Synthesis,Spectral Characterization,DNA Binding Studies and Antimicrobial Activity of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) Complexes with 4-Aminoantipyrine Schiff Base of Ortho-Vanillin

A series of transition metal complexes of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) have been synthesized involving the Schiff base, 2,3-dimethyl-1-phenyl-4-(2-hydroxy-3-methoxy benzylideneamino)-pyrazol-5-one(L), obtained by condensation of 4-aminoantipyrine with 3-methoxy salicylaldehyde. Structural features were obtained from their FT-IR, UV–vis, NMR, ESI Mass, elemental analysis, magnetic moments, molar conductivity and thermal analysis studies. The Schiff base acts as a monovalent bidentate ligand, coordinating through the azomethine nitrogen and phenolic oxygen atom. Based on elemental and spectral studies six coordinated geometry is assigned to Co(II), Ni(II), Fe(III) and VO(IV) complexes and four coordinated geometry is assigned to Zn(II) complex. The interaction of metal complexes with Calf thymus DNA were carried out by UV–VIS titrations, fluorescence spectroscopy and viscosity measurements. The binding constants (K_b) of the complexes were determined as 5?×?10⁵ M^?1 for Co(II) complex, 1.33?×?10⁴ M^?1 for Ni(II) complex, 3.33?×?10⁵ M^?1 for Zn(II) complex, 1.25?×?10⁵ M^?1 for Fe(III) complex and 8?×?10⁵ M^?1 for VO(IV) complex. Quenching studies of the complexes indicate that these complexes strongly bind to DNA. Viscosity measurements indicate the binding mode of complexes with CT DNA by intercalation through groove. The ligand and it’s metal complexes were screened for their antimicrobial activity against bacteria. The results showed the metal complexes to be biologically active, while the ligand to be inactive.     

Influence of Fe(III) on the Fluorescence of Lysozyme: a Facile and Direct Method for Sensitive and Selective Sensing of Fe(III)

Lysozyme is widely used for the synthesis of nanomaterials (e.g., gold nanoparticle) to fluorescently sense metal ions. However, the effect of metal ions on the fluorescence of lysozyme is not studied yet. Herein, we have explored the interactions of lysozyme with different metal ions to develop a direct sensing platform for Fe(III). It has been observed that the fluorescence of lysozyme was slightly decreased in the presence of Cu(II), Hg(II), As(V), Co(II), Cd(II), Cr(II), Fe(II), Mn(II), Pb(II), and Zn(II), while a significant decrease in the lysozyme fluorescence was observed for Fe(III). The effect of thermal stability on the fluorescence quenching was also studied from 25 to 60 °C. In the present study, the lysozyme sensing probe was able to selectively and accurately detect 0.5–50 ppm of Fe(III) with a LOD of 0.1 ppm (1.8 µM) at 25 °C.

     

Hg(II) Selective Complexation by Chromoionophoric Calix[4]arene Derivative

The present article describes an exploration regarding Hg(II) selective complexation behavior of 5,11,17,23-tetrakis[(N,N-dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (4). The binding affinity of 4 toward selected transition metal ions such as Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) have been investigated by UV-visible and fluorescence spectroscopies. From the results it has been noticed that 4 confers a pronounced preference for Hg(II) in complexation phenomenon even in the presence of other metal ions. The results of Job's plot analysis reveal 1:1 host-guest complex formation between Hg(II) and 4. The FT-IR spectroscopy also supports the complexation affinity of 4 for Hg(II).     

Infrared Spectra of Some Metal (II) Complexes of 2-Aminomethylpyridine

Abstract

Band assignments in the IR spectra (700–150 cm^?1) of [M(amp)₃] (ClO₄)₂ (amp = 2-aminomethylpyridine; M = Mn(II), Fe(II), Co(II), Ni(II), Zn(II), [Zn(amp)₂Cl₂] and [Pt(amp)Cl₂] derived from amp-ND₂, their unlabelled analogues, [Zn(amp)₂X₂] (X = Br, I) and [Pt(amp)Br₂] are discussed.     

