Synthesis and characterization of copper(II) and cobalt(II) complexes with two new potentially hexadentate Schiff base ligands. X-ray crystal structure determination of one copper(II) complex

Two new potentially hexadentate N₂O₄ Schiff base ligands 2-((z)-(2-(2-(2-((z)-3,5-di-tert-butyl-2-hydroxybenzylideneamino) phenoxy) phenoxy) phenylimino) methyl)-4,6-di-tert-butylphenol [H₂L¹] and 2-((z)-(2-(2-(2-((z)-3,5-di-tert-butyl-2-hydroxybenzylideneamino) phenoxy)-5-tert-butylphenoxy) phenylimino) methyl)-4,6-di-tert-butylphenol [H₂L²] were prepared from the reaction of 3,5-di-tert-butyl-2-hydroxy benzaldehyde with 1,2-bis(2′-aminophenoxy)benzene or 1,2-bis(2′-aminophenoxy)-4-t-butylbenzene, respectively. From the direct reaction of ligands [H₂L¹] and [H₂L²] with copper(II) and cobalt(II) salts in methanolic solution and in the presence of N(Et)₃ the neutral [CuL¹], [CuL²], [CoL¹] and [CoL²] complexes were prepared. All complexes were characterized by IR spectra, elemental analysis, magnetic susceptibility, mass spectra, molar conductance (Λ_m), UV-Vis spectra and in the case of [CuL²] with X-ray diffraction. X-ray crystal structure of [CuL²] showed that the complex contains copper(II) in a distorted square planar environment of N₂O₂ donors. Three CH/π interactions were observed in the molecular structure of latter complex.     

Synthesis and crystal structure of tetra- and hexanuclear uranium(IV) complexes with hexadentate compartmental Schiff-base ligands

Treatment of UCl4 with the hexadentate Schiff bases H2Li in thf gave the expected [ULiCl2(thf)] complexes [H2Li=N,N'-bis(3-methoxysalicylidene)-R and R = 2,2-dimethyl-1,3-propanediamine (i= 1), R = 1,3-propanediamine (i= 2), R = 2-amino-benzylamine (i= 3), R = 2-methyl-1,2-propanediamine (i= 4), R = 1,2-phenylenediamine (i= 5)]. The crystal structure of [UL4Cl2(thf)] (4) shows the metal in a quite perfect pentagonal bipyramidal configuration, with the two Cl atoms in apical positions. Reaction of UCl4 with H4Li in pyridine did not afford the mononuclear products [U(H2Li)Cl2(py)x] but gave instead polynuclear complexes [H4Li=N,N'-bis(3-hydroxysalicylidene)-R and R = 1,3-propanediamine (i= 6), R = 2-amino-benzylamine (i= 7) or R = 2-methyl-1,2-propanediamine (i= 8)]. In the presence of H4L6 and H4L7 in pyridine, UCl4 was transformed in a serendipitous and reproducible manner into the tetranuclear U(iv) complexes [Hpy]2[U4(L6)2(H2L6)2Cl6] (6a) and [Hpy]2[U4(L7)2(H2L7)2Cl6][U4(L7)2(H2L7)2Cl4(py)2] (7), respectively. Treatment of UCl4 with [Zn(H2L6)] led to the formation of the neutral compound [U4(L6)2(H2L6)2Cl4(py)2] (6b). The hexanuclear complex [Hpy]2[U6(L8)4Cl10(py)4] (8) was obtained by reaction of UCl4 and H4L8. The centrosymmetric crystal structures of 6a.2HpyCl.2py, 6b.6py, 7.16py and 8.6py illustrate the potential of Schiff bases as associating ligands for the design of polynuclear assemblies.     

Synthesis and characterization of two zinc(II) macrocyclic Schiff-base complexes containing piperazine moiety, crystal structure of one complex

Two symmetrical and asymmetrical Zn(II) complexes of a pentadentate (N₅) macrocyclic Schiff-base ligands, were prepared via templated [1 + 1] cyclocondensation of 2,6-diacetylpyridine with two different amines containing piperazine moiety. The complexes have been characterized by a variety of methods including, IR, FAB mass spectrometry, elemental analysis and conductivity measurements. The crystal structure of the asymmetric complex, [ZnL¹Br]ClO₄ was determined by X-ray diffraction. It is shown that in the solid state the complex adopts a distorted pentagonal–pyramidal geometry, with the macrocycle in the pentagonal plane and the bromide ion in the axial position.     

