarboxylate and L² = 4-([3-(morpholin-4-yl)propyl]iminomethyl)phenecarboxylate, have been synthesized and characterized. X-ray crystallographic analysis reveals that silver ions in 1 are bridged by L¹ to form a one-dimensional zigzag chain, while three silver ions in 2 are linked by L² to produce a two-dimensional coordination polymer. Guest water molecules in 1 generate a one-dimensional hydrogen-bonded chain. Both 1 and 2 offer high antibacterial activity against Gram-positive bacteria Staphylococcus aureus with MIC values of 0.26 and 0.24 mM and to exhibit good inhibitory activity against urease with the respective IC₅₀ values of 3.5 ± 0.1 and 3.8 ± 0.2 μM.     

Synthesis and antitumor activity of new silver(I)-N-heterocyclic carbene complexes

Abstract

In this study, two novel benzimidazole-based N-heterocyclic carbene ligands (1a-b) and their silver(I) complexes (2a-b) were synthesized. All new compounds were characterized by FT-IR, LC-MS, ¹H NMR, and ¹³C NMR spectroscopies. The in vitro antitumor activities of NHC ligands (1a-b) and their silver(I) complexes (2a-b) against DU-145 human prostate cancer cells, MDA-MB-231 and MCF-7 human breast cancer cells and L-929 (normal cells adipose from mouse) were also determined using MTT analysis for 24?h, 48?h, and 72?h. The results showed that while NHC ligands did not have in vitro antitumor activity on MCF-7, MDA-MB-231 and DU-145 cells, Ag(I)-NHC complexes have in vitro antitumor activities. The in vitro antitumor activity of 2a was found to be lower than that of 2b. Ag(I)-NHC complexes were observed to have higher IC₅₀ values for non-cancerous cell lines than cancer cells.     

Synthesis,crystal structure,and antimicrobial activity of silver(I) complexes derived from 3-nitrobenzoic acid and diamines

Russian Journal of Coordination Chemistry - Two new silver(I) complexes, [Ag2(NBA)2(DAC)] (I) and [Ag2(NBA)2(DAB)] (II), where NBA, DAC, and DAB are 3-nitrobenzoate, 1,2-diaminocyclohexane, and...     

Synthesis,characterization, and evaluation of silver(I) complexes with mixed-ligands of thiosemicarbazones and diphenyl(p-tolyl)phosphine as biological agents

Five new silver(I) complexes were synthesized with mixed ligands of thiosemicarbazone derivatives and diphenyl(p-tolyl)phosphine in search of new biologically active compounds. A CHN elemental analysis, powder X-ray diffraction (PXRD) data and several spectroscopic techniques such as Fourier-transform infrared spectroscopy, energy-dispersive X-ray, ¹H, ¹³C, and ³¹P{¹H} NMR were performed to elucidate the structure of these complexes. Elemental analysis suggested that the stoichiometry of the complexes formed by the reaction of silver nitrate with thiosemicarbazone in the presence of (p-tolyl)PPh₂ was indeed 1:2:1 molar ratio. The silver ions were discovered to be coordinated to the sulfur of thiosemicarbazone and phosphorus of (p-tolyl)PPh₂, having a tetrahedral geometry based on the spectroscopic data obtained. The PXRD patterns were studied to see the degree of crystallinity of the complexes. The in vitro antiproliferative activity of these complexes was investigated toward the MDA-MB-231 and MCF-7 breast cancer cell lines, as well as the HT-29 colon cancer cell line, which yielded IC₅₀ values in low micromolar range. The antiplasmodial activity of these complexes was also examined against chloroquine-resistant Plasmodium falciparum parasite which demonstrated good activity and further tested for their selectivity index.     

