Syntheses and crystal structures of two Schiff-base copper(II) complexes with urease inhibition

Two new copper(II) complexes, [CuL1(N₃)] (1) and [CuL2(NCS)] (2) (HL1 = 4-chloro-2-[(2-piperidin-1-ylethylimino)methyl]phenol, HL2 = 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol), were prepared and structurally characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. Complex 1 is an azide coordinated mononuclear complex, while complex 2 is a terminal thiocyanate coordinated mononuclear complex. The coppers in both complexes are four-coordinate, square-planar. Both complexes show potent urease inhibitory properties.     

Synthesis,crystal structure,and antibacterial activity of mononuclear nickel(II) and cobalt(III) Schiff-base complexes

Four new mononuclear complexes, [Ni(L¹)(NCS)₂] (1), [Ni(L²)(NCS)₂] (2), [Co(L¹)(N₃)₂]ClO₄ (3), and [Co(L²)(N₃)₂]ClO₄ (4), where L¹ and L² are N,N′-bis[(pyridin-2-yl)methylidene]butane-1,4-diamine and N,N′-bis[(pyridin-2-yl)benzylidene]butane-1,4-diamine, respectively, have been prepared. The syntheses have been achieved by reaction of the respective metal perchlorate with the tetradentate Schiff bases, L¹ and L², in presence of thiocyanate (for 1 and 2) or azide (for 3 and 4). The complexes have been characterized by microanalytical, spectroscopic, single crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1–4 are distorted octahedral geometries. The antibacterial activity of all the complexes and their constituent Schiff bases have been tested against Gram-positive and Gram-negative bacteria.     

Synthesis,crystal structures,and urease inhibition studies of two new Schiff-base copper complexes derived from n-butylamine

Two Schiff-base copper(II) complexes, bis(N-n-butyl-5-chlorosalicylaldiminato) copper(II) (1) and bis(N-n-butyl-4-methoxysalicylaldiminato) copper(II) (2), were synthesized and their solid-state structures were determined by X-ray crystallography. Complex 1 displays a distorted square-planar geometry, while 2 possesses square-planar geometry. Copper(II) complexes 1 and 2 showed strong inhibitory activity against jack bean urease (IC₅₀?=?2.7, 3.5?µmol?L^?1), compared with acetohydroxamic acid (IC₅₀?=?63.00?µmol?L^?1). A molecular modeling study was carried out via the DOCK program to gain understanding of the potent inhibitory activity of these copper species against jack bean urease.     

Synthesis,crystal structure,spectroscopy, and nuclease activity of copper(II) complexes containing N,N-bis(2-pyridylmethyl)amine ligand

[Cu(bpea)Cl]ClO₄ (1) and a new copper(II) complex [Cu(bpma)(Ph-COO)(H₂O)]ClO₄ (2) [bpea?=?N,N-bis(2-pyridylmethyl)ethylamine; bpma?=?N,N-bis(2-pyridylmethyl)methylamine] have been synthesized. Complex 2 was crystallized in monoclinic space group P2₁/c with unit cell parameters a ?=?16.460(6)?Å, b ?=?11.222(4)?Å, c?=?12.522(5)?Å, and β?=?97.985(6)°. Interactions of the complexes with calf thymus DNA (CT-DNA) have been investigated by UV absorption, fluorescence, and cyclic voltammetry; thus, modes of CT-DNA binding for the complexes have been proposed. Furthermore, DNA cleavage activities by the complexes were performed in the absence of any external agents. The influence of complex concentration or reaction time on the DNA cleavage was studied.     

Synthesis and crystal structure determination of copper(II) and iron(III) complexes of 2-(2-pyridyl)benzothiazole

Two complexes [Cu^II(pbt)(dmf)Cl₂] and [Fe^III(pbt)Cl₃], where pbt is 2-(2-pyridyl)benzothiazole, and dmf is dimethylformamide, were prepared by the reaction of metal chlorides with pbt solutions. The structures of the products were identified by elemental analysis, usual spectroscopic methods and X-ray diffraction analysis. The crystal data revealed penta-coordination around both metal ions, with trigonal bipyramidal geometries. 2-(2-pyridyl)benzothiazole binds to both Cu^II and Fe^III in the N,N-chelation manner and leaves the S atom uncoordinated.     

