Synthesis,crystal structures and Jack bean urease inhibitory activity of copper(II) complexes with 4-bromo-N′-(2-hydroxy-5-methoxybenzylidene)benzohydrazide

A new hydrazone 4-bromo-N′-(2-hydroxy-5-methoxybenzylidene)benzohydrazide (HL) was prepared and characterized by infrared and UV–vis spectra, as well as single-crystal X-ray diffraction. With the hydrazone as ligand, two new copper(II) complexes were prepared, [Cu₂L₂(NCS)₂]·4H₂O (1) and [CuBrL]·CH₃OH (2). The complexes were characterized by infrared and UV–vis spectra, and single-crystal X-ray diffraction. The Cu in 1 is in a square pyramidal coordination geometry and that in 2 is in a square planar coordination geometry. The two complexes show effective Jack bean urease inhibitory activity, with IC₅₀ values of 23.5 and 2.7 μM, respectively. A molecular docking study of 2 with the urease was performed. The relationship between the structure and urease inhibitory activity indicated that copper complex with square planar coordination is a better model for urease inhibition.     

Synthesis and crystal structures of cobalt(III), copper(II), nickel(II) and zinc(II) complexes derived from 4-methoxy-N′-(pyridin-2-ylmethylene)benzohydrazide with urease inhibitory activity

Abstract

Urease catalyzes the decomposition of urea into ammonia, which has harmful effects on both human health and fertile soil. Aiming at exploring novel urease inhibitors, a series of hydrazone compounds and their Co^III, Cu^II, Ni^II, and Zn^II complexes were prepared from 4-methoxy-N'-(pyridin-2-ylmethylene)benzohydrazide (HL). They are [CoClL(NCS)] (1), [CoL₂]·Cl·CH₃OH·H₂O (2), [CuL(NCNCN)]_n·nCH₃OH (3), [NiL(HL)]·ClO₄·CH₃OH (4) and [ZnClL(OH₂)]·CH₃OH (5). The compounds were characterized by physico-chemical methods. Structures of the complexes were further confirmed by single crystal X-ray diffraction. The metal ions in 1, 3, and 5 display square pyramidal coordination and 2 and 4 display octahedral coordination. The inhibitory effects of the compounds on Jack bean urease were evaluated. The results showed that 3 has effective urease inhibitory activity, with IC₅₀ value of (7.3?±?1.0) μmol L^?1.     

Synthesis,characterization and crystal structures of copper(II), zinc(II) and vanadium(V) complexes,derived from 3-methyl-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide,with antibacterial activity

Three copper(II), zinc(II), and vanadium(V) complexes, [CuL(HL)]ClO₄ (1), [ZnL₂] (2) and [VO₂L] (3), where L is the anionic form of 3-methyl-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide (HL), were prepared and characterized by IR, UV–vis and single-crystal X-ray determination. X-ray analysis indicates that the complexes are mononuclear species, with the Cu and Zn ions in 1 and 2 in octahedral coordination, and with the V ion in 3 in trigonal bipyramidal coordination. The hydrazone compound and the three complexes were evaluated for antibacterial activities. The copper complex has effective activities.     

Synthesis and crystal structures of three new complexes derived from 3-(pyridin-3′-yl)-5-(pyridin-2′′-yl)-1,2,4-triazole

Three new coordination complexes, [Cd₂(ppt)₂(cpba)]?·?(H₂O)₂ (1), [Zn(ppt)₂]?·?(H₂O) (2), and [Zn(MoO₄)(Hppt)] (3) (H₂cpba: 3-(2′-carboxy-phenoxy)-benzoic acid; Hppt: 3-(pyridin-3′-yl)-5-(pyridin-2′′-yl)-1,2,4-triazole), were synthesized under hydrothermal conditions. Their structures have been determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric analyses. X-ray diffraction analyses revealed that Cd(II) ions are linked by ppt^? to form a ladder-shaped structure along the a-axis and further displays a 2-D supramolecular architecture with cpba^2? along the c-axis. In 2, each Zn(ppt)₂ fragment is linked by the nitrogen of pyridin-3′-yl from the neighboring Zn(ppt)₂ forming a V-shaped chain. Compound 3 consists of a ladder structure, in which each {MoO₄} unit is a bridge linking three Zn(Hppt)²⁺ fragments.     