Synthesis,structure, and biological evaluation of three Cu(II) and Ni(II) (E)-3-(3,4-dimethoxyphenyl)acrylate complexes with organic diamines as potential urease inhibitors

Three new complexes (1–3) have been synthesized and characterized by X-ray single crystal determination and evaluated for inhibitory activity on jack bean urease. All the complexes contained a new cinnamic acid derivative as the ligand (C₁₁H₁₂O₄), (E)-3-(3,4-dimethoxyphenyl)acrylic acid, and crystallized in monoclinic C2/c space group. Complex 1 (C₁₁H₁₁O₄)₄(C₃N₂H₈)₂Cu₂ (C₃N₂H₈?=?1,2-diaminopropane) was obtained with a?=?20.488(2), b?=?19.596(2), c?=?15.2500(13), β?=?93.502(2)°, V?=?6111.2(10)?ų, Z?=?4, R ₁ ?=?0.0616, and wR ₂ ?=?0.2059. Complex 2 (C₁₁H₁₁O₄)₄(C₃N₂H₈)₂Cu₂ (C₃N₂H₈=1,3-diaminopropane) was obtained with a?=?20.2494(12), b?=?19.5732(12), c?=?14.8940(8), β?=?96.884(2)°, V?=?5860.6(6)?ų, Z?=?4, R ₁ ?=?0.0409, and wR ₂ ?=?0.1107. Complex 3 (C₁₁H₁₁O₄)₂(C₂N₂H₆)₂Ni₂·H₂O (C₂N₂H₆?=?ethylenediamine) was obtained with a?=?28.359(2), b?=?6.5422(5), c?=?16.8587(14), β?=?101.359(2)°, V?=?3066.5(4)?ų, Z?=?4, R ₁ ?=?0.0422, and wR ₂ ?=?0.1190. It was found that copper(II) complexes 1 [IC₅₀?=?4.71?μM] and 2 [IC₅₀?=?3.15?μM] showed strong inhibitory activity against jack bean urease compared with acetohydroxamic acid [IC₅₀?=?10.01?μM] as a positive reference. Unfortunately, 3 exhibited no inhibitory activity.     

Synthesis and crystal structures of four mixed-ligand silver(I) complexes with sandwich-like structure

The reaction of AgNO₃, with combinations of 4,4′-bipyridine (bpy), 1,2-di(4-pyridyl)ethylene (dpe), hexanedioic acid (HA), pyridine-3,5-dicarboxylic acid (pdc) and 3,3′4,4′-biphenyltetracarboxylic acid (bptc) in aqueous alcohol at room temperature produces block-like crystals of [Ag₂(bpy)₂](HA)₂·6H₂O, [Ag₂(bpy)₂(H₂O)](pdc)·3H₂O, [Ag₄(bpy)₄](bptc)·14H₂O and [Ag₂(dpe)₂(H₂O)₂](HA)·6H₂O. All four compounds consist of parallel 1D infinite bpy/dpe-silver cationic chains, interspersed with organic anions that play the role of charge compensation in the crystal structure. The lattice water molecules are situated among the framework of the crystal structure and stabilized by rich hydrogen-bonding interactions, which may play a role in the orientation of the organic anions in the crystal packing.     

Diruthenium(I,I) saccharinate complexes: Synthesis, molecular structure, and evaluation as catalysts for carbenoid reactions of diazoacetates

The dinuclear ruthenium complexes [Ru₂(μ-sac)₂(CO)₆] (1), [Ru₂(μ-sac)₂(CH₃CN)₂(CO)₄] (3), [Ru₂(μ-sac)₂(CO)₅(PPh₃)] (4) and [Ru₂(μ-sac)₂(CO)₄(PPh₃)₂] (5) as well as the tetranuclear ruthenium complex [Ru₂(μ-sac)₂(CO)₅]₂ (2) (sac = saccharinate, C₇H₄NO₃S⁻) were synthesized starting from Ru₃(CO)₁₂ and saccharin. X-ray crystal structure analysis of 1, 3A × p-xylene, 4 × CH₂Cl₂ and 5 × 3CH₂Cl₂ showed that the core is bridged through the amidate moieties of the two saccharinate ligands, with a head-tail arrangement in complexes 1, 3A and 5, and a head-head arrangement in 4. For complex 3, an equilibrium mixture of the head-head regioisomer 3A and a second species 3b exists in solution. Complexes 1 and 2 are suitable catalysts for the cyclopropanation of nucleophilic alkenes (styrene, cyclohexene and 2-methyl-2-butene) with methyl diazoacetate.     