Synthesis and crystal structure of three new copper(II) complexes with a tridentate amine and its Schiff bases

Three new mononuclear complexes of copper(II), viz. [Cu(L)(N₃)Cl] (1), [Cu(L′)(H₂O)]ClO₄ (2) and [Cu(L″)] (3) where L = N-(3-aminopropyl)-N-methylpropane-1,3-diamine, L′ = 2-(N-{3-[(3-aminopropyl)(methyl)amino]propyl}ethanimidoyl)phenolate ion and L″ = 2,2′-{(methylimino)bis[propane-3,1-diylnitrilo(1E)eth-1-yl-1-ylidene]}diphenolate ion, have been prepared. The synthesis of complex 1 has been achieved by reacting copper chloride with the triamine (L) and sodium azide in a 1:1:1 M ratio. The other two compounds have been synthesized by the reaction of copper perchlorate with the same triamine, L, plus 2-hydroxyacetophenone in a molar ratio of 1:1:1 (for 2) and 1:1:2 (for 3), so that the respective tetradentate and pentadentate Schiff bases HL′ and H₂L″ are formed in situ to bind the copper(II) ions. The complexes have been characterized by microanalytical, spectroscopic and single crystal X-ray diffraction studies. Structural studies reveal that the mononuclear units of all the three complexes adopt a distorted square pyramidal geometry and are held together by either intermolecular H-bonding (in 1 and 2) or C-H?π interactions (in 3) to form supramolecular networks in the solid state.     

Synthesis,crystal structure and characterization of 3-thiophene aldehyde thiosemicarbazone and its complexes with cobalt(II), nickel(II) and copper(II)

The reaction of cobalt(II), nickel(II), copper(II) chlorides and bromides with 3-thiophene aldehyde thiosemicarbazone (3TTSCH) leads to the formation of a series of new complexes: [Co(3TTSC)₂], [Ni(3TTSC)₂], [CuCl(3TTSC)]₂, [CuBr(3TTSC)]₂ and [CuBr₂(3TTSCH)]. The crystal structures of the free ligand and of the compound [Ni(3TTSC)₂] have been determined by X-ray diffraction methods. For all these complexes, the central ion is coordinated through the sulfur and the azomethine nitrogen atom of the thiosemicarbazone. [Co(3TTSC)₂], [Ni(3TTSC)₂] and [CuBr₂(3TTSCH)] are mononuclear species, while [CuCl(3TTSC)]₂ and [CuBr(3TTSC)]₂ are binuclear complexes.     

Synthesis and crystal structures of cobalt(III) and zinc(II) complexes with Schiff bases

Two new cobalt(III) and zinc(II) complexes, [Co(L¹)₂ (H₂O)] · ClO₄ (I) and [Ni(L²)₂ (H₂O)₂] · 2ClO₄ (II), where L¹ is the deprotonated form of 5-methoxy-2-[(2-morpholin-4-ylethylimino)methyl]phenol, and L² is the zwitterionic form of 2-[(2-isopropylaminoethylimino)methyl]-5-methoxyphenol, were synthesized and structurally characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. The crystal of I is monoclinic: space group P2₁/c, a = 11.1512(4), b = 28.2424(11), c = 10.9655(4) Å, β = 95.746(2)°, V = 3436.1(2) ų, Z = 4. The crystal of II is triclinic: space group P2₁/c, a = 8.1441(2), b = 10.4531(3), c = 10.8849(3) Å, α = 84.0240(10)°, β = 76.9800(10)°, γ = 74.2280(10)°, V = 867.92(4) ų, Z = 1. Complex I consists of a mononuclear cobalt(III) complex cation and a perchlorate anion. Complex II consists of a crystallographic centrosymmetric mononuclear nickel(II) complex cation and two perchlorate anions. Each metal atom in the complexes is in an octahedral coordination.     

Synthesis,crystal structure and antibacterial activity of manganese(III) and cobalt(III) complexes containing pentadentate Schiff bases of a common amine and thiocyanate

Abstract

Four new mononuclear Schiff base manganese(III) and cobalt(III) complexes viz. [Mn(L¹)(NCS)] (1), [Mn(L²)(NCS)] (2), [Co(L³)(NCS)] (3), and [Co(L⁴)(NCS)]·0.5CH₃OH·0.5H₂O (4), containing thiocyanate as a common pseudohalide ion are reported. The pentadentate Schiff base ligands H₂L¹, H₂L², H₂L³, and H₂L⁴ were obtained by the condensation of substituted salicylaldehydes with N-(3-aminopropyl)-N-methylpropane-1,3-diamine. The syntheses of the complexes have been achieved by the reaction of manganese(II) perchlorate or cobalt(II) perchlorate with the respective Schiff bases in the presence of thiocyanate in methanol medium. Complexes 1–4 have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1–4 adopt nearly similar structures containing the MN₄O₂ (M?=?Mn, Co) chromophore in which each central M(III) ion adopts a distorted octahedral geometry. Weak intermolecular H-bonding interactions are operative in these complexes to bind the molecular units. The antibacterial activity of 1–4 and their constituent Schiff bases has been tested against some common bacteria.     