Syntheses and crystal structures of oxovanadium(V) complexes derived from N′-[1-(2-hydroxynaphthyl)ethylidene]-4-nitrobenzohydrazide and 2-hydroxy-N′-[1-(2-hydroxynaphthyl)ethylidene]benzohydrazide

Reactions of bis(acetylacetonato)oxovanadium(IV) with N??-[1-(2-hydroxynaphthyl)ethylidene]-4-nitrobenzohydrazide (H₂HNB) and 2-hydroxy-N??-[1-(2-hydroxynaphthyl)ethylidene]benzohydrazide (H₂HHB), respectively, product two oxovanadium(V) species with the formulas [VO(OMe)(HNB)]₂ (I) and [VO(OMe)(HHB)] (II). The complexes I and II have been characterized by elemental analysis, IR spectra, and single crystal X-ray diffraction. The crystal of I is monoclinic: space group P2₁/n, a = 8.208(2), b = 14.528(3), c = 16.418(3) ?, ?? = 97.887(3)°, V = 1939.3(7) ?³, Z = 2. The crystal of II is triclinic: space group P $P\bar 1$ a = 8.334(2), b = 10.236(2), c = 11.337(2) ?, ?? = 80.91(3)°, ?? = 75.41(3)°, ?? = 75.63(3)°, V = 902.0(3) ?³, Z = 2. Complex I is a methoxide-bridged dimeric oxovanadium(V) complex, and complex II is a mononuclear oxovanadium(V) complex. The V atom in I is in an octahedral coordination, and that in II is in a square pyramidal coordination.     

Synthesis,crystal structure and DFT calculations of octahedral nickel(II) complexes derived from N′-[(E)-phenyl(pyridin-2-yl)methylidene]benzohydrazide

The two new nickel(II) complexes, [Ni(HL)(L)](NO₃)?H₂O (1) and [Ni(L)₂] (2) (where HL/L = N′-[(E)-phenyl(pyridin-2-yl)methylidene]benzohydrazide), have been synthesized and characterized by elemental analysis, spectroscopic, magnetic susceptibility, and cyclic voltammetric measurements. Single-crystal X-ray analysis of [Ni(HL)(L)](NO₃)?H₂O (1) and [Ni(L)₂] (2) has revealed the presence of a distorted octahedral geometry around nickel(II). The X-ray and spectral characterizations have confirmed the existence of the keto-enol form of the ligands in the complexes. The electronic structures and spectral properties of the ligands and the complexes have been explained by DFT and TDDFT calculations. Superoxide dismutase activity of these complexes has also been measured.     

Syntheses and crystal structures of mixed-ligand copper(II)–imidazole–carboxylate complexes

The syntheses, characterization, and crystal structures of the reaction products of Cu²⁺ with imidazole (Himz) and different aromatic carboxylates, viz.: [Cu(Himz)₂(cinn)₂(H₂O)] (1), [Cu(Himz)₂(paba)₂] (2) and [Cu(Himz)₂(clba)₂] (3) (cinn^– = C₉H₇O₂^–, paba^– = C₇H₆NO₂^–, clba^– = C₇H₄ClO₂^–) are described and studied by spectroscopic (UV–visible, FTIR) measurements. Single-crystal X-ray diffraction analyses indicate that each complex is monomeric. The metal ion in 1 adopts square-pyramidal coordination geometry arising from two imidazole nitrogens, two cinnamate oxygens, and an apical aqua. The metal ions of 2 and 3, however, assume a square planar configuration, which is realized by coordination of two nitrogens of two imidazoles and two oxygens; in both complexes, the imidazole moieties are trans to each other. TGA results indicate that upon heating, these complexes lose their carboxylate anions first, followed by removal of the imidazole molecules.     

Syntheses and crystal structures of cobalt(II) and zinc(II) complexes with 4′-methoxy-5,6,7-trihydroxyisoflavone-3′-sulfonate