Mononuclear Co(III) and Ni(II) Complexes with Polypyridyl Ligands, [Co(phen)2(taptp)]3+ and [Ni(phen)2(taptp)]2+: Synthesis, Photocleavage and DNA-binding

Two novel, mixed ligand complexes of cobalt(III) and nickel(II), [Co(phen)₂(taptp)]³⁺ (1) and [Ni(phen)₂(taptp)]²⁺ (2) (phen = 1,10-phenanthroline and taptp = 4,5,9,18-tetraazaphenanthreno [9,10-b]triphenylene), were synthesized and characterized by elemental analyses, UV-visible and NMR spectroscopies. The binding interactions of the two complexes with DNA have been investigated using absorption and emission spectroscopy methods and electrophoresis measurement mode. The intrinsic binding constants for these complexes to DNA are in the order of 10⁵. In Tris buffer, the Co(III) complex shows a moderate luminescence which was enhanced after binding to DNA. However for complex Ni(II), no emission was observed in Tris buffer. The [Co(phen)₂(taptp)]³⁺ and [Ni(phen)₂(taptp)]²⁺ can cause the photocleavage of DNA supercoiled pBR322 upon irradiation by 360 nm light. Based on the data, an intercalative mode of DNA binding is suggested for the two complexes.     

EPR investigation of the spin-spin interactions in a Cu(II)-Gd(III)-Fe(III) heterospin system

The spin-spin interactions in a system that contains three different spin carriers, [{LCu}Gd(H₂O)₃×{Fe(CN)₆}] _n ·4nH₂O (1) [L²⁻, N,N-propylenedi(3-methoxysalicylideneiminato)], were investigated by electron paramagnetic resonance spectroscopy. Additional information was obtained by analyzing the discrete heterobinuclear system [LCu(OH₂)Gd(O₂NO)₃] (2), which contains the Cu(II)-Gd(III) pair also existing in the structure of 1, and the compounds [{LCu}Gd(H₂O)₃{Co(CN)₆}] _n ·3.5nH₂O and [{LCu}La(H₂O)₃×{Fe(CN)₆}] _n ·4nH₂O, which are isostructural with 1 and in which the paramagnetic low-spin Fe(III) and Gd(III) ions were replaced by diamagnetic low-spin Co(III) and La(III), respectively. The investigations were carried out in the temperature range of 293–4 K in both X- and Q-bands and also using a dual-mode X-band. The experimental spectra of the Cu(II)-Gd(III) pairs in 2 were interpreted as the sum of spectra of the ground spin state with total S = 4 and the excited state with S = 3 appearing due to the ferromagnetic exchange interaction between Cu(II) and Gd(III) ions. By fitting the experimental and simulated spectra, the zero-field splitting parameters of the Gd(III) ion are estimated and it is shown that no influence of the anisotropic interaction is detected. The magnetic properties of 1 are discussed from the perspective of the interaction of the Cu(II)-Gd(III) binuclear fragments with the Fe(III) ions.     

Stereochemistry of New Nitrogen Containing Heterocyclic Aldehydes. II. Novel Bis-Bidentate Azodye Compounds

A novel family of chelating bis-bidentate azodye compounds¹ with Cu(II), Co(II), Ni(II), Fe(II), Hg(II), Pd(II), UO₂(II), Fe(III), Cr(III), La(III), Ru(III) and Zr(IV) has been prepared and characterized on the basis of analytical, magnetic, ¹H and ¹³C NMR, EPR and electronic spectral studies. Tentative structures for the polymeric complexes are proposed. The important IR bands and the main ¹H and ¹³C signals are assigned and discussed relative to the molecular structure. Various EPR parameters for Cμ(II), have been calculated. The ligand acts as a dibasic bis-bidentate chelating agent coordinating through CO, N=N, COOH and OH groups by replacement of a proton from the two latter groups. Considerable interest has also been focused on the synthesis of the azo compound and its polymeric metal complex due to its wide potential applications. The thermal decomposition behavior of the complexes is also discussed.     