Synthesis,characterization, and antioxidant activities of three Cu(II) complexes with Schiff-base ligands

Cu(II) complexes of three bis(pyrrol-2-yl-methyleneamine) ligands were synthesized and characterized by elemental analyses, mass spectra, and IR spectra. X-ray diffraction analysis shows that [CuL³]₂ is a dinuclear complex with an extremely distorted square-planar geometry. Furthermore, the antioxidant activities of the compounds have been investigated. The electrochemical properties of the Cu(II) complexes have also been studied by cyclic voltammetry. The Cu(II) complexes show similar superoxide dismutase (SOD) activity compared with that of the native Cu, Zn-SOD.     

Synthesis,crystal structures and characterization of two Cu(II) complexes with asymmetric sulfonamide Schiff-base ligands

Reaction of the N-tosyl-1,2-diaminopropane or N-tosyl-1,2-diaminobenzene with salicylaldehyde forms two new asymmetric sulfonamide Schiff bases, N-[2-(2-hydroxybenzylideneamino)propyl]-4-methylbenzenesulfonamide (H₂L¹ ) and N-[2-(2-hydroxybenzylideneamino)phenyl]-4-methylbenzenesulfonamide (H₂L² ). Two new complexes [CuL ^x (H₂O)] (x = 1 for 1, x = 2 for 2) constructed from H₂L ^x have been prepared and characterized via X-ray single-crystal diffraction, elemental analysis, FT-IR, UV-Vis, TGA, quantum chemical calculations, and photoluminescence measurements. Weak C–H ··· π, hydrogen bonds, π–π, and Cu ··· O weak interactions lead to 3-D supramolecular architecture, 1, and 1-D double chain, 2.     

Synthesis and crystal structure of Mn(II) complexes with novel macrocyclic Schiff-base ligands containing piperazine moiety

A series of Mn(II) macrocyclic Schiff-base complexes [MnLⁿCl]⁺ (n = 1–4) have been prepared via the Mn(II) templated [1+1] cyclocondensation of 2,6-diacetylpyridine or 2,6-pyridinedicarbaldehyde with the symmetrical 1,4-bis(3-aminopropyl)piperazine or the novel asymmetrical N,N′(2-aminoethyl)(3-aminopropyl)piperazine linear amines containing piperazine moiety. The complexes have been characterized by elemental analyses, IR, FAB-MS, magnetic studies and conductivity measurements. The crystal structure of [MnL²(CH₃OH)Cl](ClO₄) and [MnL⁴Cl](PF₆) complexes have also been determined showing the metal ion in a N₄OCl pentagonal bipyramidal or N₄Cl highly distorted octahedral geometry, respectively.     

Novel ternary cobalt(II) and nickel(II) complexes of N-phthaloylglycinate. Synthesis, characterization and X-ray crystal structure

A new series of N-phthaloylglycineate (N-phthgly) ternary complexes of cobalt(II) and nickel(II) with imidazole (imi), N-methylimidazole (mimi) and 2,2′-bipyridyl (bipy) have been synthesized and characterized by elementary analyses, IR spectroscopy, thermogravimetric analysis. X-ray crystal structure analyses of the three complexes of [Co(mimi)₂(N-phthgly)₂] (1), [Co(bipy)(OH₂)₄](N-phthgly)₂ (2) and [Ni(imi)₂(N-phthgly)₂(OHCH₃)₂] (3) were also carried out. In complex (1), the Co(II) exists in a distorted tetrahedral enviroment, where two nitrogen atoms of two methylimidazole molecules and two oxygen atoms of the carboxylate group of two N-phthaloylglycinate molecules are coordinated. On the other hand, in complex (2) the cobalt atom coordinates a 2,2′-bipyridine molecule and four water oxygen atoms forming a distorted octahedral conformation. A molecule of N-phthaloylglycinate is connected by van der waals contact and H-bonds. For complex (3), the nickel atom is surrounded by four oxygens (two oxygens of two different N-phthaloylglycinate molecules and two of methanol ligand) in the basal plane of octahedron along with two imidazole nitrogen atoms at the apical positions. Strong intramolecular H-bond exists between the uncoordinated carboxylic oxygen of the N-phthaloylglycinate ligand and the O–H of the methanol group.     

