Sample records for zinc guanidine complexes

  1. Zinc catalyzed Guanylation reaction of Amines with Carbodiimides/ Isocyanate leading to Guanidines/Urea derivatives formation



    We report the highly chemo-selective catalytic addition of N–H bonds from various aromaticamines to carbodiimides and isocyanates using (Ar-BIAO)ZnCl2 complexes [Ar-BIAO = N-(aryl)iminoacenapthenone,Ar = 2,6-$Me_{2}C_{6}H_{3}$ (1), 2,4,6 $Me_{3}C_{6}H_{2}$ (2), $2,6-^{i}$ $Pr_{2}C_{6}_H{3} (3)] as the pre-catalyst to prepareguanidine and urea derivatives in 55-90% yield. The complex 3 showed higher catalytic activity than analogouscomplexes 1 and 2 under similar reaction conditions. The catalytic guanylation of N–H bonds with heterocumulenesdisplays a broad substrate scope. The amines having electron donating groups underwent higher conversionthan the amines having electron withdrawing groups to afford corresponding guanidine or urea derivatives.A possible mechanism involving penta-coordinated zinc transition state for the catalytic reaction is presented.

  2. Theoretical investigation on organolanthanide guanidinate complexes

    Salima; Lakehal; Nadia; Ouddai


    Density functional theory (DFT) calculations were carried out on the compounds Cp2Ln-guan for Ln=Y, Lu, Yb, Dy and Gd, [guan=(iPrN)2CN(iPr)2]. The results were compared with the X-ray structures that were available from the literature; the calculations reproduced quite well the experimental structural features in these complexes exhibiting distorted tetrahedron geometry. The calculated evolution of the Ln-guan bond as a function of the cation showed that lanthanide-ligand distances increased with the increa...

  3. Formation and structure of the first metal complexes comprising amidino-guanidinate ligands.

    Sroor, Farid M; Liebing, Phil; Hrib, Cristian G; Gräsing, Daniel; Hilfert, Liane; Edelmann, Frank T


    The first metal complexes comprising amidino-guanidinate ligands have been prepared and structurally characterized, namely bis-[μ-N,N',N'',N'''-tetraisopropyl-1-(1-butyl-amidinato)guanidinato-κ(3)N(1),N(2):N(2)]bis-[(tetra-hydro-furan)lithium], [Li2(C18H37N4)2(C4H8O)2], (2), and [bis-(tetra-hydro-furan)-lithium]-di-μ-chlorido-{(N,N'-di-cyclo-hexyl-1-butyl-amidinato-κ(2)N(1),N(2))[N,N',N'',N'''-tetra-cyclo-hexyl-1-(1-butyl-amidinato)guanidinato-κ(2)N(1),N(2)]holmate(III)}, [HoLiCl2(C4H8O)2(C17H31N2)(C30H53N4)], (3). The novel lithium amidino-guanidinate precursors Li[ (n) BuC(=NR)(NR)C(NR)2] [1: R = Cy (cyclo-hex-yl), 2: R = (i) Pr) were obtained by treatment of N,N'-diorganocarbodi-imides, R-N=C=N-R (R = (i) Pr, Cy), with 0.5 equivalents of n-butyl-lithium under well-defined reaction conditions. An X-ray diffraction study of 2 revealed a ladder-type dimeric structure in the solid state. Reaction of anhydrous holmium(III) chloride with in situ-prepared 2 afforded the unexpected holmium 'ate' complex [ (n) BuC(=NCy)(NCy)C(NCy)2]Ho[ (n) BuC(NCy)2](μ-Cl)2Li(THF)2 (3) in 71% yield. An X-ray crystal structure determination of 3 showed that this complex contains both an amidinate ligand and the new amidino-guanidinate ligand.

  4. Formation and structure of the first metal complexes comprising amidino­guanidinate ligands

    Sroor, Farid M.; Liebing, Phil; Hrib, Cristian G.; Gräsing, Daniel; Hilfert, Liane; Edelmann, Frank T.


    The first metal complexes comprising amidino­guanidinate ligands have been prepared and structurally characterized, namely bis­[μ-N,N′,N′′,N′′′-tetraisopropyl-1-(1-butyl­amidinato)guanidinato-κ3 N 1,N 2:N 2]bis­[(tetra­hydro­furan)lithium], [Li2(C18H37N4)2(C4H8O)2], (2), and [bis­(tetra­hydro­furan)­lithium]-di-μ-chlorido-{(N,N′-di­cyclo­hexyl-1-butyl­amidinato-κ2 N 1,N 2)[N,N′,N′′,N′′′-tetra­cyclo­hexyl-1-(1-butyl­amidinato)guanidinato-κ2 N 1,N 2]holmate(III)}, [HoLiCl2(C4H8O)2(C17H31N2)(C30H53N4)], (3). The novel lithium amidino­guanidinate precursors Li[nBuC(=NR)(NR)C(NR)2] [1: R = Cy (cyclo­hex­yl), 2: R = iPr) were obtained by treatment of N,N′-diorganocarbodi­imides, R—N=C=N—R (R = iPr, Cy), with 0.5 equivalents of n-butyl­lithium under well-defined reaction conditions. An X-ray diffraction study of 2 revealed a ladder-type dimeric structure in the solid state. Reaction of anhydrous holmium(III) chloride with in situ-prepared 2 afforded the unexpected holmium ‘ate’ complex [nBuC(=NCy)(NCy)C(NCy)2]Ho[nBuC(NCy)2](μ-Cl)2Li(THF)2 (3) in 71% yield. An X-ray crystal structure determination of 3 showed that this complex contains both an amidinate ligand and the new amidino­guanidinate ligand. PMID:27840700

  5. A new family of metal borohydride guanidinate complexes: Synthesis, structures and hydrogen-storage properties

    Wu, Hui; Zhou, Xiuquan; Rodriguez, Efrain E.; Zhou, Wei; Udovic, Terrence J.; Yildirim, Taner; Rush, John J.


    We report on a new class of complex hydrides: borohydride guanidinate complexes (MBH4·nCN3H5, M=Li, Mg, and Ca). They can be prepared via facile solid-state synthesis routes. Their crystal structures were successfully determined using a combination of X-ray diffraction, first-principles calculations and neutron vibrational spectroscopy. Among these compounds, Mg(BH4)2·6CN3H5 is composed of large complex Mg[CN3H5]62+ cations and surrounding BH4- ions, while Ca(BH4)2·2CN3H5 possesses layers of corner-sharing Ca[BH4]4(CN3H5)2 octahedra. Our dehydrogenation results show that ≈10 wt% hydrogen can be released from MBH4·nCN3H5 (M=Li, Mg, and Ca) at moderate temperatures with minimal ammonia and diborane contamination thanks to the synergistic effect of C-N bonds from guanidine and hydridic H from borohydrides leading to a weakening of the N-H bonds, thus impeding ammonia gas liberation. Further tuning the dehydrogenation with different cation species indicates that Mg(BH4)2·nCN3H5 can exhibit the optimum properties with nearly thermally neutral dehydrogenation and very high purity hydrogen release.

  6. Synergistic effects of chitosan-guanidine complexes on enhancing antimicrobial activity and wet-strength of paper.

    Sun, Shengling; An, Qiaozhi; Li, Xu; Qian, Liying; He, Beihai; Xiao, Huining


    Chitosan-guanidine complexes were prepared by reacting chitosan and polyhexamethylene guanidine hydrochloride or crosslinked polyhexamethylene guanidine hydrochloride in the presence of sodium tripolyphosphate as a crosslinking agent. The complexes, used as functional additives for paper, synergistically improved wet-strength and antimicrobial activities. In comparison with the control sample, the wet/dry strength ratio of hand-sheets treated with the complexes was increased from 2.65% up to 23.3%. The MIC values of the chitosan-PHGH and chitosan-PHGHE complexes against Escherichia coli were 15.6 and 31.2 microg mL(-1), respectively, thus demonstrating excellent antimicrobial activity. Hand-sheets treated with the complexes exhibited antibacterial activity against E. coli and Staphylococcus aureus. The release of the guanidine polymers included in the complexes was dynamically monitored using UV and the results showed the amount released exceeded 80%. Atomic force microscopy images indicated that the antimicrobial mechanism of the complexes was likely due to membrane damage. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  7. Theoretical characterization and design of highly efficient iridium (III) complexes bearing guanidinate ancillary ligand.

    Ren, Xin-Yao; Wu, Yong; Wang, Li; Zhao, Liang; Zhang, Min; Geng, Yun; Su, Zhong-Min


    A density functional theory/time-depended density functional theory was used to investigate the synthesized guanidinate-based iridium(III) complex [(ppy)2Ir{(N(i)Pr)2C(NPh2)}] (1) and two designed derivatives (2 and 3) to determine the influences of different cyclometalated ligands on photophysical properties. Except the conventional discussions on geometric relaxations, absorption and emission properties, many relevant parameters, including spin-orbital coupling (SOC) matrix elements, zero-field-splitting parameters, radiative rate constants (kr) and so on were quantitatively evaluated. The results reveal that the replacement of the pyridine ring in the 2-phenylpyridine ligand with different diazole rings cannot only enlarge the frontier molecular orbital energy gaps, resulting in a blue-shift of the absorption spectra for 2 and 3, but also enhance the absorption intensity of 3 in the lower-energy region. Furthermore, it is intriguing to note that the photoluminescence quantum efficiency (ΦPL) of 3 is significantly higher than that of 1. This can be explained by its large SOC value(n=3-4) and large transition electric dipole moment (μS3), which could significantly contribute to a larger kr. Besides, compared with 1, the higher emitting energy (ET1) and smaller (2) value for 3 may lead to a smaller non-radiative decay rate. Additionally, the detailed results also indicate that compared to 1 with pyridine ring, 3 with imidazole ring performs a better hole injection ability. Therefore, the designed complex 3 can be expected as a promising candidate for highly efficient guanidinate-based phosphorescence emitter for OLEDs applications. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Surface-complex films of guanidine on tantalum nitride electrochemically characterized for applications in chemical mechanical planarization

    Rock, S.E.; Crain, D.J. [Department of Physics, Clarkson University, Potsdam, NY 13699-5820 (United States); Pettit, C.M. [Department of Physics, Emporia State University, Emporia, KS 66801-5087 (United States); Roy, D., E-mail: [Department of Physics, Clarkson University, Potsdam, NY 13699-5820 (United States)


    Chemical mechanical planarization (CMP) of tantalum nitride is an essential step of material processing in the fabrication of integrated circuits. This CMP step often involves the chemical formation of a structurally weak oxide-complex film on the wafer surface, followed by selective removal of the film with mechanical abrasion under reduced loading. The present work investigates certain chemical aspects of this strategy of TaN-CMP by using guanidine carbonate (GC) as a surface complexing agent, and employing electrochemical experiments. The experiments are designed to study the chemical and electrochemical origins of the CMP-specific surface complex films formed on a TaN wafer in acidic solutions of GC and hydrogen peroxide. Open circuit potential, polarization resistance, and electrochemical impedance measurements are employed to probe the surface effects that facilitate material removal in chemically prevailing CMP of TaN. The results are discussed in view of designing slurry variables to support barrier layer planarization with reduced roles of mechanical abrasion.

  9. Electronic structure and luminescence of tellurium (IV) halide complexes with guanidine and caesium cations

    Dotsenko, A. A.; Shcheka, O. L.; Vovna, V. I.; Korochentsev, V. V.; Mirochnik, A. G.; Sedakova, T. V.


    The present paper continues a series of publications on the investigation of complex compounds of s2 ions and their properties. The structure of the valence levels of Cs2TeX6, (HGu)2TeCl6 complexes (where X = Cl, Br; HGu+ - guanidinium) is examined, the orbital nature of luminescence excitation is established, and the relationship of properties with the electronic structure is determined by means of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT).

  10. The guanidine and maleic acid (1:1) complex. The additional theoretical and experimental studies

    Drozd, Marek; Dudzic, Damian


    On the basis of experimental literature data the theoretical studies for guanidinium and maleic acid complex with using DFT method are performed. In these studies the experimental X-ray data for two different forms of investigated crystal were used. During the geometry optimization process one equilibrium structure was found, only. According to this result the infrared spectrum for one theoretical molecule was calculated. On the basis of potential energy distribution (PED) analysis the clear-cut assignments of observed bands were performed. For the calculated molecule with energy minimum the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were obtained and graphically illustrated. The energy difference (GAP) between HOMO and LUMO was analyzed. Additionally, the nonlinear properties of this molecule were calculated. The α and β (first and second order) hyperpolarizability values are obtained. On the basis of these results the title crystal was classified as new second order NLO generator.

  11. Chirality sensing with stereodynamic biphenolate zinc complexes.

    Bentley, Keith W; de Los Santos, Zeus A; Weiss, Mary J; Wolf, Christian


    Two bidentate ligands consisting of a fluxional polyarylacetylene framework with terminal phenol groups were synthesized. Reaction with diethylzinc gives stereodynamic complexes that undergo distinct asymmetric transformation of the first kind upon binding of chiral amines and amino alcohols. The substrate-to-ligand chirality imprinting at the zinc coordination sphere results in characteristic circular dichroism signals that can be used for direct enantiomeric excess (ee) analysis. This chemosensing approach bears potential for high-throughput ee screening with small sample amounts and reduced solvent waste compared to traditional high-performance liquid chromatography methods.

  12. Geometrical and optical benchmarking of copper guanidine-quinoline complexes: insights from TD-DFT and many-body perturbation theory.

    Jesser, Anton; Rohrmüller, Martin; Schmidt, Wolf Gero; Herres-Pawlis, Sonja


    We report a comprehensive computational benchmarking of the structural and optical properties of a bis(chelate) copper(I) guanidine-quinoline complex. Using various (TD-)DFT flavors a strong influence of the basis set is found. Moreover, the amount of exact exchange shifts metal-to-ligand bands by 1 eV through the absorption spectrum. The BP86/6-311G(d) and B3LYP/def2-TZVP functional/basis set combinations were found to yield results in best agreement with the experimental data. In order to probe the general applicability of TD-DFT to excitations of copper bis(chelate) charge-transfer (CT) systems, we studied a small model system that on the one hand is accessible to methods of many-body perturbation theory (MBPT) but still contains simple guanidine and imine groups. These calculations show that large quasiparticle energies of the order of several electronvolts are largely offset by exciton binding energies for optical excitations and that TD-DFT excitation energies deviate from MBPT results by at most 0.5 eV, further corroborating the reliability of our TD-DFT results. The latter result in a multitude of MLCT bands ranging from the visible region at 3.4 eV into the UV at 5.5 eV for the bis(chelate) complex. Molecular orbital analysis provided insight into the CT within these systems but gave mixed transitions. A meaningful transition assignment is possible, however, by using natural transition orbitals. Additionally, we performed a thorough conformational analysis as the correct description of the copper coordination is crucial for the prediction of optical spectra. We found that DFT identifies the correct conformational minimum and that the MLCTs are strongly dependent on the torsion of the chelate angles at the copper center. From the results, it is concluded that extensive benchmarking allows for the quantitative analyses of the CT behavior of copper bis(chelate) complexes within TD-DFT.

  13. Geometrical and optical benchmarking of copper(II) guanidine-quinoline complexes: insights from TD-DFT and many-body perturbation theory (part II).

    Hoffmann, Alexander; Rohrmüller, Martin; Jesser, Anton; dos Santos Vieira, Ines; Schmidt, Wolf Gero; Herres-Pawlis, Sonja


    Ground- and excited-state properties of copper(II) charge-transfer systems have been investigated starting from density-functional calculations with particular emphasis on the role of (i) the exchange and correlation functional, (ii) the basis set, (iii) solvent effects, and (iv) the treatment of dispersive interactions. Furthermore (v), the applicability of TD-DFT to excitations of copper(II) bis(chelate) charge-transfer systems is explored by performing many-body perturbation theory (GW + BSE), independent-particle approximation and ΔSCF calculations for a small model system that contains simple guanidine and imine groups. These results show that DFT and TD-DFT in particular in combination with hybrid functionals are well suited for the description of the structural and optical properties, respectively, of copper(II) bis(chelate) complexes. Furthermore, it is found an accurate theoretical geometrical description requires the use of dispersion correction with Becke-Johnson damping and triple-zeta basis sets while solvent effects are small. The hybrid functionals B3LYP and TPSSh yielded best performance. The optical description is best with B3LYP, whereby heavily mixed molecular transitions of MLCT and LLCT character are obtained which can be more easily understood using natural transition orbitals. An natural bond orbital analysis sheds light on the donor properties of the different donor functions and the intraguanidine stabilization during coordination to copper(I) and (II).

  14. Anti-ulcer activity of a slow-release zinc complex, zinc monoglycerolate (Glyzinc).

    Rainsford, K D; Whitehouse, M W


    A slow-release zinc complex, zinc monoglycerolate (ZMG) was examined for its potential gastroprotective activity in various gastric ulcer models. These models comprised (a) oral or parenteral non-steroidal anti-inflammatory drugs (NSAIDs) given to rats whose gastrointestinal mucosa was pre-sensitized by prior development of arthritis, oleyl alcohol-induced inflammation and cold exposure, (b) oral ethanol (12.5-100%) with and without added 4% HCl, (c) intraperitoneal reserpine (5 mg kg-1) in arthritic and normal rats and in normal mice, (d) oral NSAIDs given to mice in which acid and pepsin production was stimulated by co-administration of intraperitoneal bethanechol chloride (5 mg kg-1) to enhance ulcer development, and (e) NSAIDs given to carrageenan-inflamed rats to determine effects of ZMG on paw inflammation. In these models, ZMG given orally was effective in preventing development of gastric lesions, except with propionic acid NSAIDs; the effective doses being apparently dependent on the severity of the mucosal injury. In many of the models ZMG was superior to zinc sulphate and other zinc salts or metal ion complexes investigated but was slightly more effective or equipotent compared with zinc acexamate. ZMG did not impair the anti-oedemic effects of NSAIDs. ZMG is thus an effective agent in preventing ulcer development in a wide range of model systems and may be more effective than zinc salts because of the controlled slow-release of zinc from the complex.

  15. Molecular structure and DFT investigations on new cobalt(II) chloride complex with superbase guanidine type ligand

    Saied M Soliman; Morsy A M Abu-Youssef; Jörg Albering; Ayman El-Faham


    The new [Co(btmgn)Cl2] complex and the 1,8-bis(tetramethylguanidino)naphthalene (btmgn) ligand were synthesized and characterized. The X-ray single crystal investigation showed distorted tetrahedral geometry around the Co(II) ion. The geometry of the btmgn and [Co(btmgn)Cl2] complex was optimized using the B3LYP/6–311G(d,p) method. The calculated geometric parameters at the optimized structure of the [Co(btmgn)Cl2] complex showed good agreement with our reported X-ray structure. The two tetramethylguanidino groups are in a cis-type position to the naphthalene ring plane both in the free and coordinated btmgn. The large red shift of the C=N mode upon coordination indicates the strong ligand–metal interactions. The calculated natural charges using natural bond orbital (NBO) analysis at the two coordinated Cl-atoms are not equivalent. Also the two LP(4)Cl → LP*(3)Co intramolecular charge transfer interaction energies (E(2)) are 29.00 and 39.17 kcal/mol, respectively. The two Co-Cl bonds are not equivalent where the longer Co-Cl bond has more electronegative chlorine atom than the shorter one. Molecular electrostatic potential (MEP) study of the btmgn ligand showed that the N4 and N7 atoms are the most reactive nucleophilic centers for the coordination with the Co2+ ion. The [Co(btmgn)Cl2] complex has higher polarizability (0), first hyperpolarizability (0) and lower energy gap (E) than the free ligand. The TD-DFT calculations predicted the transition bands at 337.2 nm (f=0.2299, H→L) and 342.6 nm (f=0.1465, H-2/H→L) for the btmgn and [Co(btmgn)Cl2], respectively.

  16. A Photoluminescence Study of the Changes Induced in the Zinc White Pigment by Formation of Zinc Complexes.

    Artesani, Alessia; Gherardi, Francesca; Nevin, Austin; Valentini, Gianluca; Comelli, Daniela


    It is known that oil paintings containing zinc white are subject to rapid degradation. This is caused by the interaction between the active groups of binder and the metal ions of the pigment, which gives rise to the formation of new zinc complexes (metal soaps). Ongoing studies on zinc white paints have been limited to the chemical mechanisms that lead to the formation of zinc complexes. On the contrary, little is known of the photo-physical changes induced in the zinc oxide crystal structure following this interaction. Time-resolved photoluminescence spectroscopy has been applied to follow modifications in the luminescent zinc white pigment when mixed with binder. Significant changes in trap state photoluminescence emissions have been detected: the enhancement of a blue emission combined with a change of the decay kinetic of the well-known green emission. Complementary data from molecular analysis of paints using Fourier transform infrared spectroscopy confirms the formation of zinc carboxylates and corroborates the mechanism for zinc complexes formation. We support the hypothesis that zinc ions migrate into binder creating novel vacancies, affecting the photoluminescence intensity and lifetime properties of zinc oxide. Here, we further demonstrate the advantages of a time-resolved photoluminescence approach for studying defects in semiconductor pigments.

  17. Effect of the ratio of zinc amino acid complex to zinc sulfate on the performance of Holstein cows

    Nayeri, A; Upah, N C; Sucu, E; Sanz-Fernandez, M V; DeFrain, J M; Gorden, P J; Baumgard, L H


    Multiparous (n=70) and primiparous (n=66) Holstein cows were balanced by 305-d previous mature-equivalent milk yield and parity and assigned to 1 of 3 dietary treatments to evaluate the ratio of zinc sulfate to zinc amino acid complex (CZ...

  18. Theoretical investigation on homoleptic Yttrium tri-guanidinates

    Salima Lakehal


    Full Text Available The electronic and molecular structures of the homoleptic Yttrium tris-guanidinates complexes Y[(NiPr2CNR1R2]3, [R1 = R2 = Me, Et and iPr] have been investigated employing DFT calculations in order to understand the structures, bonding and energies of the interactions between Yttrium metal and guanidinate ligands. The effect of the substitution on nitrogen position of guanidinate in these complexes has been also investigated employing DFT and TDDFT calculations for six kinds of models obtained by alternative substitution of alkyl on nitrogen of the guanidinate ligands. The results reveal that the substitution position plays a crucial role in the geometric structure by affecting the torsion angle and the HOMO–LUMO transitions. The energy decomposition analysis indicates a majority of ionic bonding in all systems; the exception is in the M4 (Y[(NYR2CNCR1R2]3; R = Et and R1 = R2 = H which present a significant degree of covalency.

  19. Mononuclear Phenolate Diamine Zinc Hydride Complexes and Their Reactions With CO2.

    Brown, Neil J; Harris, Jonathon E; Yin, Xinning; Silverwood, Ian; White, Andrew J P; Kazarian, Sergei G; Hellgardt, Klaus; Shaffer, Milo S P; Williams, Charlotte K


    The synthesis, characterization, and zinc coordination chemistry of the three proligands 2-tert-butyl-4-[tert-butyl (1)/methoxy (2)/nitro (3)]-6-{[(2'-dimethylaminoethyl)methylamino]methyl}phenol are described. Each of the ligands was reacted with diethylzinc to yield zinc ethyl complexes 4-6; these complexes were subsequently reacted with phenylsilanol to yield zinc siloxide complexes 7-9. Finally, the zinc siloxide complexes were reacted with phenylsilane to produce the three new zinc hydride complexes 10-12. The new complexes 4-12 have been fully characterized by NMR spectroscopy, mass spectrometry, and elemental analyses. The structures of the zinc hydride complexes have been probed using VT-NMR spectroscopy and X-ray diffraction experiments. These data indicate that the complexes exhibit mononuclear structures at 298 K, both in the solid state and in solution (d8-toluene). At 203 K, the NMR signals broaden, consistent with an equilibrium between the mononuclear and dinuclear bis(μ-hydrido) complexes. All three zinc hydride complexes react rapidly and quantitatively with carbon dioxide, at 298 K and 1 bar of pressure over 20 min, to form the new zinc formate complexes 13-15. The zinc formate complexes have been analyzed by NMR spectroscopy and VT-NMR studies, which reveal a temperature-dependent monomer-dimer equilibrium that is dominated by the mononuclear species at 298 K.

  20. The effect of different complexing agents on the properties of zinc sulfide thin films deposited from aqueous solutions


    The zinc sulfide (ZnS) thin films were prepared on glass substrates by chemical bath deposition using the aqueous solutions of zinc chloride, thiourea, pH regulator and complexing agent (ammonia and hydrazine hydrate, trisodium citrate or sodium hydroxide). The calculations of boundary conditions for formation of zinc sulfide and zinc hydroxide were made at various zinc salt concentrations with different complexing agents. The structural, morphology and optical properties of the ZnS thin film...

  1. Polycyclic Guanidine Alkaloids from Poecilosclerida Marine Sponges.

    Sfecci, Estelle; Lacour, Thierry; Amade, Philippe; Mehiri, Mohamed


    Sessile marine sponges provide an abundance of unique and diversified scaffolds. In particular, marine guanidine alkaloids display a very wide range of biological applications. A large number of cyclic guanidine alkaloids, including crambines, crambescins, crambescidins, batzelladines or netamins have been isolated from Poecilosclerida marine sponges. In this review, we will explore the chemodiversity of tri- and pentacyclic guanidine alkaloids. NMR and MS data tools will also be provided, and an overview of the wide range of bioactivities of crambescidins and batzelladines derivatives will be given.

  2. Zinc surface complexes on birnessite: A density functional theory study

    Kwon, Kideok D.; Refson, Keith; Sposito, Garrison


    Biogeochemical cycling of zinc is strongly influenced by sorption on birnessite minerals (layer-type MnO2), which are found in diverse terrestrial and aquatic environments. Zinc has been observed to form both tetrahedral (Zn{sup IV}) and octahedral (Zn{sup VI}) triple-corner-sharing surface complexes (TCS) at Mn(IV) vacancy sites in hexagonal birnessite. The octahedral complex is expected to be similar to that of Zn in the Mn oxide mineral, chalcophanite (ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O), but the reason for the occurrence of the four-coordinate Zn surface species remains unclear. We address this issue computationally using spin-polarized Density Functional Theory (DFT) to examine the Zn{sub IV}-TCS and Zn{sup VI}-TCS species. Structural parameters obtained by DFT geometry optimization were in excellent agreement with available experimental data on Zn-birnessites. Total energy, magnetic moments, and electron-overlap populations obtained by DFT for isolated Zn{sup IV}-TCS revealed that this species is stable in birnessite without a need for Mn(III) substitution in the octahedral sheet and that it is more effective in reducing undersaturation of surface O at a Mn vacancy than is Zn{sub VI}-TCS. Comparison between geometry-optimized ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O (chalcophanite) and the hypothetical monohydrate mineral, ZnMn{sub 3}O{sub 7} {center_dot} H{sub 2}O, which contains only tetrahedral Zn, showed that the hydration state of Zn significantly affects birnessite structural stability. Finally, our study also revealed that, relative to their positions in an ideal vacancy-free MnO{sub 2}, Mn nearest to Zn in a TCS surface complex move toward the vacancy by 0.08-0.11 {angstrom}, while surface O bordering the vacancy move away from it by 0.16-0.21 {angstrom}, in agreement with recent X-ray absorption spectroscopic analyses.

  3. The Zinc-Schiff Base-Novicidin Complex as a Potential Prostate Cancer Therapy

    Milosavljevic, Vedran; Haddad, Yazan; Merlos Rodrigo, Miguel Angel; Moulick, Amitava; Polanska, Hana; Hynek, David; Heger, Zbynek; Kopel, Pavel; Adam, Vojtech


    Prostate cancer cells control energy metabolism by chelating intracellular zinc. Thus, zinc delivery has been a popular therapeutic approach for prostate cancer. Here, we propose the use of the membrane-penetrating peptide Novicidin connected to zinc-Schiff base as a carrier vehicle for the delivery of zinc to prostate cells. Mass spectrometry, electrochemistry and spectrophotometry confirmed the formation/stability of this complex and provided insight regarding the availability of zinc for complex interactions. This delivery system showed minor toxicity in normal PNT1A cells and high potency towards PC3 tumor cells. The complex preferentially penetrated PC3 tumor cells in contrast to confinement to the membranes of PNT1A. Furthermore, zinc uptake was confirmed in both cell lines. Molecular analysis was used to confirm the activation of zinc stress (e.g., ZnT-1) and apoptosis (e.g., CASP-1). Our results strongly suggest that the zinc-Schiff base-Novicidin complex has great potential as a novel anticancer drug. PMID:27727290

  4. A novel kind of TSV slurry with guanidine hydrochloride

    Jiao, Hong; Yuling, Liu; Baoguo, Zhang; Xinhuan, Niu; Liying, Han


    The effect of a novel alkaline TSV (through-silicon-via) slurry with guanidine hydrochloride (GH) on CMP (chemical mechanical polishing) was investigated. The novel alkaline TSV slurry was free of any inhibitors. During the polishing process, the guanidine hydrochloride serves as an effective surface-complexing agent for TSV CMP applications, the removal rate of barrier (Ti) can be chemically controlled through tuned selectivity with respect to the removal rate of copper and dielectric, which is helpful to modifying the dishing and gaining an excellent topography performance in TSV manufacturing. In this paper, we mainly studied the working mechanism of the components of slurry and the skillful application guanidine hydrochloride in the TSV slurry. Project supported by the Major National Science and Technology Special Projects (No. 2009ZX02308), the Fund Project of Hebei Provincial Department of Education, China (No. QN2014208), the Natural Science Foundation of Hebei Province, China (No. E2013202247), and Colleges and Universities Scientific research project of Hebei Province, China (No. Z2014088).

  5. Optoelectronic Properties of Color-Tunable Mixed Ligand-Based Light-Emitting Zinc Complexes

    Singh, Devender; Bhagwan, Shri; Saini, Raman Kumar; Tanwar, Vijeta; Nishal, Vandna


    A series of mixed ligand-based zinc complexes (Zn1-Zn5); [(8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn1), [(5-chloro-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn2), [(5,7-dichloro-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn3), [(2-methyl-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn4) and [(5,7-dimethyl-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn5) were synthesized and characterized. The photophysical properties of zinc complexes were examined by ultraviolet-visible absorption and photoluminescence emission spectroscopy. All prepared metal complexes produced intense luminescence on excitation with a UV light source. In this study, the color-tunable characteristics of metal complexes were investigated by introducing the electron-donating and electron-withdrawing groups on the 8-hydroxyquinoline ligand. The emission spectra of metal complexes showed emission wavelength at 500 nm for [ZnHBI(q)], 509 nm for [ZnHBI(Clq)], 504 nm for [Zn(HBI)(Cl2q)], 496 nm for [ZnHBI (Meq)] and 573 nm for [ZnHBI(Me2Q)] materials. A temperature-dependent PL spectrum was used to study the emission profile of zinc complex and observed that variation in the temperature altered the position and the intensity of emission peak. The synthesized metal complex also exhibited good thermal stability (>300°C). Photophysical characteristics of color-tunable light-emitting zinc complexes suggested that these materials could be efficiently used for emissive display device applications.

  6. Computational protocol for predicting the binding affinities of zinc containing metalloprotein-ligand complexes.

    Jain, Tarun; Jayaram, B


    Zinc is one of the most important metal ions found in proteins performing specific functions associated with life processes. Coordination geometry of the zinc ion in the active site of the metalloprotein-ligand complexes poses a challenge in determining ligand binding affinities accurately in structure-based drug design. We report here an all atom force field based computational protocol for estimating rapidly the binding affinities of zinc containing metalloprotein-ligand complexes, considering electrostatics, van der Waals, hydrophobicity, and loss in conformational entropy of protein side chains upon ligand binding along with a nonbonded approach to model the interactions of the zinc ion with all the other atoms of the complex. We examined the sensitivity of the binding affinity predictions to the choice of Lennard-Jones parameters, partial atomic charges, and dielectric treatments adopted for system preparation and scoring. The highest correlation obtained was R2 = 0.77 (r = 0.88) for the predicted binding affinity against the experiment on a heterogenous dataset of 90 zinc containing metalloprotein-ligand complexes consisting of five unique protein targets. Model validation and parameter analysis studies underscore the robustness and predictive ability of the scoring function. The high correlation obtained suggests the potential applicability of the methodology in designing novel ligands for zinc-metalloproteins. The scoring function has been web enabled for free access at as BAPPL-Z server (Binding Affinity Prediction of Protein-Ligand complexes containing Zinc metal ions).

  7. Zinc

    ... slow wound healing, poor sense of taste and smell, diarrhea, and nausea. Moderate zinc deficiency is associated ... nose, as it might cause permanent loss of smell. In June 2009, the US Food and Drug ...

  8. Defect Chemistry and Microstructure of Complex Perovskite Barium Zinc Niobate

    Peng, Ping


    This dissertation presents a systematic study of the characterization of the phase transitions, microstructures, defects and transport properties of undoped and doped complex perovskite barium zinc niobate (BZN). Complex perovskite BZN is a paraelectric material while its parent material barium titanate is ferroelectric. With codoping of (Zn + 2Nb) into Ti site, BaTiO_3 shows three distinguished features. First, the Curie temperature is lowered; second, the three phase transitions (cubic-tetragonal-orthorhombic-rhombohedral) coalesce; and lastly, the transition becomes diffuse showing a typical 2nd order phase transition compared with 1st order in undoped BaTiO_3. Complex microchemical ordering is another characteristic of BZN. Stoichiometric BZN shows a mixture of two types of ordering schemes. 1:1, 1:2 ordered microdomains and the disordered matrix co-exist. The 1:1 type ordering involves an internal charge imbalance which inhibits the growth of 1:1 type of ordered microdomains. The 1:2 type ordering is consistent with the chemical composition of BZN. These ordering patterns can be modified by either adjustment of the Zn/Nb ratio or by doping. The defect structure of the stoichiometric BZN is closely related to that of BaTiO_3. Stoichiometric BZN is an insulator with wide band gap (~ 3.70 eV). Undoped BZN has a high oxygen vacancy concentration which comes from three possible sources, such as unavoidable acceptor impurities, due to their natural abundance, Zn/Nb ratio uncertainty due to processing limitations, and high temperature ZnO loss due to sintering process. The oxygen vacancy concentration for undoped BZN lays in the neighborhood of 1500 ppm (atm.). The compensation defects for various dopants have also been identified. Both electrons and holes conduct by a small polaron mechanism. Various thermodynamic parameters, such as enthalpies of oxidation and reduction, mass action constants for intrinsic electronic disorder, oxidation and reduction have been

  9. Toxic and nontoxic components of botulinum neurotoxin complex are evolved from a common ancestral zinc protein

    Inui, Ken [Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493 (Japan); Japan Society for the Promotion of Science, 1-8 Chiyoda-ku, Tokyo 102-8472 (Japan); Sagane, Yoshimasa [Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493 (Japan); Miyata, Keita [Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493 (Japan); Japan Society for the Promotion of Science, 1-8 Chiyoda-ku, Tokyo 102-8472 (Japan); Miyashita, Shin-Ichiro [Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493 (Japan); Suzuki, Tomonori [Department of Bacteriology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558 (Japan); Shikamori, Yasuyuki [Agilent Technologies International Japan, Ltd. Takaura-cho 9-1, Hachioji-shi, Tokyo 192-0033 (Japan); Ohyama, Tohru; Niwa, Koichi [Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493 (Japan); Watanabe, Toshihiro, E-mail: [Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493 (Japan)


    Highlights: Black-Right-Pointing-Pointer BoNT and NTNHA proteins share a similar protein architecture. Black-Right-Pointing-Pointer NTNHA and BoNT were both identified as zinc-binding proteins. Black-Right-Pointing-Pointer NTNHA does not have a classical HEXXH zinc-coordinating motif similar to that found in all serotypes of BoNT. Black-Right-Pointing-Pointer Homology modeling implied probable key residues involved in zinc coordination. -- Abstract: Zinc atoms play an essential role in a number of enzymes. Botulinum neurotoxin (BoNT), the most potent toxin known in nature, is a zinc-dependent endopeptidase. Here we identify the nontoxic nonhemagglutinin (NTNHA), one of the BoNT-complex constituents, as a zinc-binding protein, along with BoNT. A protein structure classification database search indicated that BoNT and NTNHA share a similar domain architecture, comprising a zinc-dependent metalloproteinase-like, BoNT coiled-coil motif and concanavalin A-like domains. Inductively coupled plasma-mass spectrometry analysis demonstrated that every single NTNHA molecule contains a single zinc atom. This is the first demonstration of a zinc atom in this protein, as far as we know. However, the NTNHA molecule does not possess any known zinc-coordinating motif, whereas all BoNT serotypes possess the classical HEXXH motif. Homology modeling of the NTNHA structure implied that a consensus K-C-L-I-K-X{sub 35}-D sequence common among all NTNHA serotype molecules appears to coordinate a single zinc atom. These findings lead us to propose that NTNHA and BoNT may have evolved distinct functional specializations following their branching out from a common ancestral zinc protein.

  10. Zinc Pyrithione: A Topical Antimicrobial With Complex Pharmaceutics.

    Schwartz, James R


    Zinc pyrithione (ZPT) is an active material that has been used for over 50 years to effectively treat dandruff and seborrheic dermatitis (D/SD). It has become the most common material for that purpose, its use has expanded to include other skin benefits such as skin hygiene. However, there is much about ZPT that is unappreciated. It is a rationally developed molecule that was modeled after the naturally occurring antimicrobial aspergillic acid. The molecular basis for its antifungal activity has been elucidated. The efficacy of ZPT originates from two attributes. First, it has a very broad antimicrobial spectrum of activity, including fungi, gram-positive and -negative bacteria. Second, the material has very low solubility, resulting in formulation and delivery as a particulate material, which has distinct performance advantages. The particles are deposited and retained on the target skin surfaces even when delivered from rinse-off products. These particles slowly release molecularly active material to interact with the surface fungal and bacteria cells to control their population, functioning as slow-release reservoirs to provide extended and persistent benefits. This particulate nature, though, results in complex pharmaceutics to realize the full efficacy benefits; it is common to see products with the same ZPT level having widely varying levels of clinical performance. Several product matrix-determined factors directly impact resultant benefits: ZPT must be retained on the skin surface achieving uniform spatial distribution laterally as well as within hair follicles (especially on scalp); ZPT must be maintained as a physically stable dispersion in product; ZPT must be maintained in a chemically active form as there are many chemical reactions that can occur that can harm ZPT bioactivity. The benefits achievable by employing ZPT require significant pharmaceutics expertise to realize the full benefits of this active material.

  11. Synthesis of zinc sulphide nanoparticles from thermal decomposition of zinc N-ethyl cyclohexyl dithiocarbamate complex

    Abdullah, Nurul Hidayah [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Zainal, Zulkarnain, E-mail: [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Silong, Sidik [UiTM Negeri Sembilan, Kampus Kuala Pilah, Pekan Parit Tinggi, 72000 Kuala Pilah, Negeri Sembilan (Malaysia); Tahir, Mohamed Ibrahim Mohamed; Tan, Kar-Ban [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Chang, Sook-Keng [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)


    Synthesis of nanostructured semiconductor materials from various single source precursors has been massively explored for potential applications in modern technology. Thermal decomposition method has been employed to prepare nanoparticles zinc sulphide from zinc N-ethyl cyclohexyl dithiocarbamate precursor. Effect of heat treatment at different calcination duration on the structural, morphological, compositional and band gap properties of zinc sulphide were investigated. The obtained samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) analysis. XRD showed the precursor was decomposed to hexagonal zinc sulphide after 2–6 h of calcination duration at 400 °C. The sizes of zinc sulphide (ZnS) nanoparticles obtained from TEM analysis were about 6–11 nm. The existence of the hexagonal ZnS phase is not affected by the calcination duration, while only a slight difference in the crystallinity and crystallite size of ZnS is observed from XRD analysis. EDX analyses reveal that the as-prepared ZnS nanoparticles have an approximate composition of Zn and S close to 1:1, giving a possible composition of ZnS. Besides, direct band gap energy of ZnS was found to be around 3.78–3.95 eV. - Highlights: • Zinc N-ethyl cyclohexyl dithiocarbamate was used as single source precursor. • No surfactant was used in the preparation of ZnS nanoparticles. • Pure phase nanostructured ZnS is obtained. • A good stoichiometric sample with an average atomic ratio of Zn:S close to 1:1.

  12. The chemistry and biology of guanidine natural products.

    Berlinck, Roberto G S; Romminger, Stelamar


    The present review discusses the isolation, structure determination, synthesis, biosynthesis and biological activities of secondary metabolites bearing a guanidine group. Topics include non-ribosomal peptides, alkaloids, guanidine-bearing terpenes, polyketides and shikimic acid derivatives from natural sources. A critical analysis of some yet underdeveloped aspects of guanidine metabolites is also presented.

  13. The impact of tertiary wastewater treatment on copper and zinc complexation.

    Constantino, C; Gardner, M; Comber, S D W; Scrimshaw, M D; Ellor, B


    Tightening quality standards for European waters has seen a move towards enhanced wastewater treatment technologies such as granulated organic carbon treatment and ozonation. Although these technologies are likely to be successful in degrading certain micro-organic contaminants, these may also destroy compounds which would otherwise complex and render metals significantly less toxic. This study examined the impact of enhanced tertiary treatment on the capacity of organic compounds within sewage effluents to complex copper and zinc. The data show that granulated organic carbon treatment removes a dissolved organic carbon (DOC) fraction that is unimportant to complexation such that no detrimental impact on complexation or metal bioavailability is likely to occur from this treatment type. High concentrations of ozone (>1 mg O3/mg DOC) are, however, likely to impact the complexation capacity for copper although this is unlikely to be important at the concentrations of copper typically found in effluent discharges or in rivers. Ozone treatment did not affect zinc complexation capacity. The complexation profiles of the sewage effluents show these to contain a category of non-humic ligand that appears unaffected by tertiary treatment and which displays a high affinity for zinc, suggesting these may substantially reduce the bioavailability of zinc in effluent discharges. The implication is that traditional metal bioavailability assessment approaches such as the biotic ligand model may overestimate zinc bioavailability in sewage effluents and effluent-impacted waters.

  14. [Zinc].

    Couinaud, C


    Zinc is indispensable for life from bacteria to man. As a trace element it is included in numerous enzymes or serves as their activator (more than 80 zinc metallo-enzymes). It is necessary for nucleic acid and protein synthesis, the formation of sulphated molecules (insulin, growth hormone, keratin, immunoglobulins), and the functioning of carbonic anhydrase, aldolases, many dehydrogenases (including alcohol-dehydrogenase, retinal reductase indispensable for retinal rod function), alkaline phosphatase, T cells and superoxide dismutase. Its lack provokes distinctive signs: anorexia, diarrhea, taste, smell and vision disorders, skin lesions, delayed healing, growth retardation, delayed appearance of sexual characteristics, diminished resistance to infection, and it may be the cause of congenital malformations. Assay is now simplified by atomic absorption spectrophotometry in blood or hair. There is a latent lack prior to any disease because of the vices of modern eating habits, and this increases during stress, infections or tissue healing processes. Its lack is accentuated during long-term parenteral feeding or chronic gastrointestinal affections. Correction is as simple as it is innocuous, and zinc supplements should be given more routinely during surgical procedures.

