Ni(II) and Cu(II) complexes of bidentate thiosemicarbazone ligand: Synthesis,structural, theoretical,biological studies and molecular modeling

The conventional condensation and refluxing process was employed to synthesize Ni(II) and Cu(II) complexes of Methylcarbamatethiosemicarbazone ligand. Reactions were carried out at the pH of 7. The molar ratio of the ligand and metal salt was 2:1. The structures of the synthesized metal complexes were suggested by different analytical techniques such as magnetic susceptibility, molar conductance, IR, EPR and UV spectroscopy. Experimental studies confirmed the octahedral geometry for all the complexes. The geometry of the ligand and complexes were also confirmed by theoretical studies. The complexes were investigated for biological action against pathogenic fungi (C. krusei, C. albican) and bacteria (S. aureus, E. coli). The antimicrobial results confirmed superior inhibition potential of the metal complexes as compared with the parent ligand. The enhanced antimicrobial activities might be due to the chelation. Molecular-docking assays confirmed the strong interaction of ligand with target antimicrobial protein DNA gyrase-B.     

Formation Constants And Metal To Ligand Ratios For Calcein Blue- Metal Complexes

Abstract

The formation constants of Calcein Blue-cadmium (II) and lead (II) complexes as well as their ligand to metal ratios were determined by a polarographic technique. The formation constants of Calcein Blue-copper (II) and silver (I) complexes as well as their ligand to metal ratios were determined by a potentiometric technique.     

Metal Complexes with Alizarin Complexone AC: Electronic Absorption Spectra and Ligand Structure

The character of the electronic absorption spectra of metal complexes with alizarin complexone AC is determined by the ionization degree of the ligand and the ratio between its excited states with different contributions of tautomeric 9,10-, 1,10-, 2,9-, and 1,2-anthraquinoid resonance structures. It was found by the spectrophotometric, quantum-chemical, and correlation methods that the ligand in metal complexes can exist in three forms, namely, neutral and two ionized forms (containing one or two deprotonated hydroxy groups). For each of the latter two forms, four excited states with the dominating contribution of the 9,10-, 1,10-, 2,9-, or 1,2-anthraquinoid resonance structures are possible. The formation of red monometallic complexes involves the peri- or ortho-hydroxycarbonyl group in anthraquinoid tautomers (mostly, 1,2- and 2,9-structures). The color of bimetallic complexes is determined by four anthraquinoid structures of the ligand (from red 9,10- to blue 1,10-anthraquinones). Fluorine-containing complexes exist only as 1,2- and 1,10-anthraquinoid structures, which are responsible for their blue color. The known metal complexes with Alizarin Complexone AS were classified by their structures.     

源自天然席夫碱的过渡金属配合物在分光光度法测天然水中的Fe(Ⅲ)的应用

描述了一种新颖、简便的合成含五齿配位基的大环席夫碱配体的方法,制备和表征了该席夫碱的1∶1包合物。用化学和光谱学方法测定了标题配合物的组成,认为在所有配合物中配位金属原子取八面体结构。数据表明:配体起O2N4六齿结构而每个环绕金属原子在八面体环境中。配合物的红外和1H NMR光谱符合中心金属原子的配位结果。用分光光度法测定了配合物的稳定常数。用共轭余量法(CR method)计算了在热分解的不同阶段配合物活化的动力学和热力学参数。此外,用抑菌圈直径法筛选了配体及其金属配合物抑制细菌和真菌的能力。用回收率试验研究了天然螯合配体在不同天然水体中对Fe(Ⅲ)离子配合作用的影响。     

Metal–Organic Organopolymeric Hybrid Framework by Reversible [2+2] Cycloaddition Reaction

Organic polymers are usually amorphous or possess very low crystallinity. The metal complexes of organic polymeric ligands are also difficult to crystallize by traditional methods because of their poor solubilities and their 3D structures can not be determined by single‐crystal X‐ray crystallography owing to a lack of single crystals. Herein, we report the crystal structure of a 1D Zn^II coordination polymer fused with an organic polymer ligand made in situ by a [2+2] cycloaddition reaction of a six‐fold interpenetrated metal–organic framework. It is also shown that this organic polymer ligand can be depolymerized in a single‐crystal‐to‐single‐crystal (SCSC) fashion by heating. This strategy could potentially be extended to make a range of monocrystalline metal organopolymeric complexes and metal–organic organopolymeric hybrid materials. Such monocrystalline metal complexes of organic polymers have hitherto been inaccessible for materials researchers.     