Synthesis,crystal structure and spectral characterization of Co(II) complexes with acylpyrazolone ligands

The three new Cobalt(II) complexes [Co(L¹)₂(H₂O)₂] (1), [Co(L²)₂(H₂O)₂] (2), and [Co(L³)₂(H₂O)₂] (3) have been synthesized by interaction of acyl pyrazolone ligands, 4-(4-chlorobenzoyl)3-methyl1-phenyl1H-pyrazole5(4H)-one (HL¹), 4-(4-chlorobenzoyl)1-(3-chlorophenyl)3-methyl1H-pyrazole5(4H)-one (HL²) and 5-methyl4-(4-methylbenzoyl)2-phenyl2,4-dihydro3H-pyrazole3-one (HL³) with CoCl₂.6H₂O. The complexes were screened using FTIR, UV–Vis, TGA, and Single Crystal X-ray diffraction spectroscopic techniques. A relative study of the ligands’ FTIR spectra and their metal complexes reveal the formation, sifting, and disappearance of several bands during complexation. Other interpretations stipulated that these three complexes are mononuclear and exhibited octahedral geometry around Co²⁺.Triclinic crystal system, Distortion in Octahedral geometry, and Intermolecular hydrogen bonding confirmed by Single-crystal XRD analysis of [Co(L³)₂(EtOH)₂] complex.     

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 and crystal structure of dinuclear nickel (Ⅱ) complex

The crystal structure of Ni(Ⅱ) complex with 3-hydroxyl-1, 5-diazacycloheptane-N, N'-diacetate was determined by X-ray diffraction method. Crystal data for Ni2 (C9H14N2O5)2·2H2O: monoclinic, space group P21/n, a = 1.1717(5), b = 0.9794(3), c = 1.2971(2) nm, β= 96.62(3), V= 1.4786(7) nm3, Dc = 1.377 g/cm3, Z = 2,μ=13.321 cm-1 (Mo-Kα), F(000)=640. The final R and Rw are 0.075 and 0.089 respectively. The Ni(Ⅱ) ion forms 2:2 complex with ligand. Two ligands are bridged by two Ni(Ⅱ) atoms which are bridged by two O atoms. Every Ni(Ⅱ) is coordinated by two N atoms and four 0 atoms. The coordination polyhedron of the Ni(Ⅱ) ion is a distorted octahedron.     

Synthesis, characterization, and X-ray crystal structures of copper(II) and nickel(II) complexes with Schiff base

New copper(II) complexes, [Cu₂L¹L²] · ClO₄ (I) and [Ni(L³)₂] (II), where L¹ is the monoanionic form of 2-[1-(2-emthylaminoethylimino)ethyl]phenol, L² is the dianionic form of N,N′-ethylene-bis(2-hydroxyacetophenonylideneimine), L³ is the mono-anionic form of 2-(1-iminoethyl)phenol, were prepared and characterized using elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction. In complex I, the Cu(1) atom is coordinated by the NNO tridentate ligand L¹ and the two phenolate O atoms of L², forming a square pyramidal geometry. The Cu(2) atom in complex I is coordinated by the NNOO tetradenate ligand L², forming a square planar geometry. The Ni atom in complex II is coordinated by two phenolate O and two imine N atoms from two ligands L³, forming a square planar geometry. In the crystal structure of I, the perchlorate anions are linked to the dinuclear copper(II) complex cations through intermolecular N-H...O hydrogen bonds. In the crystal structure of II, the mononuclear nickel complex molecules are linked through intermolecular N-H...O hydrogen bonds, forming a trimer.     