Abstract Sodium 4′-methoxy-5,6,7-trihydroxyisoflavone-3′-sulfonate (1) is synthesized by the sulfonation of 6-hydroxybiochanin A and its structure is characterized by elemental analysis, ¹H-NMR, and IR spectroscopy. It is assembled with cobalt(II) or zinc(II), hexaquacobalt(II) bis(4′-methoxy-5,6,7-trihydroxyisoflavone-3′-sulfonate) tetrahydrate (2) and hexaquazinc(II) bis(4′-methoxy-5,6,7-trihydroxyisoflavone-3′-sulfonate) tetrahydrate (3) are obtained and characterized by IR spectroscopy. Simultaneously, their three-dimensional structures are determined by single-crystal X-ray analysis. It turns out that 2 and 3 are isomorphous and crystallize in the triclinic crystal system, space group P-1. Hydrophilic regions are defined by O–H···O hydrogen bonds involving the coordinated water molecules, the included water molecules, and sulfonate groups. Aromatic π...π stacking interactions assemble the isoflavone skeletons into columns and these columns formed hydrophobic regions. The sulfonate group is an important bridge as a structural link between the hydrophilic regions and the hydrophobic regions. Hydrogen bonds, π...π stacking interactions and the electrostatic interactions assemble 2 and 3 into three-dimensional network structures. Graphical abstract Sodium 4′-methoxy-5,6,7-trihydroxyisoflavone-3′-sulfonate (1) is synthesized and assembled with cobalt(II) or zinc(II). Hexaquacobalt(II) bis(4′-methoxy-5,6,7-trihydroxyisoflavone-3′-sulfonate) tetrahydrate (2) and hexaquazinc(II) bis(4′-methoxy-5,6,7-trihydroxyisoflavone-3′-sulfonate) tetrahydrate (3) are obtained and determined by single-crystal X-ray analysis. It turns out that 2 and 3 are isomorphous and assembled into three-dimensional network structures, characterized by hydrophilic regions defined by hydrogen bonds involving the coordinated water molecules, the included water molecules, and the sulfonate groups and by hydrophobic columns, formed by the isoflavone skeletons, interacting through π...π stacking interactions.      

Synthesis,structural studies,and antibacterial activity of zinc,copper, and silver complexes derived from N′-(1-(pyrazin-2-yl)ethylidene)isonicotinohydrazide

The multidentate Schiff-base ligand N′-(1-(pyrazin-2-yl)ethylidene)isonicotinohydrazide (HL) has been prepared. Reaction with zinc, copper, and silver nitrate afford three complexes, [Zn(HL′)₂](NO₃)₂·3H₂O (1), {[Cu₂(L)₂(NO₃)(H₂O)₂]·NO₃}_n (2) and {[Ag₂(L)₂]·3H₂O}_n (3). These complexes have been characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. In 1, HL is a neutral tridentate ligand, whereas in 2 and 3, HL is a deprotonated tetradentate ligand. The hydrogen bonding interactions between NO₃^? and the host framework result in various supramolecular polymeric structures: a 2-D layer for 1 and 3-D network for 2 and 3. The antibacterial activities of these complexes have been investigated and the results indicate that 3 showed good antibacterial activities.     

Syntheses,crystal structures and magnetic properties of two cyano-bridged copper(I)–copper(II) mixed-valence complexes

Two cyano-bridged copper(II)–copper(I) mixed-valence assemblies, Cu(EAM)₂[Cu(CN)₂]₂ 1 (EAM?=?ethanolamine) and Cu(DETA)[Cu(CN)₂]₂·0.5H₂O 2 (DETA?=?diethylenetriamine), have been prepared and structurally and magnetically characterized. IR spectra indicate the presence of bridging cyano groups in both 1 and 2, confirmed by structure analyses; Cu(I)–CN–Cu(II), Cu(I)–CN–Cu(I) and Cu(I)–Cu(I) metal bond linkages are evident. In the lattice, a 3D network is formed by two [Cu(CN)₂]?^? units and one [Cu(EAM)₂]²⁺unit for 1. Variable temperature magnetic susceptibilities, measured in the 5–300?K range, indicate weak antiferromagnetic exchange interactions in complex 1.     

Syntheses,crystal structures,and fluorescence of two complexes constructed by N ′-(pyridin-2-ylmethylene)-2-( 1H -1,2,4-triazol-1-yl)acetohydrazide

Two new binuclear complexes, Cd₂(HL)₂(NO₃)₄?·?(CH₃OH)₂ (1) and Cu₂(L)₂(ClO₄)₂ (2), based on N′-(pyridin-2-ylmethylene)-2-(1H-1,2,4-triazol-1-yl)acetohydrazide (HL) and Cd(II) and Cu(II) salts have been synthesized and characterized by single crystal X-ray diffraction. Hydrogen bonds and π–π interactions extend both binuclear molecules, a 3-D supramolecular framework for 1 and 1-D staggered chains for 2. Fluorescence of both complexes is discussed.     

Synthesis,crystal structures,and superoxide dismutase activity of two isostructural copper(II)–zinc(II) complexes derived from N,N′-bis(4-methoxysalicylidene)cyclohexane-1,2-diamine

Two new isostructural copper(II)–zinc(II) complexes, [CuZnLBr₂] (1) and [CuZnLCl₂] (2) (H₂L = N,N′-bis(4-methoxysalicylidene)cyclohexane-1,2-diamine), have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. Both complexes crystallize in the P-1 space group. The Cu in each complex is four-coordinate square planar with two imines and two phenolates of L. The Zn in each complex is four-coordinate tetrahedral with two phenolates of L and two halides (Br for 1 and Cl for 2). The superoxide dismutase (SOD) activity of the complexes indicates that both complexes are rudimentary models for SOD.     