Synthesis,urease inhibitory activities,and molecular docking studies of two Cu(II) complexes

Two mononuclear copper(II) complexes, [Cu(C₄H₃N₂O₂)₂?·?4H₂O] (1) and [Cu(C₁₂H₁₁N₂O₂Cl₂)₂] (2), were synthesized and structurally characterized by single-crystal X-ray analysis. The copper(II) adopts a square-planar environment in 1, while the geometry in 2 can be described as distorted square-pyramidal. Complexes 1 and 2 were evaluated for their inhibitory activities against jack bean urease in vitro and both were found to have strong inhibitory activities comparable to that of acetohydroxamic acid. A docking simulation was performed to position 2 into the jack bean urease active site to determine the probable binding conformation.     

Synthesis, a case of isostructural packing, and antimicrobial activity of silver(I)quinoxaline nitrate, silver(I)(2,5-dimethylpyrazine) nitrate and two related silver aminopyridine compounds

The synthesis and low temperature crystal structures of [Ag(quinoxaline)]n(NO3)n, 1, [Ag(2,5-dimethylpyrazine)(NO3)]n, 2 and [Ag4(3-aminopyridine)4(NO3)4]n 3 are presented. The quinoxaline compound forms a 1D coordination polymer with the characteristic linear 2-coordination figure of silver(I), the N-Ag-N angle being 164.2(1) degrees, and only weak silver-nitrate interactions. In addition there is an interaction giving pairs of parallel chains as the main structural theme. The 2,5-dimethylpyrazine compound has approximately trigonal-planar coordination, also binding one nitrate at the relatively short Ag-O distances 2.444(3) angstroms and 2.484(3) angstroms, respectively, for the two crystallographically different silver atoms. This also results in a 1D coordination polymer that, despite the large differences in the Ag(I) coordination environment, is isostructural with 1. [Ag4(3-aminopyridine)4(NO3)4]n 3 forms a 2D coordination polymer by bridging nitrate ions. The antimicrobial activity of 1-3, and also of [Ag3(2-aminopyridine)4](NO3)3, 4 was screened for 13 different pathogens and substantial activity was shown for 1 against Escherichia coli and Pseudomonas aeruginosa (MIC 4 microg cm(-3)) and somewhat lower activity was registered against Sarcina lutea and Salmonella typhi for 1, Bordetella bronchiseptica for 2, Salmonella typhi and Pseudomonas aeruginosa for 3, and Escherichia coli and Shigella sonnie for 3 (MIC 8 microg cm(-3)). Only low activity was shown against the yeast Candida albicans for 1, 2 and 4 whereas no activity against this pathogen was registered for 3.     

Synthesis and crystal structures of two polymeric silver(I) complexes with polyamines and terephthalic acid

Two polymeric silver(I) complexes, [Ag₄(TAA)₂(TA)₂] · 2[Ag(TA)₂] (I) and [Ag₂(TA)(BA)] _n (II), where TAA is tris(2-aminoethyl)amine, TA is terephthalic acid, BA is butane-1,4-diamine, were synthesized and structurally characterized by elemental analyses and X-ray diffraction. Complex I consists of mononuclear [Ag(TA)₂] units and TA-bridged tetranuclear [Ag₄(TAA)₂(TA)₂] units, which are further linked via Ag…Ag interactions to form chains. In complex II, the silver atoms are linked by the TA and BA groups to form chains, which are further linked via Ag…Ag interactions to form layers. In both complexes, molecules are finally linked through intermolecular hydrogen bonds to form three-dimensional networks.     

Synthesis,characterization and crystal structure of new silver(I) and palladium(II) complexes containing 1,2,4-triazole moieties

The reaction of 4-amino-5-ethyl-2H-1,2,4-triazole-3(4H)-thione (AETT, L1) with 2-thiophen carbaldehyde in methanol leads to the corresponding Schiff-base HL1a. The reaction of L1 with AgNO₃ in ethanol gives the ionic complex [{[Ag(L1)]NO₃}₂]_n (1). The ionic complex [(PPh₃)₂Ag(HL1a)₂]NO₃ · CH₃CN (2) can be obtained by the reaction of HL1a with [(PPh₃)₂Ag]NO₃ in methanol and acetonitrile solution, while its reaction with [(PPh₃)₂PdCl₂] in the presence of sodium acetate in methanol leads to the neutral complex [(PPh₃)₂Pd(L1a)₂] · 4MeOH (3). All the compounds were characterized by infrared spectroscopy, elemental analyses as well as by X-ray diffraction studies.     