Synthesis and structural characterization of nickel(II) hexaazamacrotetracyclic complexes with phthalate ligands

Highly crosslinked polymeric networks formed by cyclodextrins (CD) have recently been shown to be highly versatile nanosponge systems, being for instance very efficient both for drug delivery and for pollutants removal. Here we report some molecular simulation results for dry and hydrated CD nanosponge models aimed to study their swelling behavior. We also report simulation results about the water mobility in these systems in terms of the calculated diffusion coefficient of “free” and of “bound” water molecules confined within the nanosponge cavities. Furthermore, we also suggest the presence of surface-constrained water molecules temporarily bound to the network surface but eventually set free in the bulk.     

Synthesis and characterization of a thioether Schiff base ligand and its metal complexes and crystal structure determination of the nickel(II) complex

Reactions of 1,2-di(o-aminophenylthio)ethane with 3-ethoxy-2-hydroxybenzaldehyde yield the new hexadentate N₂S₂O₂ donor thioether Schiff base 1,2-bis(2-((2-(thio)phenylimino)methyl)-6-ethoxyphenol)ethane (H₂L). Ni(II), Zn(II), Cd(II), and Hg(II) complexes of this ligand were prepared. Of these complexes, [NiL]·2H₂O has been structurally characterized by X-ray crystallography. The coordination geometry around Ni(II) was described as octahedral. Zn(II), Cd(II), and Hg(II) complexes and the Schiff base ligand have been characterized by CHN analyses, molar conductivity, UV–vis, FT-IR, ¹H, and ¹³C NMR spectroscopy.     

Nickel(II) complexes of tetradentate NSNO pyridylthioazophenol ligands: Synthesis,characterization and crystal structure

Two sets of nickel(II) complexes of a series of tetradentate NSNO ligands were synthesized and isolated in their pure form. All these complexes, formulated as [Ni(L)Cl]₂ and [Ni(L)(N₃)]₂ [HL = pyridylthioazophenols], were characterized using physicochemical and spectroscopic tools. The solid-state structures of two complexes (1a and 2a) were established by X-ray crystallography. The geometry about the nickel ion of the complexes is octahedral and the complexes are dimeric in nature. In 1, two Ni(II) ions are bridged by two Cl⁻ anions while in 2 they are bridged by two azide ions in a μ-1,1-bridging fashion.     

Synthesis and characterization of three novel manganese(II) octaaza macrocyclic Schiff base complexes containing a phenanthroline and two pyridyl units as pendant arms. X-ray crystal structure determination of one manganese(II) complex

Three new branched hexadentate amines (N₆), 3,6-bis(2-pyridylmethyl)-3,6-diazaoctane-1,8-diamine (1), 3,7-bis(2-pyridylmethyl)-3,7-diazanonane-1,9-diamine (2) and 3,8-bis(2-pyridylmethyl)-3,8-diazadecane-1,10-diamine (3) have been synthesized. Subsequently, three novel Schiff base macrocyclic complexes containing a phenanthroline and two 2-pyridylmethylpendant arms have been prepared by template [1+1] cyclocondensation of 2,9-dicarboxaldehyde-1,10-phenanthroline and the branched hexadentate amines (1–3), in the presence of Mn(II) in methanol. These complexes have ligands with 18-, 19- and 20-membered hexaaza macrocycles and two 2-pyridylmethyl pendant arms (L¹, L² and L³, respectively). All the complexes have been characterized by elemental analysis and IR spectroscopy. The crystal structure of [MnL¹](ClO₄)₂ · 3CH₃CN was determined and indicates that in the solid state the complex adopts a slightly distorted hexagonal bipyramidal geometry with the Mn(II) ion located within a hexaaza macrocycle with the two 2-pyridylmethyl pendant arms coordinating in axial positions.     