Cyclometalated complexes containing ferrocenyl Schiff base: Preparation,characterization, DFT calculations,application in cancer and biological researches and MOE studies

A series of transition metal (II/III) complexes containing organometallic Schiff base ligand (H₂L) had been synthesized and characterized by using elemental analysis (C, H, N, M), molar conductivity, IR, UV–Vis, ¹H NMR and mass spectral analysis. Also, their TG and DTG behaviors were investigated. The ligand was prepared by condensation of 4-aminosalicylic acid with 2-acetylferrocene in 1:1 M ratio. The data of elemental analysis indicated that the prepared complexes were synthesized also in a 1:1 M ratio. The ligand behaved as neutral bidentate ligand that coordinated to metal ions through protonated O-phenolic and protonated carboxylic-OH groups. All complexes had octahedral structure. DFT calculations for H₂L ligand were determined with some parameters such as HOMO-LUMO energy gab, electronegativity and chemical hardness–softness. Antimicrobial activity of both H₂L Schiff base ligand and its metal complexes was tested against different strains of bacteria and fungi species. Furthermore, all compounds had been screened for their anticancer activities against breast cancer (MCF-7) cell line. [Cu(H₂L)(H₂O)₂Cl₂]·2H₂O complex had the lowest IC₅₀ value = 47.3 µg/mL. For determining the more effective and probable binding mode between the H₂L ligand, Co(II) and Zn(II) complexes with different active sites of 4K3V, 2YLB and 3DJD receptors, so molecular docking studies were investigated.     

酚醛基质苯并咪唑螯合树脂的合成及配位性能

通过1,4-对苯二酚二缩水甘油醚和2,2′-二苯并咪唑二乙胺反应合成四苯并咪唑单体(TBMZ),经甲醛等缩合生成酚醛聚合物为基质的苯并咪唑螯合树脂(PTBMZs)。 新型螯合树脂配基含量达2.1~3.02 mmol/g。新树脂及其单体结构经13C核磁共振谱、FT-IR红外光谱、元素分析和DSC分析确证。 测定了Cu2+、Ni2+、Zn2+、Cd2+和Co2+氯化物在pH值为1.0~6.0的缓冲溶液中的配位容量。 实验结果表明,该类螯合树脂对Cu2+有高度的选择性,KCuX≥4.3非竞争条件下,PTBMZ-1的最大配位容量为1.15 mmol/g(pH=5.0,Cu2+),PTBMZ-2的最大配位容量为0.97 mmol/g(pH=5.0,Cu2+),配基占有率分别为35.9%,33.4%。 PTBMZ-1树脂对Cu2+吸附较快,t1/2=21 min。 电子顺磁共振谱和FT-IR光谱分析结果表明,形成n(金属离子)∶n(配基)=1∶2的螯合物为主。     

Détermination de constantes de stabilité de chélates par résonance magnétique nucléaire du proton

In a solution containing an excess of two metal ions in regard to a ligand (e.g. NTA) a competitive equilibrium is established. The measure, by proton NMR. spectroscopy, of the individual concentrations of both chelates, and eventually of the free ligand, allows to determine the ratio of the stability constants of the two complexes. As an illustration the ratios of the stability constant of the 1:1 nitrilotriacetate chelates of Pb and Zn, respectively Mo and W, were determined.     