  15. A Zinc Morpholine Complex Prevents HCl/Ethanol-Induced Gastric Ulcers in a Rat Model.

    Salama, Suzy M; Gwaram, Nura Suleiman; AlRashdi, Ahmed S; Khalifa, Shaden A M; Abdulla, Mahmood A; Ali, Hapipah M; El-Seedi, Hesham R


    Zinc is a naturally occurring element with roles in wound healing and rescuing tissue integrity, particularly in the gastrointestinal system, where it can be detected in the mucosal and submucosal layers. Zinc chelates are known to have beneficial effects on the gastrointestinal mucosa and in cases of gastric ulcer. We synthesized complexes of zinc featuring a heterocyclic amine binding amino acids then investigated their ability to enhance the gastric self-repair. Zinc-morpholine complex, Zn(L)SCN, namely showed strong free-radical scavenging, promotion of the DNA and RNA polymerases reconstruction and suppression of cell damage. The complex's mode of action is proposed to involve hydrogen bond formation via its bis(thiocyanato-k)zinc moiety. Zn(L)SCN complex had potent effects on gastric enzymatic activity both in vitro and in vivo. The complex disrupted the ulcerative process as demonstrated by changes in the intermediate metabolites of the oxidative pathway - specifically, reduction in the MDA levels and elevation of reduced glutathione together with an attenuation of oxidative DNA damage. Additionally, Zn(L)SCN restored the gastric mucosa, inhibited the production of pro-inflammatory cytokines (IL-6, TNF and the caspases), and preserved the gastric mucous balance. Zn(L)SCN thus exhibited anti-oxidative, anti-inflammatory and anti-apoptotic activities, all of which have cytoprotective effects on the gastric lining.

  16. Synthesis, characterization, and antibacterial activities of a novel nanohydroxyapatite/zinc oxide complex.

    Zhou, G.; Li, Yubao; Xiao, W.; Zhang, L.; Zuo, Y.; Xue, J.; Jansen, J.A.


    Nanohydroxyapatite (n-HA)/zinc oxide (ZnO) complex was synthesized by a direct precipitation method, and the antibacterial capability and antibacterial mechanism of this complex were investigated in this article. Transmission electron microscope (TEM), Fourier transform infrared, X-ray photoelectron

  17. Unique Ligand-Based Oxidative DNA Cleavage by Zinc(II) Complexes of Hpyramol and Hpyrimol

    Maheswari, P.U.; Barends, S.; Özalp-Yaman, S.; de Hoog, P.; Casellas, H.; Teat, S.J.; Massera, C.; Lutz, M.; Spek, A.L.; van Wezel, G.P.; Gamez, P.; Reedijk, J.


    The zinc(II) complexes reported here have been synthesised from the ligand 4-methyl-2-N-(2-pyridylmethyl)aminophenol (Hpyramol) with chloride or acetate counterions. All the five complexes have been structurally characterised, and the crystal structures reveal that the ligand Hpyramol gradually unde

  18. A role for dZIP89B in Drosophila dietary zinc uptake reveals additional complexity in the zinc absorption process.

    Richards, Christopher D; Warr, Coral G; Burke, Richard


    Dietary zinc is the principal source of zinc in eukaryotes, with its uptake and distribution controlled by a complex network of numerous membrane-spanning transport proteins. Dietary absorption is achieved by members of the SLC39A (ZIP) gene family, which encode proteins that are generally responsible for the movement of zinc into the cytosol. ZIP4 is thought to be the primary mammalian zinc uptake gene in the small intestine, with mutations in this gene causing the zinc deficiency disease Acrodermatitis enteropathica. In Drosophila, dual knockdown of the major dietary zinc uptake genes dZIP42C.1 (dZIP1) and dZIP42C.2 (dZIP2) results in a severe sensitivity to zinc-deficient media. However, the symptoms associated with ZIP4 loss can be reversed by zinc supplementation and dZIP42C.1 and 2 knockdown has minimal effect under normal dietary conditions, suggesting that additional pathways for zinc absorption exist in both mammals and flies. This study provides evidence that dZIP89B is an ideal candidate for this role in Drosophila, encoding a low-affinity zinc uptake transporter active in the posterior midgut. Flies lacking dZIP89B, while viable and apparently healthy, show indications of low midgut zinc levels, including reduced metallothionein B expression and compensatory up-regulation of dZIP42C.1 and 2. Furthermore dZIP89B mutants display a dramatic resistance to toxic dietary zinc levels which is abrogated by midgut-specific restoration of dZIP89B activity. We postulate that dZIP89B works in concert with the closely related dZIP42C.1 and 2 to ensure optimal zinc absorption under a range of dietary conditions.

  19. Anti-inflammatory, antinociceptive and ulcerogenic activity of a zinc-diclofenac complex in rats

    Santos L.H.


    Full Text Available We investigated the anti-inflammatory, antinociceptive and ulcerogenic activity of a zinc-diclofenac complex (5.5 or 11 mg/kg in male Wistar rats (180-300 g, N = 6 and compared it to free diclofenac (5 or 10 mg/kg and to the combination of diclofenac (5 or 10 mg/kg and zinc acetate (1.68 or 3.5 mg/kg. The carrageenin-induced paw edema and the cotton pellet-induced granulomatous tissue formation models were used to assess the anti-inflammatory activity, and the Hargreaves model of thermal hyperalgesia was used to assess the antinociceptive activity. To investigate the effect of orally or intraperitoneally (ip administered drugs on cold-induced gastric lesions, single doses were administered before exposing the animals to a freezer (-18ºC for 45 min in individual cages. We also evaluated the gastric lesions induced by multiple doses of the drugs. Diclofenac plus zinc complex had the same anti-inflammatory and antinociceptive effects as diclofenac alone. Gastric lesions induced by a single dose administered per os and ip were reduced in the group treated with zinc-diclofenac when compared to the groups treated with free diclofenac or diclofenac plus zinc acetate. In the multiple dose treatment, the complex induced a lower number of the most severe lesions when compared to free diclofenac and diclofenac plus zinc acetate. In conclusion, the present study demonstrates that the zinc-diclofenac complex may represent an important therapeutic alternative for the treatment of rheumatic and inflammatory conditions, as its use may be associated with a reduced incidence of gastric lesions.

  20. Zinc complexes as fluorescent chemosensors for nucleic acids: new perspectives for a "boring" element.

    Terenzi, Alessio; Lauria, Antonino; Almerico, Anna Maria; Barone, Giampaolo


    Zinc(II) complexes are effective and selective nucleic acid-binders and strongly fluorescent molecules in the low energy range, from the visible to the near infrared. These two properties have often been exploited to quantitatively detect nucleic acids in biological samples, in both in vitro and in vivo models. In particular, the fluorescent emission of several zinc(II) complexes is drastically enhanced or quenched by the binding to nucleic acids and/or upon visible light exposure, in a different fashion in bulk solution and when bound to DNA. The twofold objective of this perspective is (1) to review recent utilisations of zinc(II) complexes as selective fluorescent probes for nucleic acids and (2) to highlight their novel potential applications as diagnostic tools based on their photophysical properties.

  1. Thermokinetics of the Formation Reaction of Zinc Histidine Complex

    GAO,Sheng-Li(高胜利); CHEN,San-Ping(陈三平); HU,Rong-Zu(胡荣祖); SHI,Qi-Zhen(史启祯)


    The enthalpy change of reaction of zinc chloride with L-α-histidine in the temperature range of 25-50 ℃ has been determined by a microcalorimeter. On the basis of experimental and calculated results, three thermodynamics parameters (the activation enthalpy, the activation entropy, the activation free energy), the rate constant and three kinetic parameters (the activation energy, the pre-exponential constant and the reaction order) of the reaction, and the standard enthalpy of formarion of Zn(His)2+ (aq.) are obtained. The results showed that the title reaction easily took place at the studied temperature.

  2. Spontaneous resolution of a bis(eta(1)-methylcyclopentadienyl)zinc complex

    Olsson, S.; Lennartson, A.


    Two crystalline complexes of bis(eta(1)-methylcyclopentadienyl)zinc, [Zn(C5H4Me)(2)(py)(2)] (1), where py is pyridine, and [Zn(C5H4Me)(2)(teeda)], 2, where teeda is N,N,N',N'-tetraethylethylenediamine have been isolated. The crystal structures of 1 and 2 are the first crystal structures for Zn(C5H4......Me)(2) complexes reported in the literature; both structures display eta(1)-coordination of the methylcyclopentadienyl ring to zinc, and both compounds display chirogenic alpha-carbon atoms. While 1 forms racemic crystals, 2 undergoes spontaneous resolution and crystals of 2 are thus enantiomerically...

  3. The self-aggregation of chiral threonine-linked porphyrins and their zinc(Ⅱ) complexes


    The self-aggregation of chiral threonine-linked porphyrins and their zinc(Ⅱ) complexes in water-alcohol system and water-alcohol-NaCl system has been studied by circular dichroism (CD),UV-Vis absorption spectra and fluorescence spectra methods.The experiment results indicate that chiral threonine-linked porphyrins and their zinc(Ⅱ) complexes have two different kinds of aggregates in water-alcohol system and water-alcohol-NaCl system.And the porphyrins may form highly organized and orientated aggregates in water-alcohol-NaCl system.The aggregates in water-alcohol-NaCl system may have helical structures.

  4. Superoxide disproportionation driven by zinc complexes with various steric and electrostatic properties.

    Wada, Akira; Jitsukawa, Koichiro; Masuda, Hideki


    Attractive models: Synthetic Zn(II) complexes were investigated as models of copper-zinc superoxide dismutase. Superoxide underwent a unique disproportionation reaction in the electrostatic sphere of the complexes (see picture; bpy=2,2'-bipyridyl). The effectiveness of the Zn(II) complexes in inducing the disproportionation of superoxide depended on both the Lewis acidity and the coordination geometry of the Zn center.

  5. Preparation and Electronic Property Investigation of Zinc(II)-Schiff Base Complexes in the Confined Space

    Peng Shang; Lei Zhang


    Metal-Schiff base complexes have attracted continued research interest regarding their intriguing and useful features, while the electronic properties of these complexes in the confined space have not been sufficiently addressed in previous studies. In this work, a new zinc(II)-Schiff base complex bis(N-dodecyl salicylideneiminato)Zn(II) (1) was synthesized and subsequently loaded in an inorganic solid host. A large red shift (~40 nm) of the absorption onset was recorded, when the microenviro...

  6. Competitive Complexation of Copper and Zinc by Sequentially Extracted Humic Substances from Manure Compost

    LIU Shuai; WANG Xu-dong; LU Li-lan; DIAO Shi-rong; ZHANG Jun-feng


    Chicken manure with similar content of copper and zinc was chosen to conduct a composting experiment to investigate the changes of organic carbon and humus substance complexed copper (HS-Cu) and zinc (HS-Zn), which were extracted by water (H2O), sodium hydroxide (NaOH), and sodium pyrophate-NaOH mixture (Na4P2O7-NaOH), sequentially. Distributions of copper and zinc in fulvic acids (FA) and humic acids (HA) in the three extracts were studied. During manure composting, the concentrations of copper and zinc increased from about 500 mg kg-' in the raw material to 1100 mg kg-1 in the final products. HS-Cu in H2O, NaOH, and Na4P2O7-NaOH extracts occupied 6.7, 26.7, and 19% averagely of total copper and HS-Zn represented 2.7, 13.7, and 17% averagely of total zinc in compost, respectively. In water extracts, both HA and FA mainly complexed with Cu and the mole ratio of Cu to Zn was 2.8 in HA fractions and was 2.6 in FA fractions, respectively. HA mainly complexed with copper, so that the ratios of HA-Cu to HA-Zn averaged 3.4 in NaOH extracts. FA had a similar potential to complex with copper and zinc, so that the ratio of FA-Cu to FA-Zn was close to 1. In Na4P2O7-NaOH extracts, HA or FA had a similar potential to complex with copper and zinc. The ratio of HS-Cu to HS-Zn was close to 1. With manure composting, Na4P2O7-NaOH extractable HS-Zn increased to a level as high as HS-Cu. This indicated that more and more stable complexes of HS-Zn were formed in the late decomposition period. The competition between copper and zinc to be complexed with humic substance became weaker and weaker with the decomposition process.

  7. Nonlinear optical response of tetra and mono substituted zinc phthalocyanine complexes

    Fashina, Adedayo; Nyokong, Tebello, E-mail:


    The nonlinear absorption properties of 6 mono-substituted and 3 symmetric zinc phthalocyanine complexes have been studied in dimethylsulfoxide (DMSO) using 10 ns pulses at 532 nm. The non linear absorption of the complexes has been studied using the Z-scan technique. The study showed that both the singlet and triplet excited states contribute to the non linear absorption behavior. The nonlinear third-order susceptibility and second-order hyperpolarizability values of the complexes are reported. It was observed that two of the symmetric phthalocyanine complexes (5-α substituted with aminophenoxy and 9-β substituted with carboxyphenoxy) showed better and promising optical nonlinearity when compared to the other complexes studied. - Highlights: • Nonlinear absorption properties of zinc phthalocyanine are reported • Singlet and triplet excited states contribute to the non linear absorption. • Symmetrically tetra substituted phthalocyanines showed better optical nonlinearity.

  8. Mechanochemical synthesis of thioureas, ureas and guanidines.

    Štrukil, Vjekoslav


    In this review, the recent progress in the synthesis of ureas, thioureas and guanidines by solid-state mechanochemical ball milling is highlighted. While the literature is abundant on their preparation in conventional solution environment, it was not until the advent of solvent-free manual grinding using a mortar and pestle and automated ball milling that new synthetic opportunities have opened. The mechanochemical approach not only has enabled the quantitative synthesis of (thio)ureas and guanidines without using bulk solvents and the generation of byproducts, but it has also been established as a means to develop "click-type" chemistry for these classes of compounds and the concept of small molecule desymmetrization. Moreover, mechanochemistry has been demonstrated as an effective tool in reaction discovery, with emphasis on the reactivity differences in solution and in the solid state. These three classes of organic compounds share some structural features which are reflected in their physical and chemical properties, important for application as organocatalysts and sensors. On the other hand, the specific and unique nature of each of these functionalities render (thio)ureas and guanidines as the key constituents of pharmaceuticals and other biologically active compounds.

  9. Fabrication of an Organic Light-Emitting Diode from New Host π Electron Rich Zinc Complex

    Jafari, Mohammad Reza; Janghouri, Mohammad; Shahedi, Zahra


    A new π electron rich zinc complex was used as a fluorescent material in organic light-emitting diodes (OLEDs). Devices with a structure of indium tin oxide/poly (3,4-ethylenedi-oxythiophene):poly(styrenesulfonate) (PEDOT: PSS) (50 nm)/polyvinylcarbazole (60 nm)/Zn: %2 porphyrin derivatives (45 nm)/Al (150 nm) were fabricated. Porphyrin derivatives accounting for 2 wt.% in the π electron rich zinc complex were used as a host. The electroluminescence (EL) spectra of porphyrin derivatives indicated a red shift, as π electron rich zinc complex EL spectra. The device (4) has also a luminance of 3420 cd/m2 and maximum efficiency of 1.58 cd/A at 15 V, which are the highest values among four devices. The result of Commission International del'Eclairage (CIE) (X, Y) coordinate and EL spectrum of device (3) indicated that it is more red shifted compared to other devices. Results of this work indicate that π electron rich zinc complex is a promising host material for high efficiency red OLEDs and has a simple structure compared to Alq3-based devices.

  10. Zebra reaction or the recipe for the synthesis of heterodimeric zinc complexes.

    Jędrzkiewicz, D; Ejfler, J; John, Ł; Szafert, S


    A series of asymmetric heterodimeric zinc complexes have been synthesized in a direct reaction between conformationally flexible chiral/achiral homodimers. The cooperative activity of steric factors and coordination codes resulted in an intriguing chiral self-sorting process. Herein, we are reporting our recent exploration of the first example of such a type of reaction.

  11. Enantioselective Conjugate Addition of Grignard Reagents to Enones Catalyzed by Chiral Zinc(II) Complexes

    Jansen, Johan F.G.A.; Feringa, Bernard


    Various chiral zinc(II) complexes catalyze the asymmetric 1,4-addition of Grignard reagents to α,β-unsaturated ketones with high chemoselectivities (yields of 1,4-adducts, 83-99%), high regioselectivities (1,4/1,2 ratios up to 499) and modest enantioselectivities (ee up to 33%). A study of several f

  12. Studies on the Interaction between Zinc-Hydroxybenzoite Complex and Genomic DNA

    Hacali Necefoglu


    Full Text Available Zinc-Hydroxybenzoite ([Zn (H206] (p-HO-C6H4COO22H20 complex which wassynthesized and characterized by instrumental methods and the DNA samples which hadbeen isolated from cattle were allowed to interact at 37 oC for different time periods. Theinteraction of genomic DNA with this complex has been followed by agarose gelelectrophoresis at 50 V for 2 h. When DNA samples were allowed to interact with this metalcomplex, it was found that band intensities changed with the concentrations of the complex.In the result of interaction between this complex and genomic DNA samples, it wasdetermined that the intensities of bands were changed at the different concentrations of thecomplex. The brightness of the bands was increased and mobility of the bands wasdecreased, indicating the occurrence of increased covalent binding of the metal complexwith DNA. In this study it was concluded that the damage effect of ascorbate was reducedby Zinc-Hydroxybenzoite.

  13. Studies on cluster, salt and molecular complex of zinc-quinolinate

    Prithiviraj Khakhlary; Jubaraj B Baruah


    Reactions of zinc halides with 8-hydroxyquinoline (hydroxQ) in equimolar ratio were carried out in different solvents. Respective solvates of tetranuclear clusters, namely [Zn4(oxyQ)6X2].(solvent)2, (when X=Cl, Solvent=dimethylformamide (1), dimethylacetamide (2) and dimethysulphoxide (3); X = Br, solvent = dimethylformamide (4), oxyQ=quinolinate anion) were obtained. Bond parameters of these isostructural clusteres 1–4 are compared from their single crystal structures. Anhydrous form of the cluster have porous packing and is thermally stable below 250° C. Surface area of the clusters 1 and 4 are 8.933 and 6.172 m2/g, respectively. Complexes 1 and 4 can be reversibly hydrated, which is reflected in colour changes. The reaction of zinc chloride with 8-hydroxyquinoline in equimolar ratio followed by crystallization from water gave salt (HhydroxQ)2 [ZnCl4] (5) and a similar reaction followed by crystallization from 3-methylpyridine (3mepy) resulted in the molecular complex [Zn(oxyQ)2(3mepy)]. [Zn(oxyQ)2(3mepy)2].3H2O (6). Complex 5 is formed from a hydrolytic equilibrium of water with zinc chloride yielding tetrachloro zinc anion and zinc hydroxide. Taking advantage of this reaction, a composite material of ZnO@complex 5 exhibiting dual fluorescence at 450 and 575 nm on excitation at 390 nm was prepared. Fluorescence emission properties of all the complexes in solid state are compared with fluorescence emission of the ligand

  14. Structural and Functional Studies of the Protamine 2-Zinc Complex from Syrian Gold Hamster (Mesocricetus Auratus) Spermatids and Sperm

    Dolan, Cheryl E. [Univ. of California, Davis, CA (United States)


    The research described in this dissertation consists of four major areas: (1) sequence analysis of protamine 2 from Muroid rodents to identify potential zinc-binding domain(s) of protamine 2; (2) structural studies of the protamine 2-zinc complex from Syrian Gold hamster sperm and spermatids to elucidate the role of zinc during spermiogenesis; (3) structural studies of an unique protamine 2-zinc complex from chinchilla sperm; and (4) Nuclear Magnetic Resonance (NMR) studies of soluble complexes of hairpin oligonucleotides with synthetic arginine-rich peptides or protamine 1 isolated from bull sperm. First, zinc was quantitated in spermatids and sperm by Proton-Induced X-ray Emission (PIXE) to determine whether zinc is present in the early stages of spermiogenesis. The PIXE results revealed the zinc content varies proportionately with the amount of protamine 2 in both spermatid and sperm nuclei. An exception was chinchilla sperm containing twice the amount of protamine 2 than zinc. Further analyses by PIXE and X-ray Absorption Spectroscopy (XAS) of zinc bound to protamines isolated from hamster sperm confirmed the majority of the zinc is bound to protamine and identified the zinc ligands of protamine 2 in hamster spermatids and sperm in vivo. These studies established that zinc is bound to the protamine 2 precursor in hamster spermatids and the coordination of zinc by protamine 2 changes during spermiogenesis. Finally, the sequence analysis combined with the XAS results suggest that the zinc-binding domain in protamine 2 resides in the amino-terminus. Similar analyses of chinchilla sperm by XAS were performed to clarify the unusual PIXE results and revealed that chinchilla has an atypical protamine 2-zinc structure. Two protamine 2 molecules coordinate one zinc atom, forming homodimers that facilitate the binding of protamine 2 to DNA and provide an organizational scheme that would accommodate the observed species-specific protamine stoichiometry in mammalian sperm

  15. Antibacterial and antifungal activity of zinc(II complexes with some 2-methylbenzimidazole derivatives

    Podunavac-Kuzmanović Sanja O.


    Full Text Available Zinc(II chloride reacts with 2-methylbenzimidazole derivatives to give complexes of the formula ZnL2Cl2-nH2O, where L=2-methylbenzimidazole l-benzyl-2-methylbenzimida-zole and l-(4-methylbenzyl-2-methylbenzimidazole n=0, 0.5 or 1. All the ligands and their zinc(II complexes were evaluated for their in vitro antimicrobial activity against Pseudomonas aeruginosa Bacillus sp., Staphylococcus aureus, Sarcina lutea and Candida pseudotropicalis. It was found that the majority of the investigated compounds displayed in vitro antimicrobial activity against very persistent microorganisms, except for the starting ligand, 2-methylbenzimidazole and its zinc(II complex which were active only against gram-negative bacteria. None of the compounds was significantly effective against Candida pseudotropicalis, except for l-(4-methylbenzyl-2-methylbenzimidazoleandits complex, which very slightly or slightly inhibited the yeast growth. The minimum inhibitory concentration (MIC was determined for all the ligands and their complexes. The effect of ligand and complex structure on the antimicrobial activity was discussed.

  16. Zinc(II) complexes of carboxamide derivatives: Crystal structures and interaction with calf thymus DNA

    Biplab Mondal; Buddhadeb Sen; Ennio Zangrando; Pabitra Chattopadhyay


    Two mononuclear zinc(II) complexes of newly designed carboxamide derivatives, formulated as [Zn(L1)3](ClO4)2 (1) and [Zn(L2)3](ClO4)2 (2) [where L1 = -(furan-2-ylmethyl)-2-pyridinecarboxamide and L2 = -(thiophen-2-ylmethyl)-2-pyridine-carboxamide], have been isolated in pure form in the reaction of perchlorate salts of Zn(II) with ligands L1 and L2, respectively. The two complexes were characterized by physicochemical and spectroscopic tools, and by X-ray crystal structures of both ligands and the complex 1. In complex 1, zinc(II) is chelated by three ligands with a distorted octahedral geometry. The DNA-binding properties of zinc complexes 1 and 2 have been investigated by spectroscopic methods and viscosity measurements. The results suggest that both complexes 1 and 2 bind to DNA in an intercalation mode between the uncoordinated furan or thiophene chromophore and the base pairs of DNA.

  17. Synthesis, characterization, thermal and DNA-binding properties of new zinc complexes with 2-hydroxyphenones.

    Mrkalić, Emina; Zianna, Ariadni; Psomas, George; Gdaniec, Maria; Czapik, Agnieszka; Coutouli-Argyropoulou, Evdoxia; Lalia-Kantouri, Maria


    The neutral mononuclear zinc complexes with 2-hydroxyphenones (ketoH) having the formula [Zn(keto)2(H2O)2] and [Zn(keto)2(enR)], where enR stands for a N,N'-donor heterocyclic ligand such as 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen) or 2,2'-dipyridylamine (dpamH), have been synthesized and characterized by IR, UV and (1)H NMR spectroscopies. The 2-hydroxyphenones are chelated to the metal ion through the phenolate and carbonyl oxygen atoms. The crystal structures of [bis(2-hydroxy-4-methoxy-benzophenone)(2,2'-bipyridine)zinc(II)] dimethanol solvate and [bis(2-hydroxy-benzophenone)(2,2'-bipyridine)zinc(II)] dimethanol solvate have been determined by X-ray crystallography. The thermal stability of the zinc complexes has been investigated by simultaneous TG/DTG-DTA technique. The ability of the complexes to bind to calf-thymus DNA (CT DNA) has been studied by UV-absorption and fluorescence emission spectroscopy as well as viscosity measurements. UV studies of the interaction of the complexes with DNA have shown that they can bind to CT DNA and the corresponding binding constants to DNA have been calculated and evaluated. The complexes most probably bind to CT DNA via intercalation as concluded by studying the viscosity of a DNA solution in the presence of the complexes. Competitive studies with ethidium bromide (EB) have shown that the reported complexes can displace the DNA-bound EB, suggesting strong competition with EB for the intercalation site.

  18. Synthesis, Characterization and Biological Activity of an Intramolecular Stacking Zinc(Ⅱ) Complex

    GAO, Enjun; LIU, Lei; ZHU, Mingchang; WU, Qiong


    The synthesis, crystallographic analysis and spectroscopic study of a zinc(Ⅱ) complex [Zn(bipy)(pmal)(H2O)]· 2H2O (bipy=2,2'-bipyfidine, pmal=phenylmalonic acid) were carded out. The complex has been investigated by the methods of X-ray crystallography, elemental analysis and IR spectra. The binding ability of the Zn(Ⅱ) complex to calf thymus (CT-DNA) was characterized by measuring the effects on the UV spectroscopy and fluorescence spectra of DNA. The agarose gel electrophoresis experimental results suggest that the ligand planaxity of complex has a significant effect on cleaving the pBR322 plasmid DNA.

  19. Enantiomer separation by complexation SFC on immobilized Chirasil-nickel and Chirasil-zinc.

    Schurig, V; Fluck, M


    The use of complexation SFC for enantiomer separation of Lewis base selectands on chiral nickel(II)- and zinc(II)-bis[(3-heptafluorobutanoyl)-10-methylene-(1R)-camphora te] chemically bonded to poly(dimethylsiloxane) (Chirasil-nickel and Chirasil-zinc) and employed as Lewis acid selectors is described. The method is especially suited for less volatile and configurationally labile racemates. The variation of the experimental parameters temperature T, pressure p and density rho of the mobile phase carbon dioxide on the retention factor k, relative retention r and chiral separation factor alpha is studied, providing insights into the mechanisms of chiral recognition under supercritical conditions. For mecoprop methyl ester (methyl 2-(4-chloro-2-methylphenoxy)propanoate) an unusual increase of alpha at increased temperature is observed on Chirasil-nickel. Supercritical carbon dioxide does not inadvertently affect the complexation equilibria between Lewis donor selectands and the Lewis acid metal selectors during complexation SFC.

  20. Lanthanide amidinates and guanidinates in catalysis and materials science: a continuing success story.

    Edelmann, Frank T


    Today the rare-earth elements play a critical role in numerous high-tech applications. This is why various areas of rare-earth chemistry are currently thriving. In organolanthanide chemistry the search for new ligand sets which are able to satisfy the coordination requirements of the large lanthanide cations continues to be a hot topic. Among the most successful approaches in this field is the use of amidinate and guanidinate ligands of the general types [RC(NR')(2)](-) (R = H, alkyl, aryl; R' = alkyl, cycloalkyl, aryl, SiMe(3)) and [R(2)NC(NR')(2)](-) (R = alkyl, SiMe(3); R' = alkyl, cycloalkyl, aryl, SiMe(3)), which can both be regarded as steric cyclopentadienyl equivalents. Mono-, di- and trisubstituted lanthanide amidinate and guanidinate complexes are all readily available. Various rare earth amidinates and guanidinates have turned out to be very efficient homogeneous catalysts e.g. for the polymerization of olefins and dienes, the ring-opening polymerization of cyclic esters or the guanylation of amines. Moreover, certain alkyl-substituted lanthanide tris(amidinates) and tris(guanidinates) were found to be highly volatile and are thus promising precursors for ALD (= atomic layer deposition) and MOCVD (= metal-organic chemical vapor deposition) processes in materials science, e.g. for the production of lanthanide nitride thin layers. This tutorial review covers the continuing success story of lanthanide amidinates and guanidinates which have undergone an astonishing transition from mere laboratory curiosities to efficient homogeneous catalysts as well as ALD and MOCVD precursors within the past 10 years.

  1. Guanidine Soaps As Vehicles For Coating Ceramic Fibers

    Philipp, Warren H.; Veitch, Lisa C.; Jaskowiak, Martha H.


    Soaps made from strong organic base guanidine and organic fatty acids serve as vehicles and binders for coating ceramic fibers, various smooth substrates, and other problematic surfaces with thin precious-metal or metal-oxide films. Films needed to serve as barriers to diffusion in fiber/matrix ceramic composite materials. Guanidine soaps entirely organic and burn off, leaving no residues.

  2. Zinc complexes of the antibacterial drug oxolinic acid: structure and DNA-binding properties.

    Tarushi, Alketa; Psomas, George; Raptopoulou, Catherine P; Kessissoglou, Dimitris P


    The neutral mononuclear zinc complexes with the quinolone antibacterial drug oxolinic acid in the absence or presence of a nitrogen donor heterocyclic ligand 2,2'-bipyridine or 1,10-phenanthroline have been synthesized and characterized. The experimental data suggest that oxolinic acid is on deprotonated mode acting as a bidentate ligand coordinated to the metal ion through the ketone and one carboxylato oxygen atoms. The crystal structures of (chloro)(oxolinato)(2,2'-bipyridine)zinc(II), 2, and bis(oxolinato)(1,10-phenanthroline)zinc(II), 3, have been determined with X-ray crystallography. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV and fluorescence spectroscopies. UV studies of the interaction of the complexes with DNA have shown that they can bind to CT DNA and the DNA-binding constants have been calculated. Competitive studies with ethidium bromide (EB) have shown that complex 3 exhibits the ability to displace the DNA-bound EB indicating that it binds to DNA in strong competition with EB.

  3. Spectroscopic study on the photophysical properties of chlorine substituted tetraphenylporphyrinhistidine and its zinc (Ⅱ) complexes

    ZHANG Huijuan; FENG Juan; AI Xicheng; ZHANG Xingkang; YU Zhongheng; ZHANG Jianping


    The photophysical properties of ortho-Cl, meta-Cl and para-Cl substituted tetraphenylporphyrin-histidine and their zinc (Ⅱ) complexes have been studied by means of steady-state absorption and fluorescence spectroscopies, as well as time-resolved fluorescence spectroscopy. For the cases of both free-base and zinc complexes, it was found that the ortho-chlorine substitution onto the phenyl rings significantly altered the fluorescence quantum yield, the fluorescence lifetime and the ratio between radiative and nonradiative deactivation rates of the porphyrin chromophore, i.e. the photophysical parameters were quite differentfrom those of meta- and para-substi- tuted compounds. On the other hand, however, the introduction of covalently-linked histidine did not exert much effects onthe photophysical behavior of the porphyrin chromophore. The results are interpreted in terms of the steric effect and the heavy-atom effect from the chlorine atoms substituted onto the phenyl rings.

  4. Fluorescent zinc-terpyridine complex containing coordinated peroxo counter ion in aqueous medium

    S Kapoor; M S Sastry


    We describe a mixed ligand-zinc (10) complex containing coordinated peroxo ion and 2,2'2"-terpyridine and exhibiting fluorescence in the visible region (473 nm) on excitation at 390 nm in aqueous medium at room temperature. We also discuss the unusual phenomenon of enhancement of this fluorescence intensity on addition of some transition metal ions (35, 310, 40 and 39 electronic configurations).

  5. Dimerization of Human Growth Hormone by Zinc

    Cunningham, Brian C.; Mulkerrin, Michael G.; Wells, James A.


    Size-exclusion chromatography and sedimentation equilibrium studies demonstrated that zinc ion (Zn2+) induced the dimerization of human growth hormone (hGH). Scatchard analysis of 65Zn2+ binding to hGH showed that two Zn2+ ions associate per dimer of hGH in a cooperative fashion. Cobalt (II) can substitute for Zn2+ in the hormone dimer and gives a visible spectrum characteristic of cobalt coordinated in a tetrahedral fashion by oxygen- and nitrogen-containing ligands. Replacement of potential Zn2+ ligands (His18, His21, and Glu174) in hGH with alanine weakened both Zn2+ binding and hGH dimer formation. The Zn2+-hGH dimer was more stable than monomeric hGH to denaturation in guanidine-HCl. Formation of a Zn2+-hGH dimeric complex may be important for storage of hGH in secretory granules.

  6. Synthesis, characterization and biological evaluation of Rutin-zinc(II) flavonoid -metal complex.

    Ikeda, Norma Estefania Andrades; Novak, Estela Maria; Maria, Durvanei Augusto; Velosa, Adélia Segin; Pereira, Regina Mara Silva


    Synthesis of compounds analogous to natural products from secondary metabolites, such as flavonoids, is a promising source of novel drugs. Rutin (quercetin-3-O-rutinoside) is a natural flavone, which has, in its chemical structure, different sites for coordination with transition metals and the complexation with these metals enhances its biological properties. Rutin-zinc(II), a flavonoid-metal complex, was synthesized and characterized by UV-VIS, FT-IR, elemental analysis and (1)H NMR. The antioxidant and antitumor activities, as well as the cytotoxicity and in vivo toxicity of this complex were evaluated and compared with the free rutin. Rutin-zinc(II) has not shown any cytotoxicity against normal cells (fibroblasts and HUVECs) or toxicity in BALB/c mice, but has shown antioxidant activity in vitro and cytotoxicity against leukemia (KG1, K562 and Jurkat), multiple myeloma (RPMI8226) and melanoma (B16F10 and SK-Mel-28) cell lines in vitro. In Ehrlich ascites carcinoma model, Rutin-zinc(II) modulated the mitochondrial membrane potential and the expression of genes related to cell cycle progression, angiogenesis and apoptosis.

  7. Zinc complexes developed as metallopharmaceutics for treating diabetes mellitus based on the bio-medicinal inorganic chemistry.

    Yoshikawa, Yutaka; Yasui, Hiroyuki


    Biological trace metals such as iron, zinc, copper, and manganese are essential to life and health of humans, and the success of platinum drugs in the cancer chemotherapy has rapidly grown interest in developing inorganic pharmaceutical agents in medicinal chemistry, that is, medicinal inorganic chemistry, using essential elements and other biological trace metals. Transition metal complexes with unique chemical structures may be useful alternatives to the drugs available to address some of the incurable diseases. In this review, we emphasize that metal complexes are an expanding of interest in the research field of treatment of diabetes mellitus. Especially, orally active anti-diabetic and anti-metabolic syndrome zinc complexes have been developed and progressed since the discovery in 2001, where several highly potent anti-diabetic zinc complexes with different coordination structures have quite recently been disclosed, using experimental diabetic animals. In all of the complexes discussed, zinc is found to be biologically active and function by interacting with some target proteins related with diabetes mellitus. The design and screening of zinc complexes with higher activity is not efficient without consideration of the translational research. For the development of a clinically useful metallopharmaceutics, the research of zinc complexes on the long-term toxicity including side effects, clear-cut evidence of target molecule for the in vivo pharmacological action, and good pharmacokinetic property are essential in the current and future studies.

  8. Thermodynamic Complexation of Dopamine with Zinc(Ⅱ) in Media with Different Dielectric Constants



    The complexation of zinc(Ⅱ) with dopamine has been investigated by spectrophotometric measurements in mixed solvent system at an ionic strength of 0.2 mol·dm-3 sodium chloride, at (15±0.1), (25±0.1), (35±0.1 )℃ in a pH range of ca. 6 to ca. 7 with a high ratio of ligand to metal. The effect of solvent systems on protonation and complexation was discussed. Linear relationships were observed by plotting Ig K versus I/D, where K and D show stability and dielectric constants, respectively.

  9. New complexes of heteroaromatic N-oxides with europium, uranyl and zinc ions

    Zbigniew Hnatejko


    New solid complexes of europium,uranyl and zinc ions with N-oxides of 4-chloro-2,6-dimethylpyridine,quinoline and 4-methoxyquinaldinic acid in presence different anions were obtained and characterized by elemental and TG analyses,IR and luminescence spectra.The compounds are crystalline,hydrated or anhydrous salts with colours typical of metal ions.Thermal studies showed that in hydrated salts lattice or coordination water molecules are present.A role of different anions in the formation of various types of the complexes is presented.

  10. A Rac1-GDP Trimer Complex Binds Zinc with Tetrahedral and Octahedral Coordination, Displacing Magnesium

    Prehna,G.; Stebbins, E.


    The Rho family of small GTPases represent well characterized signaling molecules that regulate many cellular functions such as actin cytoskeletal arrangement and the cell cycle by acting as molecular switches. A Rac1-GDP-Zn complex has been crystallized in space group P3{sub 2}21 and its crystal structure has been solved at 1.9 {angstrom} resolution. These trigonal crystals reveal the unexpected ability of Rac1 to coordinate Zn atoms in a tetrahedral fashion by use of its biologically relevant switch I and switch II regions. Upon coordination of zinc, the switch I region is stabilized in the GDP-bound conformation and contributes to a Rac1 trimer in the asymmetric unit. Zinc coordination causes switch II to adopt a novel conformation with a symmetry-related molecule. Additionally, zinc was found to displace magnesium from its octahedral coordination at switch I, although GDP binding remained stable. This structure represents the first reported Rac1-GDP-Zn complex, which further underscores the conformational flexibility and versatility of the small GTPase switch regions.

  11. A Rac1--GDP trimer complex binds zinc with tetrahedral and octahedral coordination, displacing magnesium

    Prehna, G.; Stebbins, C


    The Rho family of small GTPases represent well characterized signaling molecules that regulate many cellular functions such as actin cytoskeletal arrangement and the cell cycle by acting as molecular switches. A Rac1-GDP-Zn complex has been crystallized in space group P3221 and its crystal structure has been solved at 1.9 {angstrom} resolution. These trigonal crystals reveal the unexpected ability of Rac1 to coordinate Zn atoms in a tetrahedral fashion by use of its biologically relevant switch I and switch II regions. Upon coordination of zinc, the switch I region is stabilized in the GDP-bound conformation and contributes to a Rac1 trimer in the asymmetric unit. Zinc coordination causes switch II to adopt a novel conformation with a symmetry-related molecule. Additionally, zinc was found to displace magnesium from its octahedral coordination at switch I, although GDP binding remained stable. This structure represents the first reported Rac1-GDP-Zn complex, which further underscores the conformational flexibility and versatility of the small GTPase switch regions.

  12. Zinc transport complexes contribute to the homeostatic maintenance of secretory pathway function in vertebrate cells.

    Ishihara, Kaori; Yamazaki, Tomohiro; Ishida, Yoko; Suzuki, Tomoyuki; Oda, Kimimitsu; Nagao, Masaya; Yamaguchi-Iwai, Yuko; Kambe, Taiho


    Zinc transporters play important roles in a wide range of biochemical processes. Here we report an important function of ZnT5/ZnT6 hetero-oligomeric complexes in the secretory pathway. The activity of human tissue-nonspecific alkaline phosphatase (ALP) expressed in ZnT5(-)ZnT7(-/-) cells was significantly reduced compared with that expressed in wild-type cells as in the case of endogenous chicken tissue-nonspecific ALP activity. The inactive human tissue-nonspecific ALP in ZnT5(-)ZnT7(-/-) cells was degraded by proteasome-mediated degradation without being trafficked to the plasma membrane. ZnT5(-)ZnT7(-/-) cells showed exacerbation of the unfolded protein response as did the wild-type cells cultured under a zinc-deficient condition, revealing that both complexes play a role in homeostatic maintenance of secretory pathway function. Furthermore, we showed that expression of ZnT5 mRNA was up-regulated by the endoplasmic reticulum stress in various cell lines. The up-regulation of the hZnT5 transcript was mediated by transcription factor XBP1 through the TGACGTGG sequence in the hZnT5 promoter, and this sequence was highly conserved in the ZnT5 genes of mouse and chicken. These results suggest that zinc transport into the secretory pathway is strictly regulated for the homeostatic maintenance of secretory pathway function in vertebrate cells.

  13. Synthesis and structures of bis-ligated zinc complexes supported by tridentate ketoimines that initiate L-lactide polymerization.

    Gerling, Kimberly A; Rezayee, Nomaan M; Rheingold, Arnold L; Green, David B; Fritsch, Joseph M


    Eight bis-ligated, homoleptic, zinc complexes were synthesized through the reaction of NNO Schiff base ketoimines bearing varying substituents with diethyl zinc in an inert atmosphere glovebox at room temperature and isolated in 62-95% yield. The complexes were characterized with (1)H, (13)C, and (19)F nuclear magnetic resonance spectroscopy, absorbance spectroscopy, high resolution mass spectrometry, elemental analysis, and single crystal X-ray crystallography. The complexes were shown to adopt distorted octahedral coordination geometry around zinc. The (1)H and (19)F NMR spectra of complexes 1-7 showed stable zinc coordination at 300 K while the effect of steric encumbrance and two trifluoromethyl groups in complex 8 was investigated with variable temperature NMR. The bis-ligated zinc complexes were effective initiators for the ring opening polymerization of L-lactide into poly-L-lactic acid (PLLA). With [L-lac]/[Zn complex] = 50, the bis-ligated zinc complexes yielded percentage conversion of 14-98% with polymerization times varying from 15-1440 min, where the longest reaction times were required when two trifluoromethyl groups were present. The addition of 4-fluorophenol co-catalyst resulted in up to a 5-fold increase in the percentage conversion in toluene solution and up to a 14-fold increase in bulk melt polymerization with reductions in the poly-dispersity index values for the isolated PLLA. Addition of 4-fluorophenol to complex 1 was studied with (1)H and (19)F NMR and appeared to yield an in situ generated zinc alkoxide complex.

  14. Coordination chemistry and reactivity of zinc complexes supported by a phosphido pincer ligand.

    D'Auria, Ilaria; Lamberti, Marina; Mazzeo, Mina; Milione, Stefano; Roviello, Giuseppina; Pellecchia, Claudio


    The preparation and characterization of new Zn(II) complexes of the type [(PPP)ZnR] in which R = Et (1) or N(SiMe(3))(2) (2) and PPP is a tridentate monoanionic phosphido ligand (PPP-H = bis(2-diphenylphosphinophenyl)phosphine) are reported. Reaction of ZnEt(2) and Zn[N(SiMe(3))(2)](2) with one equivalent of proligand PPP-H produced the corresponding tetrahedral zinc ethyl (1) and zinc amido (2) complexes in high yield. Homoleptic (PPP)(2) Zn complex 3 was obtained by reaction of the precursors with two equivalents of the proligand. Structural characterization of 1-3 was achieved by multinuclear NMR spectroscopy ((1)H, (13)C, and (31)P) and X-ray crystallography (3). Variable-temperature (1)H and (31)P NMR studies highlighted marked flexibility of the phosphido pincer ligand in coordination at the metal center. A DFT calculation on the compounds provided theoretical support for this behavior. The activities of 1 and 2 toward the ring-opening polymerization of ε-caprolactone and of L- and rac-lactide were investigated, also in combination with an alcohol as external chain-transfer agent. Polyesters with controlled molecular parameters (M(n), end groups) and low polydispersities were obtained. A DFT study on ring-opening polymerization promoted by these complexes highlighted the importance of the coordinative flexibility of the ancillary ligand to promote monomer coordination at the reactive zinc center. Preliminary investigations showed the ability of these complexes to promote copolymerization of L-lactide and ε-caprolactone to achieve random copolymers whose microstructure reproduces the composition of the monomer feed.

  15. Structural and antimicrobial properties of irradiated chitosan and its complexes with zinc

    Khan, Azam; Mehmood, Shaukat; Shafiq, Muhammad; Yasin, Tariq; Akhter, Zareen; Ahmad, Shabir


    The aim of this research was to evaluate the structural and antimicrobial properties of irradiated chitosan and its complexes with zinc. Chitosan having a molecular weight (Mη) of 220 kDa was exposed to gamma rays in dry, wet and solution forms. The chitosan-zinc complexes were prepared by varying the Mη of chitosan and Zn content. Viscometeric analysis revealed a sharp decrease in the Mη of chitosan irradiated in solution form even at lower doses compared with the dry and wet forms. X-ray diffraction patterns demonstrated variation in the crystallinity of chitosan upon exposure to gamma rays. The antibacterial response of the irradiated chitosan and its complexes against gram-positive and gram-negative bacteria demonstrated wide spectrum of effective antimicrobial activities, which increased with the dose. Additionally, the complexes exhibited excellent antifungal activity with no growth of Aspergallious fumigatus and Fusarium solani even after two weeks. These results suggested that the irradiated chitosan and its complexes with Zn can be used as antimicrobial additives for various applications.