Synthesis,Spectral Characterization,DNA/ Protein Binding,DNA Cleavage,Cytotoxicity, Antioxidative and Molecular Docking Studies of Cu(II)Complexes Containing Schiff Base-bpy/Phen Ligands

Ternary Cu(II) complexes [Cu(II)(L)(bpy)Cl] 1, [Cu(II)(L)(Phen)Cl] 2 [L = 2,3–dimethyl-1-phenyl-4(2 hydroxy-5-methyl benzylideneamino)-pyrazol-5-one, bpy = 2,2^′ bipyridine, phen =1,10 phenanthroline) were synthesized and characterized by elemental analyses, UV-Visible, FT-IR, ESR, Mass, thermogravimetric and SEM EDAX techniques. The complexes exhibit octahedral geometry. The interaction of the Cu(II) with cailf thymus DNA (CT-DNA) was explored by using absorption and fluorescence spectroscopic methods. The results revealed that the complexes have an affinity constant for DNA in the order of 10⁴ M^?1 and mode of interaction is intercalative mode. The DNA cleavage study showed that the complexes cleaved DNA without any external agent. The interaction of Cu(II) complexes with bovine serum albumin (BSA) was also studied using absorption and fluorescence techniques. The cytotoxic activity of the Cu(II) complexes was probed in HeLa (human breast adenocarcinoma cell line), B16F10 (Murine melanoma cell line) and HEPA1–6 celllines, complex 1 has good cytotoxic activity which is comparable with the doxarubicin drug, with IC₅₀ values ranging from 3 to 12.6 μM. A further molecular docking technique was employed to understand the binding of the complexes towards the molecular target DNA. Investigation of the antioxidative properties showed that the metal complexes have significant radical scavenging activity potency against DPPH radical.     

Preparation,Chemical Characterization and Electronic Spectra of 6-(2-Pyridylazo)-3-Acetamidophenol and Its Metal Complexes

The stereochemistry of new iron (III), cobalt (II), nickel (II), copper (II), zinc (II) and cadmium (II) complexes of 6-(2-pyridylazo)-3-acetamidophenol (H2L) was studied on the basis of their analytical, spectroscopic, magnetic and conductance data. the dissociation constant of the ligand, as well as the stability constants of its metal complexes had been determined by spectrophotometric method. on the basis of infrared spectra, the coordination behaviour of the ligand to the metal ions was investigated. Magnetic susceptibility and solid reflectance spectra measurements were used to infer the structure. the isolated complexes were found to have the general formulae [M (HL). xH₂O] (A).yH₂O, M = Cu (II), Zn (II), Cd (II) and Fe (HI); HL = 6-(2-pyridylazo)-3-acetamido-phenol; a = acetate in the case of Cu (II) and Zn (II) or chloride in the case of Cd (II) and Fe (Ill), x = 1-3 and y=0-5. for [M (H₂L).xH₂O]Cl₂.yH₂O, M = Ni (II) and Co (II); HL = 6-(2-pyridyl-azo)-3-acetamidophenol, x=3 and y=5-6).     

THE SYNTHESIS AND SPECTRAL CHARACTERIZATION OF NEW Cu(II), Ni(II), Co(III), AND Zn(II) COMPLEXES WITH SCHIFF BASE

ABSTRACT

Cu(II), Ni(II), Co(III) and Zn(II) complexes with Schiff base have been prepared. Ligand is derived from condensation of 1,2-bis(p>-aminophenoxy)ethane and 2- hydroxynaphthalin-1-carbaldehyde. The complexes have been characterized by elemental analyses, Λ_M, IR, UV-VIS, ¹H NMR, ¹³C NMR and magnetic measurements. The ligand is coordinated to the central metal as a tetradentade ONNO ligand. The four bonding sites are the azomethine nitrogen and aldehydic -OH groups.     