Synthesis,structures, and urease inhibition of nickel(II), zinc(II), and cobalt(II) complexes with similar hydroxy-rich Schiff bases

Four new nickel(II), zinc(II), and cobalt(II) complexes, [Zn(L¹)₂]?·?H₂O (1), [Ni(L¹)₂]?·?H₂O (2), [Ni(L²)₂] (3), and [Co(L³)₂]?·?H₂O (4), derived from hydroxy-rich Schiff bases 2-{[1-(5-chloro-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL¹), 2-{[1-(2-hydroxy-3-methoxyphenyl)methylidene]amino}-2-ethylpropane-1,3-diol (HL²), and 2-{[1-(5-bromo-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL³) have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray determination. Each metal in the complexes is six-coordinate in a distorted octahedral coordination. The Schiff bases coordinate to the metal atoms through the imino N, phenolate O, and one hydroxyl O. In the crystal structures of HL¹ and the complexes, molecules are linked through intermolecular O–H···O hydrogen bonds, forming 1-D chains. The urease inhibitory activities of the compounds were evaluated and molecular docking study of the compounds with the Helicobacter pylori urease was performed.     

Synthesis, crystal structures, and urease inhibitory activities of two azido-bridged polynuclear copper(II) complexes with Schiff bases

Two azido-bridged polynuclear Cu(II) complexes with the formulae [Cu(L1)(μ_1,3-N₃)] _n and [Cu(L2)(μ_1,3-N₃)] _n (HL1 = 2-[(2-morpholin-4-ylethylimino)methyl]phenol, HL2 = 2-methoxy-6-[(2-piperidin-1-ylethylimino)methyl]phenol), have been synthesized and characterized by physico-chemical and spectroscopic methods. The Cu atom in each of the complexes is five-coordinate in a square pyramidal geometry, with one O and two N atoms of a Schiff base ligand and one terminal N atom of a bridging azido ligand defining the base-plane, and with another terminal N atom of a symmetry-related azido ligand occupying the apical position. The molecules are linked through end-to-end azido bridges, forming one-dimensional polymeric chains. Both of the complexes show moderate inhibitory activities against jack bean urease.     

Synthesis,spectroscopic properties,crystal structure and biological activities of copper(II) 2-methylthionicotinate complexes with furopyridines

The synthesis and characterization of six new 2-methylthionicotinate (2-MeSnic) copper(II) monomeric complexes [Cu(2-MeSnic)₂L₂] (L is furo[3,2-c]pyridine—fpy, 2-methylfuro[3,2-c]pyridine—Mefpy, 2,3-dimethylfuro[3,2-c]pyridine—Me₂fpy or benzo[4,5]furo[3,2-c]pyridine—Bfp), [Cu(2-MeSnic)₂(fpy)₂(H₂O)], as well as [Cu(2-MeSnic)₂(CF₃Phfpy)₂(H₂O)₂] (CF₃Phfpy is 2-(3-trifluoromethylphenyl)furo[3,2-c]pyridine) are reported. The characterizations were based on elemental analysis, infrared, electronic and EPR spectra. The crystal structure of one of the complexes has been determined. The Cu^II atoms of [Cu(2-MeSnic)₂(fpy)₂(H₂O)] are six-coordinated in a highly distorted tetragonal–bipyramidal arrangement by two nitrogen atoms, one from each fpy, in trans-positions, by three oxygen atoms of the carboxyl groups of 2-MeSnic ligands (one monodentate, one asymmetrically bidentate), one axial position being occupied by the oxygen of a water molecule. The antimicrobial effects have been tested on various strains of bacteria, yeasts and filamentous fungi. A comparison of the IC₅₀ and MIC values has shown a decrease of inhibition activities of tested compounds in the order: [Cu(2-MeSnic)₂(Bfp)₂] > Bfp > [Cu(2-MeSnic)₂(CF₃Phfpy)₂(H₂O)₂] > [Cu(2-MeSnic)₂(Me₂fpy)₂] > CF₃Phfpy > [Cu(2-MeSnic)₂(Mefpy)₂] > Me₂fpy > [Cu(2-MeSnic)₂(fpy)₂(H₂O)] > [Cu(2-MeSnic)₂(H₂O)]₂ > Mefpy > fpy = 2-MeSnicH = CuSO₄. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis and crystal structure of nickel(II) complexes with bis(5-methyl-2-thiophenemethyl)(2-pyridylmethyl)amine

A series of nickel(II) complexes having the (Me-Tp)₂PMA ligand ((Me-Tp)₂PMA = bis(5-methyl-2-thiophenemethyl)(2-pyridylmethyl)amine) with nitrates (1), chlorides (2), and perchlorates (3) as anions were synthesized and isolated. All these complexes were successfully characterized by physicochemical methods including X-ray crystallographic analysis. In complex 1, the ligand binds in a bidentate N₂ fashion, whereas in the cases of 2 and 3 the ligand binds in the tridentate N₂S form. The coordination geometry around the nickel(II) atoms in these complexes is distorted octahedral.     