Synthesis, structure, and reactions of binuclear gold(I) complexes containing two different bridging ligands

The binuclear cycloaurated compounds [Au(2)(mu-C(6)H(3)-2-PPh(2)-n-Me)(2)] (n = 5, 1a; n = 6, 1b) react with the digold(I) complexes [Au(2)(mu-S(2)CN(n)()Bu(2))(2)] and [Au(2)(mu-dppm)(2)](PF(6))(2) to give heterobridged dinuclear complexes [Au(2)(mu-C(6)H(3)-2-PPh(2)-n-Me)(mu-S(2)CN(n)Bu(2))] (n = 5, 5a; n = 6, 5b) and [Au(2)(mu-C(6)H(3)-2-PPh(2)-n-Me)(mu-dppm)]PF(6), (n = 5, 9a; n = 6, 9b), respectively. Complex 5a exists in the solid state as an infinite zigzag chain of dimeric units with intramolecular Au-Au separations of 2.8331(3) and 2.8243(3) A for independent molecules and intermolecular Au-Au separations of 3.0653(3) and 3.1304(3) A. Both 5a and 5b undergo oxidative addition with halogens to give the heterovalent, gold(I)-gold(III) compounds [XAu(I)(mu-2-Ph(2)PC(6)H(3)-n-Me)Au(III)X(eta(2)-S(2)CN(n)Bu(2))] [n = 5, X = Cl (6a), I (8a); n = 6, X = Cl (6b), Br (7b), I (8b)]. Compound 8a has been shown by X-ray crystallography to contain a gold(III) atom coordinated in a planar array by bidentate, chelating di-n-butyldithiocarbamate, iodide, and the sigma-aryl carbon atom, together with a gold(I) atom that is linearly coordinated by the phosphorus atom of the arylphosphine and by iodide. The intramolecular gold-gold distance of 3.2201(3) A indicates little or no interaction between the metal atoms. In contrast to the behavior of the homobridged complexes 1a and 1b, the heterobridged dithiocarbamate complexes 5a and 5b give structurally similar products on reaction with halogens, irrespective of the position of the ring methyl substituent. Crystal data for [Au(2)(mu-C(6)H(3)-2-PPh(2)-5-Me)(mu-S(2)CN(n)Bu(2))] (5a): triclinic, space group P1 (No. 2), with a = 11.3398(1), b = 15.9750(2), c = 16.4400(3) A, alpha = 91.0735(9), beta = 109.3130(7), gamma = 90.7666(8) degrees, V = 2809.47(6) A(3), and Z = 4. Crystal data for [IAu(I)(mu-2-Ph(2)PC(6)H(3)-5-Me)Au(III)I(eta(2)- S(2)CN(n)Bu(2))] (8a): triclinic, space group P1 (No. 2), with a = 8.6136(2), b = 9.3273, c = 21.1518(4) A, alpha = 84.008(1), beta = 84.945(1), gamma = 75.181(1) degrees, V = 1630.54(6) A(3), and Z = 2.     

Synthesis,structure and characterization of binuclear copper(I) complexes

Binuclear copper(I) complexes [Cu(dppm)(NO3)]2 (1), dppm=Ph2PCH2PPh2, [Cu(dppm)(2,9-Me2Phen)]2(NO3)2 (2), [Cu(dppm)(I)]2 (3) and [Cu(dppm)(py)]2(NO3)2 (4), (py=pyridine) have been synthesized by ligand reduction of cupric nitrate with dppm in EtOH and characterized by elemental analyses, molecular weight determination, t.g.a., 31P-n.m.r spectra; their electronic conductivities and c.v. waves have also been measured. The results show that dppm coordinates as a bridging bidentate ligand to the CuI atoms, and that NO3 behaves as a monodentate ligand or free ion in the newly prepared complexes.