Syntheses,crystal structures and fluorescent properties of two 4,4′-dipyridylsulfide based zinc(II) and cadmium(II) helical complexes

Two allomeric helical coordination polymers, {[Zn(4,4′-dps)₂(HSSA)(H₂O)₂] · 3(H₂O)} _n (1) and {[Cd(4,4′-dps)₂(HSSA)(H₂O)₂] · 3(H₂O)} _n (2) (4,4′-dps = 4,4′-dipyridylsulfide, H₃SSA = 5-sulfosalicylic acid), have been synthesized by similar experimental methods and characterized by elemental analysis, single-crystal X-ray diffraction, and fluorescence spectra. Both crystallize in monoclinic system, space group P₂1/n, with a = 11.7947(13) Å, b = 13.7475(15) Å, c = 20.183(2) Å, and Z = 4 for 1 and a = 11.940(7) Å, b = 14.068(8) Å, c = 20.323(12) Å, and Z = 4 for 2. In both complexes, the metal (Zn^II for 1 and Cd^II for 2) are six-coordinate with a N₃O₃ donor set in a distorted octahedron. Half of the 4,4′-dps are μ ₂-bridging, linking adjacent metal centers and forming P₂1/n dimensional helical structures along the b-axis. Fluorescence measurements show that 1 and 2 have medium fluorescent emission at 402 and 405 nm, respectively.     

Synthesis,structures, and insulin-like activity of oxidovanadium(V) complexes derived from 2-chloro-N′-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide

Three new oxidovanadium(V) complexes, [VOLL′] (L = 2-chloro-N′-(3-ethoxy-2hydroxybenzylidene)benzohydrazide, L′ = acetohydroxamate for 1, methylmaltolate for 2, and ethylmaltolate for 3), have been prepared. The complexes have been characterized by physicochemical methods and single-crystal X-ray determination. Vanadium in each complex is coordinated by the NOO donor set of L, the OO donor set of L′, and one oxido, forming octahedral coordination. The complexes were administered intragastrically to both normal and alloxan-diabetic mice for two weeks. The biological activities show that the complexes at doses of 10.0 and 20.0 mg V·kg^?1 can significantly decrease the blood glucose level in alloxan-diabetic mice, but the blood glucose level in the treated normal mice was not altered.     

Syntheses,structures, and properties of Ni(II) complexes with 5,5′-bis(4-halogenphenyl)diazo-dipyrromethane

Ni(II) complexes with 5,5′-bis(4-halogenphenyl)diazo-dipyrromethane have been synthesized and characterized by X-ray crystallography. All the complexes have similar crystal structures in which Ni(II) is square-planar by coordinating to two pyrrole and two azo nitrogen atoms. The azo-pyrroles of the ligands can be converted to the hydrazone tautomer after complexing nickel. Moreover, the C–H?···?Ni interaction played an important role in directing self-assembly of the complexes. The UV-Vis spectra of the complexes showed great difference with the metal complexes of pyrrol-2-imine.     

Synthesis and crystal structure of a trinuclear copper(II) complex derived from N,N′-Bis(4-methoxysalicylidene)-1,3-pentanediamine

A trinuclear copper(II) complex [Cu₃Cl₂L₂], where L is the dianionic form of N,N′-bis(4-methoxysalicylidene)-1,3-pentanediamine, has been synthesized and characterized by means of spectroscopic methods and single crystal X-ray structure determination. The complex crystallizes in the orthorhombic space group Pnma with unit cell dimensions a = 15.301(2), b = 23.226(2), c = 12.089(1)Å, V = 4296.2(8) ų, Z = 4, R ₁ = 0.0682, and wR ₂ = 0.1590. The molecule of the complex possesses a crystallographic mirror plane symmetry with the mirror plane passes through the three Cu atoms and the two Cl atoms. The two terminal Cu atoms adopt distorted square pyramidal coordination, and the middle one adopts square planar coordination. The intramolecular Cu…Cu distances are 2.900(1) and 2.916(1) Å. The complex was tested for its antibacterial activity to assess its inhibiting potential.     