Synthesis,crystal structure and thermal stability of new copper(II) trichloroacetate complexes

We have synthesized two novel complexes of copper(II) trichloro acetate, Cu₂(CCl₃COO)₃(OH)(H₂O)₄·H₂O and Cu(CCl₃COO)₂(MeCN), and determined their crystal structures and thermal stability. While the complex with acetonitrile has a discrete binuclear paddle-wheel structure, typical of copper carboxylates, the aqua-hydroxo complex belongs to a novel unique chain–molecular type of basic copper complexes.     

Synthesis,X-ray crystal structure,and electrochemistry of polynuclear azido-bridged manganese(III) and copper(II) Schiff base complexes

New azido-bridged [Mn^III(salabza)(μ-1,3-N₃)]_n (1), and [Cu^II₄(salabza)₂(μ-1,1-N₃)₂(N₃)₂(HOCH₃)₂],(2) complexes with an unsymmetrical Schiff base ligand, {H₂salabza = N,N’-bis(salicylidene)-2-aminobenzylamine}, have been synthesized, characterized by spectroscopic and electrochemical methods, and their crystal structures have been determined by X-ray diffraction. In complex 1, each manganese(III) atom is coordinated with N₂O₂ donor atoms from salabza and two adjacent Mn(III) centers are linked by an end-to-end (EE) azide bridge to form a helical polymeric chain with octahedral geometry around the Mn(III) centers. Complex 2 is a centrosymmetric tetranuclear compound containing two types of Cu(II) centers with square pyramidal geometry. Each terminal copper atom is surrounded by N₂O₂ atoms of a salabza ligand, and the oxygen atom of the methanol molecule. Each central copper(II) ion is coordinated with two phenoxo oxygen atoms from one salabza, one terminal azido, and two end-on (EO) bridging azido ligands. The central copper(II) ions are linked to each other by the two end-on (EO) azido groups.     

Synthesis,structure and cytotoxic activity of cobalt(II), nickel(II) and copper(II) chloride complexes with acetamidrazones

Co^II, Ni^II and Cu^II chloride complexes with acetamidrazone derivatives (L ¹ )–(L ⁸ ) have been prepared, by reacting the corresponding metal chloride with the ligand in a 1:2 ratio, and characterised by chemical analysis and physical measurements. The ligand behaviour and the geometry have been assigned on the basis of i.r. spectroscopy, electronic reflectance spectra and molar conductivity values and only, where possible, the geometry has been confirmed as octahedral by X-ray structure determination. Complexes cytotoxicity on a human cellular line of adenocarcinoma was also tested. Three of the complexes present a weak cytotoxicity in vitro.     

Synthesis, crystal structure, spectroscopic and photoluminescence studies of manganese(II), cobalt(II), cadmium(II), zinc(II) and copper(II) complexes with a pyrazole derived Schiff base ligand

Varying coordination modes of the Schiff base ligand H₂L [5-methyl-1-H-pyrazole-3-carboxylic acid (1-pyridin-2-yl-ethylidene)-hydrazide] towards different metal centers are reported with the syntheses and characterization of four mononuclear Mn(II), Co(II), Cd(II) and Zn(II) complexes, [Mn(H₂L)(H₂O)₂](ClO₄)₂(MeOH) (1), [Co(H₂L)(NCS)₂] (2), [Cd(H₂L)(H₂O)₂](ClO₄)₂ (3) and [Zn(H₂L)(H₂O)₂](ClO₄)₂ (4), and a binuclear Cu(II) complex, [Cu₂(L)₂](ClO₄)₂ (5). In the complexes 1-4 the neutral ligand serves as a 3N,2O donor where the pyridine ring N, two azomethine N and two carbohydrazine oxygen atoms are coordinatively active, leaving the pyrazole-N atoms inactive. In the case of complex 5, each ligand molecule behaves as a 4N,O donor utilizing the pyridine N, one azomethine N, the nitrogen atom proximal to the azomethine of the remaining pendant arm and one pyrazole-N atom to one metal center and the carbohydrazide oxygen atom to the second metal center. The complexes 1-4 are pentagonal bipyramidal in geometry. In each case, the ligand molecule spans the equatorial plane while the apical positions are occupied by water molecules in 1, 3 and 4 and two N bonded thiocyanate ions in 2. In complex 5, the two Cu(II) centers have almost square pyramidal geometry (τ = 0.05 for Cu1 and 0.013 for Cu2). Four N atoms from a ligand molecule form the basal plane and the carbohydrazide oxygen atom of a second ligand molecule sits in the apex of the square pyramid. All the complexes have been X-ray crystallographically characterized. The Zn(II) and Cd(II) complexes show considerable fluorescence emission while the remaining complexes and the ligand molecule are fluorescent silent.