  16. A zinc complex of heparan sulfate destabilises lysozyme and alters its conformation

    Hughes, Ashley J. [Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB (United Kingdom); Diamond Light Source Ltd., Diamond House, Didcot, Oxfordshire OX11 0DE (United Kingdom); Hussain, Rohanah [Diamond Light Source Ltd., Diamond House, Didcot, Oxfordshire OX11 0DE (United Kingdom); Cosentino, Cesare; Guerrini, Marco [Istituto di Chimica e Biochimica ' G. Ronzoni' , Via G. Colombo 81, Milano 20133 (Italy); Siligardi, Giuliano [Diamond Light Source Ltd., Diamond House, Didcot, Oxfordshire OX11 0DE (United Kingdom); Yates, Edwin A., E-mail: [Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB (United Kingdom); Rudd, Timothy R., E-mail: [Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB (United Kingdom); Istituto di Chimica e Biochimica ' G. Ronzoni' , Via G. Colombo 81, Milano 20133 (Italy)


    Highlights: Black-Right-Pointing-Pointer Zinc-heparan sulfate complex destabilises lysozyme, a model amyloid protein. Black-Right-Pointing-Pointer Addition of zinc, without heparan sulfate, stabilises lysozyme. Black-Right-Pointing-Pointer Heparan sulfate cation complexes provide alternative protein folding routes. -- Abstract: The naturally occurring anionic cell surface polysaccharide heparan sulfate is involved in key biological activities and is implicated in amyloid formation. Following addition of Zn-heparan sulfate, hen lysozyme, a model amyloid forming protein, resembled {beta}-rich amyloid by far UV circular dichroism (increased {beta}-sheet: +25%), with a significantly reduced melting temperature (from 68 to 58 Degree-Sign C) by fluorescence shift assay. Secondary structure stability of the Zn-heparan sulfate complex with lysozyme was also distinct from that with heparan sulfate, under stronger denaturation conditions using synchrotron radiation circular dichroism. Changing the cation associated with heparan sulfate is sufficient to alter the conformation and stability of complexes formed between heparan sulfate and lysozyme, substantially reducing the stability of the protein. Complexes of heparan sulfate and cations, such as Zn, which are abundant in the brain, may provide alternative folding routes for proteins.

  17. A Review of Toxicity and Use and Handling Considerations for Guanidine, Guanidine Hydrochloride, and Urea.

    Ertell, Katherine GB


    This is a technical report prepared for Oregon Sustainable Energy, LLC, under Agreement 06-19 with PNNL's Office of Small Business Programs. The request was to perform a review of the toxicity and safe handling of guanidine. The request was later amended to add urea. This report summarizes the toxicity data available in the scientific literature and provides an interpretation of the results and recommendations for handling these compounds.

  18. Possible identification of zinc-vacancy-donor-impurity complexes in zinc telluride by optically detected magnetic resonance

    Bittebierre, J.; Cox, R. T.


    Application of the optically detected magnetic resonance (ODMR) technique to donor-acceptor recombination luminescence in donor-doped ZnTe crystals shows the presence of two acceptor centers having noncubic symmetry. One of these centers, labeled At, has precisely trigonal symmetry C3. In terms of a spin Hamiltonian for an effective spin S=1/2, its g factors are gzz=2.664 and gxx=gyy~=0, where z corresponds to a direction. The other center, labeled Am, has mirror symmetry CS, with gzz=2.540 and gxx~=gyy~=0.25, where the z axis is inclined at 6.7° to in a \\{110\\} plane. The g factors are interpreted by considering the effect of a low-symmetry crystal field on a J=(3/2) (Γ8) hole in ZnTe. Hyperfine splittings of magnitude 190×10-4 cm-1 for At and 180×10-4 cm-1 for Am are observed in the ODMR spectra and attributed to interactions with three equivalent or nearly equivalent Te nuclei. Center At is observed in chlorine-doped ZnTe; center Am is observed in aluminum-doped ZnTe and is very likely the acceptor called AC, known by its bound-exciton line at 2.369 eV. It is proposed that these single-acceptor centers are double-acceptor-single-donor pairs and, more precisely, that the double-acceptor constituent is the zinc vacancy. That is, the trigonal center At is VZnClTe and the mirror-symmetry center Am is VZnAlZn. If this interpretation is correct, the electronic properties of vacancy centers in ZnTe are remarkably different from those of the well-known VZn-donor-impurity associates (the ``A centers'') in ZnSe and ZnS. Whereas the latter centers are very deep centers with large pseudo-Jahn-Teller distortions, centers At and Am in ZnTe are of shallow or intermediate depth, retain the full symmetry of the vacancy-impurity complex, and have unquenched orbital angular momentum. Finally, it is suggested that the detection of zinc-vacancy acceptors in donor-doped ZnTe may help one to understand the difficulty of producing n-type material.

  19. Lanthanide amidinates and guanidinates: from laboratory curiosities to efficient homogeneous catalysts and precursors for rare-earth oxide thin films.

    Edelmann, Frank T


    For decades, the organometallic chemistry of the rare earth elements was largely dominated by the cyclopentadienyl ligand and its ring-substituted derivatives. A hot topic in current organolanthanide chemistry is the search for alternative ligand sets which are able to satisfy the coordination requirements of the large lanthanide cations. Among the most successful approaches in this field is the use of amidinate ligands of the general type [RC(NR')(2)](-) (R = H, alkyl, aryl; R' = alkyl, cycloalkyl, aryl, SiMe(3)) which can be regarded as steric cyclopentadienyl equivalents. Closely related are the guanidinate anions of the general type [R(2)NC(NR')(2)](-) (R = alkyl, SiMe(3); R' = alkyl, cycloalkyl, aryl, SiMe(3)). Two amidinate or guanidinate ligands can coordinate to a lanthanide ion to form a metallocene-like coordination environment which allows the isolation and characterization of stable though very reactive amide, alkyl, and hydride species. Mono- and trisubstituted lanthanide amidinate and guanidinate complexes are also readily available. Various rare earth amidinates and guanidinates have turned out to be very efficient homogeneous catalysts e.g. for ring-opening polymerization reactions. Moreover, certain alkyl-substituted lanthanide tris(amidinates) and tris(guanidinates) were found to be highly volatile and could thus be promising precursors for ALD (= Atomic Layer Deposition) and MOCVD (= Metal-Organic Chemical Vapor Deposition) processes in materials science and nanotechnology. This tutorial review covers the success story of lanthanide amidinates and guanidinates and their transition from mere laboratory curiosities to efficient homogeneous catalysts as well as ALD and MOCVD precursors.

  20. Novel polystyrene-anchored zinc complex:Efficient catalyst for phenol oxidation

    Alekha Kumar Sutar a; Yasobanta Das ab; Sasmita Pattnaik a; Anita Routaray a; Nibedita Nath a; Prasanta Rath b; Tungabidya Maharana c


    The novel recyclable free -ONNO- tetradentate Schiff base ligand N,N′-bis(2-hydroxy-3-methox-ybenzaldehyde)4-methylbenzene-1,2-diamine (3-MOBdMBn) was synthesized. Complexation of this ligand with zinc (3-MOBdMBn-Zn) was performed, and the catalytic activity of the complex was evaluated. The polymer-supported analog of this complex (P-3-MOBdMBn-Zn) was synthesized, and its catalytic activity was studied. These free and polymer-anchored zinc complexes were prepared by the reactions of metal solutions with one molar equivalent of unsupported 3-MOBdMBn or P-3-MOBdMBn in methanol under nitrogen. The catalytic activity of 3-MOBdMBn-Zn and P-3-MOBdMBn-Zn was evaluated in phenol oxidation. The activity of P-3-MOBdMBn-Zn was signif-icantly affected by the polymer support, and the rate of phenol conversion was around 50%for polystyrene-supported 3-MOBdMBn. The experimental results indicated that the reaction rate was affected by the polymer support, and the rate of phenol conversion was 1.64 μmol/(L·s) in the presence of polystyrene-supported 3-MOBdMBn.

  1. PIAS1-modulated Smad2/4 complex activation is involved in zinc-induced cancer cell apoptosis.

    Yang, N; Zhao, B; Rasul, A; Qin, H; Li, J; Li, X


    Prostate cancer is one of the most frequently diagnosed cancers among men. Dietary intake of nutrients is considered crucial for preventing the initiation of events leading to the development of carcinoma. Many dietary compounds have been considered to contribute to cancer prevention including zinc, which has a pivotal role in modulating apoptosis. However, the mechanism for zinc-mediated prostate cancer chemoprevention remains enigmatic. In this study, we investigated the therapeutic effect of zinc in prostate cancer chemoprevention for the first time. Exposure to zinc induced apoptosis and resulted in transactivation of p21(WAF1/Cip1) in a Smad-dependent and p53-independent manner in prostate cancer cells. Smad2 and PIAS1 proteins were significantly upregulated resulting in dramatically increased interactions between Smad2/4 and PIAS1 in the presence of zinc in LNCaP cells. Furthermore, it was found that the zinc-induced Smad4/2/PIAS1 transcriptional complex is responsible for Smad4 binding to SBE1 and SBE3 regions within the p21(WAF1/Cip1) promoter. Exogenous expression of Smad2/4 and PIAS1 promotes zinc-induced apoptosis concomitant with Smad4 nuclear translocation, whereas endogenous Smad2/4 silencing inhibited zinc-induced apoptosis accompanying apparent p21(WAF1/Cip1) reduction. Moreover, the knockdown of PIAS1 expression attenuated the zinc-induced recruitment of Smad4 on the p21(WAF1/Cip1) promoter. The colony formation experiments demonstrate that PIAS1 and Smad2/4 silencing could attenuate zinc apoptotic effects, with a proliferation of promoting effects. We further demonstrate the correlation of apoptotic sensitivity to zinc and Smad4 and PIAS1 in multiple cancer cell lines, demonstrating that the important roles of PIAS1, Smad2, and Smad4 in zinc-induced cell death and p21(WAF1/Cip1) transactivation were common biological events in different cancer cell lines. Our results suggest a new avenue for regulation of zinc-induced apoptosis, and provide a

  2. Molecular modeling of zinc paddlewheel molecular complexes and the pores of a flexible metal organic framework.

    Alzahrani, Khalid A H; Deeth, Robert J


    A new all-atom first-principles force field (FF) is constructed for the bimetallic, four-bladed zinc paddlewheel (ZPW) motif. Zinc-ligand interactions are described via Morse functions and the angular geometry at the metal centers is modeled with a pure ligand-ligand repulsion term. The ZPW-FF is principally based on 15 DFT-optimized model systems of general formula ZnPR.nL, where ZnP is the base Zn2(O2CR)4 unit, R = H, CH3 or CF3, L = NH3 or pyridine, and n = 0, 1 or 2. It correctly generates the distorted tetrahedral coordination of the uncapped [Zn2(O2CR)4] species in their ground states as well as giving reasonable structures and energies for the higher symmetry D4h transition state conformations. The zinc-ligand Morse function reference distance, r 0 , is further refined against 30 complexes located in the Cambridge Structural Database and this FF is applied to pore models of the flexible metal-organic framework (MOF) [Zn(bdc)2(dabco)]n (bdc = 1,4-benzendicarboxylate; dabco = 1,4-diazabicyclo(2.2.2)octane). A single pore model reproduces the unit cell of the evacuated MOF system while a 3×3 grid model is necessary to provide good agreement with the observed pronounced structural changes upon adsorption of either dimethylformamide or benzene.

  3. Comparison of zinc complexation properties of dissolved organic matter from surface waters and wastewater treatment plant effluents

    CHENG Tao


    Unlike natural organic matter(NOM), wastewater organic matter(WWOM) from wastewater treatment plant effluents has not been extensively studied with respect to complexation reactions with heavy metals such as copper or zinc. In this study, organic matter from surface waters and a wastewater treatment plant effluent were concentrated by reverse osmosis(RO) method. The samples were treated in the laboratory to remove trace metals and major cations. The zinc complexing properties of both NOM and the WWOM were studied by square wave anodic stripping voltammetry(SWASV). Experimental data were compared to predictions using the Windermere Humic Aqueous Model(WHAM) Version VI. We found that the zinc binding of WWOM was much stronger than that of NOM and not well predicted by WHAM. This suggests that in natural water bodies that receive wastewater treatment plant effluents the ratio of WWOM to NOM must be taken into account in order to accurately predict free zinc activities.

  4. Electrochemical and optical characterization of cobalt, copper and zinc phthalocyanine complexes.

    Lee, Jaehyun; Kim, Se Hun; Lee, Woosung; Lee, Jiwon; An, Byeong-Kwan; Oh, Se Young; Kim, Jae Pil; Park, Jongwook


    New phthalocyanine (Pc) derivatives that include the alkyl group in ligand were synthesized based on three core metals such as zinc (Zn), copper (Cu), and cobalt (Co). Electrochemical behaviors and optical properties of the new phthalocyanine derivatives with ligand and different core metal were investigated by using cyclic voltammetry, UV-Visible (UV-Vis) spectroscopy and photoluminescence (PL) spectroscopy. In UV-Vis data, maximum values of 2H, Co, Cu, and Zn complexes were 708 nm and 677 nm, 686 nm, 684 nm, respectively.

  5. Design and synthesis of a photoswitchable guanidine catalyst

    Philipp Viehmann


    Full Text Available A novel design as well as a straight-forward synthesis for a photoswitchable guanidine catalyst is reported. Intense studies of the photochromic properties demonstrated the reversible switchability of its photosensitive azobenzene moiety. Its activity in the ring-opening polymerization (ROP of rac-lactide was investigated as well. The obtained results are discussed, and an additional guanidine was synthesized and utilized in the ROP of rac-lactide in order to explain the findings.

  6. Dipyridylamide ligand dependent dimensionality in luminescent zinc 2,4-pyridinedicarboxylate coordination complexes

    Wudkewych, Megan J.; LaDuca, Robert L.


    Zinc nitrate, 2,4-pyridinedicarboxylic acid (2,4-pdcH2), and a hydrogen-bonding capable dipyridylamide ligand were combined in aqueous solution and subjected to hydrothermal reaction conditions. Three new crystalline coordination complexes were generated; their dimensionality depends crucially on the dipyridylamide length and geometric disposition of the pyridyl nitrogen donors. The three new phases were structurally characterized via single-crystal X-ray diffraction. {[H23-pina][Zn(2,4-pdc)2(H2O)2]·H2O} (1, 3-pina = 3-pyridylisonicotinamide) is a salt with protonated dipyridylamide cations and coordination complex anions. {[Zn2(2,4-pdc)2(H2O)4(3-pna)]·3H2O}n (2, 3-pna = 3-pyridylnicotinamide) shows a system of two-fold interpenetrated ruffled (6,3) coordination polymer layers. {[Zn(2,4-pdc)(H2O)2(3-pmna)]n (3, 3-pmna = 3-pyridylmethylnicotinamide) manifests a simple 1D chain topology. Luminescence was observed for two of the zinc complexes; this behavior is attributed to π-π* or π-n molecular orbital transitions. Thermal decomposition properties of the new phases are also probed.

  7. Interaction of Small Zinc Complexes with Globular Proteins and Free Tryptophan

    Joann M. Butkus


    Full Text Available A series of eight water soluble anionic, cationic, and neutral zinc(II complexes were synthesized and characterized. The interaction of these complexes with bovine serum albumin (BSA, human serum albumin (HSA, lysozyme, and free tryptophan (Trp was investigated using steady-state fluorescence spectroscopy. Static and dynamic fluorescence quenching analysis based on Stern-Volmer kinetics was conducted, and the decrease in fluorescence intensity of the Trp residue(s can be ascribed predominantly to static quenching that occurs when the Zn complex binds to the protein and forms a nonfluorescent complex. The role played by the nature of the ligand, the metal, and complex charge in quenching Trp fluorescence was investigated. The binding association constants (Ka ranged from 104 to 1010 M−1 and indicate that complexes with planar aromatic features have the strongest affinity for globular proteins and free Trp. Complexes with nonaromatic features failed to interact with these proteins at or in the vicinity of the Trp residues. These interactions were studied over a range of temperatures, and binding was found to weaken with the increase in temperature and was exothermic with a negative change in entropy. The thermodynamic parameters suggest that binding of Zn complexes to the proteins is a highly spontaneous and favorable process.

  8. An in vitro study of interactions between insulin-mimetic zinc(II) complexes and selected plasma components.

    Enyedy, Eva Anna; Horváth, László; Gajda-Schrantz, Krisztina; Galbács, Gábor; Kiss, Tamás


    The speciations of some potent insulin-mimetic zinc(II) complexes of bidentate ligands: maltol and 1,2-dimethyl-3-hydroxypyridinone with (O,O) and picolinic acid with (N,O) coordination modes, were studied via solution equilibrium investigations of the ternary complex formation in the presence of small relevant bioligands of the blood serum such as cysteine, histidine and citric acid. Results show that formation of the ternary complexes, especially with cysteine, is favoured at physiological pH range in almost all systems studied. Besides these low molecular mass binders, serum proteins among others albumin and transferrin can bind zinc(II) or its complexes. Accordingly, the distribution of zinc(II) between the small and high molecular mass fractions of the serum was also studied by ultrafiltration. Modelling calculations relating to the distribution of zinc(II), using the stability constants of the ternary complexes studied and those of the serum proteins reported in the literature, confirmed the ultrafiltration results, namely, the primary role of albumin in zinc(II) binding among the low and high molecular mass components of the serum.

  9. Dual Effect of Curcumin-Zinc Complex in Controlling Diabetes Mellitus in Experimentally Induced Diabetic Rats.

    Al-Ali, Khalil; Abdel Fatah, Hala Salah; El-Badry, Yaser Abdel-Moemen


    Ultrasound-assisted extraction of curcumin from Curcuma longa was performed in an ultrasonic bath at 30°C using ethanol for 40 min. A successful attempt has been made to prepare curcumin-zinc (Zn) complex using a simple chemical procedure. The complex formation and its stoichiometry were characterized using elemental analysis, Fourier transform (FT)-IR and UV spectroscopy which revealed the interaction of Zn(II) ion (M) with curcumin (ligand, L) to proceed via (ML) complex type formation. Oral administration of curcumin-Zn complex at a concentration of 150 mg/kg body weight/rat/d for 45 d in streptozotocin-induced diabetic rats in comparison to curcumin and/or Zn administration exerted a hypoglycemic effect. A significant reduction in blood glucose, glycosylated hemoglobin (Hb)A1c, and lipid profile parameters with an excellent improvement in plasma insulin levels have been attained. Also, the reduced activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine in the diabetic rats treated with the complex exhibited the non-toxic nature of the curcumin-Zn complex. Finally, the larger extent of the complex in hyperglycemic improvement in comparison to curcumin and/or Zn supplementation was interpreted by its dual action on glucose and insulin maintenance.

  10. Zinc and Gold Complexes in the Treatment of Breast Cancer / Kompleksi Cinka I Zlata U Lecenju Karcinoma Dojke

    Benazic Sasa


    Full Text Available Metals are essential components in indispensable biochemical processes for living organisms. This review article highlights the metals zinc and gold in the development and treatment of breast cancer. Metal compounds off er many advantages as therapeutics due to their ability to coordinate ligands in a three-dimensional configuration. In aqueous solution, they form positively charged ions that can bind to negatively charged biological molecules. Metal complexes that contain metal ions such as zinc(II and gold have received considerable attention as potential anticancer agents. Zinc is an essential trace element that plays a critical role in a wide range of cellular processes that include structural, signalling, catalytic and regulatory functions. Zinc acts as a key structural component in many proteins and enzymes, including transcription factors, cellular signalling proteins, and DNA repair enzymes, and perturbed levels of zinc in tissues may play a role in cancer aetiology and outcome. Unlike zinc, gold is feasible as a component of compounds for effective anticancer therapy. Some progress in anticancer therapy may include interactions between zinc and gold.

  11. A comparative study on the aggregating effects of guanidine thiocyanate, guanidine hydrochloride and urea on lysozyme aggregation

    Emadi, Saeed, E-mail:; Behzadi, Maliheh


    Highlights: • Lysozyme aggregated in guanidine thiocyanate (1.0 and 2.0 M). • Lysozyme aggregated in guanidine hydrochloride (4 and 5 M). • Lysozyme did not aggregated at any concentration (0.5–5 M) of urea. • Unfolding pathway is more important than unfolding per se in aggregation. - Abstract: Protein aggregation and its subsequent deposition in different tissues culminate in a diverse range of diseases collectively known as amyloidoses. Aggregation of hen or human lysozyme depends on certain conditions, namely acidic pH or the presence of additives. In the present study, the effects on the aggregation of hen egg-white lysozyme via incubation in concentrated solutions of three different chaotropic agents namely guanidine thiocyanate, guanidine hydrochloride and urea were investigated. Here we used three different methods for the detection of the aggregates, thioflavin T fluorescence, circular dichroism spectroscopy and atomic force microscopy. Our results showed that upon incubation with different concentrations (0.5, 1.0, 2.0, 3.0, 4.0, 5.0 M) of the chemical denaturants, lysozyme was aggregated at low concentrations of guanidine thiocyanate (1.0 and 2.0 M) and at high concentrations of guanidine hydrochloride (4 and 5 M), although no fibril formation was detected. In the case of urea, no aggregation was observed at any concentration.

  12. Guanidine based vehicle/binders for use with oxides, metals and ceramics

    Philipp, Warren H. (Inventor); Weitch, Lisa C. (Inventor); Jaskowiak, Martha H. (Inventor)


    The use of guanidine salts of organic fatty acids (guanidine soaps) as vehicles and binders for coating substrate surfaces is disclosed. Being completely organic, the guanidine soaps can be burned off leaving no undesirable residue. Of special interest is the use of guanidine 2-ethyl hexanoate as the vehicle and binder for coating problematic surfaces such as in coating alumina fibers with platinum or zirconia. For this application the guanidine soap is used as a melt. For other applications the guanidine soap may be used in a solution with a variety of solvents, the solution containing chlorometalates or powdered metals, refractories or ceramics.

  13. Synthesis and Characterization of Zinc β-Diketonate Complex Extended to the Macromolecular Polymers

    Mohammed A. Al-Anber


    Full Text Available A mononuclear complex of [Zn(tta2(H2O2] (3 (tta = deprotonated of 1-thenoyl-4,4,4-trifluoro­acetone (1 has been prepared by the reaction of 1-thenoyl-4,4,4-trifluoro­acetone (H-tta: 1 with Zn(OAc2.4H2O (OAc = O2CMe in a 2:1 molar ratio. Complex 3 can be extended to form a coordination polymers of general formula [Zn(tta2(X]n (X = 4,4'-bipy (4, pz (5 by the reaction of zinc atom in 3 with s-donor ligand such as 4,4-bipyridine (4,4'-bipy and pyrazin (pz. The reaction completion was controlled via FTIR and elemental analysis.

  14. Antibacterial and Antifungal Studies on Some Schiff Base Complexes of Zinc(II).

    Joseyphus, R Selwin; Nair, M Sivasankaran


    Two Schiff base ligands L1and L2 were obtained by the condensation of glycylglycine respectively with imidazole-2-carboxaldehyde and indole-3-carboxaldehyde and their complexes with Zn(II) were prepared and characterized by microanalytical, conductivity measurement, IR, UV-Vis., XRD and SEM. The molar conductance measurement indicates that the Zn(II) complexes are 1: 1electrolytes. The IR data demonstrate the tetradentate binding of L1and tridentate binding of L2. The XRD data show that Zn(II) complexes with L1and L2 have the crystallite sizes of 53 and 61nm respectively. The surface morphology of the complexes was studied using SEM. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumaniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the disc diffusion method. A comparative study of inhibition values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. Zinc ions are proven to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium.

  15. Intracellular distribution of fluorescent copper and zinc bis(thiosemicarbazonato) complexes measured with fluorescence lifetime spectroscopy.

    Hickey, James L; James, Janine L; Henderson, Clare A; Price, Katherine A; Mot, Alexandra I; Buncic, Gojko; Crouch, Peter J; White, Jonathan M; White, Anthony R; Smith, Trevor A; Donnelly, Paul S


    The intracellular distribution of fluorescently labeled copper and zinc bis(thiosemicarbazonato) complexes was investigated in M17 neuroblastoma cells and primary cortical neurons with a view to providing insights into the neuroprotective activity of a copper bis(thiosemicarbazonato) complex known as Cu(II)(atsm). Time-resolved fluorescence measurements allowed the identification of the Cu(II) and Zn(II) complexes as well as the free ligand inside the cells by virtue of the distinct fluorescence lifetime of each species. Confocal fluorescent microscopy of cells treated with the fluorescent copper(II)bis(thiosemicarbazonato) complex revealed significant fluorescence associated with cytoplasmic puncta that were identified to be lysosomes in primary cortical neurons and both lipid droplets and lysosomes in M17 neuroblastoma cells. Fluorescence lifetime imaging microscopy confirmed that the fluorescence signal emanating from the lipid droplets could be attributed to the copper(II) complex but also that some degree of loss of the metal ion led to diffuse cytosolic fluorescence that could be attributed to the metal-free ligand. The accumulation of the copper(II) complex in lipid droplets could be relevant to the neuroprotective activity of Cu(II)(atsm) in models of amyotrophic lateral sclerosis and Parkinson's disease.

  16. Synthesis, crystal structure and luminescence properties of acenaphthene benzohydrazide based ligand and its zinc(II) complex

    Kumar, Mukesh; Roy, Soumyabrata; Faizi, Md. Serajul Haque; Kumar, Santosh; Singh, Mantu Kumar; Kishor, Shyam; Peter, Sebastian C.; John, Rohith P.


    The complex compound of zinc(II) supported by (Z)-2-hydroxy-N‧-(1-oxoacenaphthylen-2(1H) ylidene)benzohydrazide ligand (H2L1) has been reported and discussed. The reaction of zinc acetate with H2L1 ligand leads to the formation of a mononuclear zinc(ii) complex, [Zn(HL1)2H2O]. The ligand, H2L1 has been characterized by elemental analysis, 1H, 13C and 1Hsbnd COSY -NMR, IR and ESI-MS, while the complex was characterized by elemental analysis, IR, and ESI-MS. The crystal structures of the free ligand H2L1 and the complex have also been determined by single crystal X-ray diffraction. The ligand chelates with metal centre with a nitrogen atom of imino moiety and an oxygen atom of enolic group. The complex shows distorted trigonal bipyramidal geometry around the metal centre with oxygen atoms lying in the equatorial plane and imino nitrogen atoms along the axial direction. The DFT/TD-DFT calculations were performed on both the ligand and its zinc complex to get insight into the structural, electronic and optical properties. The photoluminescence, fluorescence properties of the complex have been investigated.

  17. Microwave-assisted synthesis and complexation of luminescent cyanobipyridyl-zinc(II) bis(thiolate) complexes with intrinsic and ancillary photophysical tunability.

    Bagley, Mark C; Lin, Zhifan; Pope, Simon J A


    A series of cyanobipyridine-derived zinc(II) bis(thiolate) complexes are prepared rapidly and efficiently by a microwave-assisted cross-coupling/complexation sequence and display luminescence that can be modulated using intrinsic functionality and ancillary ligands.

  18. Synthesis and antibacterial activity of cephradine metal complexes : part II complexes with cobalt, copper, zinc and cadmium.

    Sultana, Najma; Arayne, M Saeed; Afzal, M


    Cephradine, the first generation cephalosporin, is active against a wide range of Gram-positive and Gram-negative bacteria including penicillinase-producing Staphylococci. Since the presence of complexing ligand may affect the bioavailability of a metal in the blood or tissues, therefore, in order to study the probable interaction of cephradine with essential and trace elements present in human body, cephradine has been reacted with cobalt, copper, zinc and cadmium metal halides in L:M ratio of 2:1 in methanol and the products recrystallized from suitable solvents to pure crystals of consistent melting points. Infrared and ultraviolet studies of these complexes were carried out and compared with ligand. Magnetic susceptibility studies of these complexes were also carried out showing their paramagnetic behavior. From the infra red studies and elemental analysis of the complexes, it has been shown that the drug molecule serves as a bidentate ligand coordinating through both its carboxylate at C-3 and beta-lactam nitrogen and the metal having a square planar or octahedral geometry. To evaluate the changes in microbiological activity of cephradine after complexation, antibacterial studies were carried out by observing the changes in MIC (minimum inhibitory concentration) of the complexes and compared with the parent drug by measuring the zone of inhibition of complexes and compared with the parent cephalosporin against both Gram-positive and Gram-negative organisms. For MIC observation, serial dilution method was employed and zone series were determined by disk diffusion method. Our investigations reveal that formation of complexes results in decrease in antibacterial activity of cephradine and MIC values are increased.

  19. Comparison of copper and zinc in vitro bioaccessibility from cyanobacteria rich in proteins and a synthetic supplement containing gluconate complexes: LC-MS mapping of bioaccessible copper complexes.

    Wojcieszek, Justyna; Witkoś, Katarzyna; Ruzik, Lena; Pawlak, Katarzyna


    An analytical procedure was proposed to estimate bioaccessibility of copper and zinc in Spirulina Pacifica tablets with respect to that of copper and zinc in gluconate complexes. Spirulina is the common name for diet supplements produced primarily from two species of cyanobacteria, namely Arthrospira platensis and Arthrospira maxima. Spirulina tablets are an excellent source of proteins, vitamins and minerals. To obtain information about the bioavailability of these elements, an in vitro bioaccessibility test was performed by application of a two-step protocol which simulated the gastric (pepsin) and intestinal (pancreatin) digestion. The species obtained were investigated by size exclusion chromatography on a chromatograph coupled to a mass spectrometer with inductively coupled plasma (SEC-ICP-MS) and an on-capillary liquid chromatograph coupled to an electrospray mass spectrometer (μ-HPLC-ESI-MS). Both copper and zinc were found to be highly bioaccessible in Spirulina tablets (90-111%) and those containing gluconate complexes (103% for Cu and 62% for Zn). In Spirulina tablets, copper was found to form two types of complex: (1) polar ones with glycine and aspartic acid and (2) more hydrophobic ones containing amino acids with cyclic hydrocarbons (phenylalanine, histidine, proline and tyrosine). Zinc and copper were also proved to form complexes during the digestion process with products of pepsin digestion, but the stability of these complexes is lower than that of the complexes formed in Spirulina. The results proving the involvement of proteins in the enhancement of copper and zinc bioaccessibility will be useful for the design of new copper and zinc supplements.

  20. An effective approach for generating a three-Cys2His2 zinc-finger-DNA complex model by docking

    Rajasekaran M


    Full Text Available Abstract Background Determination of protein-DNA complex structures with both NMR and X-ray crystallography remains challenging in many cases. High Ambiguity-Driven DOCKing (HADDOCK is an information-driven docking program that has been used to successfully model many protein-DNA complexes. However, a protein-DNA complex model whereby the protein wraps around DNA has not been reported. Defining the ambiguous interaction restraints for the classical three-Cys2His2 zinc-finger proteins that wrap around DNA is critical because of the complicated binding geometry. In this study, we generated a Zif268-DNA complex model using three different sets of ambiguous interaction restraints (AIRs to study the effect of the geometric distribution on the docking and used this approach to generate a newly reported Sp1-DNA complex model. Results The complex models we generated on the basis of two AIRs with a good geometric distribution in each domain are reasonable in terms of the number of models with wrap-around conformation, interface root mean square deviation, AIR energy and fraction native contacts. We derived the modeling approach for generating a three-Cys2His2 zinc-finger-DNA complex model according to the results of docking studies using the Zif268-DNA and other three crystal complex structures. Furthermore, the Sp1-DNA complex model was calculated with this approach, and the interactions between Sp1 and DNA are in good agreement with those previously reported. Conclusions Our docking data demonstrate that two AIRs with a reasonable geometric distribution in each of the three-Cys2His2 zinc-finger domains are sufficient to generate an accurate complex model with protein wrapping around DNA. This approach is efficient for generating a zinc-finger protein-DNA complex model for unknown complex structures in which the protein wraps around DNA. We provide a flowchart showing the detailed procedures of this approach.

  1. Synthesis, structural characterization and biological activity of a trinuclear zinc(II) complex: DNA interaction study and antimicrobial activity

    Bhaskar Biswas; Niranjan Kole; Moumita Patra; Shampa Dutta; Mousumi Ganguly


    A trinuclear zinc(II) complex [Zn3L2(-O2CCH3)2(H2O)2]·H2O·2CH3OH (1) was synthesized from an in situ reaction between zinc acetate and a Schiff base ligand (H2L = 2-((2-hydroxyphenylimino) methyl)-6-methoxyphenol). The ligand was prepared by (1:1) condensation of ortho-vanillin and ortho-aminophenol. The ligand and zinc(II) complex were characterized by elemental analysis, Fourier Transform Infrared (FTIR), 1H-Nuclear Magnetic Resonance (NMR), UV-Vis spectroscopy, Powder X-ray Diffraction (PXRD) and thermogravimetric analysis. 1 crystallizes in P-1 space group with = 11.9241(3) Å, = 12.19746 Å, = 20.47784 Å with unit cell volume is 2674.440 (Å)3. Binding property of the complex with calf thymus DNA (CT-DNA) has been investigated using absorption and emission studies. Thermal melting and viscosity experiments were further performed to determine the mode of binding of 1 with CT-DNA. Spectroscopic and viscosity investigations revealed an intercalative binding mode of 1 with CT-DNA. The ligand and its zinc complex were screened for their biological activity against bacterial species and fungi. Activity data show that the metal complex has more antibacterial and antifungal activity than the parent Schiff base ligand and against those bacterial or fungi species.

  2. Crystal structures of three complexes of zinc chloride with tri-tert-butylphosphane

    Aaron D. Finke


    Full Text Available Under anhydrous conditions and in the absence of a Lewis-base solvent, a zinc chloride complex with tri-tert-butylphosphane as the μ-bridged dimer is formed, viz. di-μ-chlorido-bis[chloridobis(tri-tert-butylphosphanezinc], [ZnCl4(C12H27P2], (1, which features a nearly square-shaped (ZnCl2 cyclic core and whose Cl atoms interact weakly with C—H groups on the phosphane ligand. In the presence of THF, monomeric dichlorido(tetrahydrofuran-κO(tri-tert-butylphosphane-κPzinc, [ZnCl2(C4H8O(C12H27P] or [P(tBu3(THFZnCl2], (2, is formed. This slightly distorted tetrahedral Zn complex has weak C—H...Cl interactions between the Cl atoms and phosphane and THF C—H groups. Under ambient conditions, the hydrolysed complex tri-tert-butylphosphonium aquatrichloridozincate 1,2-dichloroethane monosolvate, (C12H28P[ZnCl3(H2O]·C2H4Cl2 or [HPtBu3]+ [(H2OZnCl3]−·C2H4Cl2, (3, is formed. This complex forms chains of [(H2OZnCl3]− anions from hydrogen-bonding interactions between the water H atoms and Cl atoms that propagate along the b axis.

  3. Zinc deficiency in infants and children: a review of its complex and synergistic interactions.

    Krebs, Nancy F; Miller, Leland V; Hambidge, K Michael


    Zinc deficiency is estimated to contribute to over half a million deaths per year in infants and children under 5 years of age. This paper reviews the features of mild-to-moderate zinc deficiency, which include growth faltering, deficits in immune function and altered integrity and function of the gastro-intestinal tract. Sub-clinical features include oxidative stress and a pro-inflammatory state. The homeostatic response to low dietary zinc intake by increasing absorption is limited, especially if the source of zinc is of poor bioavailability, and conservation of endogenous intestinal losses is a critical component of adaptation. Owing to low zinc intakes, older breastfed infants, especially those of low birthweight, are predictably at risk of zinc deficiency if complementary food choices are unfortified and/or low in zinc. Host factors such as young age, poor intra-uterine zinc accretion owing to poor maternal status and/or prematurity, and gastro-intestinal dysfunction also potently predispose to zinc deficiency. Environmental enteropathy, which is prevalent in low-resource settings, may substantially impair zinc absorption and/or increase endogenous losses, and thus lead to relatively high zinc requirements. Emerging evidence highlights common features between chronic inflammation and zinc deficiency, and each may exacerbate the other. More investigations of zinc homeostasis in populations in low-resource settings are needed to better quantify absorption capacity and losses. Effective preventive strategies must address potentially higher zinc requirements as well as the underlying context that perpetuates a vicious cycle of zinc deficiency and multiple adverse outcomes.

  4. Two-coordinate terminal zinc hydride complexes: synthesis, structure and preliminary reactivity studies.

    Dawkins, Michael J C; Middleton, Ewart; Kefalidis, Christos E; Dange, Deepak; Juckel, Martin M; Maron, Laurent; Jones, Cameron


    The first examples of essentially two-coordinate, monomeric zinc hydride complexes, LZnH (L = -N(Ar)(SiR3)) (Ar = C6H2{C(H)Ph2}2R'-2,6,4; R = Me, R' = Pr(i) (L'); R = Pr(i), R' = Me (L*); R = Pr(i), R' = Pr(i) (L(†))) have been prepared and shown by crystallographic studies to have near linear N-Zn-H fragments. The results of computational studies imply that any PhZn interactions in the compounds are weak at best. Preliminary reactivity studies reveal the compounds to be effective for the stoichiometric hydrozincation and catalytic hydrosilylation of carbonyl compounds.

  5. Synthesis and characterization of ZnO nanoparticles by thermal decomposition of a curcumin zinc complex

    Mutasim I. Khalil


    Full Text Available ZnO nanoparticles were generated by thermal decomposition of a binuclear zinc (II curcumin complex as single source precursor. Thermal behavior of the precursor showed a considerable weight loss at about 374 °C by an exothermic reaction with a maximum weight loss rate of 14%/min. Complete decomposition of precursor was observed within 49 min with a heating rate of 10 °C/min. Synthesized nanoparticles have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and selected area electron diffraction microscopy. Results revealed monodispersed hexagonal zincite structure with an average size of 117 ± 4 nm.

  6. Mechanochemical synthesis and in vitro anti-Helicobacter pylori and uresase inhibitory activities of novel zinc(II)-famotidine complex.

    Amin, Muhammad; Iqbal, Mohammad S; Hughes, Roy W; Khan, Safyan A; Reynolds, Paul A; Enne, Virve I; Sajjad-ur-Rahman; Mirza, Akmal S


    The mechanochemical synthesis and characterization of a zinc complex with famotidine is described. The complex was characterized by microanalysis and a number of spectroscopic techniques. The complex was of M:L dihydrate type. Derivatization of famotidine with zinc appears to enhance the activity of the drug by inhibiting the growth of Helicobacter pylori (two reference and 34 clinical isolates). The complex inhibited the growth of H. pylori in an MIC range of 1-8 microg mL(-1). The anti-H. pylori activity of the zinc-famotidine complex against antibiotic-resistant strains was nearly comparable to that of antibiotic-susceptible strains. The complex was found to be far less toxic than the parent drug, as demonstrated by its higher LD(50) value. In the human urease enzyme inhibition assay the complex exhibited significant inhibition. The new complex appears to be more useful in eradicating both the antibiotic-susceptible and antibiotic-resistant strains of H. pylori.

  7. Synthesis of guanidine from ammonium thiocyanate in solid state

    Zaia Dimas A. M.


    Full Text Available Guanidine is an important substance for modern living beings as well as for the prebiotic chemistry. We studied the reaction between ammonium and thiocyanate species in solid state with different substances (river sand, kaolin, transition metals, salts of seawater and temperatures (80, 120 and 150 ºC. The recoveries of thiocyanate and ammonium in the samples with river sand or kaolin at 150 ºC were statistically different (p<0.05 from the recoveries of thiocyanate and ammonium in the sample without them. The decomposition of ammonium thiocyanate in the samples river sand or kaolin at 150 ºC was about 40%. Kaolin showed to have more effect on the synthesis guanidine than river sand, because, the concentrations of guanidine in the samples with kaolin were always bigger than in the samples with river sand. The decomposition of ammonium thiocyanate in the samples with transition metals plus river sand at 120 ºC was about 30%. The salts of seawater or transition metals plus ammonium thiocyanate plus river sand (120 ºC showed to increase the concentration of thiourea (seawater: 538%; transition metals: 357% or guanidine (seawater: 393%, transition metals: 806% when they were compared to the samples without them. When the results obtained with sample of ammonium thiocyanate were compared to the samples of ammonium thiocyanate (at 120 ºC plus salts of seawater or transition metals also an increased on the production of thiourea (168% and guanidine (268% was obtained, respectively. The yield for the synthesis of guanidine showed in this paper is better than that obtained by other authors. Experiments showed that iron (III is involving in the formation of the yellow compound and Raman spectra showed this compound could be sulphur.

  8. Preparation and Electronic Property Investigation of Zinc(II-Schiff Base Complexes in the Confined Space

    Peng Shang


    Full Text Available Metal-Schiff base complexes have attracted continued research interest regarding their intriguing and useful features, while the electronic properties of these complexes in the confined space have not been sufficiently addressed in previous studies. In this work, a new zinc(II-Schiff base complex bis(N-dodecyl salicylideneiminatoZn(II (1 was synthesized and subsequently loaded in an inorganic solid host. A large red shift (~40 nm of the absorption onset was recorded, when the microenvironment of 1 changed from the solvent ethanol to the inorganic solid medium, evidencing the confined space effect. The marked shift of the absorption onset was associated with a band-gap reduction between the highest occupied molecular orbital (HOMO and the lowest unoccupied molecular orbital (LUMO. Theoretical calculation results showed that the confined space effect is distance dependent and exerts a more profound influence on the HOMO than the LUMO within an effective distance range. An initial study implied that the confined space effect is also accompanied with the electron density variation.

  9. Purification and characterization of a native zinc-binding high molecular weight multiprotein complex from human seminal plasma.

    Yadav, Vikash Kumar; Kumar, Vijay; Chhikara, Nirmal; Kumar, Sanjay; Manral, Pallavi; Kashav, Tara; Saini, Savita; Srinivasan, A; Singh, Sarman; Singh, Tej P; Yadav, Savita


    The seminal plasma comprises secretions from various accessory sex glands. During fertilization spermatozoa undergo complex sequences of precisely timed events that are regulated by the activation of different intracellular signaling pathways. The precision and efficacy of these pathways are often influenced by the assembly and interactions of multiprotein complexes, thereby directing the flow of regulatory information. Our knowledge about these protein complexes present in human seminal plasma (HuSP) is limited. Here we report the identification and characterization of a native high molecular weight zinc-binding multiprotein complex from HuSP by utilizing 2-DE followed by MS. Twenty-six proteins representing isoforms and/or fragments of 11 different proteins were found to be assembled in this complex. Prostate-specific antigen, zinc α2-glycoprotein, prostatic acid phosphatase, and prolactin inducible protein were the major proteins of this complex. Dynamic light scattering experiments revealed changes in aggregation pattern accompanied with deviation from physiological pH and in presence of SDS. However, no significant changes were observed in the presence of physiological ligands such as zinc and fructose. The present study will be useful and contribute to guide the future studies performed for elucidation of biological significance of this native complex in HuSP.

  10. Gastroprotection studies of Schiff base zinc (II derivative complex against acute superficial hemorrhagic mucosal lesions in rats.