Characterization of Ni(II) and Cu(II) complexes of 4-(2-Quinolylmethyleneamino)-1-phenyl-2,3-dimethyl-5-pyrazolone and their analytical applications

A synthesis of the new reagent 4-(2-quinolylmethyleneamino)-1-phenyl-2,3-dimethyl-5-pyrazolone (QPP) and of its complexes with Ni(II) and Cu(II) is described. The structure of the ligand itself and the nature of the bonding in complex molecules were determined by elemental analysis, IR, and mass spectrometry. The analysis of data showed that isolated crystal metal complexes are of the ML₂ type. The composition and stability constants of the complexes in water/methanol solutions, (methanol) = 0.16, at constant temperature 25 ±1 °C and ionic strength of 0.5 M (KNO₃) at different pH (4, 6, 8, and 10) have been determined spectrophotometrically. The results indicate that the metal complexes formed in the solution have a metal-to-ligand ratio 1:2. The reaction of QPP with Ni(II) and Cu(II) in solution was quantitatively studied. The lowest detection limit for the determination of Ni is 0.3 μg/ml while that for Cu is 0.05 μg/ml under the investigated experimental Conditions.     

Effect of plant-based phenol derivatives on the formation of Cu and Ag nanoparticles

The complexes formed on the reaction of various metal ions viz., Cu(II) and Cu(I) with phenol derivatives viz. catechol, chlorogenic acid (CGA), hydroquinone and n-propyl gallate (nPG) were established by UV-visible spectroscopy. The metal/ligand complexing ratio and complexation constants have been determined. Further, we showed that nanoparticles of Cu can be prepared from metal-phenol complexes in the presence of a protein (gelatin) by γ-irradiation showing that the reduction is metal ion centered. Formation of Ag nanoparticles was also observed on photo-irradiation with xenon lamp in the presence of dihydroxy benzene. The Ag and Cu nanoparticles were characterized by transmission electron microscopy (TEM) and UV-visible absorption spectroscopy. TEM technique showed the presence of Cu and Ag nanoparticles with average size of 20 and 30 nm, respectively.     

Syntheses and structures of Mn(II), Co(II), and Zn(II) complexes of 1,3-diterpyridyl-substituted p-tert-butylcalix[4]arene

The calix[4]arene-based podand which incorporates two terpyridine functions in 1,3-alternate positions with flexible propylene spacers at lower rim has been prepared and subjected to complexation studies with some transition metal ions. Single-crystal structures of Mn(II), Co(II), and Zn(II) complexes were determined by X-ray diffraction. These metal complexes are formed with a 2?:?1 ratio of metal and ligand. Coordination of each metal is five-coordinate distorted trigonal-bipyramidal geometry by three nitrogen atoms from a terpyridyl unit and two chloride atoms.     

Application of permeation liquid membrane and scanned stripping chronopotentiometry to metal speciation analysis of colloidal complexes

The potential of permeation liquid membrane (PLM) to obtain dynamic metal speciation information for colloidal complexes is evaluated by measurements of lead(II) and copper(II) complexation by carboxyl modified latex nanospheres of different radii (15, 35, 40 and 65 nm). The results are compared with those obtained by a well characterized technique: stripping chronopotentiometry at scanned deposition potential (SSCP). Under the PLM conditions employed, and for large particles or macromolecular ligands, membrane diffusion is the rate-limiting step. That is, the flux is proportional to the free metal ion concentration with only a small contribution from labile complexes. In the absence of ligand aggregation in the PLM channels, good agreement was obtained between the stability constants determined by PLM and SSCP for both metals.     

Isoelectric focusing of small non-covalent metal species from plants

IEF is known as a powerful electrophoretic separation technique for amphoteric molecules, in particular for proteins. The objective of the present work is to prove the suitability of IEF also for the separation of small, non-covalent metal species. Investigations are performed with copper-glutathione complexes, with the synthetic ligand ethylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid (EDDHA) and respective metal complexes (Fe, Ga, Al, Ni, Zn), and with the phytosiderophore 2'-deoxymugineic acid (DMA) and its ferric complex. It is shown that ethylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid and DMA species are stable during preparative scale IEF, whereas copper-glutathione dissociates considerably. It is also shown that preparative scale IEF can be applied successfully to isolate ferric DMA from real plant samples, and that multidimensional separations are possible by combining preparative scale IEF with subsequent HPLC-MS analysis. Focusing of free ligands and respective metal complexes with di- and trivalent metals results in different pIs, but CIEF is usually needed for a reliable estimation of pI values. Limitations of the proposed methods (preparative IEF and CIEF) and consequences of the results with respect to metal speciation in plants are discussed.     