Optical and electrochemical properties of cyclometalated Pd(II) and Pt(II) complexes with a metal-metal chemical bond

Cyclometalated [M(C^N)(μ-(N-S))]₂ complexes ((M = Pd(II), Pt(II)), (C^N)^? are the deprotonated forms of 2-tolylpyridine and benzo[h]quinoline, and (N-S)^? are pyridine-2-thiolate and benzothiazole-2-thiolate ions) are studied by ¹H NMR, IR, electronic-absorption, and emission spectroscopy, as well as by voltammetry. It is shown that the formation of the metal-metal chemical bond and the σ _dz2 ^* orbital as a HOMO of complexes leads to the long-wavelength spin-allowed (410–512 nm) and spin-forbidden (595–673 nm) optical transitions σ _dz2 ^* ?π _(C^N) ^* in the absorption and phosphorescence spectra, as well as to the two-electron and successive one-electron oxidation with the formation of binuclear Pt(III) and Pd(III) complexes. The substitution of Pt(II) by Pd(II) is characterized by hypso- and bathochromic shifts of the spin-allowed and forbidden σ _dz2 ^* ?π _(C^N) ^* optical transitions in the absorption and phosphorescence spectra of complexes, by phosphorescence quenching of Pd(II) complexes in liquid solutions, and by an anodic shift of the oxidation potential of Pd(II) complexes compared with Pt(II) complexes.     

Novel Bioactive Co(II), Cu(II), Ni(II) and Zn(II) Complexes with Schiff Base Ligand Derived from Histidine and 1,3-Indandione: Synthesis,Structural Elucidation,Biological Investigation and Docking Analysis

Novel bioactive complexes of Co(II), Cu(II), Ni(II) and Zn(II) metal ions with Schiff base ligand derived from histidine and 1,3-indandione were synthesized and thoroughly characterized by various analytical and spectral techniques. The biological investigations were carried out to examine the efficiency of the binding interaction of all the complexes with calf thymus DNA (CT-DNA). The binding properties were studied and evaluated quantitatively by K_b and K_sq values using UV-visible, fluorescence spectroscopy and voltammetric techniques. The experimental results revealed that the mode of binding of all the complexes with CT-DNA is via intercalation. It is further verified by viscosity measurements and thermal denaturation experiments. From the results of the cleavage study with pUC19 DNA it is inferred that all the complexes possess excellent cleaving ability. The present investigation proved that the binding interaction of all the complexes are significantly strong and the order of binding strength of the complexes is [Ni(L)₂] (K_b = 3.11 × 10⁶ M^?1) > [Co(L)₂] (K_b = 2.89 × 10⁶ M^?1) > [Cu(L)₂] (K_b = 2.64 × 10⁶ M^?1) > [Zn(L)₂] (K_b = 2.41 × 10⁵ M^?1). The complexes were also screened for antibacterial and anticandidal activity. The in vitro cytotoxicity of the ligand and complexes on the NIH/3 T3 mouse fibroblast cell lines were examined using CellTiter-Blue® (CTB) Cell viability assay, which unveiled that all the complexes exhibit more potent activities against NIH/3 T3 cells. Among all the complexes [Zn(L)₂] complex showed the maximum efficiency.     

Synthesis,Characterization and Antibacterial Activity of Some Transition Metal Complexes of 2-N-(isatinamino)-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene

Metal complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) with a Schiff base derived from isatin and 2-amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene were synthesised and characterised by elemental analysis, conductance measurements, magnetic susceptibility, UV-Vis, IR, ¹H NMR and EPR spectral studies. The spectral data revealed that the ligand acted as a neutral tridentate, coordinating to the metal ion through the azomethine nitrogen, ester carbonyl and carbonyl oxygen of the isatin moiety. The EPR spectral data indicated that metal-ligand bonds have considerable covalent character. The copper(II) complex was subjected to X-ray diffraction and cyclic voltammetric studies. The ligand and the metal complexes were screened for their antibacterial activity and it has been observed that the metal complexes are more potent bactericides than the ligand.     