    Shahram Golbabapour

    Full Text Available BACKGROUND: The study was carried out to assess the gastroprotective effect of the zinc (II complex against ethanol-induced acute hemorrhagic lesions in rats. METHODOLOGY/PRINCIPAL FINDING: The animals received their respective pre-treatments dissolved in tween 20 (5% v/v, orally. Ethanol (95% v/v was orally administrated to induce superficial hemorrhagic mucosal lesions. Omeprazole (5.790×10(-5 M/kg was used as a reference medicine. The pre-treatment with the zinc (II complex (2.181×10(-5 and 4.362×10(-5 M/kg protected the gastric mucosa similar to the reference control. They significantly increased the activity levels of nitric oxide, catalase, superoxide dismutase, glutathione and prostaglandin E2, and decreased the level of malondialdehyde. The histology assessments confirmed the protection through remarkable reduction of mucosal lesions and increased the production of gastric mucosa. Immunohistochemistry and western blot analysis indicated that the complex might induced Hsp70 up-regulation and Bax down-regulation. The complex moderately increased the gastroprotectiveness in fine fettle. The acute toxicity approved the non-toxic characteristic of the complex (<87.241×10(-5 M/kg. CONCLUSION/SIGNIFICANCE: The gastroprotective effect of the zinc (II complex was mainly through its antioxidant activity, enzymatic stimulation of prostaglandins E2, and up-regulation of Hsp70. The gastric wall mucus was also a remarkable protective mechanism.

  11. Topical erythromycin-zinc acetate complex lotion versus topical erythromycin gel in treatment of mild to moderate acne vulgaris

    Hayder R. Al-Hamamy


    Full Text Available Introduction: Topical antibiotics are the main step in the treatment of mild to moderate acne vulgaris. Erythromycin is one of the effective topical therapies for this disease. Zinc sulfate 5% solution was reported to be effective in treatment of acne vulgaris and rosacea. Aim: To compare the effectiveness and side effects of topical erythromycin in combination with zinc and erythromycin alone in treatment of mild to moderate acne vulgaris. Material and Methods: This single, blind, therapeutic, comparative study was done in the Department of Dermatology – Baghdad Teaching Hospital, Baghdad, Iraq; from May 2012 – August 2013.Scoring of acne was carried out and the patients were examined every two weeks for 10 weeks of treatment. One month after stopping drugs, patients were evaluated for drug complications and disease recurrence. Eighty patients fulfilling enrollment criteria were included in this study. Patients were divided into two groups: Group A (40 patients treated twice daily with topical erythromycin-zinc complex lotion and Group B (40 patients treated twice daily with topical 2% erythromycin gel. Results: Both topical erythromycin-zinc lotion and erythromycin gel were statistically an effective therapy starting after 6 weeks treatment and up to 4 weeks after stopping treatment. Erythromycin-zinc lotion was more effective and act earlier than erythromycin gel starting from 4 weeks of therapy till the end of treatment (after 10 week and even after 4 weeks after stopping the treatment (p value <0.0001. Conclusions: Erythromycin-zinc complex lotion was an effective and well tolerated topical therapy for mild to moderate inflammatory acne vulgaris and was more effective than erythromycin gel alone.

  12. Synthesis and characterization of heteroleptic copper and zinc complexes with saccharinate and aminoacids. Evaluation of SOD-like activity of the copper complexes.

    Santi, Eduardo; Viera, Inés; Mombrú, Alvaro; Castiglioni, Jorge; Baran, Enrique J; Torre, María H


    Five new copper and zinc heteroleptic complexes with saccharin and aminoacids with general stoichiometry Na(2)[M(sac)(2)(aa)(2)].nH(2)O (M denotes Cu or Zn, sac the saccharinate ion, and aa the aminoacids) were synthesized and characterized by elemental and thermogravimetric analysis, conductimetric measurements and IR, Raman and UV-vis spectroscopies. In all the complexes, copper and zinc ions coordinated with the aminoacids through the terminal amine and carboxylate residues and with saccharin through the heterocyclic nitrogen atom. Besides, the superoxide dismutase-like activity of the heteroleptic copper complexes was evaluated and compared with the homoleptic copper amino acid complexes with the aim to observe the influence of the saccharin coordination.

  13. Synthesis, characterization and anticancer activity of kaempferol-zinc(II) complex.

    Tu, Lv-Ying; Pi, Jiang; Jin, Hua; Cai, Ji-Ye; Deng, Sui-Ping


    According to the previous studies, the anticancer activity of flavonoids could be enhanced when they are coordinated with transition metal ions. In this work, kaempferol-zinc(II) complex (kaempferol-Zn) was synthesized and its chemical properties were characterized by UV-VIS, FT-IR, (1)H NMR, elemental analysis, electrospray mass spectrometry (ES-MS) and fluorescence spectroscopy, which showed that the synthesized complex was coordinated with a Zn(II) ion via the 3-OH and 4-oxo groups. The anticancer effects of kaempferol-Zn and free kaempferol on human oesophageal cancer cell line (EC9706) were compared. MTT results demonstrated that the killing effect of kaempferol-Zn was two times higher than that of free kaempferol. Atomic force microscopy (AFM) showed the morphological and ultrastructural changes of cellular membrane induced by kaempferol-Zn at subcellular or nanometer level. Moreover, flow cytometric analysis indicated that kaempferol-Zn could induce apoptosis in EC9706 cells by regulating intracellular calcium ions. Collectively, all the data showed that kaempferol-Zn might be served as a kind of potential anticancer agent.

  14. Guanidine-catalyzed enantioselective desymmetrization of meso-aziridines

    Zhang, Yan


    An amino-indanol derived chiral guanidine was developed as an efficient Brønsted base catalyst for the desymmetrization of meso-aziridines with both thiols and carbamodithioic acids as nucleophiles, which provided 1,2-difunctionalized ring-opened products in high yields and enantioselectivities. © The Royal Society of Chemistry.

  15. Spin interaction in octahedral zinc complexes of mono- and diradical Schiff and mannich bases.

    Orio, M; Philouze, C; Jarjayes, O; Neese, F; Thomas, F


    The four Schiff bases 2-tert-butyl-4-methoxy-6-[(pyridin-2-ylmethylimino)methyl]phenol, 2,4-di-tert-butyl-6-[(pyridin-2-ylmethylimino)methyl]phenol, 2-tert-butyl-4-methoxy-6-(quinolin-8-yliminomethyl)phenol, and 2,4-di-tert-butyl-6-(quinolin-8-yliminomethyl)phenol) as well as one Mannich base, N,N',N,N'-bis[(2-hydroxy-3,5-di-tert-butylbenzyl)(2-pyridylmethyl)]ethylenediamine, and their zinc bis-phenolate complexes 1-5, respectively, have been prepared. The complexes 4 and 5 have been characterized by X-ray diffraction crystallography, showing a zinc ion within an octahedral environment, with a cis orientation of the phenolate moieties. 1-5 exhibit in their cyclic voltammetry curves two anodic reversible waves attributable to the successive oxidation of the phenolates into phenoxyl radicals. Bulk electrolysis at ca. +0.1 V affords the zinc-coordinated monophenoxyl radical species (1(*))(+)-(5(*))(+) characterized by UV-vis absorption bands at 400-440 nm. The more stable radicals are (3(*))(+) and (4(*))(+) (half-life higher than 90 min at 298 K), likely due to the increased charge delocalization within the quinoline moieties. These species exhibit a significant additional near-IR band (epsilon > 1650 M(-1) cm(-1)) attributed to a CT transition. In the two-electron-oxidized species (1(**))(2+)-(5(**))(2+) the radical spins present a weak magnetic coupling. EPR reveals an antiferromagnetic exchange interaction for (1(**))(2+)-(4(**))(2+), whereas an unusual ferromagnetic exchange coupling is operative in (5(**))(2+). The weak magnitude of experimental |J| values (within the 1-5 cm(-1) range) as well as their sign could be well reproduced by DFT calculations at the B3LYP level. The small energy gap between the ground and the first excited spin states allows us to investigate the zero-field splitting (ZFS) of the triplet by EPR spectroscopy. This parameter is found to be axial for all systems, with |D| values of 0.0163 cm(-1) for (1(**))(2+), 0.0182 cm(-1) for (2

  16. Superiority of zinc complex of acetylsalicylic acid to acetylsalicylic acid in preventing postischemic myocardial dysfunction.

    Korkmaz, Sevil; Atmanli, Ayhan; Li, Shiliang; Radovits, Tamás; Hegedűs, Peter; Barnucz, Enikő; Hirschberg, Kristóf; Loganathan, Sivakkanan; Yoshikawa, Yutaka; Yasui, Hiroyuki; Karck, Matthias; Szabó, Gábor


    The pathophysiology of ischemic myocardial injury involves cellular events, reactive oxygen species, and an inflammatory reaction cascade. The zinc complex of acetylsalicylic acid (Zn(ASA)2) has been found to possess higher anti-inflammatory and lower ulcerogenic activities than acetylsalicylic acid (ASA). Herein, we studied the effects of both ASA and Zn(ASA)2 against acute myocardial ischemia. Rats were pretreated with ASA (75 mg/kg) or Zn(ASA)2 (100 mg/kg) orally for five consecutive days. Isoproterenol (85 mg/kg, subcutaneously [s.c.]) was applied to produce myocardial infarction. After 17-22 h, animals were anesthetized with sodium pentobarbital (60 mg/kg, intraperitoneally [i.p.]) and both electrical and mechanical parameters of cardiac function were evaluated in vivo. Myocardial histological and gene expression analyses were performed. In isoproterenol-treated rats, Zn(ASA)2 treatment normalized significantly impaired left-ventricular contractility index (Emax 2.6 ± 0.7 mmHg/µL vs. 4.6 ± 0.5 mmHg/µL, P < 0.05), increased stroke volume (30 ± 3 µL vs. 50 ± 6 µL, P < 0.05), decreased systemic vascular resistance (7.2 ± 0.7 mmHg/min/mL vs. 4.2 ± 0.5 mmHg/min/mL, P < 0.05) and reduced inflammatory infiltrate into the myocardial tissues. ECG revealed a restoration of elevated ST-segment (0.21 ± 0.03 mV vs. 0.09 ± 0.02 mV, P < 0.05) and prolonged QT-interval (79.2 ± 3.2 ms vs. 69.5 ± 2.5 ms, P < 0.05) by Zn(ASA)2. ASA treatment did not result in an improvement of these parameters. Additionally, Zn(ASA)2 significantly increased the mRNA-expression of superoxide dismutase 1 (+73 ± 15%), glutathione peroxidase 4 (+44 ± 12%), and transforming growth factor (TGF)-β1 (+102 ± 22%). In conclusion, our data demonstrate that oral administration of zinc and ASA in the form of bis(aspirinato)zinc(II) complex is superior to ASA in preventing electrical

  17. Comparison and analysis on the serum-binding characteristics of aspirin-zinc complex and aspirin.

    Zhang, Hua-Xin; Zhang, Qun; Wang, Hong-Lin; Li, Li-Wei


    This study was designed to compare the protein-binding characteristics of aspirin-zinc complex (AZN) with those of aspirin itself. AZN was synthesized and interacted with a model transport protein, human serum albumin (HSA). Three-dimensional fluorescence, ultraviolet-visible and circular dichroism (CD) spectra were used to characterize the interaction of AZN with HSA under physiological conditions. The interaction mechanism was explored using a fluorescence quenching method and thermodynamic calculation. The binding site and binding locality of AZN on HSA were demonstrated using a fluorescence probe technique and Förster non-radiation energy transfer theory. Synchronous fluorescence and CD spectra were employed to reveal the effect of AZN on the native conformation of the protein. The HSA-binding results for AZN were compared with those for aspirin under consistent experimental conditions, and indicated that aspirin acts as a guide in AZN when binding to Sudlow's site I, in subdomain IIA of the HSA molecule. Moreover, compared with aspirin, AZN showed greater observed binding constants with, but smaller changes in the α-helicity of, HSA, which proved that AZN might be easier to transport and have less toxicity in vivo. Copyright © 2017 John Wiley & Sons, Ltd.

  18. Syntheses and Structures of Blue Luminescent Zinc(Ⅱ) Complexes with 2,6-Bis(imino)pyridyl Ligands

    FAN Rui-qing; ZHU Dong-sheng; MU Ying; SU Qing


    @@ Luminescent coordination compounds with nitrogen-containing ligands have attracted much attention due to their good performance in sensor and electroluminescent device techniques[1-17]. To develop new luminescent materials, a large number of d10 metal complexes, especially zinc complexes, with the nitrogen-containing ligands have been synthesized and their luminescence behaviour have been studied[1-11]. It has been found that for a given complex, the size of the π-conjugated system of the ligand and the electronic effect of substituents at the ligand are important factors for modulating its luminescent properties[5,8,9].

  19. Synthesis and structural determination of zinc complexes based on an anilido-aldimine ligand containing an O-donor pendant arm: zinc alkoxide derivative as an efficient initiator for ring-opening polymerization of cyclic esters.

    Wang, Chao-Hsiang; Li, Chen-Yu; Huang, Bor-Hunn; Lin, Chu-Chieh; Ko, Bao-Tsan


    Zinc complexes bearing the anilido-aldiminate AA(OMe) ligand (AA(OMe)-H = (E)-2,6-diisopropyl-N-(2-(((2-methoxyethyl)imino)methyl)phenyl)aniline) were synthesized in a stepwise method and were structurally characterized. The reaction of AA(OMe)-H (1) with one equivalent of diethyl zinc (ZnEt2) furnishes a three-coordinated and mononuclear zinc complex [(AA(OMe))ZnEt] (2). Further reaction of 2 with a stoichiometric amount of benzyl alcohol (BnOH) affords a four-coordinated and dinuclear zinc benzylalkoxide complex [(AA(OMe))Zn(μ-OBn)]2 (3). In the presence of two equivalents of AA(OMe)-H with ZnEt2, a homoleptic and four-coordinated zinc complex [(AA(OMe))2Zn] (4) is formed. The geometry around the zinc centres of 3 and 4 are both distorted tetrahedrals, while 2 adopts a different coordination mode with a slightly distorted trigonal planar geometry. The variable-temperature (1)H NMR studies of 3 illustrate that 3 exhibits a dinuclear structure in solution at low temperature as well as in the solid state. While raising the temperature, it drifts towards dissociation to form a mononuclear zinc benzylalkoxide species, which coexists in solution. The ring-opening polymerizations of ε-caprolactone (ε-CL) and β-butyrolactone (β-BL) catalyzed by complexes 3 and 4 are investigated. The ε-CL and β-BL polymerizations initiated by zinc alkoxide 3 were demonstrated to have living characteristics and to proceed in a controlled manner with narrow polydispersity indices (PDIs high monomer-to-initiator ratio (1200/1) initiated by 3 has also been reported.

  20. Industrialization of New Process to Electrolysis Zinc from Zinc Chloride and Ammonia Complex%氯化锌氨络合物制锌新工艺的工业化实践

    邓良勋; 吴保庆


    用氯化铵与含氧化锌原料反应生成氯化锌氨络合物,净化后电解制取阴极锌.介绍了该流程的原理及工业试生产的有关情况.%The zinc chloride and ammonia complex was produced by reacting ammonium chloride with zinc oxide containing raw materials, after purification which was used to produce cathode zinc via electrolysis process.The principles of this process and industrialization pilot production were introduced in detail.

  1. A Metal-Amino Acid Complex-Derived Bifunctional Oxygen Electrocatalyst for Rechargeable Zinc-Air Batteries.

    Ding, Yanjun; Niu, Yuchen; Yang, Jia; Ma, Liang; Liu, Jianguo; Xiong, Yujie; Xu, Hangxun


    Bifunctional oxygen electrocatalyst: A metal-amino acid complex is developed to prepare high-performance mesoporous carbon electrocatalyst for both oxygen reduction and oxygen evolution reactions. Such prepared catalyst can be used to assemble rechargeable zinc-air batteries with excellent durability. This work represents a new route toward low-cost, highly active, and durable bifunctional electrocatalysts for cutting-edge energy conversion devices.

  2. Zinc triggers a complex transcriptional and post-transcriptional regulation of the metal homeostasis gene FRD3 in Arabidopsis relatives.

    Charlier, Jean-Benoit; Polese, Catherine; Nouet, Cécile; Carnol, Monique; Bosman, Bernard; Krämer, Ute; Motte, Patrick; Hanikenne, Marc


    In Arabidopsis thaliana, FRD3 (FERRIC CHELATE REDUCTASE DEFECTIVE 3) plays a central role in metal homeostasis. FRD3 is among a set of metal homeostasis genes that are constitutively highly expressed in roots and shoots of Arabidopsis halleri, a zinc hyperaccumulating and hypertolerant species. Here, we examined the regulation of FRD3 by zinc in both species to shed light on the evolutionary processes underlying the evolution of hyperaccumulation in A. halleri. We combined gene expression studies with the use of β-glucuronidase and green fluorescent protein reporter constructs to compare the expression profile and transcriptional and post-transcriptional regulation of FRD3 in both species. The AtFRD3 and AhFRD3 genes displayed a conserved expression profile. In A. thaliana, alternative transcription initiation sites from two promoters determined transcript variants that were differentially regulated by zinc supply in roots and shoots to favour the most highly translated variant under zinc-excess conditions. In A. halleri, a single transcript variant with higher transcript stability and enhanced translation has been maintained. The FRD3 gene thus undergoes complex transcriptional and post-transcriptional regulation in Arabidopsis relatives. Our study reveals that a diverse set of mechanisms underlie increased gene dosage in the A. halleri lineage and illustrates how an environmental challenge can alter gene regulation. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  3. Synthesis, crystal structure and spectroscopic properties of a supramolecular zinc(II) complex with N2O2 coordination sphere.

    Dong, Wen-Kui; Zhang, Li-Sha; Sun, Yin-Xia; Zhao, Meng-Meng; Li, Gang; Dong, Xiu-Yan


    A new hexa-coordinated zinc(II) complex, namely [ZnL(H2O)2]n, with N2O2 coordination sphere (H2L=4,4'-dibromo-6,6'-dichloro-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol) has been synthesized and structurally characterized by elemental analyses, IR, UV-vis spectra and TG-DTA analyses, etc. Crystallographic data are monoclinic, space group P2(1)/c, a=24.634(2)Å, b=10.144(1)Å, c=7.9351(6)Å, β=91.371(2)°, V=1982.4(3)Å(3), Dc=2.099 g/cm(3), Z=4. The zinc(II) complex exhibits a slightly distorted octahedral geometry with halogen-substituted Salen-type bisoxime forming the basal N2O2 coordination sphere and two oxygen atoms from two coordinated water molecules in the axial position. The hydrogen-bonding and π-π stacking interactions have stabilized the zinc(II) complex molecules to form a self-assembling infinite dual metal-water chain-like structure with the nearest Zn⋯Zn distance of 4.954(4)Å.

  4. Main group chemistry of 9-hydroxophenalenone: Syntheses and structural characterization of the alkaline earth and zinc complexes

    Arup Mukherjee; Prinson P Samuel; Carola Schulzke; Swadhin K Mandal


    Herein, we report the synthesis and characterization of 9-hydroxophenalenone based alkaline earth and zinc complexes.The reaction of 9-hydroxophenalenone (HO,O-PLY (1)) with one equivalent of KN(SiMe3)2 and MI2 in THF yields heteroleptic complexes [(O,O-PLY)M(THF)]I [M= Mg (2), Ca (3), Sr (4), Ba (5); n = 1-4], while use of two equivalents of KN(SiMe3)2 in THF (with respect to PLY) produces homoleptic complex (O,O-PLY)2Mg(THF)2 (6). Moreover, reaction between two equivalents of 1 with one equivalent of ZnMe2 in THF produces complex (O,O-PLY)2Zn(THF)2 (7). All these complexes were characterized by NMR spectroscopy and elemental analyses. The solid state structures of complexes 2, 6 and 7 were established by single crystal X-ray diffraction analysis.

  5. Synthesis and crystal structure of 5-(4'-carboxyphenyl)-10,15,20-tri(4¢-t-butylphenyl)porphinato zinc(II) complex

    P Bhyrappa; C Arunkumar; J J Vittal


    Synthesis and crystal structure of 5-(4'-carboxyphenyl)-10,15,20-tri(4'--butylphenyl)porphinato zinc(II) have been presented. The title complex shows interesting hydrogen-bonded dimeric structure in the solid state.

  6. Silica-grafted diethylzinc and a silsesquioxane-based zinc alkyl complex as catalysts for the alternating oxirane-carbon dioxide copolymerization

    Duchateau, Robbert; van Meerendonkt, Wouter J.; Huijser, Saskia; Staal, Bastiaan B. P.; van Schilt, Marcus A.; Gerritsen, Gijsbert; Meetsma, Auke; Koning, Cor E.; Kemmere, Maartje F.; Keurentjes, Jos T. F.


    A novel zinc silsesquioxane complex ([(c-C5H9)(7)Si7O11(OSiMePh2)](2)Zn4Me4 (1)) has been used as a model compound for silica-grafted zinc catalysts in the copolymerization of cyclohexene oxide and CO2. Complex 1 exists as a dimer in the solid state and is moderately active in the copolymerization,

  7. Synthesis of substituted guanidines using Zn-Al hydrotalcite catalyst

    Lakshmi Kantam Mannepalli; Venkanna Dupati; Swarna Jaya Vallabha; Manorama Sunkara V


    Substituted guanidines were synthesized by the guanylation of amines with carbodiimides using Zn-Al hydrotalcite (Zn-Al HT) catalyst. Zn-Al HT was prepared by co-precipitation method and characterized by X-ray powder diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman and Thermogravimetric-Differential Thermal Analysis (TG-DTA). The heterogeneous catalyst afforded moderate to good yields (∼ 50-60 %) of substituted guanidines in toluene at 110°C in 12 h. The catalyst was recovered quantitatively by simple filtration and reused for three cycles with consistent activity. The XRD and FTIR studies of the used catalyst shows no variation in the structure of the catalyst even after three recycles.

  8. Synthesis of guanidine from ammonium thiocyanate in solid state

    Zaia Dimas A. M.; Santana Henrique de; Toppan Rodrigo; Zaia Cássia T. B. V.


    Guanidine is an important substance for modern living beings as well as for the prebiotic chemistry. We studied the reaction between ammonium and thiocyanate species in solid state with different substances (river sand, kaolin, transition metals, salts of seawater) and temperatures (80, 120 and 150 ºC). The recoveries of thiocyanate and ammonium in the samples with river sand or kaolin at 150 ºC were statistically different (p

  9. Trifluoroacetyl as an orthogonal protecting group for guanidines.

    Bartoli, Sandra; Jensen, Kim B; Kilburn, Jeremy D


    The trifluoroacetyl moiety has been used as a new protecting group for guanidine functionality. The protecting group is easily cleaved under mild basic conditions and is complementary to the Boc, Cbz, and Ddpe protecting groups. The protecting group can be applied to peptide synthesis in solution as well as on a solid phase as it is orthogonal to a Boc and Cbz strategy and semiorthogonal to an Fmoc strategy.

  10. Complexation of zinc in organic soils--EXAFS evidence for sulfur associations.

    Karlsson, Torbjörn; Skyllberg, Ulf


    Even if it is generally accepted that associations with natural organic matter (NOM) to a great extent determine the bioavailability and mobility of trace metals in soils and waters, the knowledge about the identity of NOM functional groups involved is still limited. In this study, extended X-ray absorption fine structure (EXAFS) spectroscopy was used to determine the coordination chemistry of zinc (Zn) in two organic soils (500-10,000 microg Zn g(-), pH 5.6-7.3). In both soils Zn was coordinated by a mixture of oxygen/nitrogen (O/N) and sulfur (S) ligands in the first coordination shell. In average, 0.4-0.9 S atoms were located at a distance of 2.29-2.33 angstom, well in agreement with a 4-fold coordination with thiolates (RS-) in proteins. In addition 2.7-3.7 O/N atoms were located at 1.99-2.04 angstrom. The improved merit of fit by inclusion of S atoms was shown to be significant after adjusting for the improvement caused merely by increasing the number of fitting parameters. Two second shell Zn-C distances were used in our model: 3.0-4.2 carbon (C) atoms, associated to first shell O/N, were encountered at an average distance of 2.84 amgstrom, and 0.4-0.9 C atoms, associated to first shell S, were encountered at an average distance of 3.32 angstrom. These Zn-C distances are well in agreement with distances determined in well-defined organic molecules. It is concluded that Zn forms mainly inner-sphere complexes with a mixture of 4-fold coordination with S and O/N ligands and 6-fold coordination with O ligands in organic soils.

  11. Synthesis, characterization and thermal behavior of antibacterial and antifungal active zinc complexes of bis (3(4-dimethylaminophenyl)-allylidene-1,2-diaminoethane

    Montazerozohori, Morteza, E-mail: [Department of Chemistry, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Zahedi, Saeedeh [Department of Chemistry, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Naghiha, Asghar [Department of Animal Sciences, Faculty of Agriculture, Yasouj University, Yasouj (Iran, Islamic Republic of); Zohour, Mostafa Montazer [Genetics of Non-Communicable Disease Research Center, Zahedan University of Medical Sciences, Zahedan (Iran, Islamic Republic of)


    In this work, synthesis of a new series of zinc halide/pseudohalide complexes of a bidentate Schiff base ligand entitled as bis (3-(4-dimethylaminophenyl)-allylidene)-1,2-diaminoethane(L) is described. The ligand and its zinc complexes were characterized by various techniques such as elemental analysis, FT-IR, UV–visible, {sup 1}H and {sup 13}C NMR spectra, cyclic voltammetry, and conductometry. Accordingly ZnLX{sub 2} (X = Cl{sup −}, Br{sup −}, I{sup −}, SCN{sup −} and N{sub 3}{sup −}) was suggested as molecular formula of the complexes. Redox behaviors of ligand and its zinc complexes were investigated by cyclic voltammetry method. Furthermore, the ligand and its zinc halide/pseudohalide complexes were tested for their in vitro antibacterial activities against two gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two gram negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Also in vitro antifungal activities of them against Candida albicans and Aspergillus niger were investigated. The results indicated that all compounds are antibacterial and antifungal active. Thermal behaviors of ligand and its zinc complexes were studied from room temperature to 1100 °C under argon atmosphere. It was found that the ligand and zinc iodide are decomposed completely via three and four steps respectively while other zinc complexes leave out the metal or organometallic compounds as final residuals after 3–4 decomposition steps at above temperature range. Moreover evaluation of some thermo-kinetic parameters such as activation energy (∆E{sup ⁎}), enthalpy (∆H{sup ⁎}), entropy (∆S{sup ⁎}) and Gibbs free energy change (∆G{sup ⁎}) of the thermal decomposition steps were performed based on the Coats–Redfern relation. - Highlights: • Some novel complexes of Zn(II) with a bidentate Schiff base ligand have been synthesized. • Redox behavior of ligand and zinc complexes was investigated by cyclic voltammetry. • The

  12. Oral administration of Bis(aspirinato)zinc(II) complex ameliorates hyperglycemia and metabolic syndrome-like disorders in spontaneously diabetic KK-A(y) mice: structure-activity relationship on zinc-salicylate complexes.

    Yoshikawa, Yutaka; Adachi, Yusuke; Yasui, Hiroyuki; Hattori, Masakazu; Sakurai, Hiromu


    In recent years, the number of patients suffering from diseases, such as cancer, apoplexy, osteoporosis, hypertension, and type 2 diabetes mellitus is increasing worldwide. Type 2 diabetes, a lifestyle-related disease, is recognized as a serious disease. Various types of pharmaceutics for diabetes have been used. Since the relationship between diabetes and biometals such as vanadium, copper, and zinc ions has been recognized for many years, we have been developing the anti-diabetic metal complexes as new candidates. We found that several zinc(II) (Zn) complexes exhibit glucose-lowering activity for treating type 2 diabetes. High doses of salicylates have been known to reverse hyperglycemia and hyperinsulinemia in type 2 diabetic patients. These findings strongly suggest that the combined use of Zn and salicylates achieves the synergism in treating type 2 diabetes. Because aspirin, acetyl salicylic acid, has a chelating ability, we used it as a ligand to Zn. Several Zn-salicylate complexes were prepared and their biological activities were examined in this study. The complexes with an electron-withdrawing group in the ligand exhibited higher in vitro insulinomimetic activity than those of Zn complexes with an electron-donating group in the ligand. When bis(aspirinato)Zn (Zn(asp)₂) complex was orally administered on KK-A(y) mice with hereditary type 2 diabetes, the diabetic state was improved. In addition, this complex exhibited normalizing effects on serum adiponectin level and high blood pressure in metabolic syndrome. In conclusion, Zn(asp)₂ complex is newly proposed as a potent anti-diabetic and anti-metabolic syndrome agent.

  13. Designing ancillary ligands for heteroleptic/homoleptic zinc complex formation: synthesis, structures and application in ROP of lactides.

    Jędrzkiewicz, D; Ejfler, J; Gulia, N; John, Ł; Szafert, S


    Synthesis and characterization of a series of new amino-phenol/naphthol ligands (L(1,2)-H) have been developed and their respective zinc complexes ( 1 and 2-Zn ) have been synthesized. The molecular structures of L(1)-H and 1, 2-Zn were explored in detail by NMR, single-crystal X-ray studies and DFT calculations, which confirmed the existence of complexes as stabile dimers both in a solution and in the solid state. All complexes mediate the ring-opening polymerization (ROP) of lactide highly efficiently, at room temperature, in a controlled fashion. The influence of the architecture of the ligand on the desired homo/heteroleptic complex formation, as well as the relationship between the initiator design and the catalytic activity have been investigated.

  14. Highly microporous carbons derived from a complex of glutamic acid and zinc chloride for use in supercapacitors

    Dong, Xiao-Ling; Lu, An-Hui; He, Bin; Li, Wen-Cui


    The selection of carbon precursor is an important factor when designing carbon materials. In this study, a complex derived from L-glutamic acid and zinc chloride was used to prepare highly microporous carbons via facile pyrolysis. L-glutamic acid, a new carbon precursor with nitrogen functionality, coordinated with zinc chloride resulted in a homogeneous distribution of Zn2+ on the molecular level. During pyrolysis, the evaporation of the in situ formed zinc species creates an abundance of micropores together with the inert gases. The obtained carbons exhibit high specific surface area (SBET: 1203 m2 g-1) and a rich nitrogen content (4.52 wt%). In excess of 89% of the pore volume consists of micropores with pore size ranging from 0.5 to 1.2 nm. These carbons have been shown to be suitable for use as supercapacitor electrodes, and have been tested in 6 M KOH where a capacitance of 217 F g-1 was achieved at a current density of 0.5 A g-1. A long cycling life of 30 000 cycles was achieved at a current density of 1 A g-1, with only a 9% loss in capacity. The leakage current through a two-electrode device was measured as 2.3 μA per mg of electrode and the self-discharge characteristics were minimal.

  15. Synthesis, characterization and thermal behavior of antibacterial and antifungal active zinc complexes of bis (3(4-dimethylaminophenyl)-allylidene-1,2-diaminoethane.

    Montazerozohori, Morteza; Zahedi, Saeedeh; Naghiha, Asghar; Zohour, Mostafa Montazer


    In this work, synthesis of a new series of zinc halide/pseudohalide complexes of a bidentate Schiff base ligand entitled as bis (3-(4-dimethylaminophenyl)-allylidene)-1,2-diaminoethane(L) is described. The ligand and its zinc complexes were characterized by various techniques such as elemental analysis, FT-IR, UV-visible, (1)H and (13)C NMR spectra, cyclic voltammetry, and conductometry. Accordingly ZnLX2 (X=Cl(-), Br(-), I(-), SCN(-) and N3(-)) was suggested as molecular formula of the complexes. Redox behaviors of ligand and its zinc complexes were investigated by cyclic voltammetry method. Furthermore, the ligand and its zinc halide/pseudohalide complexes were tested for their in vitro antibacterial activities against two gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two gram negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Also in vitro antifungal activities of them against Candida albicans and Aspergillus niger were investigated. The results indicated that all compounds are antibacterial and antifungal active. Thermal behaviors of ligand and its zinc complexes were studied from room temperature to 1100 °C under argon atmosphere. It was found that the ligand and zinc iodide are decomposed completely via three and four steps respectively while other zinc complexes leave out the metal or organometallic compounds as final residuals after 3-4 decomposition steps at above temperature range. Moreover evaluation of some thermo-kinetic parameters such as activation energy (∆E*), enthalpy (∆H*), entropy (∆S*) and Gibbs free energy change (∆G*) of the thermal decomposition steps were performed based on the Coats-Redfern relation.

  16. New dinuclear copper(II) and zinc(II) complexes for the investigation of sugar-metal ion interactions.

    Bera, Manindranath; Patra, Ayan


    We have studied the binding interactions of biologically important carbohydrates (D-glucose, D-xylose and D-mannose) with the newly synthesized five-coordinate dinuclear copper(II) complex, [Cu(2)(hpnbpda)(μ-OAc)] (1) and zinc(II) complex, [Zn(2)(hpnbpda)(μ-OAc)] (2) [H(3)hpnbpda=N,N'-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N'-diacetic acid] in aqueous alkaline solution. The complexes 1 and 2 are fully characterized both in solid and solution using different analytical techniques. A geometrical optimization was made of the ligand H(3)hpnbpda and the complexes 1 and 2 by molecular mechanics (MM+) method in order to establish the stable conformations. All carbohydrates bind to the metal complexes in a 1:1 molar ratio. The binding events have been investigated by a combined approach of FTIR, UV-vis and (13)C NMR spectroscopic techniques. UV-vis spectra indicate a significant blue shift of the absorption maximum of complex 1 during carbohydrate coordination highlighting the sugar binding ability of complex 1. The apparent binding constants of the substrate-bound copper(II) complexes have been determined from the UV-vis titration experiments. The binding ability and mode of binding of these sugar substrates with complex 2 are indicated by their characteristic coordination induced shift (CIS) values in (13)C NMR spectra for carbon atoms C1, C2, and C3 of sugar substrates.

  17. A spectrophotometric method for the determination of zinc, copper, and cobalt ions in metalloproteins using Zincon.

    Säbel, Crystal E; Neureuther, Joseph M; Siemann, Stefan


    Zincon (2-carboxy-2'-hydroxy-5'-sulfoformazylbenzene) has long been known as an excellent colorimetric reagent for the detection of zinc and copper ions in aqueous solution. To extend the chelator's versatility to the quantification of metal ions in metalloproteins, the spectral properties of Zincon and its complexes with Zn(2+), Cu(2+), and Co(2+) were investigated in the presence of guanidine hydrochloride and urea, two common denaturants used to labilize metal ions in proteins. These studies revealed the detection of metals to be generally more sensitive with urea. In addition, pH profiles recorded for these metals indicated the optimal pH for complex formation and stability to be 9.0. As a consequence, an optimized method that allows the facile determination of Zn(2+), Cu(2+), and Co(2+) with detection limits in the high nanomolar range is presented. Furthermore, a simple two-step procedure for the quantification of both Zn(2+) and Cu(2+) within the same sample is described. Using the prototypical Cu(2+)/Zn(2+)-protein superoxide dismutase as an example, the effectiveness of this method of dual metal quantification in metalloproteins is demonstrated. Thus, the spectrophotometric determination of metal ions with Zincon can be exploited as a rapid and inexpensive means of assessing the metal contents of zinc-, copper-, cobalt-, and zinc/copper-containing proteins.

  18. Synthesis and Crystal Structure of Zinc(Ⅱ) Complex with Isonicotinate Containing a Three-dimensional Hydrogen-bond Network


    A zinc complex, [Zn(iso)2(H2O)4](iso=C6H4NO2-), was synthesized and characterized by elemental analysis, thermal analysis and IR spectrum studies. The crystal structure of the complex was determined by X-ray diffraction. The crystal crystallizes in the triclinic system, molecular formula ZnC12H16N2Os, Mr=381.64, space group P1 with a = 6.338(1 ), b =6.919(1), c=9.277(1), a =96.28(1),β =104.91(1 ),γ =112.85(1)°, V=352.12(9)A3, Z=1, Dc=l.80g·cm-3 and F(000)=196, μ =l.791mm-1. The crystal structure was solved by direct methods for final R=0.0204 and Rw=0.0542 for 1258 observed reflections with [Fo>4 σ (Fo)]. The crystal structure reveals that zinc ion is trans-octahedral with two pyridyl nitrogens and two aque oxygens at the equational positions and two aqua oxygens at the axial positions. The complex forms a three-dimensional network through intermolecular hydrogen bonds.

  19. Spectral and Electroluminescent Properties of Binuclear Zinc Complexes with Halogen-Substituted Derivatives of 1,2,4-Triazole

    Kopylova, T. N.; Degtyarenko, K. M.; Samsonova, L. G.; Gadirov, R. M.; Gusev, A. N.; Shul'gin, V. F.; Meshkova, S. B.


    Spectral properties of binuclear zinc complexes in chloroform solutions and polyvinylcarbazole (PVC) films are investigated. It is demonstrated that incorporation of a halogen atom (chlorine or bromine) in a ligand benzene ring leads to a small shift of the spectrum toward the red region and a reduction of the fluorescence quantum yield. The fluorescence and phosphorescence spectra at T = 77K are investigated. The fluorescence undergoes a blue shift of about 30 nm and multiply increases in the intensity, and the phosphorescence is observed at 540-580 nm. The phosphorescence lifetime is estimated. The electroluminescent properties of metal complexes in structures with thermal vacuum spin coating of complexes and in PVC films are investigated.

  20. Recommended Guanidine Suppressor for the Next-Generation Caustic-Side Solvent Extraction Process

    Moyer, Bruce A [ORNL; Delmau, Laetitia Helene [ORNL; Duncan, Nathan C [ORNL; Ensor, Dale [Tennessee Technological University; Hill, Talon G [ORNL; Lee, Denise L [ORNL; Roach, Benjamin D [ORNL; Sloop Jr, Frederick {Fred} V [ORNL; Williams, Neil J [ORNL


    The guanidine recommended for the Next-Generation Caustic-Side is N,N ,N -tris(3,7-dimethyloctyl)guanidine (TiDG). Systematic testing has shown that it is significantly more lipophilic than the previously recommended guanidine DCiTG, the active extractant in the commercial guanidine product LIX -79, while not otherwise changing the solvent performance. Previous testing indicated that the extent of partitioning of the DCiTG suppressor to the aqueous strip solution is significantly greater than expected, potentially leading to rapid depletion of the suppressor from the solvent and unwanted organic concentrations in process effluents. Five candidate guanidines were tested as potential replacements for DCiTG. The tests included batch extraction with simulated waste and flowsheet solutions, third-phase formation, emulsion formation, and partition ratios of the guanidine between the solvent and aqueous strip solution. Preliminary results of a thermal stability test of the TiDG solvent at one month duration indicated performance approximately equivalent to DCiTG. Two of the guanidines proved adequate in all respects, and the choice of TiDG was deemed slightly preferable vs the next best guanidine BiTABG.

  1. Synthesis of bicyclic guanidines via cascade hydroamination/Michael additions of mono-N-acryloylpropargylguanidines.

    Kwon, Ki-Hyeok; Serrano, Catherine M; Koch, Michael; Barrows, Louis R; Looper, Ryan E


    A cascade silver(I)-catalyzed hydroamination/Michael addition sequence has been developed to deliver highly substituted bicyclic guanidines. This transformation gives rise to geometrically and constitutionally stable ene-guanidines and generates a remote stereocenter with moderate to high diastereoselectivity.

  2. New nanocomposites based on layered aluminosilicate and guanidine containing polyelectrolytes

    Khashirov, Azamat A.; Zhansitov, Azamat A.; Khashirova, Svetlana Yu. [Kabardino-Balkarian State University a. Kh.M. Berbekov, 173 Chernyshevskogo st., 360004, Nalchik (Russian Federation); Zaikov, Genadiy E. [N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 4, Kosygin St., 119991, Moscow (Russian Federation)


    The new functional nanomaterials based on layered aluminosilicate and guanidine containing polyelectrolytes combining high bactericidal activity with an increased ability to bind to heavy metals and organic pollutants were received. To prove the chemical structure of the model compounds (zwitterionic delocalized resonance structures AG/MAG and PAG/PMAG), as well as the presence of such structures in nanocomposites received on their basis and the MMT, IR, {sup 1}H NMR spectroscopy, X-ray diffraction studies and nanoindentation/sclerometry followed by scanning the surface in the area of the indentation were used.

  3. Syntheses, structural variations and fluorescence studies of two dinuclear zinc(II) complexes of a Schiff base ligand with an extended carboxylate side arm

    Shit, Shyamapada; Sasmal, Ashok; Dhal, Piu; Rizzoli, Corrado; Mitra, Samiran


    A potentially tetradentate Schiff base ligand containing carboxylic acid group, HL, (E)-2-((pyridin-2-yl)methyleneamino)-5-chlorobenzoic acid is synthesized and characterized. Reaction of HL with hydrated zinc(II) trichloroacetate and zinc(II) trifluoroacetate under similar reaction condition yields two discrete dinuclear complexes, [Zn(L)(Cl)]2 (1) and [Zn(L)(CF3COO)]2 (2) and characterized by different physicochemical methods. Single crystal X-ray structural characterization reveals different ligating properties of the coordinated anionic ligand (L-) in its zinc(II) complexes. The side arm carboxylate of L- shows μ1,3-carboxylato-bridging mode in 1 and connects zinc(II) atoms in syn-anti fashion while it exhibits a μ1,1-carboxylato-bridging mode in 2. The metal ions display distorted square pyramidal geometries in both the structures and associated with different degrees of distortions. The fluorescence spectra of HL and its zinc(II) complexes recorded in methanol at room temperature which reveal the enhancement of emission intensity for the complexes compared to that of the free ligand. Thermogravimetric analyses (TGA) reveal high thermal stabilities of the complexes.

  4. Zinc-prolinamide complex catalyzed direct asymmetric aldol reactions in the presence of water


    An efficient direct asymmetric aldol reaction with zinc triflate and prolinamides as combined catalysts is reported.A series of chiral prolinamides have been designed and used in the direct aldol reaction resulting in the desired products with excellent yields(up to 94% yield) and high enantioselectivities(up to 96% ee).Water was found to play a significant role in the formation of the aldol products,which suggests a new strategy in the design of new organic catalysts.

  5. The complex interface chemistry of thin-film silicon/zinc oxide solar cell structures.

    Gerlach, D; Wimmer, M; Wilks, R G; Félix, R; Kronast, F; Ruske, F; Bär, M


    The interface between solid-phase crystallized phosphorous-doped polycrystalline silicon (poly-Si(n(+))) and aluminum-doped zinc oxide (ZnO:Al) was investigated using spatially resolved photoelectron emission microscopy. We find the accumulation of aluminum in the proximity of the interface. Based on a detailed photoemission line analysis, we also suggest the formation of an interface species. Silicon suboxide and/or dehydrated hemimorphite have been identified as likely candidates. For each scenario a detailed chemical reaction pathway is suggested. The chemical instability of the poly-Si(n(+))/ZnO:Al interface is explained by the fact that SiO2 is more stable than ZnO and/or that H2 is released from the initially deposited a-Si:H during the crystallization process. As a result, Zn (a deep acceptor in silicon) is "liberated" close to the silicon/zinc oxide interface presenting the inherent risk of forming deep defects in the silicon absorber. These could act as recombination centers and thus limit the performance of silicon/zinc oxide based solar cells. Based on this insight some recommendations with respect to solar cell design, material selection, and process parameters are given for further knowledge-based thin-film silicon device optimization.

  6. Effect of glucosamine conjugation to zinc(II) complexes of a bis-pyrazole ligand: syntheses, characterization and anticancer activity.