Impact of ligand protonation on higher-order metal complexation kinetics in aqueous systems

The impact of ligand protonation on the complexation kinetics of higher-order complexes is quantitatively described. The theory is formulated on the basis of the usual situation for metal complex formation in aqueous systems in which the exchange of water for the ligand in the inner coordination sphere is rate-determining (Eigen mechanism). We derive expressions for the general case of lability of ML(n) species that account for the contributions from all outer-sphere complexes to the rate of complex formation. For dynamic complexes, dissociation of ML is usually the rate-determining step in the overall process ML(n) --> M. Under such conditions, it is the role of ligand protonation in the step ML --> M that is relevant for the kinetic flux. 1:2 complexes of Cd(II) with pyridine-2,6-dicarboxylic acid fall into this category, and their lability at a microelectrode is reasonably well predicted by the differentiated approach. For non-dynamic systems, the kinetic flux arising from dissociation of higher-order complexes contributes to the rate-determining step. In this case, the weighted contribution of protonated and unprotonated outer-sphere complexes in all contributing dissociation reactions must be taken into account. The kinetic flux arising from the dissociation of 1:2 complexes of Ni(II) with bicine at a conventional electrode was quite well described by this combined approach. The results establish the generic role of ligand protonation within the overall framework of metal complexation kinetics in which complexes may be dynamic to an extent that depends on the operational time scale of the measurement technique.     

新型含丙腈基和咪唑基三脚架配体-银(Ⅰ)配合物的合成与结构

设计合成了同时含有丙腈基和咪唑基的新型三脚架配体N,N-二(3-丙腈基)-[3-(1-咪唑基)]正丙胺(L),并与银盐按1:1和2:1的比例反应分别得到了配合物{[AgL]X}n (X = BF4-,1a;X = ClO4-,1b)和{[Ag(L)2]ClO4}n(2),并用X-射线单晶结构分析和电喷雾质谱等方法对其进行了表征。结构分析结果表明,配合物1a和1b为一维链状结构,而配合物2则为单核结构。表明金属盐和配体的比例对配合物结构有很大影响。     

Synthesis, spectral, thermal and antimicrobial studies of some new tri metallic biologically active ceftriaxone complexes

Iron, cobalt, nickel and copper complexes of ceftriaxone were prepared in 1:3 ligand:metal ratio to examine the ligating properties of the different moieties of the drug. The complexes were found to have high percentages of coordinated water molecules. The modes of bonding were discussed depending on the infrared spectral absorption peaks of the different allowed vibrations. The Nujol mull electronic absorption spectra and the magnetic moment values indicated the Oh geometry of the metal ions in the complexes. The ESR spectra of the iron, cobalt, and copper complexes were determined and discussed. The thermal behaviors of the complexes were studied by TG and DTA techniques. The antimicrobial activities of the complexes were examined and compared to that of the ceftriaxone itself.     

Adsorption properties of thermally stable and biologically active polyurea: its synthesis and spectral aspects