Synthesis,characterization, and antimicrobial activities of nickel(II) and copper(II) Schiff-base complexes

Ni(II) and Cu(II) metal complexes of simple unsymmetrical Schiff-base ligands derived from salicylaldehyde/5-methylsalicylaldehyde and ethylenediamine or diaminomaleonitrile (DMN) were synthesized. The ligands and their complexes were characterized by elemental analysis, ¹H NMR, FT IR, and mass spectroscopy. The electronic spectra of the complexes show d–d transitions in the region at 450–600 nm. Electrochemical studies of the complexes reveal that all mononuclear complexes show a one-electron quasi-reversible reduction wave in the cathodic region. ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry, with nuclear hyperfine spin 3/2. The copper(II) complexes show a normal room temperature magnetic moment value μ _eff = 1.70–1.74 BM which is close to the spin only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts were also carried out. The in vitro antimicrobial activity of the investigated compounds was tested against human pathogenic bacterias such as Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia, Pseudomonas aeruginosa and Escherichia coli. The antifungal activity was tested against Candida albicans. Generally, the metal complexes have higher antimicrobial activity than the free ligands.     

Synthesis,characterization, and X-ray crystal structures of metal complexes with new Schiff-base ligands and their antibacterial activities

Two new potentially hexadentate Schiff bases, [H₂L¹] and [H₂L²], were prepared by condensation of 2-(3-(2-aminophenoxy)naphthalen-2-yloxy)benzenamine with 3,5-di-tert-butyl-2-hydroxy benzaldehyde and o-vanillin, respectively. Reaction of these ligands with cobalt(II) chloride, copper(II) perchlorate, and zinc(II) nitrate gave complexes ML. The ligands and their complexes have been characterized by a variety of physico-chemical techniques. The solid and solution state investigations show that the complexes are neutral. Molecular structures of [CuL¹], [CoL¹]?·?C₇H₈, and [ZnL²]?·?CH₃CN, which have been determined by single-crystal X-ray diffraction, indicate that [CuL¹] and [ZnL²]?·?CH₃CN display distorted square planar and distorted trigonal-bipyramidal geometry, respectively; the geometry around cobalt in [CoL¹]?·?C₇H₈ is almost exactly between trigonal bipyramidal and square pyramidal. The synthesized ligands and their complexes were screened for their antibacterial activities against eight bacterial strains and the ligands and complexes have antibacterial effects. The most effective ones are [CuL²] against Proteus vulgaris, Serratia marcescens, Staphylococcus subtilis, [H²L¹] against S. subtilis, and [H₂L²] against S. subtilis.     

Spectral studies of copper(II) complexes of tridentate acylhydrazone ligands with heterocyclic compounds as coligands: X-ray crystal structure of one acylhydrazone copper(II) complex

Six copper(II) complexes of 2-hydroxy-4-methoxybenzaldehyde nicotinoylhydrazone (H2hmbn), 2-hydroxy-4-methoxyacetophenone nicotinoylhydrazone (H2hman), 2-hydroxy-4-methoxybenzaldehyde benzoylhydrazone (H2hmbb) and 2-hydroxy-4-methoxyacetophenone benzoylhydrazone (H2hmab) have been synthesized. The complexes viz. [Cu(hmbn)](2)·2H(2)O (1), [Cu(hman)](2) (2), [Cu(hmbb)](2)·2H(2)O (3), [Cu(hmbb)phen]·1(1/2)H2O (4), [Cu(hmbb)(bipy)·H2O] (5) and [Cu(hmab)phen] (6) were characterized by different physicochemical techniques. The crystal structure of [Cu(hman)phen] is obtained and it has a distorted square pyramidal geometry with π-π stacking interactions and significant C-H π interactions.     

Synthesis and crystal structure of two Cu(II) complexes with benzimidazole ligands

Two new copper(II) complexes (I, II) with benzimidazole ligands have been synthesized and characterized by elemental analysis and X-ray single-crystal diffraction. Compound I is triclinic, P \(\bar 1\), a = 11.4205(6), b = 13.0956(7), c = 18.2305(9) Å, α = 85.960(1)°, β = 80.388(0)°, γ = 77.517(1)°, V = 2623.0(2) ų, Z = 2; compound II is monoclinic, C2/c, a = 24.2684(11), b = 17.5247(8), c = 19.3149(15) Å, β = 122.710(1)°, V = 6911.9(7) ų, Z = 4. In both compounds, Cu(II) atoms are coordinated by four benzimidazole nitrogen atoms in a slightly distorted tetrahedral fashion.