    Bhattacharyya, Sudipta; Sarkar, Amrita; Dey, Suman Kr; Mukherjee, Arindam


    The bis(3,5-dimethyl-1H- pyrazol-1yl)acetic acid (bdmpza) ligand was conjugated with tert-butyl-N-(2-aminoethyl) carbonate, methyl-2-amino-4-(methylthio)butanoate and 1,3,4,6-tetra-O-acetyl-β-d-glucosamine hydrochloride via amide coupling method to form three ligands L1-L3 which were then reacted with Zn(II) salts to form four zinc complexes (1-4). The complexes were characterized by (1)H NMR, (13)C NMR, electrospray ionization mass spectrometry (ESI-MS), FT-IR, CHN analyses. Complexes 1, 2 and 4 were also characterized by single crystal X-ray diffraction. It was found that Zn(II) salts could selectively remove the acetyl group from anomeric position leaving everything else intact. The cytotoxicity studies of the ligand and the complexes showed that the conjugation to acetylated glucosamine enhances cytotoxic ability although the complexes become more hydrophilic. Cytotoxicity studies in human breast adenocarcinoma (MCF-7), human cervical cancer (HeLa WT) and human lung adenocarcinoma (A549) showed that the acetylated glucosamine conjugation to the bis-pyrazole ligated Zn(II) complex led to 2-4 fold increase in cytotoxicity (IC50 values ca. 57-80μM) against HeLa WT and MCF-7 cell lines. The Zn(II) complex bearing the acetylated glucosamine inhibits the cell cycle in the G2/M phase of MCF-7 cell line. ICP-MS data shows more accumulation of Zn(II) inside the cell upon use of complex 4 as compared to Zn(II) salts or the other presented complexes. Further studies suggest that the mitochondrial transmembrane potential changes in the presence of complex 4 and caspase-7 is activated by Zn(II) salts but the activation is much more by complex 4 and hence there is apoptosis and dose dependent chromatin condensation/nuclear fragmentation as observed by microscopy.

  7. Synthesis and DNA cleavage activities of mononuclear macrocyclic polyamine zinc(II), copper(II), cobalt(II) complexes which linked with uracil.

    Wang, Xiao-Yan; Zhang, Ji; Li, Kun; Jiang, Ning; Chen, Shan-Yong; Lin, Hong-Hui; Huang, Yu; Ma, Li-Jian; Yu, Xiao-Qi


    Mononuclear macrocyclic polyamine zinc(II), copper(II), cobalt(II) complexes, which could attach to peptide nucleic acid (PNA), were synthesized as DNA cleavage agents. The structures of these new mononuclear complexes were identified by MS and (1)H NMR spectroscopy. The catalytic activities on DNA cleavage of these mononuclear complexes with different central metals were subsequently studied, which showed that copper complex was better catalyst in the DNA cleavage process than zinc and cobalt complexes. The effects of reaction time, concentration of complexes were also investigated. The results indicated that the copper(II) complexes could catalyze the cleavage of supercoiled DNA (pUC 19 plasmid DNA) (Form I) under physiological conditions to produce selectively nicked DNA (Form II, no Form III produced) with high yields. The mechanism of the cleavage process was also studied.

  8. Theoretical and experimental evaluation of structural and optical properties of novel zinc-benzimidazole metal complex doped in polystyrene matrices

    Praveen, P. A.; Babu, R. Ramesh


    A novel zinc incorporated benzimidazole metal complex (diacetobis (1H-benzimidazole) Zn(II)) is synthesized by a simple chemical route. The structure of the obtained complex is predicted using FTIR and EPR spectroscopy and further confirmed using semiempirical simulation of vibrational frequencies. Theoretical energy gap of the complex is about 3.2 eV and the hyperpolarizability calculations show that the third harmonic generation dominates over other mechanisms in the complex. Recorded absorption spectrum of the complex shows a broad absorption band between 200 and 300 nm corresponding to π-π transitions. To evaluate the third order nonlinear optical properties experimentally, the complex is doped into a polystyrene matrix with different weight percentages and fabricated as freestanding films. The films are subjected to Z-scan analysis and from the open and closed aperture scans the samples are found to have a reverse saturable absorption and self focusing effect. The calculated third order susceptibilities are of the order of 10-4 esu, which is one of the largest values reported in literature.

  9. Design, synthesis and characterization of zinc-morin, a metal flavonol complex and evaluation of its antidiabetic potential in HFD-STZ induced type 2 diabetes in rats.

    Sendrayaperumal, V; Iyyam Pillai, S; Subramanian, S


    The present study deals with the synthesis, characterization of zinc-morin complex and evaluation of its antidiabetic efficacy in High Fat Diet (HFD)-fedStreptozotocin (STZ) induced diabetic rats. Oral administration of zinc-morin complex to diabetic rats (5mg/kg body weight/day) for a period of 30 days resulted in the decreased levels of blood glucose and HbA1c. Oral administrations of the zinc-morin complex for 30 days significantly improved hyperglycemia, glucose intolerance, and insulin resistance. The elevated levels of lipid peroxides declined and the antioxidant competence was found to be improved in diabetic rats treated with the complex. The status of the lipid and lipoprotein profile in the serum was normalized upon treatment. Levels of TNFα decreased upon treatment with the complex. The altered levels of adipokines such as adiponectin and leptin were normalized upon treatment with the complex. In conclusion, the present study indicates that the zinc-morin complex possesses antidiabetic, antidyslipidemic and antioxidant potentials in HFD-fedSTZ induced diabetic rats.

  10. Synthesis, X-ray crystal structures and thermal analyses of some new antimicrobial zinc complexes: New configurations and nano-size structures.

    Masoudiasl, A; Montazerozohori, M; Naghiha, R; Assoud, A; McArdle, P; Safi Shalamzari, M


    Some new five coordinated ZnLX2 complexes, where L is N3-Schiff base ligand obtained by condensation reaction between diethylenetriamine and (E)-3-(2-nitrophenyl)acrylaldehyde and X (Cl(-), Br(-), I(-), N3(-) and NCS(-)), were synthesized and characterized by FT-IR, (1)H and (13)CNMR, UV-visible, ESI-mass spectra and molar conductivity measurements. The structures of zinc iodide and thiocyanate complexes were determined by X-ray crystallographic analysis. The X-ray results showed that the Zn (II) center in these complexes is five-coordinated in a distorted trigonal-bipyramidal configuration. Zinc iodide and thiocyanate complexes crystallize in the monoclinic and triclinic systems with space groups of C2/c and P1- with eight and two molecules per unit cell respectively. The crystal packing of the complexes consists of intermolecular interactions such as C-H(…)O and C-H(…)I, C-H(···)S, N(…)O, together with π-π stacking and some other unexpected interactions. The mentioned interactions cause three-dimensional supramolecular structure in the solid state. Zinc complexes were also prepared in nano-structure by sonochemical method confirmed by XRD, SEM and TEM analyses. Moreover, ZnO nanoparticles were synthesized by direct thermolysis of zinc iodide complex. Furthermore, antimicrobial and thermal properties of the compounds were completely investigated.

  11. Peptide-based FeS4 complexes: the zinc ribbon fold is unsurpassed to stabilize both the FeII and FeIII states.

    Jacques, Aurélie; Latour, Jean-Marc; Sénèque, Olivier


    Whereas Zn(Cys)4 zinc fingers exist with different protein folds, only the zinc ribbon fold is found in rubredoxin Fe(Cys)4 sites. To assess the significance of this observation, we have investigated the binding and stability of Fe(2+) and Fe(3+) ions by a set of four peptides designed to model Zn(Cys)4 zinc fingers with various folds, i.e. zinc ribbon, treble clef and a loosened zinc ribbon fold. All peptides were shown by means of UV-Vis and CD spectroscopies to form stable 1 : 1 Fe(II)/peptide complexes with binding constants higher than 10(7) M(-1) at pH 7. Their oxidation into Fe(III) complexes and the stability of the latter were compared. The UV-Vis absorption and CD spectroscopic properties of the Fe(II) and Fe(III) complexes were analysed with respect to the structures of the zinc analogues in order to get insight into the local arrangement of the Fe(Cys)4 core around the metal ion. The chemical stability of these complexes was rationalized according to the shielding from the solvent provided by the various peptide folds to the FeS4 core. In addition, we showed that whereas UV-visible spectra inform only on the FeS4, the information derived from the corresponding CD spectra extend to the Cβ orientation and the peptide fold. The results presented here demonstrate that while the zinc ribbon fold is not strictly required to obtain a Fe(Cys)4 site, it affords a drastically superior protection of the site toward external redox agents. This finding brings new clues to engineer stable and redox-active Fe(Cys)4 sites in de novo proteins.

  12. Large fluorescence response by alcohol from a bis(benzoxazole)-zinc(II) complex: the role of excited state intramolecular proton transfer.

    Wang, Junfeng; Chu, Qinghui; Liu, Xiumin; Wesdemiotis, Chrys; Pang, Yi


    The formation of a bis(HBO) anion is known to turn on the fluorescence to give red emission, via controlling the excited-state intramolecular proton transfer (ESIPT). The poor stability of the formed anion, however, hampered its application. The anion stability is found to be greatly improved by attaching the anion to Zn(2+) cation (i.e., forming zinc complex), whose emission is at λem ≈ 550 and 760 nm. Interestingly, addition of methanol to the zinc complex induces a remarkable red fluorescence (λem ≈ 630 nm, φfl ≈ 0.8). With the aid of spectroscopic studies ((1)H NMR, UV-vis, fluorescence, and mass spectra), the structures of the zinc complexes are characterized. The emission species is identified as a dimer-like structure. The study thus reveals an effective fluorescence switching mechanism that could further advance the application of ESIPT-based sensors.

  13. Syntheses and solid state structures of zinc (II) complexes with Bi-dentate -(Aryl)imino-acenapthenone (Ar-BIAO) ligands

    Srinivas Anga; Supriya Rej; Kishor Naktode; Tigmansu Pal; Tarun K Panda


    We have synthesized five zinc complexes of molecular formulae [ZnCl2(2,6-dimethylphenyl-BIAO)]2 (1a), [ZnBr2(2,6-dimethylphenyl-BIAO)]2 (1b), [ZnI2(2,6-dimethylphenyl-BIAO)]2(1c), [ZnBr2(mes-BIAO)]2(2b) and [ZnBr2(dipp-BIAO)] (3b) with rigid unsymmetrical iminoacenaphthenone ligands, (2,6-dimethylphenyl-BIAO) (1), (mesityl-BIAO) (2) and (2,6-diisopropylphenyl-BIAO) (3). The zinc complex 1a was prepared by the reaction of ZnCl2 and neutral (mesityl-BIAO) (1). However, complexes 1b, 2b and 3b were obtained by the treatment of ZnBr2 and neutral ligands 1-3 respectively in 1:1 molar ratio in dichloromethane at ambient temperature. In a similar reaction of ZnI2 with (2,6-dimethylphenyl-BIAO) (1) in dichloromethane the corresponding iodo-complex 1c was obtained in good yield. All the zinc (II) complexes are characterized by FT-IR, 1H and 13C{1H} NMR spectroscopic techniques. The solid state structures of the complexes 1a, 1b, 1c, 2b and 3b are confirmed by single crystal X-ray diffraction analysis. The molecular structures of complexes 1a, 1b, 1c and 2b reveal the dimeric nature of the complexes and subsequently the centre atom zinc is penta-coordinated to adopt distorted trigonal bipyramidal geometry around it. In contrast, the complex 3b is in monomeric in nature due to bulkier size of the ligand and zinc ion is tetra coordinated to adopt distorted tetrahedral geometry.

  14. (Pyridine)(tetrahydroborato)zinc complex, (Zn(BH{sub 4}){sub 2}(py)), as a new stable, efficient and chemoselective reducing agent for reduction of carbonyl compounds

    Zeynizadeh, Behzad; Faraji, Fariba [Urima Univ., Urima (Iran, Islamic Republic of)


    (Pyridine)(tetrahydroborato)zinc complex, (Zn(BH{sub 4}){sub 2}(py)), as a stable white solid, was prepared quantitatively by complexation of an equimolar amount of zinc tetrahydroborate and pyridine at room temperature. This reagent can easily reduce variety of carbonyl compounds such as aldehydes, ketones, acyloins, {alpha}-diketones and {alpha},{beta}-unsaturated carbonyl compounds to their corresponding alcohols in good to excellent yields. Reduction reactions were performed in ether or THF at room temperature or under reflux conditions. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing agent.

  15. Synthesis aspects, structural, spectroscopic, antimicrobial and room temperature ferromagnetism of zinc iodide complex with Schiff based ligand

    Shakila, K.; Kalainathan, S.


    In this paper, we report the successful growth of complex compound of zinc iodide with thiocarbamide by slow evaporation method. The single crystal XRD study reveals that the crystal belongs to monoclinic system with centrosymmetric space group and powder XRD analysis shows that the perfect crystalline nature of the crystal. The presence of functional group and element were confirmed from FT-IR and EDAX analysis. Optical absorbance of the grown crystal was studied by UV-Vis spectrophotometer. The optical constants were calculated from the optical absorbance data such as refractive index (n), extinction coefficient (K) and reflectance (R). The optical band gap (Eg) of thiocarbamide zinc iodide crystal is 4.22 eV. The magnetic properties of grown crystal have been determined by Vibrating Sample Magnetometry (VSM). Room temperature magnetization revealed a ferromagnetic behaviour for the grown crystal. The antibacterial and antifungal activities of the title compound were performed by well diffusion method and MIC method against the standard bacteria like Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and against fungus like Aspergillus niger, Rhizopus sps and Penicillium sps. Thermal behaviour of the crystal has been investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA).

  16. Characteristic differences in the formation of complex coacervate core micelles from neodymium and zinc-based coordination polymers.

    Yan, Yun; Besseling, Nicolaas A M; de Keizer, Arie; Stuart, Martien A Cohen


    In this paper we compare the formation of complex coacervate core micelles (C3Ms) from two different tricompontent mixtures, namely neodymium, the bisligand L2EO4 and the poly(cation)-block-poly(neutral) diblock copolymer P2MVP41-b-PEO205, and zinc, L2EO4 and P2MVP41-b-PEO205 mixed systems. Three sets of titration experiments were carried out for each system: (i) titration of diblock copolymer P2MVP41-b-PEO205 with the stoichiometric mixture of metal ions and bisligands, (ii) titration of a mixture of diblock copolymer and bisligand with metal ions, and (iii) titration of a mixture of diblock copolymer and metal ions with bisligands. In all the above three cases, micelles are found to form either in a broad range of charge ratios or in a broad range of metal/bisligand ratios. Upon addition of Nd2-(L2EO4)3 coordination polymer to P2MVP41-b-PEO205 solution, and upon addition of Nd3+ to a mixture of L2EO4 and P2MVP41-b-PEO205, micelles are found to form immediately after the first addition, whereas micelles show up in the similar zinc system only after a certain threshold Zn-(L2EO4) or Zn2+ concentration. This difference can be traced to the different structures of the Nd2-(L2EO4)3 and Zn-(L2EO4) coordination compounds. At very low concentrations, Zn-(L2EO4) are ring-like oligomers, but Nd2-(L2EO4)3 are larger networks. The network structure favors the formation of coacervate micellar core with P2MVP41-b-PEO205. Moreover, excess of Nd3+ ions will break up the C3Ms, while the same amount of Zn2+ has hardly any effect on the C3Ms. The breakdown of C3Ms by Nd3+ is due to the charge inversion of the coordination complex with increasing [Nd3+]/[L2EO4] ratio, which results in repulsive interaction between the coordination complex and the diblock copolymer, whereas no such interaction can occur in the zinc system.

  17. Synthetic, spectral and solution studies on imidazolate-bridged copper(II)-copper(II) and copper(II)-zinc(II) complexes

    Subodh Kumar; R N Patel; P V Khadikar; K B Pandeya


    Synthesis, spectral and solution studies on 2-ethyl imidazolate-bridged (2-EtIm) homo-binuclear copper(II)-copper(II) and hetero-binuclear copper(II)-zinc(II) homologue are described. Magnetic moment values of homo-binuclear complexes indicate that the imidazolate group can mediate antiferromagnetic interactions. Optical spectra of hetero-binuclear complex at varying H values suggest that the imidazolate-bridged complex is stable over the H-range 7 15-10 0.

  18. Synthesis, Spectral Characterization, and Biochemical Evaluation of Antidiabetic Properties of a New Zinc-Diosmin Complex Studied in High Fat Diet Fed-Low Dose Streptozotocin Induced Experimental Type 2 Diabetes in Rats

    Veerasamy Gopalakrishnan


    Full Text Available In view of the established antidiabetic properties of zinc, the present study was aimed at evaluating the hypoglycemic properties of a new zinc-diosmin complex in high fat diet fed-low dose streptozotocin induced experimental type 2 diabetes in rats. Zinc-diosmin complex was synthesized and characterized by various spectral studies. The complexation between zinc ions and diosmin was further evidenced by pH-potentiometric titrations and Job’s plot. Diabetic rats were orally treated with zinc-diosmin complex at a concentration of 20 mg/kg b.w./rat/day for 30 days. At the end of the experimental period, the rats were subjected to oral glucose tolerance test. In addition, HOMA-IR and various biochemical parameters related to glucose homeostasis were analyzed. Treatment with zinc-diosmin complex significantly improved the glucose homeostasis in diabetic rats. Treatment with zinc-diosmin complex significantly improved insulin sensitivity, at least in part, through enhancing protein metabolism and alteration in the levels of muscle and liver glycogen. The assay of clinical marker enzymes revealed the nontoxic nature of the complex. Determination of renal tissue markers such as blood urea and serum creatinine indicates the renoprotective nature of the complex. These findings suggest that zinc-diosmin complex is nontoxic and has complimentary potential to develop as an antihyperglycemic agent for the treatment of diabetes mellitus.

  19. Affecting proton mobility in activated peptide and whole protein ions via lysine guanidination.

    Pitteri, Sharon J; Reid, Gavin E; McLuckey, Scott A


    We have evaluated the effect of lysine guanidination in peptides and proteins on the dissociation of protonated ions in the gas phase. The dissociation of guanidinated model peptide ions compared to their unmodified forms showed behavior consistent with concepts of proton mobility as a major factor in determining favored fragmentation channels. Reduction of proton mobility associated with lysine guanidination was reflected by a relative increase in cleavages occurring C-terminal to aspartic acid residues as well as increases in small molecule losses. To evaluate the effect of guanidination on the dissociation behavior of whole protein ions, bovine ubiquitin was selected as a model. Essentially, all of the amide bond cleavages associated with the +10 charge state of fully guanidinated ubiquitin were observed to occur C-terminal to aspartic acid residues, unlike the dissociation behavior of the +10 ion of the unmodified protein, where competing cleavage N-terminal to proline and nonspecific amide bond cleavages were also observed. The +8 and lower charge states of the guanidinated protein showed prominent losses of small neutral molecules. This overall fragmentation behavior is consistent with current hypotheses regarding whole protein dissociation that consider proton mobility and intramolecular charge solvation as important factors in determining favored dissociation channels, and are also consistent with the fragmentation behaviors observed for the guanidinated model peptide ions. Further evaluation of the utility of condensed phase guanidination of whole proteins is necessary but the results described here confirm that guanidination can be an effective strategy for enhancing C-terminal aspartic acid cleavages. Gas phase dissociation exclusively at aspartic acid residues, especially for whole protein ions, could be useful in identifying and characterizing proteins via tandem mass spectrometry of whole protein ions.

  20. Zinc(II) and Cadmium(II) complexes with N4-coordinate pyrazole based ligand: Syntheses, characterization and structure

    Solanki, Ankita; Sadhu, Mehul H.; Kumar, Sujit Baran; Mitra, Partho


    A series of six new mononuclear zinc(II) complexes of the type [Zn(X)(dbdmp)]Y (1-6) (X = N3-/NCO-/NCS-, Y = ClO4-/PF6-, and dbdmp = N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine), two binuclear cadmium(II) complexes [{Cd(dbdmp)}2(μ-N3)2](Y)2 (7-8) and three mononuclear cadmium(II) complexes [Cd(NCO)(dbdmp)]Y (Y = ClO4-/PF6-) (9-10) and [Cd(NCS)2(dbdmp)] (11) have been synthesized and characterized by physico-chemical methods. Crystal structures of the complexes [Zn(N3)(dbdmp)]ClO4 (1), [{Cd(dbdmp)}2(μ-N3)2](ClO4)2 (7), [Cd(NCO)(dbdmp)]ClO4 (9) and [Cd(NCS)2(dbdmp)] (11) have been solved by single crystal X-ray diffraction studies and showed that [Zn(N3)(dbdmp)]ClO4 (1) and [Cd(NCO)(dbdmp)]ClO4 (9) have distorted trigonal bipyramidal geometry, [Cd(NCS)2(dbdmp)] (11) and [(dbdmp)Cd(μ-N3)]2(ClO4)2 (7) have distorted octahedral geometry.

  1. Comments on "Synthesis aspects, structural, spectroscopic, antimicrobial and room temperature ferromagnetism of zinc iodide complex with Schiff based ligand" by K. Shakila and S. Kalainathan, Spectrochim. Acta 135 A (2015) 1059-1065

    Srinivasan, Bikshandarkoil R.; Nadkarni, V. S.


    Shakila and Kalainathan report on the synthetic and structural aspects of a zinc iodide complex with Schiff based ligand, which exhibits room temperature ferromagnetism. In this comment, many points of criticism, concerning the characterization of this so called zinc iodide complex of Schiff based ligand are highlighted to prove that the title paper is completely erroneous.

  2. Synthesis of Macrocyclic Hexaoxazole (6OTD Dimers, Containing Guanidine and Amine Functionalized Side Chains, and an Evaluation of Their Telomeric G4 Stabilizing Properties

    Keisuke Iida


    Full Text Available Structure-activity relationship studies were carried out on macrocyclic hexaoxazole (6OTD dimers, whose core structure stabilizes telomeric G-quadruplexes (G4. Two new 6OTD dimers having side chain amine and guanidine functional groups were synthesized and evaluated for their stabilizing ability against a telomeric G4 DNA sequence. The results show that the 6OTD dimers interact with the DNA to form 1:1 complexes and stabilize the antiparallel G4 structure of DNA in the presence of potassium cation. The guanidine functionalized dimer displays a potent stabilizing ability of the G4 structure, as determined by using a FRET melting assay (ΔTm=14 °C.

  3. Cadmium complexes bearing (Me2)N^E^O(-) (E = S, Se) organochalcogenoalkoxides and their zinc and mercury analogues.

    Pop, Alexandra; Bellini, Clément; Şuteu, Răzvan; Dorcet, Vincent; Roisnel, Thierry; Carpentier, Jean-François; Silvestru, Anca; Sarazin, Yann


    Heteroleptic zinc and cadmium complexes of the type [{(Me2)N^E^O(R2)}M-Nu]n (M = Zn, Cd; E = S, Se; R = CH3, CF3; Nu = N(SiMe3)2, I, Cl; n = 1-2) were prepared by reacting the alcohol proteo-ligands {(Me2)N^E^O(R2)}H with [M(N(SiMe3)2)2] (M = Zn, Cd) or [XMN(SiMe3)2] (M = Zn, X = Cl; M = Cd, X = I) in an equimolar ratio. These group 12 metal complexes were characterised in solution by multinuclear NMR spectroscopy and their solid-state structures were determined by X-ray diffractometry. The ligands {(Me2)N^E^O((CH3)2)}(-) bearing CH3 groups in α position to the alkoxide behave as κ(2)-O,E-bidentate moieties (E = S, Se) and form centro-symmetric dinuclear O-bridged heteroleptic alkoxo-amido complexes both with zinc and cadmium, with four-coordinate metal centres resting in tetrahedral environments. By contrast, complexes supported by the CF3-substituted {(Me2)N^E^O((CF3)2)}(-) crystallise as tetrahedral mononuclear species, with tridentate κ(3)-N,O,E-coordinated ligands. These structural differences resulting from changes in the ligand skeleton and in the electron-donating properties of the alkoxide were also observed in solution. Attempts to prepare congeneric heteroleptic mercury complexes from [Hg(N(SiMe3)2)2] unexpectedly only afforded homoleptic bis(alkoxide)s such as [{(Me2)N^S^O((CF3)2)}2Hg]. Owing to the strong Hg-C bond, treatment of [PhHgN(SiMe3)2] with {(Me2)N^S^O((CF3)2)}H afforded the heteroleptic, T-shaped [{(Me2)N^S^O((CF3)2)}HgPh] mercuric alkoxide upon elimination of hexamethyldisilazane. [{(Me2)N^S^O((CF3)2)}2Hg] and [{(Me2)N^S^O((CF3)2)}HgPh] constitute very rare examples of structurally characterised mercuric alkoxides.

  4. Exploring zinc coordination in novel zinc battery electrolytes.

    Kar, Mega; Winther-Jensen, Bjorn; Forsyth, Maria; MacFarlane, Douglas R


    The coordination of zinc ions by tetraglyme has been investigated here to support the development of novel electrolytes for rechargeable zinc batteries. Zn(2+) reduction is electrochemically reversible from tetraglyme. The spectroscopic data, molar conductivity and thermal behavior as a function of zinc composition, between mole ratios [80 : 20] and [50 : 50] [tetraglyme : zinc chloride], all suggest that strong interactions take place between chloro-zinc complexes and tetraglyme. Varying the concentration of zinc chloride produces a range of zinc-chloro species (ZnClx)(2-x) in solution, which hinder full interaction between the zinc ion and tetraglyme. Both the [70 : 30] and [50 : 50] mixtures are promising electrolyte candidates for reversible zinc batteries, such as the zinc-air device.

  5. Complexes cobalt(II, zinc(II and copper(II with some newly synthesized benzimidazole derivatives and their antibacterial activity



    Full Text Available The preparation and properties of some complexes of cobalt(II, zinc(II and copper(II with several newly synthesized benzimidazole derivatives (L are reported. The complexes, of the general formula [MCl2L2] (M=Co(II, Zn(II and [CuCl2L(H2O], have a tetrahedral structure. The complexes were characterized by elemental analysis, molar conductivity, magnetic susceptibility measurements, IR and absorption electronic spectra. The antibacterial activitiy of the benzimidazoles and their complexes was evaluated against Erwinia carotovora subsp. carotovora and Erwinia amylovora. The complexes were found to be more toxic than the ligands.

  6. Bioavailability and Electroreactivity of Zinc Complexed to Strong and Weak Organic Ligands.

    Kim, Ja-Myung; Baars, Oliver; Morel, François M M


    Laboratory experiments have established the importance of complexation by organic ligands in determining the bioavailability of trace metals to marine phytoplankton, while electrochemical measurements with field samples have demonstrated that a large fraction of bioactive trace metals are complexed to strong organic ligands in seawater. Using the model organic ligands, EDTA and histidine, we show a quantitative correspondence between the bioavailability of Zn to the diatom Thalassiosira weissflogii, and its reduction at -1.2 V (vs Ag/AgCl) on a hanging mercury drop electrode. Equilibrium calculations and polarographic data indicate that Zn bound in inorganic complexes and the 1:1 Zn-histidine complex, but not in the 1:2 Zn-histidine complex or the Zn-EDTA complexes, is taken up by the organism and reduced at the electrode surface, confirming a previous report of the bioavailability of weak Zn complexes. Electrochemical measurements of Zn speciation in seawater do not generally reveal the presence of weak (and potentially bioavailable) complexes; but such measurements (particularly by Anodic Stripping Voltammetry) should nonetheless often provide good estimates of the bioavailable Zn concentrations. These results can likely be generalized to other bioactive divalent trace metals.

  7. Complex nanospherulites of zinc oxide and native amorphous boron in the lunar regolith from Mare Crisium

    Mokhov, A. V.; Kartashov, P. M.; Gornostaeva, T. A.; Asadulin, En. E.; Bogatikov, O. A.


    During the study of tea-colored impact glass fragments from the sample of lunar regolith delivered to Earth by the Luna 24 automatic station by transmission electron microscopy, the composition variations of the previously described high-carbonaceous film, the presence of at least three composition types of glasses, and unusual nanospherulites with Zn-B-N-O composition were discovered. As a part of a nonuniform high-carbonaceous oxygen-bearing film, sites enriched in either Na, S, Si, or Ca were detected. All these sites, as well as the whole film, are electron-amorphous; however, crystalline graphite was also found. Two types of nanospherulites are composed of amorphous ZnO and regular interstratifications of crystalline ZnO and amorphous boron layers with insignificant participation of adsorbed nitrogen. It is supposed that the formation of zinc-boron nanospherulites was caused by a fast-flowing explosive process and probably was modulated by high-frequency acoustic oscillations in a cloud of evaporated high-temperature ionized gas during the impact event.

  8. Efficient catalytic phosphate ester cleavage by binuclear zinc(II) pyrazolate complexes as functional models of metallophosphatases.

    Penkova, Larysa V; Maciag, Anna; Rybak-Akimova, Elena V; Haukka, Matti; Pavlenko, Vadim A; Iskenderov, Turganbay S; Kozłowski, Henryk; Meyer, Franc; Fritsky, Igor O


    A series of dizinc(II) complexes based on the pyrazolate ligands 3-[(1E)-N-hydroxyethanimidoyl]-4-methyl-1H-pyrazole-5-carboxylic acid (H(3)L(1)), (1E,1'E)-1,1'-(4-methyl-1H-pyrazole-3,5-diyl)diethanone dihydrazone (HL(2)), (E,E)-(4-methyl-1H-pyrazole-3,5-diyl)bis(methylmethanone) dioxime (H(3)L(3)), (E,E)-(4-phenyl-1H-pyrazole-3,5-diyl)bis(phenylmethanone) dioxime (H(3)L(4)), and 1H-pyrazole-3,5-dicarboxylic acid (H(3)L(5)) have been synthesized and investigated as functional models of phosphoesterases, focusing on correlations between the hydrolytic activity and molecular parameters of the bimetallic core. Speciation of the various dizinc complexes in solution has been determined potentiometrically, and the structures in the solid state have been established by X-ray crystallography. The hydrolysis of two phosphoesters, an RNA model 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) and the pesticide paraoxon-ethyl (POE), promoted by the dinuclear phosphoesterase model complexes has been investigated in DMSO/buffered water (1:1) at 50 degrees C as a function of complex concentration, substrate concentration, and pH. Drastic differences in the hydrolytic activities of [Zn(2)(HL(1))(2)](0), [Zn(2)(L(2))(2)](2+), [Zn(2)(H(2)L(3))(2)](2+), and [Zn(2)(HL(5))(2)](2-) are observed and can be attributed to molecular peculiarities. Pyrazolate-bridged dinuclear zinc(II) complexes seem to provide a sufficient number of coordination sites for both activating the substrate and generating the nucleophile, where the phosphate esters are preferentially bound in a bidentate bridging fashion (in the case of HPNP) and in a monodentate fashion (in the case of POE).

  9. Synthesis of guanidines from azides: a general and straightforward methodology in carbohydrate chemistry.

    Santana, Andrés G; Francisco, Cosme G; Suárez, Ernesto; González, Concepción C


    The ability of the guanidinylating reagent N',N''-diBoc-N-triflyl-guanidine (GN-Tf) to react with in situ formed free amines from azides in carbohydrate scaffolds was explored. This reaction proved to be an efficient method to prepare guanidine derivatives in a one-pot manner with good to excellent yields, either with primary or secondary azides with different substitution patterns. Labile protecting groups such as benzyl ethers are not removed under these hydrogenolytic conditions.

  10. Hybrid scorpionate/cyclopentadienyl magnesium and zinc complexes: synthesis, coordination chemistry, and ring-opening polymerization studies on cyclic esters.

    Garcés, Andrés; Sánchez-Barba, Luis F; Alonso-Moreno, Carlos; Fajardo, Mariano; Fernández-Baeza, Juan; Otero, Antonio; Lara-Sánchez, Agustín; López-Solera, Isabel; Rodríguez, Ana María


    The reaction of the hybrid scorpionate/cyclopentadienyl lithium salt [Li(bpzcp)(THF)] [bpzcp = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethylcyclopentadienyl] with 1 equiv of RMgCl proceeds cleanly to give very high yields of the corresponding monoalkyl kappa(2)-NN-eta(5)-C(5)H(4) magnesium complexes [Mg(R)(kappa(2)-eta(5)-bpzcp)] (R = Me 1, Et 2, (n)Bu 3, (t)Bu 4, CH(2)SiMe(3) 5, CH(2)Ph 6). Hydrolysis of the hybrid lithium salt [Li(bpzcp)(THF)] with NH(4)Cl/H(2)O in ether cleanly affords the two previously described regioisomers: (bpzcpH) 1-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethyl]-1,3-cyclopentadiene (a) and 2-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethyl]-1,3-cyclopentadiene (b). Subsequent reaction of the bpzcpH hybrid ligand with ZnR(2) quantitatively yields the monoalkyl kappa(2)-NN-eta(1)(pi)-C(5)H(4) zinc complexes [Zn(R){kappa(2)-eta(1)(pi)-bpzcp}] (R = Me 7, Et 8, (t)Bu 9, CH(2)SiMe(3) 10). Additionally, magnesium alkyls 1, 2, 4, and 5 can act as excellent cyclopentadienyl and alkyl transfers to the zinc metal center and yield zinc alkyls 7-10 in good yields. The single-crystal X-ray structures of the derivatives 4, 5, 7, and 10 confirm a 4-coordinative structure with the metal center in a distorted tetrahedral geometry. Interestingly, whereas alkyl magnesium derivatives 4 and 5 present a eta(5) coordination mode for the cyclopentadienyl fragment, zinc derivatives 7 and 10 feature a peripheral eta(1)(pi) arrangement in the solid state. Furthermore, the reaction of the hybrid lithium salt [Li(bpzcp)(THF)] with 1 equiv of ZnCl(2) in tetrahydrofuran (THF) affords very high yields of the chloride complex [ZnCl{kappa(2)-eta(1)(pi)-bpzcp}] (11). Compound 11 was used as a convenient starting material for the synthesis of the aromatic amide zinc compound [Zn(NH-4-MeC(6)H(4)){kappa(2)-eta(1)(pi)-bpzcp}] (12), by reaction with the corresponding aromatic primary amide lithium salt. Alternatively, aliphatic amide and alkoxide derivatives were

  11. Syntheses, structures and luminescence behaviour of some zinc(II) complexes containing acetate and tetradentate Schiff bases

    Ashis Kumar Maji; Subhasis Roy; Somnath Choubey; Rajarshi Ghosh; Barindra Kumar Ghosh


    Two mononuclear compounds of the types pentacoordinated [Zn(L1)(OAc)]PF6·H2O (1) and hexacoordinated [Zn(L2)(OAc)]PF6 (2) [L1 = N,N′-(bis(pyridin-2-yl)formylidene)-1,3-propanediamine; L2 = N,N′-(bis(pyridin-2-yl)benzylidene)-1,4-butanediamine] have been synthesized using one-pot reactions of a 1:1:1 molar ratio of Zn(OAc)2.2H2O, L1/L2, ammonium hexafluorophosphate in MeOH at room temperature. Compounds 1 and 2 are characterized on the basis of microanalytical, spectroscopic, thermal and other physicochemical results. Single crystal X-ray structural study reveals that the zinc(II) centre in 1 is coordinated by four N atoms of the Schiff base L1 and one O atom of terminal acetate with a ZnN4O chromophore, whereas in 2, the zinc(II) centre is bound by four N atoms of the tailored Schiff base L2 and two O atoms of the chelated acetate. In the crystalline state, mononuclear units in 1 are engaged in weak cooperative intermolecular O-H⋯O and C-H⋯F hydrogen bonds affording a 1D chain. The individual units of 2 are packed by ⋯ and anion⋯ interactions to form a 2D sheet structure. The complexes show reasonable thermal stabilities and display intraligand → ∗ fluorescence in solid state at room temperature.

  12. Complexing ability of (-)-cytisine--synthesis, spectroscopy and crystal structures of the new copper and zinc complexes.

    Przybył, Anna K; Kubicki, Maciej; Jastrzab, Renata


    For the first time the NMR spectra of quinolizidine alkaloid with Cu(II) are studied. Structures of new complexes of (-)-cytisine with Cu(+2) and Zn(+2) cations are visualized, discussed in detail and characterized by spectroscopic methods: ESI-MS, NMR, UV-vis, EPR and crystallographic methods. In solution metal coordinates through the protonated nitrogen atoms of secondary amino groups (in piperidine ring) of cytisine molecule. While in solid state the most stable structures of the complexes are those in which the coordination of Cu(II) and Zn(II) salts is realized solely through the lactam carbonyl oxygen atom.

  13. Excited state intramolecular proton transfer (ESIPT) in six-coordinated zinc(ii)-quinoxaline complexes with ligand hydrogen bonds: their fluorescent properties sensitive to axial positions.

    Sakai, Ken-Ichi; Takahashi, Sami; Kobayashi, Ataru; Akutagawa, Tomoyuki; Nakamura, Takayoshi; Dosen, Masaaki; Kato, Masako; Nagashima, Umpei


    Zinc(ii)-quinoxaline complexes, [Zn(hqxc)(2)(py)(2)] and [Zn(hqxc)(2)(DMSO)(2)] (hqxc = 3-hydroxy-2-quinoxalinecarboxylate, py = pyridine, DMSO = dimethyl sulfoxide), were prepared and characterized by X-ray crystallography and fluorescence spectroscopy. In both complexes, the zinc ion is six-coordinated by two equatorial bidentate hqxc ligands with an intramolecular hydrogen bond and two axial monodentate ligands such as pyridine or DMSO. In spite of similar coordination geometries, there is a remarkable difference between their solid-state fluorescent properties. The pyridine complex is strongly fluorescent (fluorescence quantum yield Phi = 0.22), giving rise to a significantly Stokes-shifted spectrum. From its thin film photopumped by a nitrogen gas laser, amplified spontaneous emission was observed. These results suggest that the fluorescence occurs by way of excited-state intramolecular proton-transfer (ESIPT) in the hydrogen bond of hqxc. On the other hand, the DMSO complex shows fluorescent intensity (Phi = 0.08) lower than that of the pyridine complex, and shows normal emission in addition to ESIPT emission. From IR measurements for these complexes, it is concluded that axial ligands influence the hydrogen bond strength of the equatorial hqxc ligand via zinc and thus the ESIPT efficiency.

  14. Magnesium, zinc, aluminium and gallium hydride complexes of the transition metals.

    Butler, Michael J; Crimmin, Mark R


    The preparation and applications of heterobimetallic complexes continue to occupy researchers in the fields of organometallic, main group, and coordination chemistry. This interest stems from the promise these complexes hold as precursors to materials, reagents in synthesis and as new catalysis. Here we survey and organise the state-of-the-art understanding of the TM-H-M linkage (M = Mg, Zn, Al, Ga). We discuss the structure and bonding in these complexes, their known reactivity, and their largely unrealised potential in catalysis.

  15. Kinetic Analysis of Guanidine Hydrochloride Inactivation of β-Galactosidase in the Presence of Galactose

    Charles O. Nwamba


    Full Text Available Inactivation of purified β-Galactosidase was done with GdnHCl in the absence and presence of varying [galactose] at 50°C and at pH 4.5. Lineweaver-Burk plots of initial velocity data, in the presence and absence of guanidine hydrochloride (GdnHCl and galactose, were used to determine the relevant and max values, with p-nitrophenyl β-D-galactopyranoside (pNPG as substrate, S. Plots of ln([]∞−[] against time in the presence of GdnHCl yielded the inactivation rate constant, A. Plots of A versus [S] at different galactose concentrations were straight lines that became increasingly less steep as the [galactose] increased, showing that A was dependent on [S]. Slopes and intercepts of the 1/[]∞ versus 1/[] yielded +0 and ′+0, the microscopic rate constants for the free enzyme and the enzyme-substrate complex, respectively. Plots of +0 and ′+0 versus [galactose] showed that galactose protected the free enzyme as well as the enzyme-substrate complex (only at the lowest and highest [galactose] against GdnHCl inactivation. In the absence of galactose, GdnHCl exhibited some degree of non-competitive inhibition. In the presence of GdnHCl, galactose exhibited competitive inhibition at the lower [galactose] of 5 mM which changed to non-competitive as the [galactose] increased. The implications of our findings are further discussed.

  16. Metal complexes as templates: syntheses, structures, and luminescent properties of two zinc phosphonocarboxylates with ABW-zeolite topology.

    Chen, Zhenxia; Yang, Haiyang; Deng, Mingli; Ling, Yun; Weng, Linhong; Zhou, Yaming


    Two novel zinc phosphonocarboxylates, Zn(3)(pbc)(2)(bpy)(H(2)O)·H(2)O (1) and Zn(2)(pbc)(2)·Zn(bpy)(H(2)O)(4)·2H(2)O (2) (pbc = 4-phosphono-benzoic acid, bpy = 2,2'-bipyridine), were hydrothermally synthesized and structurally characterized. Both of them exhibit zeolitic ABW topology in which double-zigzag inorganic chains are cross-linked by the organic parts. It is notable that the metal complex Zn(bpy)(H(2)O)(x) plays different roles in the two compounds. In 1, the Zn(bpy)(H(2)O) units coordinate with the phosphonate and carboxylate oxygen atoms and participate in the construction of the three-dimensional framework. In 2, the in situ generated [Zn(bpy)(H(2)O)(4)](2+) cation acts as a template, which directs the ABW-type open-framework by strong hydrogen bonds. It is the first example where a metal complex is used as a template in the synthesis of metal phosphonates. The luminescent properties of 1 and 2 are also investigated.

  17. An exploratory investigation of polar organic compounds in waters from a lead–zinc mine and mill complex

    Rostad, Colleen E.; Schmitt, Christopher J.; Schumacher, John G.; Leiker, Thomas J.


    Surface water samples were collected in 2006 from a lead mine-mill complex in Missouri to investigate possible organic compounds coming from the milling process. Water samples contained relatively high concentrations of dissolved organic carbon (DOC; greater than 20 mg/l) for surface waters but were colorless, implying a lack of naturally occurring aquatic humic or fulvic acids. Samples were extracted by three different types of solid-phase extraction and analyzed by electrospray ionization/mass spectrometry. Because large amounts of xanthate complexation reagents are used in the milling process, techniques were developed to extract and analyze for sodium isopropyl xanthate and sodium ethyl xanthate. Although these xanthate reagents were not found, trace amounts of the degradates, isopropyl xanthyl thiosulfonate and isopropyl xanthyl sulfonate, were found in most locations sampled, including the tailings pond downstream. Dioctyl sulfosuccinate, a surfactant and process filtering aid, was found at concentrations estimated at 350 μg/l at one mill outlet, but not downstream. Release of these organic compounds downstream from lead-zinc mine and milling areas has not previously been reported. A majority of the DOC remains unidentified.

  18. Photo- and electroluminescent properties of zinc(II) complexes with tetradentate Schiff bases, derivatives of salicylic aldehyde

    Vashchenko, A. A.; Lepnev, L. S.; Vitukhnovskii, A. G.; Kotova, O. V.; Eliseeva, S. V.; Kuz'mina, N. P.


    It is studied how the introduction of various substituents into the composition of organic ligands affects the photoluminescence spectra of new zinc(II) complexes with tetradentate Schiff bases H2L (derivatives of salicylic aldehyde (H2SAL1, H2SAL2) and o-vanillin (H2MO1, H2MO2) with ethylenediamine and o-phenylenediamine) in the form of bulk solids and thin films. It is demonstrated that the emission spectra of bulk solid complexes without o-phenylenediamine bridges (ZnSAL1 and ZnMO1) contain additional long-wavelength bands compared to the spectra of corresponding thin films. In the case of films obtained from [ZnSAL1]2 dimer complexes, the long-wavelength band is dominant. At the same time, the photoluminescence spectra of ZnSAL2 and ZnMO2 complexes with o-phenylenediamine bridges are similar in the case of solid samples and thin films. The electroluminescent properties of organic light-emitting diodes (OLEDs) with the ITO/α-NPD/ZnL/Ca:Al structure are studied. The bathochromic shift of the electroluminescence peaks of OLEDs with respect to the photoluminescence spectra of bulk solid samples and thin films is probably related to the formation of exciplexes at the α-NPD/ZnL interface. The electroluminescence spectra of OLEDs based on [ZnSAL1]2 show a hypsochromic shift of the emission maximum, which can be caused by a shift of the recombination region into the α-NPD layer.