Novel polymer metal complexes were prepared by the condensation polymerization of a polymeric ligand with transition metal ions of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). The polymeric ligand was prepared by the addition polymerization of urea with toluene 2,4‐diisocyanate in 1:1 molar ratio. The polymeric ligand and its polymer metal complexes were characterized by elemental analysis, Fourier transform infrared spectroscopy, ¹³C‐NMR, and¹H‐NMR (nuclear magnetic resonance). The geometry was determined by electronic spectra and magnetic moment measurement. Thermogravimetric analysis (TGA) was utilized to find out the degradation process of the polyurea ligand and the polymer metal complexes. The TGA data revealed that all the metal‐containing polyureas are much more thermally stable than the corresponding polyurea ligand. The surface morphology of the polyurea ligand and cobalt(II)‐containing polyureas was determined by scanning electron micrographs. The antibacterial and antifungal activities of all the synthesized polymers were investigated against Staphylococcus aureus, Escherichia coli, and Bacillus subtilis (bacteria) and Aspergillus niger, Candida albicans, and Aspergillus flavus (fungi). These compounds show remarkably good biocidal activities, which were enhanced after complexation with the metal. Batch adsorption studies of the ligand were carried out for malachite green dye, and the polyurea ligand was found to be a good adsorbent for this dye. Copyright © 2011 John Wiley & Sons, Ltd.     

The direct electrochemical synthesis of tin,cobalt, copper,zinc, cadmium and silver 7-formyl-8-hydroxyquinoline complexes

Summary Main group and transition metal complexes of 7-formyl-8-hydroxyquinoline have been synthesized by an electrochemical technique using a sacrifical anode in a non-aqueous solution of the ligand, and characterized by elemental analyses and i.r. spectra. The ligand acts as a monobasic tri-dentate chelating agent coordinating through C=N, C=O and OH groups by replacement of a proton from the latter group. The electrical conductivities of the complexes were measured at different temperatures and annealing times. Their activation energies were calculated; the value obtained for the Zn^II complex lay in the range reported for semiconducting materials.Physics Department, Faculty of Science, Sana'a University.     

Polymer‐supported metal complexes as antibacterial agents: synthesis,characterization and thermal degradation kinetics

Polymeric metal complexes were prepared using a synthesized novel terpolymer ligand involving anthranilic acid–o‐toluidine–formaldehyde by a polycondensation technique. The synthesized ligand and its metal complexes were characterized using elemental analysis and molar conductivity measurements, and FT‐IR, electronic, electron spin resonance and NMR (¹H and ¹³C) spectral methods. The surface morphology and the nature of the synthesized compounds were examined using scanning electron microscopy and X‐ray diffraction. The thermal stabilities of the ligand and its metal complexes were determined using thermogravimetric analysis (TGA). From the TGA results, various kinetic parameters, i.e. activation energy and order of reaction, and thermodynamic parameters, i.e. entropy change, apparent entropy, frequency factor and free energy change, were determined using the Freeman–Carroll and Sharp–Wentworth methods. In addition, a thermal degradation model was also proposed using the Phadnis–Deshpande method. The thermal stability of the ligand and its metal complexes was found to be appreciably high; in particular, the ligand showed very high stability compared to its metal complexes due to intramolecular hydrogen bonding. Furthermore, the synthesized compounds were subjected to in vitro antibacterial studies with various microorganisms. The results of the studies confirmed that the compounds showed better antibacterial results than a standard antibacterial drug. Copyright © 2014 John Wiley & Sons, Ltd.     

Preconcentration of trace metal ions by combined complexation-anion exchange : Part 2. Cobalt,zinc, cadmium and lead with 8-hydroxyquinoline-5-sulfonic acid [1]

The ligand, 8-hydroxyquinoline-5-sulfonic acid, forms anionic complexes with cobalt(II), zinc(II), cadmium(II), and lead(II), each resulting complex showing a high affinity for anion-exchange resins. The effect of pH, ligand/metal ratio, volume, and concentration on percent retention of the anionic complexes by an anion-exchange resin are reported. At optimum conditions, all four metals are quantitatively retained by the column. Zinc, cadmium and lead(II) ions are completely eluted with 11 ml or less of 2 M HN0₃; cobalt(II) is totally removed by 12 M HCl and 2 M HNO₃. Concentration enhancements of 100-fold are easily achieved. All four anionic complexes can be left on the column for 7 days and still be quantitatively (99%) recovered. A ligand-loaded resin column can also remove all four metals quantitatively. Distribution coefficients for the metal complexes and their ligand/metal ratios were determined by using batch methods that may also serve as the isolation procedure.