Synthesis and Characterization of New Cationic Fe(III),Co(II) and Ni(II) Complexes Containing Isatin/Triphenylphosphine Mixed Ligands

New cationic Fe(III),Co(II) and Ni(II) mixed ligand complexes containing both triphenylphosphine and isatin ligands were prepared and characterized using conventional physical and chemical methods of analysis

(I.R., UV-Vis., and ¹H NMR). Microanalytical data of the investigated complexes are consistent with the formulations. [Fe(Isa)₂ {P(Ph)₃}₂]³⁺, [Co(Isa)₂ {P(Ph)₃}₂]²⁺ and [Ni(Isa)₂ {P(Ph)₃}₂]²⁺, (Where Isa = Isatin and P(Ph)₃ = Triphenylphosphine).

The prepared complexes are soluble in polar solvents and could be of potential use in bio-inorganic applications.     

Bifunctional Calix[4]arene Sensor for Pb(II) and Cr2O7 2− Ions

A readily available chromionophore 5,11,17,23-tetra-tert-butyl-25,27-bis(hydrazidecarbonylmethoxy)-26,28-dihydroxycalix[4]arene (HCC4) was employed as a chromogenic sensing probe selective for Pb(II) and Cr₂O₇ ^2? ions among a series of various ions such as Li(I), Na(I), K(I), Rb(I), Ba(II), Sr(II), Al(III), Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) as well as Cr₂O₇ ^2?, CH₃CO₂ ^?, Br^?, Cl^?, F^?, I^?, ClO₄ ^? and NO₃ ^? that have been examined by UV-visible and fluorescence spectroscopic techniques. The HCC4 in DCM-MeCN system forms 2:1 (ligand-metal) complex with Pb(II). It also shows 2:1 stoichiometry with Cr₂O₇ ^2?. The complexation phenomenon has been confirmed by FTIR spectroscopy that favors the selective nature of HCC4 with Pb(II) and Cr₂O₇ ^2?. Thermal gravimetric analysis (TGA) also supports its utility in drastic conditions.     

Vibrational Spectroscopic Studies of 3,4-Lutidine Metal (II) Tetracyanonickelate Complexes

Infrared and Raman spectra of seven new metal (II) 3,4-lutidine tetracyanonickelate complexes, M(3,4 L)₂ Ni(CN)₄ [where 3,4 L = 3,4 - dimethyl-pyridine or 3,4-lutidine; M = Mn, Fe, Co, Zn, Ni, Cu or Cd] (abbreviated to M - Ni - 3,4 L) have been investigated. Spectroscopic and magnetic susceptibility measurements indicate that the compounds have the structure of Hofmann-type complexes. The copper complex has spectral features different from the other compounds.     

Incorporation of Siderophore Binding Sites in a Dipodal Fluorescent Sensor for Fe(III)

A new fluorescent probe 3, has been developed for the detection of Fe(III) in water based samples. The design of 3 involved the incorporation of Fe(III) binding sites observed in naturally occurring Siderophores into a synthetic sensing assembly. The probe, containing two Schiff base receptors connected to a mesitylene platform, was prepared in two steps. The dipodal sensor displayed good selectivity for Fe(III) when tested against other physiological and environmentally important metal ions, in HEPES buffered solution at pH 7.0, through a quenching of the fluorescent intensity. Stern-Volmer analysis of this quenching interaction indicated a 1:1 (host : guest) binding stoichiometry between the probe and Fe(III). The association constant, K _a calculated using the Benesi-Hildebrand equation was found to be 3.8 × 10⁴ M⁻¹. Crucially, the sensor was capable of measuring Fe(III) competitively in solutions containing both Fe(III) and Cu(II). Thus, the adoption of Fe(III) binding sites found in nature, into synthetic luminescent assemblies has proven an effective design strategy for the development of new Fe(III) probes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