  19. Complexes of myo-Inositol-Hexakisphosphate (IP6) with Zinc or Lanthanum for the Decorporation of Radiocesium.

    Ogawa, Kazuma; Aoki, Miho; Fukuda, Tadahisa; Kadono, Sumi; Kiwada, Tatsuto; Odani, Akira


    Radioactive nuclides leak into the surrounding environment after nuclear power plant disasters, such as the Chernobyl accident and the Fukushima Daiichi Nuclear Power Plant disaster. Cesium-137 ((137)Cs) (t1/2=30.1 year), a water-soluble radionuclide with a long physical half-life, contaminates aquatic ecosystems and food products. In humans, (137)Cs concentrates in muscle tissue and has a long biological half-life, indicating it may be harmful. myo-Inositol-hexakisphosphate (IP6) is a compound found in grain, beans, and oil seeds. IP6 has the ability to form insoluble complexes with metals, including lanthanum (La) and zinc (Zn). We hypothesized that La-IP6 and Zn-IP6 may promote the elimination of (137)Cs from the body through the adsorption of La-IP6 and Zn-IP6 to (137)Cs in the gastrointestinal tract. Therefore, in this study, we evaluated the adsorptive capacity of La-IP6 and Zn-IP6 complexes with (137)Cs in vitro and in vivo. La-IP6 and Zn-IP6 complexes were stable in acidic solution (pH 1.2) at 37°C. In vitro binding assays indicated that La-IP6 and Zn-IP6 complexes adsorbed (137)Cs, with the adsorption capacity of Zn-IP6 to (137)Cs greater than that of La-IP6. To evaluate the usefulness of La-IP6 and Zn-IP6 in vivo, La-IP6 or Zn-IP6 was administrated to mice after intravenous injection of (137)Cs. However, the biodistribution of (137)Cs in the La-IP6 treated group and the Zn-IP6 treated group was nearly identical to the non-treated control group, indicating that La-IP6 and Zn-IP6 were not effective at promoting the elimination of (137)Cs in vivo.

  20. Novel Zinc(II) Complexes of Heterocyclic Ligands as Antimicrobial Agents: Synthesis, Characterisation, and Antimicrobial Studies

    Yamgar, Ramesh S.; Nivid, Y.; Nalawade, Satish; Mandewale, Mustapha; Atram, R. G.; Sawant, Sudhir S.


    The synthesis and antimicrobial activity of novel Zn(II) metal complexes derived from three novel heterocyclic Schiff base ligands 8-[(Z)-{[3-(N-methylamino)propyl]imino}methyl]-7-hydroxy-4-methyl-2H-chromen-2-one, 2-[(E)-{[4-(1H-1,2,4-triazol-1-ylmethyl)phenyl]imino}methyl]phenol, and (4S)-4-{4-[(E)-(2-hydroxybenzylidene)amino]benzyl}-1,3-oxazolidin-2-one have been described. These Schiff base ligands and metal complexes are characterised by spectroscopic techniques. According to these data, we propose an octahedral geometry to all the metal complexes. Antimicrobial activity of the Schiff base ligand and its metal complexes was studied against Gram negative bacteria: E. coli and Pseudomonas fluorescens, Gram positive bacteria: Staphylococcus aureus, and also against fungi, that is, C. albicans and A. niger. Some of the metal complexes show significant antifungal activity (MIC < 0.2 μg/mL). The “in vitro” data has identified [Zn(NMAPIMHMC)2]·2H2O, [Zn(TMPIMP)2]·2H2O, and [Zn(HBABO)2]·2H2O as potential therapeutic antifungal agents against C. albicans and A. niger. PMID:24707242

  1. Coordination Chemistry of Polyaromatic Thiosemicarbazones 2: Synthesis and Biological Activity of Zinc, Cobalt, and Copper Complexes of 1-(Naphthalene-2-ylethanone Thiosemicarbazone

    Marc-Andre LeBlanc


    Full Text Available A novel thiosemicarbazone from 2-acetonaphthone (represented as acnTSC has been synthesized and its basic coordination chemistry with zinc(II, cobalt(II, and copper(II explored. The complexes were characterized by elemental analysis and various spectroscopic techniques and are best formulated as [M(acnTSC2Cl2] with the metal likely in an octahedral environment. The anticancer activity of the complexes was determined against a panel of human colon cancer cells (HCT-116 and Caco-2. The compounds bind to DNA via an intercalative mode with binding constants of 9.7×104 M-1, 1.8×105 M-1, and 9.5×104 M-1 for the zinc, cobalt, and copper complexes, respectively.

  2. Radical pathway in catecholase activity with zinc-based model complexes of compartmental ligands.

    Guha, Averi; Chattopadhyay, Tanmay; Paul, Nanda Dulal; Mukherjee, Madhuparna; Goswami, Somen; Mondal, Tapan Kumar; Zangrando, Ennio; Das, Debasis


    Four dinuclear and three mononuclear Zn(II) complexes of phenol-based compartmental ligands (HL(1)-HL(7)) have been synthesized with the aim to investigate the viability of a radical pathway in catecholase activity. The complexes have been characterized by routine physicochemical studies as well as X-ray single-crystal structure analysis: [Zn(2)(H(2)L(1))(OH)(H(2)O)(NO(3))](NO(3))(3) (1), [Zn(2)L(2)Cl(3)] (2), [Zn(2)L(3)Cl(3)] (3), [Zn(2)(L(4))(2)(CH(3)COO)(2)] (4), [Zn(HL(5))Cl(2)] (5), [Zn(HL(6))Cl(2)] (6), and [Zn(HL(7))Cl(2)] (7) [L(1)-L(3) and L(5)-L(7) = 2,6-bis(R-iminomethyl)-4-methylphenolato, where R= N-ethylpiperazine for L(1), R = 2-(N-ethyl)pyridine for L(2), R = N-ethylpyrrolidine for L(3), R = N-methylbenzene for L(5), R = 2-(N-methyl)thiophene for L(6), R = 2-(N-ethyl)thiophene for L(7), and L(4) = 2-formyl-4-methyl-6-N-methylbenzene-iminomethyl-phenolato]. Catecholase-like activity of the complexes has been investigated in methanol medium by UV-vis spectrophotometric study using 3,5-di-tert-butylcatechol as model substrate. All complexes are highly active in catalyzing the aerobic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylbenzoquinone (3,5-DTBQ). Conversion of 3,5-DTBC to 3,5-DTBQ catalyzed by mononuclear complexes (5-7) is observed to proceed via formation of two enzyme-substrate adducts, ES1 and ES2, detected spectroscopically, a finding reported for the first time in any Zn(II) complex catalyzed oxidation of catechol. On the other hand, no such enzyme-substrate adduct has been identified, and 3,5-DTBC to 3,5-DTBQ conversion is observed to be catalyzed by the dinuclear complexes (1-4) very smoothly. EPR experiment suggests generation of radicals in the presence of 3,5-DTBC, and that finding has been strengthened by cyclic voltammetric study. Thus, it may be proposed that the radical pathway is probably responsible for conversion of 3,5-DTBC to 3,5-DTBQ promoted by complexes of redox-innocent Zn(II) ion. The ligand

  3. In vitro DNA binding studies of the sweetening agent saccharin and its copper(II) and zinc(II) complexes.

    Icsel, Ceyda; Yilmaz, Veysel T


    The interactions of fish sperm DNA (FS-DNA) with the sodium salt of sweetener saccharin (sacH) and its copper and zinc complexes, namely [M(sac)2(H2O)4]·2H2O (M=Cu(II) or Zn(II)) were studied by using UV-Vis titration, fluorometric competition, thermal denaturation, viscosity and gel electrophoresis measurements. The intrinsic binding constants (Kb) obtained from absorption titrations were estimated to be 2.86 (±0.06)×10(4)M(-1) for Na(sac), 6.67 (±0.12)×10(4)M(-1) for Cu-sac and 4.01 (±0.08)×10(4)M(-1) for Zn-sac. The Cu-sac complex binds to FS-DNA via intercalation with a KA value of 50.12 (±0.22)×10(4)M(-1) as evidenced by competitive binding studies with ethidium bromide. Moreover, competition experiments with Hoechst 33258 are indicative of a groove binding mode of Na(sac) and Zn-sac with binding constants of 3.13 (±0.16)×10(4)M(-1) and 5.25 (±0.22)×10(4)M(-1), respectively. The spectroscopic measurements indicate a moderate DNA binding affinity of Na(sac) and its metal complexes. The suggested binding modes are further confirmed by the thermal denaturation and viscosity measurements. In addition, Cu-sac and Zn-sac show weak ability to damage to pBR322 supercoiled plasmid DNA.

  4. Electrochemical investigation of the surface-modifying roles of guanidine carbonate in chemical mechanical planarization of tantalum

    Rock, S.E.; Crain, D.J.; Zheng, J.P. [Department of Physics, Clarkson University, Potsdam, NY 13699-5820 (United States); Pettit, C.M. [Department of Physics, Emporia State University, Emporia, KS 66801-5087 (United States); Roy, D., E-mail: [Department of Physics, Clarkson University, Potsdam, NY 13699-5820 (United States)


    Highlights: {yields} This work contributes to the development of CMP slurries for Ta and Cu at low pressure. {yields} We present here a model of the chemical mechanism of the CMP of Ta and Cu using guanidine slurries. {yields} Removal of Ta occurs as structurally weak guanidinium-tantalic-acid surface complexes. {yields} The results will be useful for the CMP processing of interconnects with low-k dielectrics. {yields} We demonstrate the utility of electro-analytical techniques in the development of CMP slurries. - Abstract: The fabrication of interconnect structures for semiconductor devices requires low down-pressure chemical mechanical planarization (CMP) of Ta barrier layers. Guanidine carbonate (GC) serves as an effective surface-complexing agent for such CMP applications, where the rate of Ta removal can be chemically controlled through pH-tuned selectivity with respect to the removal of Cu lines. Electrochemical techniques are employed in this work to study the surface-modifying roles of GC that make this chemical an attractive complexing agent for Ta CMP. In addition, the effects of including H{sub 2}O{sub 2} (an oxidizer) and dodecyl benzene sulfonic acid (DBSA, a dissolution inhibitor for Cu) in GC-based CMP solutions are investigated to examine the selective CMP mechanisms of Ta and Cu in these solutions. The results suggest that the removal of Ta is supported in part by structurally weak guanidinium-tantalic-acid surface complexes formed on Ta/Ta{sub 2}O{sub 5}. The bicarbonate/carbonate anions of GC also facilitate Ta removal through the generation of ion-incorporated tantalum pentoxide. DBSA strongly affects the CMP chemistry of Cu, but exhibits relatively weaker effects on the surface activity of Ta, and thus plays a vital role in dictating the selectivity of Ta:Cu polish rates.

  5. Synthesis and Uncommon Structural Characterization of Novel Zinc and Cadmium Complexes with Imino Nitroxide Radical

    WANG Shu-Ping; GAO Dong-Zhao; LIAO Dai-Zheng; JIANG Zong-Hui; YAN Shi-Ping


    Two novel complexes {[Zn(IM4py)2(tp)(H2O)]·2H2O}n 1 and {[Cd(IM4py)2(tp)- (H2O)]·1.25H2O}n 2 (IM4py=2-(4'-pyridinyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and tp=terephthalate dianion) have been synthesized and characterized by elemental analyses, IR spectrum and single-crystal X-ray diffraction. Crystal data for complex 1: monoclinic, space group C2/c, a=20.648(7), b=12.130(4), c=14.036(4) (A), β=106.351(5)°, C32H42N6O9Zn, Mr=720.09, V=3373.3(2) (A)3, Z=4, Dc=1.418 g/cm3, μ(MoKα)= 0.790 mm-1, F(000)=1512, the final R=0.0407 and Wr=0.0894 for 3480 independent reflections with Rint=0.0432. Crystal data for complex 2: monoclinic, space group C2/c, a=21.332(6), b=12.063(3), c=14.246(4) (A), β=106.704(4)°, C32H40.50N6O8.25Cd, Mr=753.60, V=3511.2(2) (A)3, Z=4, Dc=1.426 g/cm3, μ(MoKα)= 0.679 mm-1, F(000)=1554, the final R=0.0419 and Wr=0.0961 for 3627 independent reflections with Rint=0.0440. The framework structures of complexes 1 and 2 are 3-D networks via the hydrogen bonds among 1-D chains. The notable characteristics of the two complexes are that the coordination polyhedron of Zn(Ⅱ) adopts a rare distorted five-coordinate square pyramidal geometry in 1, and the Cd(Ⅱ) complex exhibits an unusual distorted seven-coordinate pentagonal bipyramid in 2.

  6. Tris (isodecyl) guanidine degradation in the MCU system

    Peters, T. B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)


    The current solvent blend consists of four components; an extractant, the modifier, a suppressor, and the diluent. Of the four components, only the suppressor – tris(isodecyl)guanidine (TiDG) has exhibited an appreciable depletion rate during facility operations.∇ Using data derived from MCU process samples, SRNL derived a method to predict the TiDG depletion based upon time and volume of feed processed. With the current data set, the following formula can estimate the TiDG concentrations after processing: At = [A0×exp(-0.000900×t)] – [5.39E-06×volume] where At is the TiDG concentration (mM) at time t (days), A0 is the TiDG concentration (mM) at time = 0, and volume is the amount of salt solution processed in gallons from time 0 to time t. The ability to use this formula as a predictive tool is limited due to the number of data points obtained for this scope of work. As such, this formula should not be used to precisely predict future TiDG concentrations.

  7. Structural Determination of Bis-histidinopeptide Zinc Complexes by 15N NMR (HMBC) Spectra

    ZHOU,Cheng-He; Juan F.Miravet; M.Isabel Burguete; Santiago V.Luis; BAI,Xue; YUAN,Yong


    @@ Polynitrogen receptors such as bis-histidine peptides possess strong ability to bind metals, which play much important roles in medicinal, bioinorganic, bioorganic, biomimetic and supramolecular chemistry. In order to investigate the interaction of these hosts with a variety of neutral, cationic and anionic guests, several techniques, for example, NMR,potentiometric tirations and monocrystal X-ray diffraction have been employed. Among them NMR is a powerful technique for unraveling the structure of polynitrogen receptors as long as they are in solution where the rapid tumbling of molecules averages out the anisotropies such as chemical shift and dipole-dipole interactions. General 1H NMR approach has been widely used for the study of host-guest interaction, but it is difficult for the accurate measurement in complexes structures, particularly metal complexes structures in which how the polynitrogen receptors bind metal, and which nitrogen binds metal and so on.

  8. The role of zinc on the chemistry of complex intermetallic compounds

    Xie, Weiwei [Iowa State Univ., Ames, IA (United States)


    Combining experiments and electronic structure theory provides the framework to design and discover new families of complex intermetallic phases and to understand factors that stabilize both new and known phases. Using solid state synthesis and multiple structural determinations, ferromagnetic β-Mn type Co8+xZn12–x was analyzed for their crystal and electronic structures.

  9. Application of a topical biomimetic electrical signaling technology to photo-aging: a randomized, double-blind, placebo-controlled trial of a galvanic zinc-copper complex.

    Chantalat, Jeannette; Bruning, Elizabeth; Sun, Ying; Liu, Jue-Chen


    The first signs of facial skin photo-aging often occur in the skin of the periorbital area and include sagging, loss of firmness and definition, and sallowness. Epidermal wounds have been shown to alter the trans-epithelial electrical potential creating an electric signal that directs cell migration in epithelial wound healing; this electric field declines sharply with age. A topical galvanic zinc-copper complex, which couples elemental zinc and copper to create a biomimetic electric field, has demonstrated anti-inflammatory activity and extracellular matrix improvement in vitro, including collagen and elastin production. To evaluate the efficacy and tolerability of a galvanic zinc-copper complex on photo-aging parameters in a randomized, double-blind, placebo-controlled clinical trial. In this eight-week study, women (40-65 years) with mild to moderate photo-aging were randomized to use placebo or 1 of 3 galvanic zinc-copper complex compositions (gel and activating moisturizer). Efficacy evaluations included clinical grading, specialized clinical imaging, and subject self-assessments performed at baseline, 15-30 minutes after product application and after 1, 2, 4, and 8 weeks. Tolerability was based on adverse events and clinical grading of irritation. Significance was set at P?0.05 versus baseline and between treatment groups. The study was completed by 124 women. Compositions containing the galvanic zinc-copper complex showed statistically significant clinical improvements versus placebo and baseline rapidly (15-30 min) after application and through week 8. Clinical grading showed significant improvement versus placebo in skin radiance and under-eye dark circles 15-30 minutes after first application with continued improvement through week 8, and in overall photo-damage, fine lines, lifted appearance of the eyes, and under-eye wrinkles starting after two weeks and continuing through week 8. Test compositions were well tolerated. This galvanic zinc-copper complex

  10. N,N’-diisopropylthiourea and N,N’-dicyclohexyl-thiourea zinc(II complexes as precursors for the synthesis of ZnS nanoparticles

    J. Raftery


    Full Text Available The single X-ray crystal structures of zinc (II complexes of N,N’-diisopropylthiourea and N,N’ dicyclohexylthiourea weredetermined.These complexes, similar to other alkylthioureas, were found to be effective as precursors for the preparation of hexadecylamine-capped ZnS nanoparticles. The complexes are air-stable, easy to prepare and inexpensive. They pyrolyse cleanly to give high-quality ZnS nanoparticles, which show quantum confinement effects in their absorption spectra and close to band-edge emission. Their broad diffraction patterns are typicalof nanosized particles while their transmission electronmicroscopy images showed agglomerates of needle-like platelet nanoparticles.

  11. Synthesis and physico-chemical characterization of zinc(II, nickel(II and cobalt(II complexes with 2-phenyl-2-imidazoline

    Podunavac-Kuzmanović Sanja O.


    Full Text Available Chlorides and nitrates of zinc(II, nickel(II and cobalt(II react with 2-phenyl-2-imidazoline to give complexes of the type [ML2X2]·nH2O (M=Zn, Ni or Co; L=2-phenyl-2-imidazoline; X=Cl or NO3; n=0, 1 or 2. The complexes were synthesized and characterized by elemental analysis of the metal molar conductivity, magnetic susceptibility measurements and IR spectra. The molar conductances of the zinc(II complexes in DMF solutions indicate that the complexes behave as non-electrolytes. The values of magnetic conductivity in the case of nickel(II complexes indicate that one of the coordinated anions (chloride or nitrate has been replaced by DMF molecule. The molar conductivity values of cobalt(II complexes indicate the partial substitution of coordinated anions with solvent molecules. The room temperature effective magnetic moments and IR data of the complexes suggest that all Zn(II, Ni(II and Co(II complexes have a tetrahedral configuration, which is realized by participation of the pyridine nitrogen of two organic ligand molecules, and two chloride or nitrate anions typical for these classes of organic ligands.

  12. Preparation of Zinc Oxide (ZnO) Thin Film as Transparent Conductive Oxide (TCO) from Zinc Complex Compound on Thin Film Solar Cells: A Study of O2 Effect on Annealing Process

    Muslih, E. Y.; Kim, K. H.


    Zinc oxide (ZnO) thin film as a transparent conductive oxide (TCO) for thin film solar cell application was successfully prepared through two step preparations which consisted of deposition by spin coating at 2000 rpm for 10 second and followed by annealing at 500 °C for 2 hours under O2 and ambient atmosphere. Zinc acetate dehydrate was used as a precursor which dissolved in ethanol and acetone (1:1 mol) mixture in order to make a zinc complex compound. In this work, we reported the O2 effect, reaction mechanism, structure, morphology, optical and electrical properties. ZnO thin film in this work shows a single phase of wurtzite, with n-type semiconductor and has band gap, carrier concentration, mobility, and resistivity as 3.18 eV, 1.21 × 10-19cm3, 11 cm2/Vs, 2.35 × 10-3 Ωcm respectively which is suitable for TCO at thin film solar cell.

  13. Synthesis and molecular structure of a zinc complex of the vitamin K3 analogue phthiocol

    Kathawate, Laxmi; Sproules, Stephen; Pawar, Omkar; Markad, Ganesh; Haram, Santosh; Puranik, Vedavati; Salunke-Gawali, Sunita


    The complex [Zn(phthiocol)2(H2O)2]; 1, where phthiocol is 2-hydroxy-3-methyl-1,4-naphthoquinone, has been synthesized and characterized by elemental analysis, FT-IR, 1H NMR, UV-vis spectroscopy, thermogravimetric (TG) analysis, electrochemical and single crystal X-ray diffraction studies. The νCO stretch shifts to lower frequencies upon complexation of phthiocol to Zn2+. 1H NMR spectra show an upfield shift of the benzenoid ring protons in 1. There is a bathochromic shift of the LMCT band in the UV-vis spectra of 1. Single crystal X-ray structure of 1 show distorted octahedral geometry around Zn2+. Two phthiocol ligands are in plane with the metal, while water molecules are trans to this plane. Coordination of deprotonated phthiocol ligands is 'trans, trans' to Zn2+. Intra as well as intermolecular interactions are observed in 1. Molecules of 1 show three dimensional network through CH⋯O and OH⋯O interactions. Additional anodic peaks are observed in cyclic voltammogram of phthiocol ligand due to oxidation of reduced species formed during reduction. One-electron reduction of 1 is shown to be reversible and DFT studies define this redox event as ligand-centered.

  14. Iron and zinc complexation in wild-type and ferritin-expressing wheat grain: implications for mineral transport into developing grain

    Neal, Andrew L; Geraki, Kalotina; Borg, Søren


    We have used synchrotron-based X-ray fluorescence and absorption techniques to establish both metal distribution and complexation in mature wheat grains. In planta, extended X-ray absorption fine structure (EXAFS) spectroscopy reveals iron phytate and zinc phytate structures in aleurone cells...... of ferritin-expressing grains is quite different from that in wild-type grain. This may explain why the raised levels of minerals transported to the developing grain accumulate within the crease region of the transgenic grain....

  15. Carboxylated dithiafulvenes and tetrathiafulvalene vinylogues: synthesis, electronic properties, and complexation with zinc ions

    Yunfei Wang


    Full Text Available A class of carboxyl and carboxylate ester-substituted dithiafulvene (DTF derivatives and tetrathiafulvalene vinylogues (TTFVs has been synthesized and their electronic and electrochemical redox properties were characterized by UV–vis spectroscopic and cyclic voltammetric analyses. The carboxyl-TTFV was applied as a redox-active ligand to complex with Zn(II ions, forming a stable Zn-TTFV coordination polymer. The structural, electrochemical, and thermal properties of the coordination polymer were investigated by infrared spectroscopy, cyclic voltammetry, powder X-ray diffraction, and differential scanning calorimetric analyses. Furthermore, the microscopic porosity and surface area of the Zn-TTFV coordination polymer were measured by nitrogen gas adsorption analysis, showing a BET surface of 148.2 m2 g−1 and an average pore diameter of 10.2 nm.

  16. Self-assembly of a helical zinc-europium complex: speciation in aqueous solution and luminescence

    Emmanuel eDeiters


    Full Text Available Two new tridentate(NNO-bidentate(NN compartmental ligands, HL5 and HL6, are synthesized from pyridine and benzimidazole synthons. They react in aqueous solution under physiological conditions with ZnII, LnIII, or a mixture thereof, to yield complexes of different stoichiometries, 1:3, 2:2, 2:3, 1:1:3, the speciation of which is established by UV-visible titrations and ESI mass spectrometry. Photophysical studies of the EuIII-containing solutions in Tris-HCl 0.1 M (pH = 7.4 show that lanthanide luminescence arises from a unique N6O3 coordination site with pseudo D3 symmetry. Relevant parameters such as crystal field splitting, lifetime, radiative lifetime and intrinsic quantum yield perfectly match those reported for dinuclear 4f-4f helicates in which the EuIII ion has the same coordination environment.

  17. Human ABCB1 confers cells resistance to cytotoxic guanidine alkaloids from Pterogyne nitens.

    Satake, Kazuhiro; Tsukamoto, Megumi; Mitani, Yuji; Regasini, Luis Octavio; da Silva Bolzani, Vanderlan; Efferth, Thomas; Nakagawa, Hiroshi


    Multidrug resistance (MDR) caused by human ABCB1 (P-glycoprotein/MDR1) is one of the major obstacles in chemotherapy. To understand the mechanism of MDR by ABCB1 and circumvent the MDR, in the present study, we established human ABCB1-expressing cells (Flp-In-293/ABCB1 cells) and examined the cytotoxic effects of four guanidine alkaloids from Pterogyne nitens (galegine, nitensidine A, pterogynidine and pterogynine) using Flp-In-293/Mock and Flp-In-293/ABCB1 cells. The activity of ABCB1 in Flp-In-293/ABCB1 cells were confirmed by typical substrates for ABCB1 (taxol and vinblastine) in MTT assay. Flp-In-293/ABCB1 cells were also resistant to the four guanidine alkaloids as well as taxol and vinblastine compared to Flp-In-293/Mock cells although the four guanidine alkaloids exhibited cytotoxicity against the two Flp-In-293 cells. Furthermore, the four guanidine alkaloids were also found to stimulate the ATPase activity of ABCB1 in ATPase assays. These results suggest that ABCB1 can confer the resistance to the cytotoxic guanidine alkaloids by transporting them.

  18. Metal-Based Biologically Active Compounds: Synthesis, Spectral, and Antimicrobial Studies of Cobalt, Nickel, Copper, and Zinc Complexes of Triazole-Derived Schiff Bases

    Kiran Singh


    Full Text Available A series of cobalt, nickel, copper, and zinc complexes of bidentate Schiff bases derived from the condensation reaction of 4-amino-5-mercapto-3-methyl/ethyl-1,2,4-triazole with 2,4-dichlorobenzaldehyde were synthesized and tested as antimicrobial agents. The synthesized Schiff bases and their metal complexes were characterized with the aid of elemental analyses, magnetic moment measurements, spectroscopic and thermogravimetric techniques. The presence of coordinated water in metal complexes was supported by infrared and thermal gravimetric studies. A square planar geometry was suggested for Cu(II and octahedral geometry proposed for Co(II, Ni(II, and Zn(II complexes. The Schiff bases and their metal complexes have been screened for antibacterial (Pseudomonas aeruginosa, Bacillus subtilis and antifungal activities (Aspergillus niger, A. flavus. The metal complexes exhibited significantly enhanced antibacterial and antifungal activity as compared to their simple Schiff bases.

  19. Mechanistic implications in the phosphatase activity of Mannich-based dinuclear zinc complexes with theoretical modeling.

    Sanyal, Ria; Zhang, Xuepeng; Kundu, Priyanka; Chattopadhyay, Tanmay; Zhao, Cunyuan; Mautner, Franz A; Das, Debasis


    An "end-off" compartmental ligand has been synthesized by an abnormal Mannich reaction, namely, 2-[bis(2-methoxyethyl)aminomethyl]-4-isopropylphenol yielding three centrosymmetric binuclear μ-phenoxozinc(II) complexes having the molecular formula [Zn2(L)2X2] (Zn-1, Zn-2, and Zn-3), where X = Cl(-), Br (-), and I (-), respectively. X-ray crystallographic analysis shows that the ZnO3NX chromophores in each molecule form a slightly distorted trigonal-bipyramidal geometry (τ = 0.55-0.68) with an intermetallic distance of 3.068, 3.101, and 3.083 Å (1-3, respectively). The spectrophotometrical investigation on their phosphatase activity established that all three of them possess significant hydrolytic efficiency. Michaelis-Menten-derived kinetic parameters indicate that the competitiveness of the rate of P-O bond fission employing the phosphomonoester (4-nitrophenyl)phosphate in 97.5% N,N-dimethylformamide is 3 > 1 > 2 and the kcat value lies in the range 9.47-11.62 s(-1) at 298 K. Theoretical calculations involving three major active catalyst forms, such as the dimer-cis form (D-Cis), the dimer-trans form (D-Trans), and the monoform (M-1 and M-2), systematically interpret the reaction mechanism wherein the dimer-cis form with the binuclear-bridged hydroxide ion acting as the nucleophile and one water molecule playing a role in stabilizing the leaving group competes as the most favored pathway.

  20. Russian Nesting Doll Complexes of Molecular Baskets and Zinc Containing TPA Ligands.

    Zhiquan, Lei; Polen, Shane; Hadad, Christopher M; RajanBabu, T V; Badjić, Jovica D


    In this study, we examined the structural and electronic complementarities of convex 1-Zn(II), comprising functionalized tris(2-pyridylmethyl)amine (TPA) ligand, and concave baskets 2 and 3, having glycine and (S)-alanine amino acids at the rim. With the assistance of (1)H NMR spectroscopy and mass spectrometry, we found that basket 2 would entrap 1-Zn(II) in water to give equimolar 1-Zn⊂2in complex (K = (2.0 ± 0.2) × 10(3) M(-1)) resembling Russian nesting dolls. Moreover, C3 symmetric and enantiopure basket 3, containing (S)-alanine groups at the rim, was found to transfer its static chirality to entrapped 1-Zn(II) and, via intermolecular ionic contacts, twist the ligand's pyridine rings into a left-handed (M) propeller (circular dichroism spectroscopy). With molecular baskets embodying the second coordination sphere about metal-containing TPAs, the here described findings should be useful for extending the catalytic function and chiral discrimination capability of TPAs.

  1. Differential effects of zinc and magnesium ions on mineralization activity of phosphatidylserine calcium phosphate complexes.

    Wu, Licia N Y; Genge, Brian R; Wuthier, Roy E


    Mg(2+) and Zn(2+) are present in the mineral of matrix vesicles (MVs) and biological apatites, and are known to influence the onset and progression of mineral formation by amorphous calcium phosphate (ACP) and hydroxyapatite (HAP). However, neither has been studied systematically for its effect on mineral formation by phosphatidylserine-Ca(2+)-Pi complexes (PS-CPLX), an important constituent of the MV nucleation core. Presented here are studies on the effects of increasing levels of Mg(2+) and Zn(2+) on the process of mineral formation, either when present in synthetic cartilage lymph (SCL), or when incorporated during the formation of PS-CPLX. Pure HAP and PS-CPLX proved to be powerful nucleators, but ACP took much longer to induce mineral formation. In SCL, Mg(2+) and Zn(2+) had significantly different inhibitory effects on the onset and amount of mineral formation; HAP and PS-CPLX were less affected than ACP. Mg(2+) and Zn(2+) caused similar reductions in the rate and length of rapid mineral formation, but Zn(2+) was a more potent inhibitor on a molar basis. When incorporated into PS-CPLX, Mg(2+) and Zn(2+) caused significantly different effects than when present in SCL. Even low, subphysiological levels of Mg(2+) altered the inherent structure of PS-CPLX and markedly reduced its ability to induce and propagate mineral formation. Incorporated Zn(2+) caused significantly less effect, low (<20 microM) levels causing almost no inhibition. Levels of Zn(2+) present in MVs do not appear to inhibit their nucleational activity.

  2. Separation of copper, iron, and zinc from complex aqueous solutions for isotopic measurement

    Borrok, D.M.; Wanty, R.B.; Ridley, W.I.; Wolf, R.; Lamothe, P.J.; Adams, M.


    The measurement of Cu, Fe, and Zn isotopes in natural samples may provide valuable information about biogeochemical processes in the environment. However, the widespread application of stable Cu, Fe, and Zn isotope chemistry to natural water systems remains limited by our ability to efficiently separate these trace elements from the greater concentrations of matrix elements. In this study, we present a new method for the isolation of Cu, Fe, and Zn from complex aqueous solutions using a single anion-exchange column with hydrochloric acid media. Using this method we are able to quantitatively separate Cu, Fe, and Zn from each other and from matrix elements in a single column elution. Elution of the elements of interest, as well as all other elements, through the anion-exchange column is a function of the speciation of each element in the various concentrations of HCl. We highlight the column chemistry by comparing our observations with published studies that have investigated the speciation of Cu, Fe, and Zn in chloride solutions. The functionality of the column procedure was tested by measuring Cu, Fe, and Zn isotopes in a variety of stream water samples impacted by acid mine drainage. The accuracy and precision of Zn isotopic measurements was tested by doping Zn-free stream water with the Zn isotopic standard. The reproducibility of the entire column separation process and the overall precision of the isotopic measurements were also evaluated. The isotopic results demonstrate that the Cu, Fe, and Zn column separates from the tested stream waters are of sufficient purity to be analyzed directly using a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS), and that the measurements are fully-reproducible, accurate, and precise. Although limited in scope, these isotopic measurements reveal significant variations in ??65Cu (- 1.41 to + 0.30???), ??56Fe (- 0.56 to + 0.34???), and ??66Zn (0.31 to 0.49???) among samples collected from different

  3. Dynamic Assembly Inclusion Complexes of Tweezer-type Bis(zinc porphyrin) with 5,15-Di(4-pyridyl)porphyrin Derivatives

    ZHOU,Zai-Chun; YANG,Yi; ZHU,Yi-Zhou; ZHENG,Jian-Yu


    Dynamic assembly inclusion complexes of tweezer-type bis(zinc porphyrin) (1) with di(4-pyridyl)porphyrin derivatives have been designed and constructed. The complexes are induced by Zn-N coordination, and the weak binding allows the large-size di(4-pyridyl)poiphyrin guests in random rotation. Dynamic characteristics of these assemblies, such as ligand exchange and dynamic fluorescence quenching, have been investigated by 'H NMR, UV-Vis and fluorescence spectra. The stability of such assembly has pronounced dependence on the size-matching effect and thermal effect.

  4. Zinc finger domain of Su(Hw) protein is required for the formation of functional Su(Hw)-dependent insulator complex.

    Golovnin, A K; Molodina, V V; Georgiev, P G; Melnikova, L S


    This study is devoted to clarifying the role of Mod(mdg4)-67.2 and Su(Hw) proteins in the interaction between Su(Hw)-dependent insulator complexes and identifying the specific domains of the Su(Hw) protein required for insulation or mutual neutralization of insulators. Using genetic techniques and experiments in yeast two-hybrid system, we have demonstrated that the zinc finger domain of the Su(Hw) protein is involved in forming a functional insulator complex and cannot be replaced with the DNA-binding domain of the GAL4 protein.

  5. Synthesis and structure elucidation of fluoro substituted guanidines as potential therapeutic agents

    Ullah, Waseem; Imtiaz-ud-Din; Raheel, Ahmad; Badshah, Amin; Tahir, Muhammad Nawaz


    Six new fluoro -substituted guanidines (1-6) were synthesized and characterized by 1H and 13C NMR spectroscopy to ascertain the structures in solution (DMSO) besides the solid state information collected through FT IR and single crystal X-ray spectroscopy. The XRD data for (1-3) show that molecules are stabilized by strong intramolecular hydrogen bonding. The compounds were also preliminary bio-assayed for anti-microbial studies and show good to moderate activities. The anti-oxidant data revealed that o and p-substituted fluoro-guanidines enhances their DPPH scavenging ability significantly.

  6. Macrocyclic prolinyl acyl guanidines as inhibitors of β-secretase (BACE).

    Boy, Kenneth M; Guernon, Jason M; Wu, Yong-Jin; Zhang, Yunhui; Shi, Joe; Zhai, Weixu; Zhu, Shirong; Gerritz, Samuel W; Toyn, Jeremy H; Meredith, Jere E; Barten, Donna M; Burton, Catherine R; Albright, Charles F; Good, Andrew C; Grace, James E; Lentz, Kimberley A; Olson, Richard E; Macor, John E; Thompson, Lorin A


    The synthesis, evaluation, and structure-activity relationships of a class of acyl guanidines which inhibit the BACE-1 enzyme are presented. The prolinyl acyl guanidine chemotype (7c), unlike compounds of the parent isothiazole chemotype (1), yielded compounds with good agreement between their enzymatic and cellular potency as well as a reduced susceptibility to P-gp efflux. Further improvements in potency and P-gp ratio were realized via a macrocyclization strategy. The in vivo profile in wild-type mice and P-gp effects for the macrocyclic analog 21c is presented.

  7. Synthesis and characterization of strontium and barium guanidinate; Synthese und Charakterisierung von Strontium- und Bariumguanidinat

    Missong, Ronja


    After investigation of the mono-alkali-metal guanidinates in recent years and the structural properties of the various compounds by means of X-ray and neutron diffraction, the guanidinates of the alkaline earth metals seemed to be well investigated. The synthesis of the mono-alkali-metal guanidinates in liquid ammonia has been further developed for the alkaline earth metal guanidinates. Strontium guanidinate was used for the first time to synthesize a compound with a twofold deprotonated guanidinate anion and to study the structure of this compound by means of spectroscopic analysis and different diffraction methods. The structure model was generated from X-ray powder diffraction data, supplemented by density function theory with the help of hydrogen position and subsequently refined and validated with highly resolved neutron diffraction data. The anion has the predicted C3h symmetry and thus resembles the appearance of a Trinacria. The compound of the barium guanidinate with the desired composition Ba (CN3H4) 2 was also investigated by means of IR spectroscopy and different diffraction methods. Structural proposals were developed from X-ray and flight time neutron diffraction data. However, the results of the refinements of these proposals were not satisfactory. In some structure-chemical aspects, however, the individual structural proposals nevertheless produced a uniform picture. The close relationship between the various structural proposals suggests that a final structure could be in many respects consistent with the various structural proposals. [German] Nachdem die Monoalkaliguanidinate in den letzten Jahren untersucht wurden und die strukturellen Eigenschaften der verschiedenen Verbindungen mittels Roentgen- und Neutronenbeugung aufgeklaert werden konnten, schien es aussichtsreich auch die Guanidinate der Erdalkalimetalle zu untersuchen. Die Synthese der Monoalkaliguanidinate in fluessigem Ammoniak wurde fuer die Erdalkalimetallguanidinate weiter entwickelt

  8. A facile synthesis of imino-protected cyclic guanidine derivatives from diamines

    Jian Hai Yuan; Xiao Xiao Yang; Hao Lin; De Xin Wang


    A convenient one-step synthesis of five-membered or six-membered imino-protected cyclic guanidine via an intramolecular ring-closure reaction of alkyl diamine (2a-2g) with 1, 3-diamino-protected methylisothiourea (la and 1b) was established and investigated. Amino guanidine such as 3-(2-aminoethyl)-l, 2-dibenzyloxycarbonylguanidine (4a) has been proved to be the intermediate of the reaction via utilizing mono-protected diamine as starting material. The intramolecular ring closure of 4a results in 2-benzyloxycarbonyliminoimidazolidine (3a). This new one-step synthesis has advantages of simple condition, easy workup procedure and reasonable yield.

  9. Synthesis, characterization, and thermal properties of homoleptic rare-earth guanidinates: promising precursors for MOCVD and ALD of rare-earth oxide thin films.

    Milanov, Andrian P; Fischer, Roland A; Devi, Anjana


    Eight novel homoleptic tris-guanidinato complexes M[(N(i)Pr)(2)CNR(2)](3) [M = Y (a), Gd (b), Dy (c) and R = Me (1), Et (2), (i)Pr (3)] have been synthesized and characterized by NMR, CHN-analysis, mass spectrometry and infrared spectroscopy. Single crystal structure analysis revealed that all the compounds are monomers with the rare-earth metal center coordinated to six nitrogen atoms of the three chelating guanidinato ligands in a distorted trigonal prism geometry. With the use of TGA/DTA and isothermal TGA analysis, the thermal characteristics of all the complexes were studied in detail to evaluate their suitability as precursors for thin film deposition by MOCVD and ALD. The (i)Pr-Me(2)N-guanidinates of Y, Gd and Dy (1a-c) showed excellent thermal characteristics in terms of thermal stability and volatility. Additionally, the thermal stability of the (i)Pr-Me(2)N-guanidinates of Y and Dy (1a, c) in solution was investigated by carrying out NMR decomposition experiments and both the compounds were found to be remarkably stable. All these studies indicate that (i)Pr-Me(2)N-guanidinates of Y, Gd and Dy (1a-c) have the prerequisites for MOCVD and ALD applications which were confirmed by the successful deposition of Gd(2)O(3) and Dy(2)O(3) thin films on Si(100) substrates. The MOCVD grown films of Gd(2)O(3) and Dy(2)O(3) were highly oriented in the cubic phase, while the ALD grown films were amorphous.

  10. Spectroscopic, crystal structural and electrochemical studies of zinc(II)-Schiff base complex obtained from 2,3-diaminobenzene and 2-hydroxy naphthaldehyde.

    Ouari, Kamel; Bendia, Sabrina; Weiss, Jean; Bailly, Corinne


    Mononuclear zinc(II) complex, [Zn(II)L], where L is a dianionic ligand, has been synthesized and characterized by elemental analysis, electronic, IR and NMR [(1)H, (13)C, DEPT, (1)H-(1)H COSY, ROESY, HSQC and HMBC] spectroscopic techniques. Structural analysis of the complex by single crystal X-ray crystallography shows the presence of a distorted square planar coordination geometry (NNOO) of the metal center. The crystal of the title complex C28H18N2O2Zn belongs to the orthorhombic system with space group Pmn21. Electrochemical behavior of the Zn(II)L complex has been investigated by cyclic voltammetry on glassy carbon and platinum electrodes in DMF at 100 mV/s scan rate.

  11. NMR investigation of dynamic processes in complexes of nickel(II) and zinc(II) with iminodiacetate, n-methyliminodiacetate and n-ethyliminodiacetate

    Wagner, M.R.


    Analysis of oxygen-17 bulk water relaxation rates with an aqueous solution of 1:1 Ni(II):ida reveals that two rate-limiting processes are involved with solvent exchange. Analysis of carbon-13 longitudinal relaxation rates of the bis-ligand complexes with zinc(II) are used to determine molecular tumbling rates and methyl rotation rates. The carbon-13 transverse relaxation rates for the carbons in the bis-ligand complex with Ni(II) are adequately fitted to the Solomon-Bloembergen equation. Three carboxylate carbon peaks are seen with the /sup 13/C spectrum of the 1:2 Ni(II):ida complex, which coalesce into a single peak above about 360 K. The mechanism and rate of ligand exchange are determined for the complexes Zn(II)L/sub 2//sup -2/ (L = mida, eida) in aqueous solution by total lineshape analysis of the proton spectrum at 500 MHz.

  12. Synthesis and characterization of mixed ligand complexes of Zn(II) and Co(II) with amino acids: Relevance to zinc binding sites in zinc fingers

    P Rabindra Reddy; M Radhika; P Manjula


    Mixed ligand complexes of Zn(II) and Co(II) with cysteine, histidine, cysteinemethylester, and histidinemethylester have been synthesized and characterized by elemental analysis, conductivity, magnetic susceptibility measurements, and infrared, 1H NMR, TGA and FAB mass spectra. In these complexes, histidine, and histidinemethylester act as bidentate ligands involving amino and imidazole nitrogens in metal coordination. Similarly, cysteine, and cysteinemethylester also act as bidentate ligands coordinating through thiol sulphur and amino nitrogen. Tetrahedral geometry has been proposed for Zn(II) and Co(II) complexes based on experimental evidence.

  13. Synthesis and characterization of a new zinc(II) complex with tetradentate azo-thioether ligand: X-ray structure, DNA binding study and DFT calculation

    Mondal, Apurba Sau; Pramanik, Ajoy Kumar; Patra, Lakshman; Manna, Chandan Kumar; Mondal, Tapan Kumar


    A new zinc(II) complex, [Zn(L)(H2O)](ClO4) (1) with azo-thioether containing NSNO donor ligand, 3-(2-(2-((pyridin-2-ylmethyl)thio)phenyl)hydrazono)pentane-2,4-dione (HL) is synthesized and characterized by several spectroscopic techniques. The distorted square based pyramidal (DSBP) geometry is confirmed by single crystal X-ray structure. The ability of the complex to bind with CT DNA is investigated by UV-vis method and the binding constant is found to be 4.16 × 104 M-1. Competitive binding study with ethidium bromide (EB) by fluorescence method suggests that the zinc(II) complex efficiently displaces EB from EB-DNA. The Stern-Volmer dynamic quenching constant, Ksv is found to be 1.2 × 104 M-1. Theoretical calculations by DFT and TDDFT/CPCM methods are used to interpret the electronic structure and UV-vis spectrum of the complex.