Synthesis,crystal structures,and selected properties of Cu(II) and Zn(II) complexes with in situ formed 2-hydroxy-N′-(propan-2-ylidene)benzohydrazide

Cu(C₁₀H₁₁O₂N₂)₂ (1) and [Zn(C₁₀H₁₂O₂N₂)₂(H₂O)₂](NO₃)₂ (2) were synthesized and characterized by elemental analysis, FT-IR spectra, UV-Vis absorption spectroscopy, and X-ray single-crystal diffraction. Both complexes show distorted octahedral geometry. In 1, Cu(II) is coordinated by four oxygen atoms from four ligands and two nitrogen atoms from two ligands. In 2, Zn(II) is coordinated by two oxygen atoms and two nitrogen atoms from two ligands, and two water molecules. The crystal structures suggest that original ligand o-carboxybenzaldehyde salicyloylhydrazone (C₁₅H₁₂O₄N₂) changed into acetone salicyloylhydrazone (C₁₀H₁₂O₂N₂). The TG-DTG curves of these complexes indicate two different decomposition processes. 1 and 2 display catalytic activities to decomposition of hydrogen peroxide. Interaction between the complexes and DNA studied by UV-Vis titration shows the insert interaction.     

Synthesis,crystal structures and catalytic activities of new palladium(II)–bis(oxazoline) complexes

Palladium–bis(oxazoline) complexes (Pd-BOX-A and Pd-BOX-B) were synthesized and characterized by ¹H, ¹³C NMR, IR and elemental analysis. The molecular structures of the complexes were confirmed by single-crystal X-ray analysis. In both cases, the palladium center is coordinated by the nitrogen atoms of the two oxazoline rings and two chloride ligands in a distorted square planar geometry. Despite the fact that the bis(oxazoline) ligand is achiral, the asymmetrical substitution on the phenyl spacer and the rigid backbone of the complex Pd-BOX-A induce inherent chirality and the compound crystallizes as a racemic mixture. Both complexes were found to be highly effective catalysts for Suzuki–Miyaura, Mizoroki–Heck and Sonogashira cross-coupling reactions. They also show excellent catalytic activities toward carbonylative coupling reactions.     

Syntheses,characterization, X-ray crystal structures and emission properties of copper(II), zinc(II) and cadmium(II) complexes of pyridyl–pyrazole derived Schiff base ligand – Metal selective ligand binding modes

The varying coordination modes of the title ligand, L [5-methyl-1-(pyridin-2-yl)-N′-[pyridin-2-ylmethylidene]pyrazole-3-carbohydrazide] towards the different metal centers is reported by preparation and characterization of Cu(II), Zn(II) and Cd(II) complexes, [Cu(L)NO₃.H₂O](NO₃) (1) [Zn(L)₂](ClO₄)₂·2DMF (2) and [Cd(L)(I)₂] (3) respectively. In 1, the neutral ligand serves as tetradentate 4 N donor where both pyridine and pyrazole nitrogen atoms of pyridyl–pyrazole part are coordinatively active, leaving the carbonyl oxygen of the carbohydrazide part inactive. The same pyridine and pyrazole N atoms remain abstained from the coordination process towards the Zn(II) and Cd(II) metal centers. For 2 and 3 the ligand behaves as a tridentate NNO donor where the two nitrogen atoms come from azomethine, pyridine of pyridine-2-carbaldehyde parts and O from carbonyl oxygen atoms (carbohydrazide part). The complex 1 and 2 are distorted octahedral while complex 3 adopts distorted square pyramidal geometry. All the complexes are X-ray crystallographically characterized.     

Synthesis and crystal structures of two zinc(II) complexes derived from N-isopropyl-N′-[1-(2-methoxyphenyl)methylidene]ethane-1,2-diamine

Two isostructural mononuclear zinc(II) complexes, [ZnLBr₂] (I) and [ZnLI₂] (II), derived from the Schiff base N-isopropyl-N′-[1-(2-methoxyphenyl)methylidene]ethane-1,2-diamine (L), have been synthesized and characterized by elemental analysis, IR spectra, and X-ray single-crystal diffraction. The crystal of I is monoclinic: space group P2₁/n, a = 14.476(1) Å, b = 7.327(1) Å, c = 17.528(1) Å, β = 101.153(1)°, V = 1824.0(3) ų, Z = 4. The crystal of II is monoclinic: space group P2₁/n, a = 14.482(1), b = 7.329(1), c = 17.528(1)Å, β = 101.195(2)°, V = 1825.0(3)ų, Z = 4. The Zn atom in each complex is four-coordinated in a tetrahedral coordination, with one imine N and one amine N atoms of L, and two halide atoms. Both complexes and the Schiff base were tested in vitro for their antibacterial activities.