DNA Binding,Cleavage and Antibacterial Activity of Mononuclear Cu(II), Ni(II) and Co(II) Complexes Derived from Novel Benzothiazole Schiff Bases

A series of novel bivalent metal complexes M(L₁)₂ and M(L₂)₂ where M = Cu(II), Ni(II), Co(II) and L₁ = 2-((benzo [d] thiazol-6-ylimino)methyl)-4-bromophenol [BTEMBP], L₂ = 1-((benzo [d] thiazol-6-ylimino)methyl) naphthalen-2-ol [BTEMNAPP] were synthesized. All the compounds have been characterized by elemental analysis, SEM, Mass, ¹H NMR, ¹³C NMR, UV–Vis, IR, ESR, spectral data and magnetic susceptibility measurements. Based on the analytical and spectral data four-coordinated square planar geometry is assigned to all the complexes. DNA binding properties of these complexes have been investigated by electronic absorption spectroscopy, fluorescence and viscosity measurements. It is observed that these binary complexes strongly bind to calf thymus DNA by an intercalation mode. DNA cleavage efficacy of these complexes was tested in presence of H₂O₂ and UV light by gel electrophoresis and found that all the complexes showed better nuclease activity. Finally the compounds were screened for antibacterial activity against few pathogens and found that the complexes have potent biocidal activity than their free ligands.     

光度法研究聚乙二醇-硫酸铵-邻苯三酚红体系中铋(Ⅲ), 铁(Ⅲ), 铜(Ⅱ), 镍(Ⅱ), 钴(Ⅱ), 铅(Ⅱ)的萃取分离

本文研究了在聚乙二醇(PEG)-硫酸铵[(NH_4)_2SO_4]-邻苯三酚红(PR)体系中Bi(Ⅲ),Fe(Ⅲ),Cu(Ⅱ),Ni(Ⅱ),Co(Ⅱ),Pb(Ⅱ)的萃取行为。实验结果表明,Bi(Ⅲ)在pH3.5～6.5及Fe(Ⅲ)在pH4.0～7.0范围内可以被PEG相几乎完全萃取,而Cu(Ⅱ),Co(Ⅱ)在pH1.0～7.0,Pb(Ⅱ)在pH2.0～7.0,Ni(Ⅱ)在pH1.0～4.5则不被萃取。从而实现了将Bi(Ⅲ)(pH3.5),Fe(Ⅲ)(pH5.0)与Cu(Ⅱ),Co(Ⅱ),Pb(Ⅱ),Ni(Ⅱ)混合离子的定量分离。同时探讨了PEG相的萃取机理。     

Synthesis and Spectral Studies of Novel Co(II), Ni(II), Cu(II), Cd(II), and Fe(II) Metal Complexes with N-[5′-Amino-2,2′-bis(1,3,4-thiadiazole)-5-yl]-2-hydroxybenzaldehyde Imine (HL)

Co(II), Ni(II), Cu(II), Cd(II), and Fe(II) complexes with Schiff base derived from 2-amino-5-(2-amino-1,3,4-thiadiazolyl)-1,3,4-thiadiazole (1) and salicylaldehyde have been prepared. The ligand and its complexes have been characterized by IR, ¹H NMR spectra, elemental analyses, magnetic susceptibility, UV-Vis. and thermogravimetry–differential thermal analysis (TGA-DTA). The analytical data show 1:2 metal-to-ligand ratio for Co(II), Ni(II), Cd(II), and Fe(II) and 2:2 metal-to-ligand ratio for Cu(II) complexes. The suggested structures for the N-[5′-Amino-2,2′-bis(1,3,4-thiadiazole)-5-yl]-2-hydroxybenzaldehyde Imine (HL) complexes of Fe(II), Co(II), and Cd(II) are octahedral, for the Ni(II) complex is tetrahedral, and for the Cu(II) complex is square-planar