  14. Carbon dioxide-water oxygen isotope fractionation factor using chlorine trifluoride and guanidine hydrochloride techniques

    Dugan, J.P. Jr.; Borthwick, J.


    A new value for the CO/sub 2/-H/sub 2/O oxygen isotope fractionation factor of 1.04145 +/- 0.000 15 (2sigma) has been determined. The data have been normalized to the V-SMOW/V-SLAP scale and were obtained by measuring isotopic compositions with the guanidine hydrochloride and chlorine trifluoride techniques.


    Borzova N. V.


    Full Text Available The aim of this work was the study of native and galactosidases from Penicillium canescens under denaturing conditions caused by guanidine hydrochloride. Calculation of kinetics and constants of enzymes inactivation was carried out on using experimental kinetic curves of enzyme denaturation. We observed significant differences in the kinetics of inactivation of native and deglycosylated α-galactosidases from P. canescens caused by guanidine hydrochloride. Native enzyme was stable within the selected range of guanidine hydrochloride concentrations (from 0.1 to 3.0 M, retaining no less than 50% of the initial enzyme activity for 3 days. Deglycosylated enzyme preparations were less stable and they lost their activity within 5–30 minutes, when they were treated with guanidine hydrochloride in concentrations above 1 M. Dissociation rate constant of native and deglycosylated forms of the enzyme differed by 10 to 100 folds. It was shown that subunit interactions play a major role in the process of inactivation of the enzyme, and the carbohydrate component is essential for stabilizing of subunit bonds and maintaining conformational stability of the enzyme under denaturing conditions of chemical agents.

  16. Interactions of biocidal guanidine hydrochloride polymer analogs with model membranes: a comparative biophysical study

    Zhongxin Zhou; Anna Zheng; Jianjiang Zhong


    Four synthesized biocidal guanidine hydrochloride polymers with different alkyl chain length,including polyhexamethylene guanidine hydrochloride and its three new analogs,were used to investigate their interactions with phospholipids vesicles mimicking bacterial membrane.Characterization was conducted by using fluorescence dye leakage,isothermal titration calorimetry,and differential scanning calorimetry.The results showed that the gradually lengthened alkyl chain of the polymer increased the biocidal activity,accompanied with the increased dye leakage rate and the increased binding constant and energy change value of polymer-membrane interaction.The polymer-membrane interaction induced the change of pretransition and main phase transition (decreased temperature and increased width) of phospholipids vesicles,suggesting the conformational change in the phospholipids headgroups and disordering in the hydrophobic regions of lipid membranes.The above information revealed that the membrane disruption actions of guanidine hydrochloride polymers are the results of the polymer's strong binding to the phospholipids membrane and the subsequent perturbations of the polar headgroups and hydrophobic core region of the phospholipids membrane.The alkyl chain structure significantly affects the binding constant and energy change value of the polymer-membrane interactions and the perturbation extent of the phospholipids membrane,which lead to the different biocidal activity of the polymer analogs.This work provides important information about the membrane disruption action mechanism of biocidal guanidine hydrochloride polymers.

  17. Elimination of the copper-zinc interference in anodic stripping voltammetry by addition of a complexing agent.

    Brandes Marques, A L; Chierice, G O


    The addition of cyanide and Triton X-100 suppress the formation of the CuZn intermetallic compound in ASV making it possible to determine traces of zinc(II) in the presence of an excess of copper ions. The precision of the method (5%) and the accuracy (error of 1.4%) in sea water are satisfactory.

  18. Mixed metal copper(II)-nickel(II) and copper(II)-zinc(II) complexes of multihistidine peptide fragments of human prion protein.

    Jószai, Viktória; Turi, Ildikó; Kállay, Csilla; Pappalardo, Giuseppe; Di Natale, Giuseppe; Rizzarelli, Enrico; Sóvágó, Imre


    Mixed metal copper(II)-nickel(II) and copper(II)-zinc(II) complexes of four peptide fragments of human prion protein have been studied by potentiometric, UV-vis and circular dichroism spectroscopic techniques. One peptide contained three histidyl residues: HuPrP(84-114) with H85 inside and H96, H111 outside the octarepeat domain. The other three peptides contained two histidyl residues; H96 and H111 for HuPrP(91-115) and HuPrP(84-114)H85A while HuPrP(84-114)H96A contained the histidyl residues at positions 85 and 111. It was found that both histidines of the latter peptides can simultaneously bind copper(II) and nickel(II) ions and dinuclear mixed metal complexes can exist in slightly alkaline solution. One molecule of the peptide with three histidyl residues can bind two copper(II) and one nickel(II) ions. H85 and H111 were identified as the major copper(II) and H96 as the preferred nickel(II) binding sites in mixed metal species. The studies on the zinc(II)-PrP peptide binary systems revealed that zinc(II) ions can coordinate to the 31-mer PrP peptide fragments in the form of macrochelates with two or three coordinated imidazol-nitrogens but the low stability of these complexes cannot prevent the hydrolysis of the metal ion in slightly alkaline solution. These data provide further support for the outstanding affinity of copper(II) ions towards the peptide fragments of prion protein but the binding of nickel(II) can significantly modify the distribution of copper(II) among the available metal binding sites.

  19. A simple and sensitive spectrofluorimetric method for the determination of furosemide using zinc(II)-1,4-bis(imidazol-1-ylmethyl)benzene complexes.

    Liu, Yali; Wang, Huijuan; Wang, Jian; Li, Yuanfang


    A novel spectrofluorometric method for the determination of furosemide (FUR) is described. The method is based on enhancement of fluorescence emission of FUR in the presence of zinc (II) complexes of 1,4-bis(imidazol-1-ylmethyl)benzene. Under optimum conditions, the enhanced fluorescence intensity is linearly related to the concentration of FUR. The proposed method has been successfully applied to the determination of FUR in pharmaceutical preparations. The possible mechanism of this reaction is discussed briefly based on data from fluorescence spectroscopy, UV-vis absorption and infrared spectroscopy. Copyright © 2012 John Wiley & Sons, Ltd.

  20. Syntheses, Characterizations, Crystal Structures and Antibacterial Activities of Two Zinc(Ⅱ) Complexes with a Schiff Base Derived from o-Vanillin and p-Toluidine


    Two new zinc(Ⅱ) complexes, [Zn2L2aCl4]·2[ZnL(CH3OH)Cl2] 1 and [ZnL2(NO3)2] 2,were synthesized by reacting ZnX2·nH2O (X = Cl-, NO3-) and a Schiff base ligand 2-[(4-me-thylphenylimino)methyl]-6-methoxyphenol (C15H15NO2, L) which was obtained by the condensation of o-vanillin (2-hydroxy-3-methoxybenzaldehyde) with p-toluidine. Both 1 and 2 were characterized by single-crystal X-ray diffraction technique, elemental analysis, molar conductance, FT-IR, UV-Vis,1H-NMR spectra and thermogravimetric analysis. The Schiff base ligand and its zinc(Ⅱ) complexes have been tested in vitro to evaluate their antibacterial activity against bacteria, viz., Escherichia Coli,Staphylococcus aureus and Bacillus Subtilis. The results show that these complexes have higher activity than the corresponding free Schiff base ligand against the same bacteria.

  1. Cobalt, nickel, copper and zinc complexes with 1,3-diphenyl-1H-pyrazole-4-carboxaldehyde Schiff bases: antimicrobial, spectroscopic, thermal and fluorescence studies.

    Singh, Kiran; Kumar, Yogender; Puri, Parvesh; Kumar, Mahender; Sharma, Chetan


    Two new Schiff bases of 1,3-diphenyl-1H-pyrazole-4-carboxaldehyde and 4-amino-5-mercapto-3-methyl/H-1,2,4-triazole [HL(1-2)] and their Cobalt, Nickel, Copper and Zinc complexes have been synthesized and characterized by elemental analyses, spectral (UV-vis, IR, (1)H NMR, Fluorescence) studies, thermal techniques and magnetic measurements. A square planar geometry for Cu(II) and octahedral geometry for Co(II), Ni(II) and Zn(II) complexes have been proposed. In order to evaluate the biological activity of Schiff bases and to assess the role of metal ion on biological activity, the pyrazole Schiff bases and their metal complexes have been studied in vitro antibacterial against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and antifungal against Aspergillus niger, and Aspergillus flavus. In most of the cases higher activity was exhibited upon coordination with metal ions.

  2. The synthesis and characterization of complexes of zinc(II, cadmium(II, platinum(II and palladium(II with potassium 3-dithiocarboxy-3-aza-5-aminopentanoate



    Full Text Available Complexes of zinc(II, cadmium(II, platinum(II and palladium(II with a new polydentate dithiocarbamate ligand, 3-dithiocarboxy-3-aza-5-aminopentanoate (daap-, of the type M(daap2·nH2O (M = Zn(II, Cd(II, n = 2, or M = Pt(II, Pd(II, n = 0, have been prepared and characterized by elemental analysis, IR and UV/VIS spectroscopy, as well as magnetic measurements. The spectra of the complexes suggest a bidentate coordination of the daap- ligand to the metal ions via the sulfur atoms of the deprotonated dithiocarbamato group. The fact that under the same experimental conditions its S-methyl ester does not form complexes could be taken as proof of the suggested coordination mode.

  3. Zinc(II) complexes containing bis-benzimidazole derivatives as a new class of apoptosis inducers that trigger DNA damage-mediated p53 phosphorylation in cancer cells.

    Liu, Shenggui; Cao, Wenqiang; Yu, Lianling; Zheng, Wenjie; Li, Linlin; Fan, Cundong; Chen, Tianfeng


    In the present study, two zinc(II) complexes containing bis-benzimidazole derivatives, Zn(bpbp)Cl2 (1) and [Zn(bpbp)2](ClO4)2·CH3CH2OH·H2O (2) (bpbp = 2,6-bis(1-phenyl-1H-benzo[d]imidazol-2-yl)pyridine), have been designed, synthesized and evaluated for their in vitro anticancer activities. The underlying molecular mechanisms through which they caused the cancer cell death were also elucidated. The complexes were identified as potent antiproliferative agents against a panel of five human cancer cell lines by comparing with cisplatin. Complex 2 demonstrated dose-dependent growth inhibition on MCF-7 human breast carcinoma cells with IC50 at 2.9 μM. Despite this potency, the complexes possessed great selectivity between human cancer cells and normal cells. Induction of apoptosis in MCF-7 cells by complex 2 was evidenced by accumulation of sub-G1 cell population, DNA fragmentation and nuclear condensation. Further investigation on intracellular mechanisms revealed that complex 2 was able to induce p53-dependent apoptosis in cancer cells by triggering DNA damage. On the basis of this evidence, we suggest that Zn(II) complexes containing bis-benzimidazole derivatives may be candidates for further evaluation as chemotherapeutic agents for human cancers.

  4. Syntheses and crystal structures of two mixed-ligand dimeric zinc complexes containing a dithiol ligand and an open chain crown ether ligand with terminal quinolyl groups

    Li, Cheng-Juan; Dou, Jian-Min; Li, Da-Cheng; Wang, Da-Qi


    Two mixed-ligand zinc complexes Zn(L)(H 2O)(mnt) ( 1) and Zn(L)(H 2O)(i-mnt) ( 2) (where L=2,6-bis(8'-quinoylyloxymethyl)pyridine, mnt =1,2-dicyanoethylene-1,2-ditholate and i-mnt =1,1-dicyanoethylene-2,2-ditholate) have been synthesized and characterized by elemental analysis, FT-IR spectra, and single-crystal X-ray diffraction. Complexes 1 and 2 both crystallize in the monoclinic system, space group C2/ c and each displays a distorted trigonal bipyramidal around zinc atom. The coordination sphere of Zn is NO 2S 2 type, where the dithiol ligand (mnt or i-mnt) and one terminal quinolyl group of L act as the chelate S, S and N, O donor sets, respectively, besides the coordination water molecules. Furthermore, there are intramolecular H-bonds occurred between the coordination water molecule and the N2, N3 atoms of the L and the molecules of 1 and 2 both form the dimers through the intermolecular π-π stacking interactions.

  5. A novel zinc finger protein Zfp277 mediates transcriptional repression of the Ink4a/arf locus through polycomb repressive complex 1

    Negishi, Masamitsu; Saraya, Atsunori; Mochizuki, Shinobu


    . METHODOLOGY/PRINCIPAL FINDINGS: We examined the function of Zinc finger domain-containing protein 277 (Zfp277), a novel zinc finger protein that interacts with the PcG protein Bmi1. Zfp277 binds to the Ink4a/Arf locus in a Bmi1-independent manner and interacts with polycomb repressor complex (PRC) 1 through......BACKGROUND: Polycomb group (PcG) proteins play a crucial role in cellular senescence as key transcriptional regulators of the Ink4a/Arf tumor suppressor gene locus. However, how PcG complexes target and contribute to stable gene silencing of the Ink4a/Arf locus remains little understood...... direct interaction with Bmi1. Loss of Zfp277 in mouse embryonic fibroblasts (MEFs) caused dissociation of PcG proteins from the Ink4a/Arf locus, resulting in premature senescence associated with derepressed p16(Ink4a) and p19(Arf) expression. Levels of both Zfp277 and PcG proteins inversely correlated...

  6. Administration of zinc complex of acetylsalicylic acid after the onset of myocardial injury protects the heart by upregulation of antioxidant enzymes.

    Korkmaz-Icöz, Sevil; Atmanli, Ayhan; Radovits, Tamás; Li, Shiliang; Hegedüs, Peter; Ruppert, Mihály; Brlecic, Paige; Yoshikawa, Yutaka; Yasui, Hiroyuki; Karck, Matthias; Szabó, Gábor


    We recently demonstrated that the pre-treatment of rats with zinc and acetylsalicylic acid complex in the form of bis(aspirinato)zinc(II) [Zn(ASA)2] is superior to acetylsalicylic acid in protecting the heart from acute myocardial ischemia. Herein, we hypothesized that Zn(ASA)2 treatment after the onset of an acute myocardial injury could protect the heart. The rats were treated with a vehicle or Zn(ASA)2 after an isoproterenol injection. Isoproterenol-induced cardiac damage [inflammatory infiltration into myocardial tissue, DNA-strand breakage evidenced by TUNEL-assay, increased 11-dehydro thromboxane (TX)B2-levels, elevated ST-segment, widened QRS complex and prolonged QT-interval] was prevented by the Zn(ASA)2 treatment. In isoproterenol-treated rats, load-independent left ventricular contractility parameters were significantly improved after Zn(ASA)2. Furthermore, Zn(ASA)2 significantly increased the myocardial mRNA-expression of superoxide dismutase-1, glutathione peroxidase-4 and decreased the level of Na(+)/K(+)/ATPase. Postconditioning with Zn(ASA)2 protects the heart from acute myocardial ischemia. Its mechanisms of action might involve inhibition of pro-inflammatory prostanoids and upregulation of antioxidant enzymes.

  7. Design, synthesis and physico-chemical investigation of a dinuclear zinc(II) complex with a novel ‘end-off’ compartmental ligand

    Anil D Naik; Vidyanand K Revankar


    A novel dinucleating pentadentate Schiff base, resulting from the condensation of 2,6-diformyl--cresol and N-methyl-indolyl-3-thiohydrazide, and its Zn complex have been prepared and characterized on the basis of elemental analysis, IR, UV-Visible, 1H NMR and 13C NMR studies. The ligand is acyclic and consists of a phenolate head unit, with two inbuilt azomethine shoulders and two indole thiohydrazide arms forming SNONS coordinating sites. NMR and IR spectral studies show that the ligand exists in thioketo form. Each Zn ion in the dinuclear core is in tetrahedral environment with endogenous phenolate bridging and exogenous acetate bridging. The zinc complex in DMF exhibits fluorescence.

  8. New tetradentate N,N,N,N-chelating α-diimine ligands and their corresponding zinc and nickel complexes: synthesis, characterisation and testing as olefin polymerisation catalysts.

    Li, Lidong; Gomes, Clara S B; Gomes, Pedro T; Duarte, M Teresa; Fan, Zhiqiang


    A series of zinc complexes of the general formula {[ZnCl(ArN=C(An)-C(An)=NAr)](+)}(2)[Zn(2)Cl(6)](2-) (where Ar = 2-(1-benzyl-1H-1,2,3-triazol-4-yl)phenyl 2a, 2-(1-(1-phenylethyl)-1H-1,2,3-triazol-4-yl)phenyl 2b, 2-(1-phenyl-1H-1,2,3-triazol-4-yl)phenyl 2c; An = acenaphthene backbone) were prepared by the condensation of acenaphthenequinone with the corresponding o-triazolyl-substituted anilines (2-(1-benzyl-1H-1,2,3-triazol-4-yl)aniline 1a, 2-(1-(1-phenylethyl)-1H-1,2,3-triazol-4-yl)aniline 1b, 2-(1-phenyl-1H-1,2,3-triazol-4-yl)aniline 1c) which were formed by the copper(I)-catalyzed Huisgen[3+2] dipolar cycloaddition between 2-ethynylaniline and the corresponding azides in high yields, using anhydrous ZnCl(2) as the metal template, in boiling glacial acetic acid. Zinc complexes of the type [ZnCl(ArN=C(An)-C(An)=NAr)](+)[ZnCl(3)(NCCH(3))](-) (4a-c) were synthesized by crystallisation of the corresponding complexes 2a-c in acetonitrile, at -20 °C. After removal of zinc dichloride from complexes 2a-c by the addition of potassium oxalate, in dichloromethane, the tetradentate N,N,N,N-chelating α-diimine ligands of the type ArN=C(An)-C(An)=NAr (5a-c) were obtained. The new ligand precursors and zinc complexes were characterised by elemental analysis, (1)H and (13)C{(1)H} NMR spectroscopy, two-dimensional NMR spectroscopy, and X-ray diffraction. Reaction of the ligand precursors 5a-c with [NiBr(2)(DME)], in dichloromethane, gave nickel complexes of the type [NiBr(2)(ArN=C(An)-C(An)=NAr)] (6a-c). The results of single crystal X-ray diffraction characterisation and magnetic susceptibility measurements demonstrated that nickel complexes 6a-c possess octahedral geometries around the nickel atoms with variable configurations, the Br atoms of which can be ionized when dissolved in methanol. In preliminary catalytic tests, complexes 6a-c revealed to be active as catalysts for the polymerisation of norbornene and styrene, when activated by cocatalyst MAO. The characterisation

  9. Synthesis, Crystal Structure and Fluorescence Property of a Five- and Six-coordinated Trinuclear Zinc(II) Complex:{[ZnL(OAc)]2Zn}·CH3COCH3

    DONG,Wen-Kui; ZHANG,Yan-Ping; ZHAO,Chun-Yu; TANG,Xiao-Lu; L(U),Zhong-Wu; ZOU,Zheng


    A novel linear trinuclear zinc(II) complex, {[ZnL(OAc)]2Zn}·CH3COCH3 (H2L: ethylenedioxybis(5-bromo-2-hydroxybenzylideneamino)), has been synthesized and structurally characterized. X-ray crystal structure of the complex reveals that three zinc(II) ions are coordinated by two tetradentate L2- units and two acetate ions acting as bridging groups. The coordination geometry around the terminal Zn(1) or Zn(1)#1 atom approaches a distorted square pyramid. The coordination sphere of the central Zn(2) atom constitutes a slightly distorted octahedral geometry. The blue-green emission from the zinc(II) complex can be observed, where the maximum emission wavelength is at 464 nm.

  10. Zinc naphthalenedicarboxylate coordination complex: A promising anode material for lithium and sodium-ion batteries with good cycling stability.

    Fei, Hailong; Feng, Wenjing; Xu, Tan


    It is important to discover new, cheap and environmental friendly electrode materials with high capacity and good cycling stability for lithium and sodium-ion batteries. Zinc 1,4-naphthalenedicarboxylate was firstly found to be stable anode materials for lithium and sodium-ion batteries. The discharge capacity can be up to 468.9mAhg(-1) after 100 cycles at a current density of 100mAg(-1) for lithium-ion batteries, while the second discharge capacity of 320.7mAhg(-1) was achieved as anode materials for sodium-ion batteries. A possible electrochemical reaction mechanism was discussed.

  11. CO2 Capture from Ambient Air by Crystallization with a Guanidine Sorbent.

    Seipp, Charles A; Williams, Neil J; Kidder, Michelle K; Custelcean, Radu


    Carbon capture and storage is an important strategy for stabilizing the increasing concentration of atmospheric CO2 and the global temperature. A possible approach toward reversing this trend and decreasing the atmospheric CO2 concentration is to remove the CO2 directly from air (direct air capture). Herein we report a simple aqueous guanidine sorbent that captures CO2 from ambient air and binds it as a crystalline carbonate salt by guanidinium hydrogen bonding. The resulting solid has very low aqueous solubility (Ksp =1.0(4)×10(-8) ), which facilitates its separation from solution by filtration. The bound CO2 can be released by relatively mild heating of the crystals at 80-120 °C, which regenerates the guanidine sorbent quantitatively. Thus, this crystallization-based approach to CO2 separation from air requires minimal energy and chemical input, and offers the prospect for low-cost direct air capture technologies.

  12. Discovery of benzothiazole guanidines as novel inhibitors of thrombin and trypsin IV.

    Karle, Michael; Knecht, Wolfgang; Xue, Yafeng


    In a project to find novel neutral P1 fragments for the synthesis of thrombin inhibitors with improved pharmacokinetic properties, fragments containing a benzothiazole guanidine scaffold were identified as weak thrombin inhibitors. WaterLOGSY (Water-Ligand Observed via Gradient SpectroscopY) NMR was used to detect fragments binding to thrombin and these fragments were followed up by Biacore A100 affinity measurements and enzyme assays. A crystal structure of the most potent compound with thrombin was obtained and revealed an unexpected binding mode as well as the key interactions of the fragment with the protein. Based on these results, the structure-based design and synthesis of a small series of optimized novel substituted benzothiazole guanidines with comparatively low pK(a) values was accomplished. Testing of these compounds against human trypsin I and human trypsin IV revealed unexpected inhibitory activity and selectivity of some of the compounds, making them attractive starting points for selective trypsin inhibitors.

  13. Tricyclic Guanidine Alkaloids from the Marine Sponge Acanthella cavernosa that Stabilize the Tumor Suppressor PDCD4

    Grkovic, Tanja; Blees, Johanna S.; Bayer, Magdalena M.; Colburn, Nancy H.; Thomas, Cheryl L.; Henrich, Curtis J.; Peach, Megan L.; McMahon, James B.; Schmid, Tobias; Gustafson, Kirk R.


    A cell-based high-throughput screen that assessed the cellular stability of a tumor suppressor protein PDCD4 (Programmed cell death 4) was used to identify a new guanidine-containing marine alkaloid mirabilin K (3), as well as the known compounds mirabilin G (1) and netamine M (2). The structures of these tricyclic guanidine alkaloids were established from extensive spectroscopic analyses. Compounds 1 and 2 inhibited cellular degradation of PDCD4 with EC50 values of 1.8 μg/mL and 2.8 μg/mL, respectively. Mirabilin G (1) and netamine M (2) are the first marine natural products reported to stabilize PDCD4 under tumor promoting conditions. PMID:25196934

  14. Novel Zinc(II) Complexes [Zn(atc-Et)2] and [Zn(atc-Ph)2]: In Vitro and in Vivo Antiproliferative Studies

    Lopes, Erica de O.; de Oliveira, Carolina G.; da Silva, Patricia B.; Eismann, Carlos E.; Suárez, Carlos A.; Menegário, Amauri A.; Leite, Clarice Q. F.; Deflon, Victor M.; Pavan, Fernando R.


    Cisplatin and its derivatives are the main metallodrugs used in cancer therapy. However, low selectivity, toxicity and drug resistance are associated with their use. The zinc(II) (ZnII) thiosemicarbazone complexes [Zn(atc-Et)2] (1) and [Zn(atc-Ph)2] (2) (atc-R: monovalent anion of 2-acetylpyridine N4-R-thiosemicarbazone) were synthesized and fully characterized in the solid state and in solution via elemental analysis, Fourier transform infrared (FTIR), ultraviolet-visible (UV-Vis) and proton nuclear magnetic resonance (1H NMR) spectroscopy, conductometry and single-crystal X-ray diffraction. The cytotoxicity of these complexes was evaluated in the HepG2, HeLa, MDA-MB-231, K-562, DU 145 and MRC-5 cancer cell lines. The strongest antiproliferative results were observed in MDA-MB-231 and HepG2 cells, in which these complexes displayed significant selective toxicity (3.1 and 3.6, respectively) compared with their effects on normal MRC-5 cells. In vivo studies were performed using an alternative model (Artemia salina L.) to assure the safety of these complexes, and the results were confirmed using a conventional model (BALB/c mice). Finally, tests of oral bioavailability showed maximum plasma concentrations of 3029.50 µg/L and 1191.95 µg/L for complexes 1 and 2, respectively. According to all obtained results, both compounds could be considered as prospective antiproliferative agents that warrant further research. PMID:27213368

  15. Bis(3-methyl-2-pyridyl)ditelluride and pyridyl tellurolate complexes of zinc, cadmium, mercury: Synthesis, characterization and their conversion to metal telluride nanoparticles.

    Kedarnath, G; Jain, Vimal K; Wadawale, Amey; Dey, Gautam K


    Treatment of an acetonitrile solution of metal chloride with bis(3-methyl-2-pyridyl)ditelluride, [Te(2)(pyMe)(2)], in the same solvent yielded complexes of composition [MCl(2){Te(2)(pyMe)(2)}] (M = Zn or Cd) whereas reactions of [MCl(2)(tmeda)] with NaTepyR (R = H or Me) gave tellurolate complexes of the general formula [M(TepyR)(2)] (M = Cd or Hg). When the cadmium complex [Cd(Tepy)(2)] was crystallized in the presence of excess tmeda, [Cd(Tepy)(2)(tmeda)] was formed exclusively. These complexes were characterized by elemental analyses, uv-vis, (1)H NMR data. The crystal structures of [ZnCl(2){Te(2)(pyMe)(2)}] and [Cd(Tepy)(2)(tmeda)] were established by single crystal X-ray diffraction. In the former zinc is coordinated to nitrogen atoms of the pyridyl group, while in the latter the coordination environment around tetrahedral cadmium is defined by the two neutral nitrogen atoms of tmeda, and two pyridyl tellurolate ligands. Thermal behavior of some of these complexes was studied by thermogravimetric analysis. Pyrolysis of [M(Tepy)(2)] in a furnace or in coordinating solvents such as hexadecylamine/tri-n-octylphosphine oxide (HDA/TOPO) at 350 and 160 degrees C, respectively gave MTe nanoparticles, which were characterized by uv-vis, photoluminiscence, XRD, EDAX and TEM.

  16. Synthesis, characterization, spectroscopic and theoretical studies of new zinc(II), copper(II) and nickel(II) complexes based on imine ligand containing 2-aminothiophenol moiety

    Shafaatian, Bita; Mousavi, S. Sedighe; Afshari, Sadegh


    New dimer complexes of zinc(II), copper(II) and nickel(II) were synthesized using the Schiff base ligand which was formed by the condensation of 2-aminothiophenol and 2-hydroxy-5-methyl benzaldehyde. This tridentate Schiff base ligand was coordinated to the metal ions through the NSO donor atoms. In order to prevent the oxidation of the thiole group during the formation of Schiff base and its complexes, all of the reactions were carried out under an inert atmosphere of argon. The X-ray structure of the Schiff base ligand showed that in the crystalline form the SH groups were oxidized to produce a disulfide Schiff base as a new double Schiff base ligand. The molar conductivity values of the complexes in dichloromethane implied the presence of non-electrolyte species. The fluorescence properties of the Schiff base ligand and its complexes were also studied in dichloromethane. The products were characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis, and conductometry. The crystal structure of the double Schiff base was determined by single crystal X-ray diffraction. Furthermore, the density functional theory (DFT) calculations were performed at the B3LYP/6-31G(d,p) level of theory for the determination of the optimized structures of Schiff base complexes.

  17. Fundamental insights into conformational stability and orbital interactions of antioxidant (+)-catechin species and complexation of (+)-catechin with zinc(II) and oxovanadium(IV)

    Yasarawan, Nuttawisit; Thipyapong, Khajadpai; Sirichai, Somsak; Ruangpornvisuti, Vithaya


    Conformational stability of (+)-catechin species in water has been examined with density functional theory, associated with the polarizable continuum model (PCM) of solvation. Factors such as electron delocalization, lone-pair electron donation and intramolecular hydrogen bonding substantially contribute to the conformational stabilization. Upon deprotonation, the HOMO and LUMO energies for (+)-catechin are both elevated; the energy gaps for the deprotonated species are narrower than the energy gap for the neutral species. The preferential deprotonation occurs at the C3'-, C5-, C7- and C4'-OH groups successively. The pKa value at 9.3 predicted for the most acidic OH group agrees well with previous experimental data; however the values are overestimated for the less acidic OH groups due to limitations of the PCM for charged solutes and/or complex nature of true deprotonation pathways. Formation of hydrogen radicals should be promoted at high pH values following the bond dissociation enthalpies. Complexation of (+)-catechin with either zinc(II) or oxovanadium(IV) is favored at the 1:1 metal-to-ligand (M:L) mole ratio, with the oxovanadium(IV) complex showing higher reaction preference. At M:L = 1:2, formation of two isomeric complexes are plausible for each type of metal ion. Effects of stoichiometry and isomerism on the computational spectral features of the possibly formed metal complexes have been described.

  18. Magnetic silica hybrids modified with guanidine containing co-polymers for drug delivery applications

    Timin, Alexander S., E-mail: [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation); RASA Center in Tomsk, Tomsk Polytechnic University, 30, Lenin Avenue, 634500 Tomsk (Russian Federation); Khashirova, Svetlana Yu. [Kabardino-Balkar State University, ul. Chernyshevskogo 173, Nal' chik, 360004 Kabardino-Balkaria (Russian Federation); Rumyantsev, Evgeniy V.; Goncharenko, Alexander A. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation)


    Guanidine containing co-polymers grafted onto silica nanoparticles to form core-shell structure were prepared by sol-gel method in the presence of γ-Fe{sub 2}O{sub 3} nanoparticles. The morphological features for uncoated and coated silica particles have been characterized with scanning electron microscopy. The results show that the polymer coated silicas exhibit spherical morphology with rough polymeric surface covered by γ-Fe{sub 2}O{sub 3} nanoparticles. The grafting amount of guanidine containing co-polymers evaluated by thermogravimetric analysis was in the range from 17 to 30%. Then, the drug loading properties and cumulative release of silica hybrids modified with guanidine containing co-polymers were evaluated using molsidomine as a model drug. It was shown that after polymer grafting the loading content of molsidomine could reach up to 3.42 ± 0.21 and 2.34 ± 0.14 mg/g respectively. The maximum drug release of molsidomine is achieved at pH 1.6 (approximately 71–75% release at 37 °C), whereas at pH 7.4 drug release is lower (50.4–59.6% release at 37 °C). These results have an important implication that our magneto-controlled silica hybrids modified with guanidine containing co-polymers are promising as drug carriers with controlled behaviour under influence of magnetic field. - Highlights: • Polymer coated silica hybrids containing γ-Fe{sub 2}O{sub 3} were prepared via sol–gel method. • Polymer grafting influences pH-response and surface properties of final products. • Molsidomine as a model drug was effectively loaded into polymer coated silicas. • The drug loading depends on the nature of grafted polymer and its content.

  19. Guanidine hydrochloride embedded polyurethanes as antimicrobial and absorptive wound dressing membranes with promising cytocompatibility

    Sahraro, Maryam; Yeganeh, Hamid, E-mail:; Sorayya, Marziyeh


    Preparation and assessments of novel absorptive wound dressing materials with efficient antimicrobial activity as well as very good cytocompatibility were described in this work. An amine terminated poly(hexamethylene guanidine hydrochloride) was prepared and used as curing agent of different epoxy-terminated polyurethane prepolymers. The structures of prepared materials were elucidated by evaluation of their {sup 1}H NMR and FTIR spectra. The recorded tensile strength of membranes confirmed the excellent dimensional stability of the film type dressings even at fully hydrated conditions. Therefore, these dressings could protect the wound bed from external forces during the healing period. The structurally optimized dressing membranes could preserve the desired moist environment over the wounded area, as a result of their balanced equilibrium, water absorption and water vapor transmission rate. Therefore, a very good condition for stimulation of self-healing of wound bed was attained. Also, owing to the presence of guanidine hydrochloride moieties embedded into the structure of dressings, efficient antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans were detected. In vitro cytotoxicity assay of the prepared dressings revealed cytocompatibility of these materials against fibroblast cells. Therefore, they could support cell growth and proliferation at the wounded area. - Highlights: • New polyurethane wound dressings with guanidine hydrochloride based antimicrobials • Maintaining moist and warm wound environment for accelerating healing • Proper tensile strength of dressings even at fully hydrated state • Excellent biocompatibility index due to proper selection of starting materials.

  20. Effect of guanidine hydrochloride on removal rate selectivity and wafer topography modification in barrier CMP

    Hailong, Li; Jin, Kang; Yuling, Liu; Chenwei, Wang; Hong, Liu; Jiaojiao, Gao


    We propose an alkaline barrier slurry containing guanidine hydrochloride (GH) and hydrogen peroxide. The slurry does not contain any corrosion inhibitors, such as benzotriazole (BTA). 3-inch samples of tantalum copper and oxide were polished to observe the removal rate. The effect of GH on removal rate selectivity along with hydrogen peroxide was investigated by comparing slurry containing GH and H2O2 with slurry containing only GH. Details about the tantalum polishing mechanism in an alkaline guanidine-based slurry and the electrochemical reactions are discussed. The results show that guanidine hydrochloride can increase the tantalum polishing rate and the selectivity of copper and barrier materials. The variation of the dishing and wire line resistance with the polishing time was measured. The dishing value after a 300 mm pattern wafer polishing suggests that the slurry has an effective performance in topography modification. The result obtained from the copper wire line resistance test reveals that the wire line in the trench has a low copper loss.

  1. Chemical-Biological Properties of Zinc Sensors TSQ and Zinquin: Formation of Sensor-Zn-Protein Adducts versus Zn(Sensor)2 Complexes.

    Nowakowski, Andrew B; Meeusen, Jeffrey W; Menden, Heather; Tomasiewicz, Henry; Petering, David H


    Fluorescent zinc sensors are the most commonly used tool to study the intracellular mobile zinc status within cellular systems. Previously, we have shown that the quinoline-based sensors Zinquin and 6-methoxy-8-p-toluenesulfonamido-quinoline (TSQ) predominantly form ternary adducts with members of the Zn-proteome. Here, the chemistries of these sensors are further characterized, including how Zn(sensor)2 complexes may react in an intracellular environment. We demonstrate that these sensors are typically used in higher concentrations than needed to obtain maximum signal. Exposing cells to either Zn(Zinquin)2 or Zn(TSQ)2 resulted in efficient cellular uptake and the formation of sensor-Zn-protein adducts as evidenced by both a fluorescence spectral shift toward that of ternary adducts and the localization of the fluorescence signal within the proteome after gel filtration of cellular lysates. Likewise, reacting Zn(sensor)2 with the Zn-proteome from LLC-PK1 cells resulted in the formation of sensor-Zn-protein ternary adducts that could be inhibited by first saturating the Zn- proteome with excess sensor. Further, a native SDS-PAGE analysis of the Zn-proteome reacted with either the sensor or the Zn(sensor)2 complex revealed that both reactions result in the formation of a similar set of sensor-Zn-protein fluorescent products. The results of this experiment also demonstrated that TSQ and Zinquin react with different members of the Zn-proteome. Reactions with the model apo-Zn-protein bovine serum albumin showed that both Zn(TSQ)2 and Zn(Zinquin)2 reacted to form ternary adducts with its apo-Zn-binding site. Moreover, incubating Zn(sensor)2 complexes with non-zinc binding proteins failed to elicit a spectral shift in the fluorescence spectrum, supporting the premise that blue-shifted emission spectra are due to sensor-Zn-protein ternary adducts. It was concluded that Zn(sensors)2 species do not play a significant role in the overall reaction between these sensors and

  2. Influence of zinc concentration on structure, complex permittivity and permeability of Ni–Zn ferrites at high frequency

    Jiang, Nan-Nan; Yang, Yang; Zhang, Yu-Xiang [School of Physics and Information Technology, Shaanxi Normal University, Xi' an 710119 (China); Zhou, Jian-Ping, E-mail: [School of Physics and Information Technology, Shaanxi Normal University, Xi' an 710119 (China); Liu, Peng [School of Physics and Information Technology, Shaanxi Normal University, Xi' an 710119 (China); Deng, Chao-Yong [Department of Electronic Science, Key Laboratory of Functional Composite Materials of Guizhou Province, Guizhou University, Guiyang 550025 (China)


    Polycrystalline soft magnetic nickel–zinc ferrites with chemical composition Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}, where x=0, 0.2, 0.4, 0.6, 0.65, 0.7, 0.75, and 0.8, were prepared by solid state reaction method. We researched the effect of zinc concentration on the lattice parameter, crystal morphology and electromagnetic properties at high frequency. Results show that ε′ and ε″ decline with increasing frequency until they reach almost constants over 3 MHz to 1 GHz. The dielectric constant achieves a maximum when the Zn concentration is 0.8. The value of ε′ slightly declines with increasing frequency in the range of 2–18 GHz. The spectra of the permeability displays a relaxation resonance for the ferrites with x=0, 0.2, and 0.4 in 3 MHz to 1 GHz frequency range. The permeability is ruled by Snoek's law, which results in the values of μ′ decreased fast below 2 GHz and smaller than 1 above 2 GHz. The value of μ′ reaches maximum and μ″ shows minimum for the samples around x=0.75 in 2–18 GHz range. The magnetic permeability μ′ decreases in an external magnetic field, and shows two resonance peaks corresponding to domain wall and spin rotation resonance. The resonance peaks shift to higher frequency with increasing the external magnetic field. But the permeability has no clear response for magnetic field when zinc concentration is much higher. - Graphical abstract: (a) Resonance frequencies for the domain wall and spin components as a function of external magnetic field and (b) illustration of magnetization process. - Highlights: • A detailed study on permittivity and permeability of Ni–Zn ferrites in 3 MHz to 18 GHz. • Magnetic field inspires two resonance peaks in permeability. • The resonance peaks shift to higher frequency with the magnetic field.

  3. Synthesis, spectral characterization and biological activity of zinc(II) complexes with 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole Schiff bases.

    Singh, A K; Pandey, O P; Sengupta, S K


    New Zn(II) complexes have been synthesized by the reactions of zinc(II) acetate with Schiff bases derived from 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole and benzaldehyde, 2-hydroxyacetophenone or indoline-2,3-dione. All these complexes are soluble in DMF and DMSO; low molar conductance values indicate that they are non-electrolytes. Elemental analyses suggest that the complexes have 1:1 stoichiometry of the type [ZnL(H(2)O)(2)], [ZnL'(OAc)(2)(H(2)O)(2)] (L=dianionic Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1, 2, 4-triazole and 2-hydroxyacetophenone or indoline-2,3-dione; L'=neutral Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1, 2, 4-triazole and benzaldehyde) and they were characterized by FT-IR, (1)H NMR, (13)C NMR and FAB mass. All these Schiff bases and their complexes have also been screened for their antibacterial activities against Bacillus subtilis, Escherichia coli and antifungal activities against Colletotrichum falcatum, Aspergillus niger, Fusarium oxysporium and Carvularia pallescence by petriplates methods.

  4. A new route for visible/near-infrared-light-driven H2 production over titania: Co-sensitization of surface charge transfer complex and zinc phthalocyanine

    Zhang, Xiaohu; Peng, Bosi; Peng, Tianyou; Yu, Lijuan; Li, Renjie; Zhang, Jing


    This work introduces a new strategy for visible/near-infrared (NIR) light responsive H2 production over TiO2 nanoparticles co-sensitized with zinc phthalocyanine derivative (Zn-tri-PcNc) and surface ligand-to-metal charge transfer (LMCT) complex, which is in situ formed on the TiO2 nanoparticles' surfaces by using ascorbic acid (AA). The in situ formed surface LMCT complex (AA-TiO2) exhibits obvious visible-light-responsive photoactivity (126.2 μmol/h) for H2 production with a high apparent quantum yield (AQY) of 16.1% at 420 nm monochromatic light irradiation. Moreover, the co-sensitized TiO2 nanoparticles (Zn-tri-PcNc-TiO2-AA) shows a much higher photoactivity (162.2 μmol/h) for H2 production than the surface LMCT complex, and broader spectral responsive region (400-800 nm) with a relatively high AQY value (0.97%) at 700 nm monochromatic light irradiation. The present result reveals a possible substitute for the conventional Ru(II)-bipyridyl complexes or organic dyes as sensitizer of semiconductors in the field of solar fuel conversion.

  5. Zinc complexing ligands in rivers in pristine peatland areas in Borneo, and rivers with agricultural and industrial anthropogenic influence in Tropical South East Asia: Elucidating the connection to oceanic regional and global distributions of Zinc ligands and bioavailable Zinc

    Carrasco, G. G.; Chen, M.


    Organic complexing ligands dominate the chemical speciation of Zn in seawater globally, affecting its bioavailability and regulating its micronutrient role. We have shown that intermediate water masses in the West Pacific indicate a connection between point sources related to marginal seas, riverine matter, benthic fluxes, and continental shelves, with ligand concentrations and binding strengths evolving along water mass trajectories. Here we will present results from recent studies in tropical South East Asia that explore rivers in pristine peatland areas in Borneo, and rivers near and around agricultural and industrial anthropogenic influence in Borneo, Singapore and Malaysia, with the aim of elucidating the importance of relatively fresh natural and agricultural land-based plant material and industrial anthropogenic material in the organic matter mix that the ligands are a part of. These results track the ligand concentration and binding strength of different sources of Zn complexing ligands obtained using ASV and modern comprehensive mathematical methods We will compare records of humic substances from coral cores near the mouth of these rivers, with the goal of ascertaining a possible link of humic substance concentrations and metal complexing ligands in the region. We will compare the results from these large sources of organic matter with the ligands observed in continental shelves, where the organic matter has suffered biochemical processes, with ligands observed in the West Pacific, after decades of bacterial respiration while travelling along water masses. We aim to compare these ligand in order to assess the relevance of these sources of complexing ligands to regulate regional and global distribution of Zn ligands and its bioavailable concentrations.

  6. Binding of Cationic Bis-porphyrins Linked with p- or m-Xylylenediamine and Their Zinc(II Complexes to Duplex DNA

    Tadayuki Uno


    Full Text Available Spectroscopic, viscometric, and molecular docking analysis of binding of cationic bis-porphyrins linked with p- or m-xylylenediamine (H2pXy and H2mXy and their zinc(II complexes (ZnpXy and ZnmXy to duplex DNA are described. H2pXy and H2mXy bound to calf thymus DNA (CTDNA stronger than unichromophoric H2TMPyP, and showed exciton-type induced circular dichroism spectra of their Soret bands. The H2TMPyP-like units of the metal-free bis-porphyrins did not intercalate into CTDNA, and thus the binding mode is outside binding with intramolecular stacking. ZnpXy showed favorable binding to A·T over G·C region, and should lie in the major groove of A·T region.

  7. Inactivation and unfolding of protein tyrosine phosphatase from Thermus thermophilus HB27 during urea and guanidine hydrochloride denaturation.

    Yejing Wang

    Full Text Available The effects of urea and guanidine hydrochloride (GdnHCl on the activity, conformation and unfolding process of protein tyrosine phosphatase (PTPase, a thermostable low molecular weight protein from Thermus thermophilus HB27, have been studied. Enzymatic activity assays showed both urea and GdnHCl resulted in the inactivation of PTPase in a concentration and time-dependent manner. Inactivation kinetics analysis suggested that the inactivation of PTPase induced by urea and GdnHCl were both monophasic and reversible processes, and the effects of urea and GdnHCl on PTPase were similar to that of mixed-type reversible inhibitors. Far-ultraviolet (UV circular dichroism (CD, Tryptophan and 1-anilinonaphthalene -8-sulfonic acid (ANS fluorescence spectral analyses indicated the existence of a partially active and an inactive molten globule-like intermediate during the unfolding processes induced by urea and GdnHCl, respectively. Based on the sequence alignment and the homolog Tt1001 protein structure, we discussed the possible conformational transitions of PTPase induced by urea and GdnHCl and compared the conformations of these unfolding intermediates with the transient states in bovine PTPase and its complex structures in detail. Our results may be able to provide some valuable clues to reveal the relationship between the structure and enzymatic activity, and the unfolding pathway and mechanism of PTPase.

  8. Formation of a unique zinc carbamate by CO2 fixation: implications for the reactivity of tetra-azamacrocycle ligated Zn(II) complexes.

    Notni, Johannes; Schenk, Stephan; Görls, Helmar; Breitzke, Hergen; Anders, Ernst


    The macrocyclic ligand [13]aneN 4 ( L1, 1,4,7,10-tetra-azacyclotridecane) was reacted with Zn(II) perchlorate and CO 2 in an alkaline methanol solution. It was found that, by means of subtle changes in reaction conditions, two types of complexes can be obtained: (a) the mu 3 carbonate complex 1, {[Zn( L1)] 3(mu 3-CO 3)}(ClO 4) 4, rhombohedral crystals, space group R3 c, with pentacoordinate zinc in a trigonal bipyramidal enviroment, and (b) an unprecedenced dimeric Zn(II) carbamate structure, 2, [Zn( L2)] 2(ClO 4) 2, monoclinic crystals, space group P2 1/ n. The ligand L2 (4-carboxyl-1,4,7,10-tetra-azacyclotridecane) is a carbamate derivative of L1, obtained by transformation of a hydrogen atom of one of the NH moieties into carbamate by means of CO 2 uptake. In compound 2, the distorted tetrahedral Zn(II) coordinates to the carbamate moiety in a monodentate manner. Most notably, carbamate formation can occur upon reaction of CO 2 with the [Zn L1] (2+) complex, which implicates that a Zn-N linkage is cleaved upon attack of CO 2. Since complexes of tetra-azamacrocycles and Zn(II) are routinely applied for enzyme model studies, this finding implies that the Zn-azamacrocycle moiety generally should no longer be considered to play always only an innocent role in reactions. Rather, its reactivity has to be taken into account in respective investigations. In the presence of water, 2 is transformed readily into carbonate 1. Both compounds have been additionally characterized by solid-state NMR and infrared spectroscopy. A thorough comparison of 1 with related azamacrocycle ligated zinc(II) carbonates as well as a discussion of plausible reaction paths for the formation of 2 are given. Furthermore, the infrared absorptions of the carbamate moiety have been assigned by calculating the vibrational modes of the carbamate complex using DFT methods and the vibrational spectroscopy calculation program package SNF.

  9. A new air-stable zinc complex based on a 1,2-phenylene-diimino-2-cyanoacrylate ligand as an efficient catalyst of the epoxide-CO2 coupling.

    Fuchs, M A; Staudt, S; Altesleben, C; Walter, O; Zevaco, T A; Dinjus, E


    A novel zinc complex based on a diethyl 1,2-phenylene-diimino-2-cyanoacrylate ligand is a very efficient catalyst in the conversion of epoxides with CO2 to organic carbonates, in the case of propylene carbonate also under mild reaction conditions. Using cyclohexene oxide leads to the formation of alternating aliphatic polycarbonates in good yields.

  10. Synthesis, Crystal Structure and Luminescent Properties of a Novel Zinc(Ⅱ) Complex of N-Acetyl-L-glutamic Acid and Imidazole Ligands

    CHENG Meng-Qi; MA Lu-Fang; WANG Li-Ya; WANG Jian-Ge


    A novel complex (Zn(Im)2(A-glu)·0.5H2O (Im = imidazole, A-glu = N-acetyl- L-glutamic acid) has been synthesized from the reaction of A-glu with Zn(CH3COO)2(2H2O in the presence of Im at 65 ℃, and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in tetragonal, space group P43212 with a = b = 8.9078(6), c = 43.458(6) (A), C26H36N10O11Zn2, Mr = 795.39, V = 3448.3(6) (A)3, Dc = 1.532 g/cm3, Z = 4, μ(MoK() = 1.461 mm(1, F(000) = 1640, the final R = 0.0453 and wR = 0.0992. X-ray analysis reveals that the crystal structure is constructed by mixed ligands. A-glu adopts the bis-monodentate coordination mode linking two adjacent metal ions to form a one-dimensional chain. Zinc(Ⅱ) ions are four-coordinated with a distorted tetrahedral geometry. Luminescent properties of the complex have been inves- tigated.

  11. Synthesis and characterization of an effective organic/inorganic hybrid green corrosion inhibitive complex based on zinc acetate/Urtica Dioica

    Salehi, E.; Naderi, Reza; Ramezanzadeh, B.


    This study aims at synthesis and characterization of an effective corrosion inhibitive complex based on zinc acetate/Urtica Dioica (ZnA-U.D) for corrosion protection of mild steel in chloride solution. The chemical structure and morphology of the complex were characterized by Fourier transform infrared spectroscopy (FT-IR), UV-vis, thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The corrosion protection performance of the mild steel samples dipped in 3.5 wt.% NaCl solutions with and without ZnA-U.D extract was investigated by visual observations, open circuit potential (OCP) measurements, electrochemical impedance spectroscopy (EIS) and polarization test. Results revealed that the ZnA successfully chelated with organic inhibitive compounds (i.e Quercetin, Quinic acid, Caffeic acid, Hystamine and Serotonin) present in the U.D extract. The electrochemical measurements revealed the effective inhibition action of ZnA-U.D complex in the sodium chloride solution on the mild steel. The synergistic effect between Zn2+ and organic compounds present in the U.D extract resulted in protective film deposition on the steel surface, which was proved by SEM and XPS analyses.

  12. Synthesis, Crystal Structure and Kinetic Mechanism of Thermal Decomposition of a Zinc(II) Complex with N-Salicylidene-p-toluidine

    ZHAO Guo-Liang; WEN Yi-Hang; YU Yu-Ye


    The title complex, Zn(C14H13NO)2Cl2 1, has been synthesized by the reaction of zinc chloride with Schiff base ligand N-salicylidene-p-toluidine and its structure was determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group Cc with a = 14.896(3), b = 12.506(2), c = 15.352(3)(A), β = 114.711(4)o, V = 2598.0(8) (A)3, C28H26ZnCl2N2O2, Mr = 558.80, Z = 4, Dc = 1.429 g/cm3, μ = 1.179 mm-1, Flack parameter = 0.027(19), F(000) = 1152, R = 0.0709 and wR = 0.1041 for 3117 observed reflections (I > 2σ(I)). In complex 1, the center Zn ion is four-coordinated by two O atoms from two Schiff base ligands and two Cl atoms in a distorted tetrahedral geometry. Additionally, the thermal decomposition of complex 1 as well as its kinetic mechanisms and equations is studied under the non-isothermal integral and differential methods in air by TG-DTG curves.

  13. A mononuclear zinc(II) complex with piroxicam: crystal structure, DNA- and BSA-binding studies; in vitro cell cytotoxicity and molecular modeling of oxicam complexes.

    Jannesari, Zahra; Hadadzadeh, Hassan; Amirghofran, Zahra; Simpson, Jim; Khayamian, Taghi; Maleki, Batool


    A new mononuclear Zn(II) complex, trans-[Zn(Pir)2(DMSO)2], where Pir(-) is 4-hydroxy-2-methyl-N-2-pyridyl-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (piroxicam), has been synthesized and characterized. The crystal structure of the complex was obtained by the single crystal X-ray diffraction technique. The interaction of the complex with DNA and BSA was investigated. The complex interacts with FS-DNA by two binding modes, viz., electrostatic and groove binding (major and minor). The microenvironment and the secondary structure of BSA are changed in the presence of the complex. The anticancer effects of the seven complexes of oxicam family were also determined on the human K562 cell lines and the results showed reasonable cytotoxicities. The interactions of the oxicam complexes with BSA and DNA were modeled by molecular docking and molecular dynamic simulation methods.

  14. A mononuclear zinc(II) complex with piroxicam: Crystal structure, DNA- and BSA-binding studies; in vitro cell cytotoxicity and molecular modeling of oxicam complexes

    Jannesari, Zahra; Hadadzadeh, Hassan; Amirghofran, Zahra; Simpson, Jim; Khayamian, Taghi; Maleki, Batool


    A new mononuclear Zn(II) complex, trans-[Zn(Pir)2(DMSO)2], where Pir- is 4-hydroxy-2-methyl-N-2-pyridyl-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (piroxicam), has been synthesized and characterized. The crystal structure of the complex was obtained by the single crystal X-ray diffraction technique. The interaction of the complex with DNA and BSA was investigated. The complex interacts with FS-DNA by two binding modes, viz., electrostatic and groove binding (major and minor). The microenvironment and the secondary structure of BSA are changed in the presence of the complex. The anticancer effects of the seven complexes of oxicam family were also determined on the human K562 cell lines and the results showed reasonable cytotoxicities. The interactions of the oxicam complexes with BSA and DNA were modeled by molecular docking and molecular dynamic simulation methods.

  15. Thermodynamics of mixed-ligand complex formation of zinc nitrilotriacetate with amino acids and dipeptides in solution

    Pyreu, Dmitrii, E-mail: [Department of Inorganic and Analytic Chemistry, Ivanovo State UniversityErmak 39, Ivanovo 153025 (Russian Federation); Gruzdev, Matvey; Kumeev, Roman [G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo (Russian Federation); Gridchin, Sergei [Ivanovo State University of Chemistry and Technology, Ivanovo (Russian Federation)


    Highlights: • Stable mixed ligand complexes of ZnNta with amino acids and dipeptides. • Histamine-like coordination mode of His in the complex ZnNtaHis. • Glycine-like coordination of Lys and Orn in the complexes ZnNtaL and ZnNtaHL • NH{sub 2}, CO-coordination mode of GlyGly in the complex ZnNtaGG. • NH{sub 2}, N{sup −} or NH2, N{sup −}, COO-coordination modes of GlyGly in the complex ZnNtaGGH{sub −1}. - Abstract: The isothermal calorimetry, pH-potentiometric titration and {sup 1}H and {sup 13}C NMR methods has been used to study the mixed-ligand complex formation in the systems Zn{sup 2+}–Nta{sup 3–}–L{sup −} (L = His, Orn, Lys, GlyGly, AlaAla) in aqueous solution at 298.15 K and the ionic strength of I = 0.5 (KNO{sub 3}). The thermodynamic parameters of formation of the mixed complexes have been determined. The relationship between the probable coordination modes of the complexone and amino acid or dipeptide molecules in the mixed-ligand complex and the thermodynamic parameters has been discussed.

  16. Reactivity of Cys4 Zinc Finger Domains with Gold(III) Complexes : Insights into the Formation of "Gold Fingers"

    Jacques, Aurélie; Lebrun, Colette; Casini, Angela; Kieffer, Isabelle; Proux, Olivier; Latour, Jean-Marc; Sénèque, Olivier


    Gold(I) complexes such as auranofin or aurothiomalate have been used as therapeutic agents for the treatment of rheumatoid arthritis for several decades. Several gold(I) and gold(III) complexes have also shown in vitro anticancer properties against human cancer cell lines, including cell lines resis

  17. Reactivity of Cys4 Zinc Finger Domains with Gold(III) Complexes : Insights into the Formation of "Gold Fingers"

    Jacques, Aurélie; Lebrun, Colette; Casini, Angela; Kieffer, Isabelle; Proux, Olivier; Latour, Jean-Marc; Sénèque, Olivier


    Gold(I) complexes such as auranofin or aurothiomalate have been used as therapeutic agents for the treatment of rheumatoid arthritis for several decades. Several gold(I) and gold(III) complexes have also shown in vitro anticancer properties against human cancer cell lines, including cell lines

  18. A series of Zn-4f heterometallic coordination polymers and a zinc complex containing a flexible mixed donor dicarboxylate ligand.

    Feng, Xun; Feng, Yu-Quan; Liu, Lang; Wang, Li-Ya; Song, Hong-Liang; Ng, Seik-Weng


    A new zinc compound, together with a corresponding series of Zn-4f heterometallic coordination polymers, namely, [Zn(H2PBDA)(PBDA)]n (1), {[Ln2(PBDA)2·2H2O] [Zn2(PBDA)2Cl2]}n [H2PBDA = 3-(pyridin-3-yl-oxy) benzene-1,2-dicarboxylic acid, and Ln = Pr(2), Nd(3), Eu(4), Gd(5), Dy(6), Ho(7), Er(8)] have been hydrothermally synthesized and characterized systematically. Polymers 2-8 feature two-dimensional (2D) 4,4 networks, containing the original 1D heterometallic double stranded chains composed of [Ln2Zn2(PBDA)2] entities. The extensive hydrogen bonding and π-π stacking interactions were observed to stabilize the extended architectures. The luminescence emission spectra of the polymers vary depending on the lanthanide(III) ion present. Informative magnetic susceptibility measurements show that the same carboxylate bridging fashion of the PBDA ligand results in the different magnetic properties occurring within the heterometallic coordination polymers. In addition, polymer 6 exhibits an interesting slow magnetic relaxation behavior at lower temperatures.

  19. The Fruitless gene in Nasonia displays complex sex-specific splicing and contains new zinc finger domains.

    Bertossa, Rinaldo C; van de Zande, Louis; Beukeboom, Leo W


    The transcription factor Fruitless exerts a broad range of functions during Drosophila development, the most apparent of which is the determination of sexual behavior in males. Although fruitless sequences are found in other insect orders, little is known about fruitless structure and function outside Diptera. We have performed a thorough analysis of fruitless transcripts in the haplo-diploid wasp Nasonia vitripennis and found both sex-specific and non-sex-specific transcripts similar to those found in Drosophila. In Nasonia, however, a novel, large fruitless transcript is present in females only. Putative binding sites for sex-specific splicing factors found in Nasonia fruitless and doublesex as well as Apis mellifera doublesex transcripts were sufficient to identify a corresponding female-specific fruitless exon in A. mellifera, suggesting that similar factors in both hymenopteran species could be responsible for sex-specific splicing of both genes. Furthermore, new C(2)H(2) zinc finger domains found in Nasonia fruitless transcripts were also identified in the fruitless locus of major holometabolous insect species but not in drosophilids. Conservation of important domains and sex-specific splicing in Diptera and Hymenoptera support the hypothesis that fruitless is an ancient gene and has conserved functions in insects. Considerable divergences in other parts of the gene are expected to underlie species-specific differences and may help to explain diversity observed in insect sexual behaviors.

  20. Synthesis, X-ray, and Spectroscopic Study of Dissymmetric Tetrahedral Zinc(II) Complexes from Chiral Schiff Base Naphthaldiminate Ligands with Apparent Exception to the ECD Exciton Chirality.

    Enamullah, Mohammed; Makhloufi, Gamall; Ahmed, Rifat; Joy, Baitul Alif; Islam, Mohammad Ariful; Padula, Daniele; Hunter, Howard; Pescitelli, Gennaro; Janiak, Christoph


    Bidentate enantiopure Schiff base ligands, (R or S)-N-1-(Ar)ethyl-2-oxo-1-naphthaldiminate (R- or S-N^O), diastereoselectively provide Λ- or Δ-chiral-at-metal four-coordinated Zn(R- or S-N^O)2 {Ar = C6H5; Zn-1R or Zn-1S and p-C6H4OMe; Zn-2R or Zn-2S}. Two R- or S-N^O-chelate ligands coordinate to the zinc(II) in a tetrahedral mode and induce Λ- or Δ-configuration at the zinc metal center. In the solid state, the R- or S-ligand diastereoselectively gives Λ- or Δ-Zn configuration, respectively, and forms enantiopure crystals. Single crystal structure determinations show two symmetry-independent molecules (A and B) in each asymmetric unit to give Z' = 2 structures. Electronic circular dichroism (ECD) spectra show the expected mirror image relationship resulting from diastereomeric excess toward the Λ-Zn for R-ligands and Δ-Zn for S-ligands in solution. ECD spectra are well reproduced by TDDFT calculations, while the application of the exciton chirality method, in the common point-dipole approximation, predicts the wrong sign for the long-wavelength couplet. A dynamic diastereomeric equilibrium (Λ vs Δ) prevails for both R- and S-ligand-metal complexes in solution, respectively, evidenced by (1)H NMR spectroscopy. Variable temperature (1)H NMR spectra show a temperature-dependent shift of the diastereomeric equilibrium and confirm Δ-Zn configuration (for S-ligand) to be the most stable one and favored at low temperature. DSC analyses provide quantitative diastereomeric excess in the solid state for Zn-2R and Zn-2S, which is comparable to the results of solution studies.

  1. Synthesis and characterization of bis-(2-cyano-1-methyl-3-{2- {{(5-methylimidazol-4-yl)methyl}thio}ethyl)guanidine copper(II) sulfate tetrahydrate

    Rahardjo, Sentot B.; Endah Saraswati, Teguh; Pramono, Edy; Fitriana, Nur


    Complex of copper(II) with 2-cyano-1-methyl-3-{2-{{(5-methylimidazol-4- yl)methyl}thio}ethyl)guanidin(xepamet) had been synthesized in 1 : 4 mole ratio of metal to the ligand in methanol. The complex was characterized by metal analysis, thermal gravimetry/differential thermal analyzer (TG/DTA), molar conductivity meter, (Fourier transform infrared spectroscopy) FT-IR, UV-Vis spectroscopy, and magnetic susceptibility balance. The molar conductivity measurement shows that the complex was 2: 1 for electrolyte and SO42- which was acting as a counter ion. The thermal analysis by Thermogravimetric (TG) indicates that the complex contained four molecules of H2O. The Infrared spectral data indicates that functional groups of (C=N) imidazole and (C-S) are coordinated to the center ion Cu2+. Magnetic moment measurement shows that the complex is paramagnetic with peff = 1.78 ± 0.01 BM. Electronic spectra of the complex show a broad band at 608 nm (16447.23 cm-1) are due to Eg→T2g transition. Based on those of characteristics, The complex formula was estimated as [Cu(xepamet)2]SO4.4H2O. The structure of [Cu(xepamet)2]SO4.4H2O complex is probably square planar.

  2. Unsymmetrical Mesoporphyrinic Complexes of Copper (II) and Zinc (II). Microwave-Assisted Synthesis, Spectral Characterization and Cytotoxicity Evaluation

    Rica Boscencu


    New unsymmetrical mesoporphyrinic complexes, namely 5-(4-hydroxyphenyl)-10,15,20–tris-(4-carboxymethylphenyl)–21,23-Zn(II)-porphine and 5-(4-hydroxyphenyl)-10,15,20–tris-(4-carboxymethylphenyl)–21,23-Cu(II)-porphine, were synthesized using a microwave irradiation method. The structures of the porphyrinic complexes were confirmed using FT-IR, UV–Vis, EPR and NMR spectral data. The spectral absorption and emission properties of the porphyrinic complexes were studied in organic solvents of diffe...

  3. Selective Covalent Chemistry via Gas-Phase Ion/ion Reactions: An Exploration of the Energy Surfaces Associated with N-Hydroxysuccinimide Ester Reagents and Primary Amines and Guanidine Groups

    Bu, Jiexun; Fisher, Christine M.; Gilbert, Joshua D.; Prentice, Boone M.; McLuckey, Scott A.


    Selective covalent bond forming reactions (referred to as covalent reactions) can occur in gas-phase ion/ion reactions and take place via the formation of a long-lived chemical complex. The gas-phase ion/ion reactivity between sulfo- N-hydroxysuccinimide (sulfo-NHS) ester reagent anions and peptide cations containing a primary amine or guanidine group has been examined via DFT calculations and complex dissociation rate measurements. The results reveal insights regarding the roles of the barriers of competing processes within the complex. When the covalent reaction is exothermic, two prototypical cases, determined by the nature of the energy surface, are apparent. The product partitioning between covalent reaction and simple proton transfer upon dissociation of the long-lived complex is sensitive to activation conditions when the transition state barrier for covalent reaction is relatively high ( case 1) but is insensitive to activation conditions when the transition state barrier is relatively low ( case 2). Covalent reaction efficiencies are very high in case 2 scenarios, such as when the reactive site is a guanidine and the anion attachment site is a guanidinium ion. Covalent reaction efficiencies are variable, and generally low, in case 1 scenarios, such as when an amine is the reactive site and an ammonium ion is the site of anion attachment. A relatively long slow-heating step prior to the complex dissociation step, however, can dramatically increase covalent reaction yield in case 1 scenarios.

  4. Deciphering the Conformational Choreography of Zinc Coordination Complexes with Standard and Novel Proton NMR Techniques Combined with DFT Methods.

    Pucheta, Jose Enrique Herbert; Prim, Damien; Gillet, Jean Michel; Farjon, Jonathan


    The presence of water has been shown to deeply impact the stability and geometry of Zn complexes in solution. Evidence for tetra- and penta-coordinated species in a pyridylmethylamine-Zn(II) model complex is presented. Novel (1) H NMR tools such as T1 -filtered selective exchange spectroscopy and pure shifted gradient-encoded selective refocusing as well as classical 2D ((1) H-(1) H) exchange spectroscopy, diffusion-ordered spectroscopy and T1 ((1) H) measurements, in combination with density functional theory methods allow the full conformational dynamics of a pyridylmethylamine-Zn(II) complex to be revealed. Four conformers and two families of complexes depending on the hydration states are elucidated.

  5. Unsymmetrical Mesoporphyrinic Complexes of Copper (II and Zinc (II. Microwave-Assisted Synthesis, Spectral Characterization and Cytotoxicity Evaluation

    Rica Boscencu


    Full Text Available New unsymmetrical mesoporphyrinic complexes, namely 5-(4-hydroxyphenyl-10,15,20–tris-(4-carboxymethylphenyl–21,23-Zn(II-porphine and 5-(4-hydroxyphenyl-10,15,20–tris-(4-carboxymethylphenyl–21,23-Cu(II-porphine, were synthesized using a microwave irradiation method. The structures of the porphyrinic complexes were confirmed using FT-IR, UV–Vis, EPR and NMR spectral data. The spectral absorption and emission properties of the porphyrinic complexes were studied in organic solvents of different polarities and the influence of solvent polarity on the wavelengths of the absorbance and fluorescence band maxima is described. The cytotoxicity evaluation of the porphyrinic complexes was performed on human colon adenocarcinoma cell line HT29 for different doses and incubation times. The obtained result indicates a lack of or low toxicity for both compounds, thus recommending them for further testing in light activation protocols.

  6. Anion-tuned self-assembly of zinc(II) fluconazole complexes: Crystal structures, luminescent and thermal properties

    Zhang, Lei; Ling, Yun; Peng, Feng; Du, Miao


    Four novel fluconazole-bridged Zn(II) complexes, [Zn(HFlu)Cl 2(DMF)] 2 ( 1), {[Zn(HFlu) 2(H 2O) 2](NO 3) 2·2DMF} n ( 2), {[Zn(HFlu) 2(H 2O) 2](NO 3) 2} n ( 3) and {[Zn(HFlu)(SCN) 2]·H 2O} n ( 4) [HFlu = 2-(2,4-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)-propan-2-ol], have been synthesized and structurally characterized by X-ray diffraction method. The structure of dimeric complex 1 consists of 20-membered macrometallacyclic ring-like structure, in which the Zn(II) ion is in a five-coordinated distorted trigonal bipyramidal geometry with the Zn⋯Zn distance of 10.265(3) Å across the cis HFlu ligand. Complex 2 shows infinite 1-D macrocyclic double chain structure with the central Zn(II) ions being six-coordinated by four HFlu ligands and two apical water molecules and with the intrachain Zn⋯Zn distance of 10.722(3) Å across the trans HFlu ligand. The crystal structure of complex 3 is analogous to that of complex 2 with the intrachain Zn⋯Zn distance of 10.654(2) Å. The structure of complex 4 consists of infinite 1-D coordination polymeric chain with the tetrahedral coordination geometry of Zn(II) ion and with the intrachain Zn⋯Zn distance of 11.173(2) Å across the cis HFlu ligand. Complexes 1- 4 show the similar fluorescence emission to the free HFlu ligand at ambient temperature and the thermal stabilities of the complexes have also been investigated.

  7. Coordination chemistry of sugar-phosphate complexes with palladium(II), rhenium(V) and zinc(II)

    Steinborn, Christian Martin


    As described before, some studies dealing with coordination chemistry of sugar phosphates are available but no analogous complexes of Zn{sup II} have been investigated yet. The primary goal of this work is, therefore, to fill this gap. In order to stay close to the active sites of enzymes such as class-II-aldolase, the simple metal fragment Zn{sup II}(dien) is used. NMR spectroscopy is used primarily as analytical method since it enables the investigation of both complex equilibria in solution and pH dependence of metal-binding sites. Since this approach is challenging due to the fast metal-ligand exchange and the absence of CIS values, it is necessary to improve the significance of NMR data collected from sugar-phosphate complexes with Zn{sup II}. Hence, further experiments are performed with molecules similar to sugar phosphates such as reducing and methylated sugars or polyols. Beside NMR spectroscopy, crystal-structure analysis will be used to get more detailed information about the binding pattern of the complexes. Additionally, sugar-phosphate complexes of Pd{sup II} are investigated. Further experiments are conducted, on the one hand, to synthesise more sugarphosphate complexes with ReVON2 fragments, and, on the other hand, to grow crystals confirming the theory about mixed sugar-core-phosphate chelation.

  8. Gastroprotective and antidepressant effects of a new zinc(II)-curcumin complex in rodent models of gastric ulcer and depression induced by stresses.

    Mei, Xueting; Xu, Donghui; Xu, Sika; Zheng, Yanping; Xu, Shibo


    Curcumin, a yellow pigment found in the rhizome of Curcuma loga, has been used to treat a variety of digestive and neuropsychiatric disorders since ancient times in China. Curcumin can chelate various metal ions to form metallocomplexes of curcumin which show greater effects than curcumin alone. This study investigated the antiulcerogenic and antidepressant effects of a Zn(II)-curcumin complex on cold-restraint stress (CRS)-induced gastric ulcers in rats, and on the forced swimming test (FST), tail suspension test (TST) and 5-hydroxy-l-tryptophan (5-HTP)-induced head twitch test in mice. CRS disrupted the rat mucosal barrier and induced gastric ulcers by decreasing the activities of the antioxidant enzymes, and increasing H(+)-K(+)-ATPase activity and malondialdehyde (MDA) level. Pretreatment with Zn(II)-curcumin (12, 24, and 48mg/kg) dose-dependently reversed these trends, reduced gastric lesions and H(+)-K(+)-ATPase activity, and increased antioxidant activities compared with control groups. Zn(II)-curcumin significantly increased HSP70 mRNA, and attenuated increased iNOS mRNA in the mucosa. Zn(II)-curcumin (17, 34, and 68mg/kg) also significantly decreased immobility time in the FST and TST, and enhanced 5-HTP-induced head twitches in mice. These results demonstrate that the Zn(II)-curcumin complex showed significant gastroprotective and antidepressant effects compared with curcumin alone via a synergistic effect between curcumin and zinc.

  9. A novel SPE-HPLC method for simultaneous determination of selected sulfonated phthalocyanine zinc complexes in mouse plasma following cassette dosing.

    Jiang, Zhou; Shao, Jingwei; Chen, Meili; Wang, Jian; Jia, Lee


    Sulfonated phthalocyanine zinc complexes (ZnPcSn) are a mixture of polymolecules with different number of the sulfonic groups. They are typical photosensitizers for photodynamic therapy (PDT). Analysis of the sulfonic phthalocyanine complexes in blood is a global technical challenge to developing this kind of photosensitizers into clinics. To circumvent the problem, we aimed at developing a novel solid-phase extraction (SPE)-HPLC method, which was primarily composed of (1) the SPE material that has both the aliphatic benzene group and hydrophilic ethylenediamino group bonded to the silica surface typically for retaining those hydrophobic compounds with some degree of hydrophilic anionic (negatively charged) functionality; and (2) the RP-Amide C16 HPLC column packed with palmitamidopropylsilane for both reversed-phase and anion exchange separation. The method was validated in terms of recovery, precision and accuracy for pharmacokinetic study with the photosensitizer following its intravenous cassette dosing to mice. The present study is the first report on using an SPE-HPLC mode to simultaneously determine the phthalocyanine-based polymolecule photosensitizer in blood. The study will aid in clinical development of photosensitizers.

  10. Solvolysis mechanisms of RNA phosphodiester analogues promoted by mononuclear zinc(II) complexes: mechanisic determination upon solvent medium and ligand effects.

    Zhang, Xuepeng; Zhu, Yajie; Gao, Hui; Zhao, Cunyuan


    The solvolysis mechanisms of RNA phosphodiester model 2-(hydroxypropyl)-4-nitrophenyl phosphate (HpPNP) catalyzed by mononuclear zinc(II) complexes are investigated in the paper via a theoretical approach. The general-base-catalyzed (GBC) and specific-base-catalyzed (SBC) mechanisms are thoroughly discussed in the paper, and the calculations indicate a SBC mechanism (also named as the direct nucleophilic attack mechanism) when the cyclization of HpPNP is promoted by the Zn:[12]aneN3 complex ([12]aneN3 = 1,5,9-triazacyclododecane). The ligand effect is considered by involving two different catalysts, and the results show that the increasing size catalyst provides a lower energy barrier and a significant mechanistic preference to the SBC mechanism. The solvent medium effect is also explored, and reduced polarity/dielectric constant solvents, such as light alcohols methanol and ethanol, are more favorable. Ethanol is proven to be a good solvent medium because of its low dielectric constant. The computational results are indicative of concerted pathways. Our theoretical results are consistent with and well interpret the experimental observations and, more importantly, provide practical suggestions on the catalyst design and selection of reaction conditions.

  11. Synthesis and characterization of bis (acetylacetonato κ-O, O') [zinc(ii)/copper(ii)] hybrid organic-inorganic complexes as solid metal organic precursors.

    Rooydell, Reza; Wang, Ruey-Chi; Brahma, Sanjaya; Ebrahimzadeh, Farzaneh; Liu, Chuan-Pu


    We have synthesized novel metal organic hybrid mixed compounds of bis (acetylacetonato κ-O, O') [zinc(ii)/copper(ii)]. Taking C10H14O4Zn0.7Cu0.3 (Z0.7C0.3AA) as an example, the crystals are composed of Z0.7C0.3AA units and uncoordinated water molecules. Single-crystal X-ray diffraction results show that the complex Z0.7C0.3AA crystallizes in the monoclinic system, space group P21/n. The unit cell dimensions are a = 10.329(4) Å, b = 4.6947(18) Å, and c = 11.369(4) Å; the angles are α = 90°, β = 91.881(6)°, and γ = 90°, the volume is 551.0(4) Å(3), and Z = 2. In this process, the M(ii) ions of Zn and Cu mix and occupy the centers of symmetrical structural units, which are coordinated to two ligands. The measured bond lengths and angles of O-M-O vary with the ratio of metal species over the entire series of the complexes synthesized. The chemistry of the as-synthesized compounds has been characterized using infrared spectroscopy, mass spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analysis, and the morphology of the products has been characterized using scanning electron microscopy. The thermal decomposition of the Z0.7C0.3AA composites measured by thermogravimetric analysis suggests that these complexes are volatile. The thermal characteristics of these complexes make them attractive precursors for metal organic chemical vapor deposition.

  12. Five-Coordinate Zinc(II Complex: Synthesis, Characterization, Molecular Structure, and Antibacterial Activities of Bis-[(E-2-hydroxy-N′-{1-(4-methoxyphenylethylidene}benzohydrazido]dimethylsulfoxidezinc(II Complex

    Zhi-Qiang Liu


    Full Text Available The titled Zn(II complex was synthesized by reacting the compound (E-2-hydroxy-N′-{1-(4-methoxyphenylethylidene}benzohydrazide with zinc(II acetate dihydrate in alkaline DMSO and ethanol solution under reflux condition for 28 hours. The resulting solid was filtered and recrystallized from the mixture of ethanol and DMSO. The hydrazone Schiff base and its Zn(II complex were characterized using 1H, 13C NMR, FTIR, UV-Vis spectroscopy, and single crystal X-ray diffraction analysis. Meanwhile, their antibacterial activities were examined using disc diffusion method. The spectral studies showed that the hydrazone Schiff base underwent keto-enol tautomerization, forming a bidentate ligand (N,O towards Zn(II ion. Surprisingly, on top of the two hydrazone Schiff base molecules which coordinated to the Zn metal center, an additional DMSO molecule was found attached to the Zn metal center in the crystal data, resulting in a 5-coordinate distorted trigonal bipyramidal Zn(II complex. Both hydrazone Schiff base and its Zn(II complexes were found to exhibit low antibacterial activity even when the concentrations were increased to 800 ppm.

  13. Novel zinc(II) and copper(II) complexes of a Mannich base derived from lawsone: Synthesis, single crystal X-ray analysis, ab initio density functional theory calculations and vibrational analysis.

    Neves, Amanda P; Vargas, Maria D; Téllez Soto, Claudio A; Ramos, Joanna M; Visentin, Lorenzo do C; Pinheiro, Carlos B; Mangrich, Antônio S; de Rezende, Edivaltrys I P


    Zinc(II) and copper(II) complexes of a tridentate Mannich base L1 derived from 2-hydroxy-1,4-naphthoquinone, pyridinecarboxyaldehyde and 2-aminomethylpyridine, [ZnL1Cl(2)]·H(2)O 1 and [CuL1Cl(2)]·2H(2)O 2, have been synthesized and fully characterized. The structure of complex 1 has been elucidated by a single crystal X-ray diffraction study: the zinc atom is pentacoordinate and the coordination geometry is a distorted square base pyramid, with a geometric structural parameter τ equal to 0.149. Vibrational spectroscopy and ab initio DFT calculations of both compounds have confirmed that the two complexes exhibit similar structures. Full assignment of the vibrational spectra was also supported by careful analysis of the distorted geometries generated by the normal modes. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Novel Bis-β-diketone-type Ligand and Its Copper and Zinc Complexes for Two-photon Biological Imaging

    ZHOU Shuang-sheng; XUE Xuan; WEI Dong; JIANG Bo; WANG Jia-feng; LU Cheng-hua


    A curcumin derivative ligand,1,7-bis(3-methoxyl-4-oxyethylacetate)phenyl-1,6-heptadiene-3,5-diketone (diethyl acetatecurcumin,abbreviated as HL),and its Cu(Ⅱ) and Zn(Ⅱ) complexes have been synthesized and characterized by elemental analyses,infrared(IR),1H NMR and molar conductivity.The experimental results show that the resulting complexes bear strong two-photon excited fluorescence(TPEF) in N,N-dimethyformamide solvent,which has been proven to be potentially useful for two-photon microscopy imaging in living cells.In addition,cytotoxicity tests show that the low-micromolar concentrations of metal-ligand complex(ML2) did not cause significant reduction in cell viability over a pcriod of,at least,24 h and should be safe for further biological studies.

  15. Synthesis and Characterization of Some New Complexes of Magnesium (II and Zinc (II with the Natural Flavonoid Primuletin

    Ştefania Felicia Bǎrbuceanu


    Full Text Available Two new metal complexes formulated as [Mg(L2(H2O2]·H2O (1 and [Zn(L2(H2O2]·0.5H2O (2, where HL = 5-hydroxyflavone (primuletin, have been synthesized and characterized by elemental and thermal analyses, molar conductance, IR, UV-Vis, 1H- and 13C-NMR, fluorescence and mass spectra. In solid state, complexes had shown higher fluorescence intensities comparing to the free ligand, and this behavior is appreciated as a consequence of the coordination process.

  16. 烟酸锌配合物的合成及结构表征%Synthesis and Crystal Structure of the Nicotinate Zinc Complex

    康海霞; 傅玉琴


    应用水热合成法合成了烟酸锌配合物,通过X-射线单晶衍射对其进行了结构表征,并通过XRD对其纯度进行了分析.X-射线单晶衍射表明,该配合物属正交晶系,空间群为Pbca,晶胞参数为a=1.4229(3) nm, b=0.69191(12) nm, c=0.85012(15) nm,α=90°,β=118.2020(10)°,γ=90°, Z=2, V =737.6(2)樻3, Mr =381.64, Dc =1.718 mg/m 3,μ=1.710 mm -1, F(000)=392,最终R 1=0.0189, wR 2=0.0532.晶体结构表明,该配合物中中心锌原子是六配位,形成了一个稍微畸变的正八面体构型,通过氢键的作用,标题化合物形成了复杂的三维的网状结构.%The nicotinate zinc complex is synthesized and characterized by X-Ray single crystal diffraction.It crystallizes in Orthorhombic, space group Pbca with a=1.4229 (3) nm, b=0.69191 (12) nm, c=0.85012 (15) nm, alpha=90 deg, beta =118.2020(10) deg, gamma =90 deg, Z =2, V =737.6(2) Å3, Mr =381.64, Dc =1.718 mg/m3 ,μ=1.710 mm-1 , F(000)=392.The Final R1=0.0189, wR2=0.0532.Crystal structure shows that the coordination environment around the Zinc can be described as a slightly distorted octahed-ron.The title compound forms a complex three-dimensional network structure through hydrogen bonding.

  17. Highly selective and sensitive DNA assay based on electrocatalytic oxidation of ferrocene bearing zinc(II)-cyclen complexes with diethylamine.

    Shiddiky, Muhammad J A; Torriero, Angel A J; Zeng, Zhanghua; Spiccia, Leone; Bond, Alan M


    A highly selective and sensitive electrochemical biosensor has been developed that detects DNA hybridization by employing the electrocatalytic activity of ferrocene (Fc) bearing cyclen complexes (cyclen = 1,4,7,10-tetraazacyclododecane, Fc[Zn(cyclen)H(2)O](2)(ClO(4))(4) (R1), Fc(cyclen)(2) (R2), Fc[Zn(cyclen)H(2)O](ClO(4))(2) (R3), and Fc(cyclen) (R4)). A sandwich-type approach, which involves hybridization of a target probe hybridized with the preimmobilized thiolated capture probe attached to a gold electrode, is employed to fabricate a DNA duplex layer. Electrochemical signals are generated by voltammetric interrogation of a Fc bearing Zn-cyclen complexes that selectively and quantitatively binds to the duplex layers through strong chelation between the cyclen complexes and particular nucleobases within the DNA sequence. Chelate formation between R1 or R3 and thymine bases leads to the perturbation of base-pair (A-T) stacking in the duplex structure, which greatly diminishes the yield of DNA-mediated charge transport and displays a marked selectivity to the presence of the target DNA sequence. Coupling the redox chemistry of the surface-bound Fc bearing Zn-cyclen complex and dimethylamine provides an electrocatalytic pathway that increases sensitivity of the assay and allows the 100 fM target DNA sequence to be detected. Excellent selectivity against even single-base sequence mismatches is achieved, and the DNA sensor is stable and reusable.

  18. Extraction of proteins with ionic liquid aqueous two-phase system based on guanidine ionic liquid.

    Zeng, Qun; Wang, Yuzhi; Li, Na; Huang, Xiu; Ding, Xueqin; Lin, Xiao; Huang, Songyun; Liu, Xiaojie


    Eight kinds of green ionic liquids were synthesized, and an ionic liquid aqueous two-phase system (ILATPS) based on 1,1,3,3-tetramethylguandine acrylate (TMGA) guanidine ionic liquid was first time studied for the extraction of proteins. Single factor experiments proved that the extraction efficiency of bovine serum albumin (BSA) was influenced by the mass of IL, K2HPO4 and BSA, also related to the separation time and temperature. The optimum conditions were determined through orthogonal experiment by the five factors described above. The results showed that under the optimum conditions, the extraction efficiency could reach up to 99.6243%. The relative standard deviations (RSD) of extraction efficiencies in precision experiment, repeatability experiment and stability experiment were 0.8156% (n=5), 1.6173% (n=5) and 1.6292% (n=5), respectively. UV-vis and FT-IR spectra confirmed that there were no chemical interactions between BSA and ionic liquid in the extraction process, and the conformation of the protein was not changed after extraction. The conductivity, DLS and TEM were combined to investigate the microstructure of the top phase and the possible mechanism for the extraction. The results showed that hydrophobic interaction, hydrogen bonding interaction and the salt out effect played important roles in the transferring process, and the aggregation and embrace phenomenon was the main driving force for the separation. All these results proved that guanidine ionic liquid-based ATPSs have the potential to offer new possibility in the extraction of proteins.

  19. Guanidine hydrochloride embedded polyurethanes as antimicrobial and absorptive wound dressing membranes with promising cytocompatibility.

    Sahraro, Maryam; Yeganeh, Hamid; Sorayya, Marziyeh


    Preparation and assessments of novel absorptive wound dressing materials with efficient antimicrobial activity as well as very good cytocompatibility were described in this work. An amine terminated poly(hexamethylene guanidine hydrochloride) was prepared and used as curing agent of different epoxy-terminated polyurethane prepolymers. The structures of prepared materials were elucidated by evaluation of their (1)H NMR and FTIR spectra. The recorded tensile strength of membranes confirmed the excellent dimensional stability of the film type dressings even at fully hydrated conditions. Therefore, these dressings could protect the wound bed from external forces during the healing period. The structurally optimized dressing membranes could preserve the desired moist environment over the wounded area, as a result of their balanced equilibrium, water absorption and water vapor transmission rate. Therefore, a very good condition for stimulation of self-healing of wound bed was attained. Also, owing to the presence of guanidine hydrochloride moieties embedded into the structure of dressings, efficient antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans were detected. In vitro cytotoxicity assay of the prepared dressings revealed cytocompatibility of these materials against fibroblast cells. Therefore, they could support cell growth and proliferation at the wounded area.

  20. Guanidination of notexin alters its membrane-damaging activity in response to sphingomyelin and cholesterol

    Pei-Hsiu Kao; Yi-Ling Chiou; Shinne-Ren Lin; Long-Sen Chang


    To elucidate the contribution of phospholipase A2 (PLA2) activity of notexin to its ability to perturb membranes, comparative studies on the interaction of notexin and guanidinated notexin (Gu-notexin) with egg yolk phosphatidylcholine (EYPC), EYPC/egg yolk sphingomyelin (EYSM) and EYPC/EYSM/cholesterol vesicles were conducted. EYSM notably reduced the membrane-damaging activity of notexin against EYPC vesicles, but had an insignificant influence on that of Gu-notexin. Unlike the effects noted with notexin, inactivation of PLA2 activity by EDTA led to a reduction in the ability of Gu-notexin to induce EYPC/EYSM vesicle leakage and to increase Gu-notexin-induced membrane permeability of EYPC/EYSM/cholesterol vesicles. The geometrical arrangement of notexin and Gu-notexin in contact with either EYPC/EYSM vesicles or EYPC/EYSM/cholesterol vesicles differed. Moreover, global conformation of notexin and Gu-notexin differed in either Ca2+-bound or metal-free states. These results indicate that notexin and Gu-notexin could induce membrane permeability without the involvement of PLA2 activity, and suggest that guanidination alters the membrane-bound mode of notexin on damaging phospholipid vesicles containing sphingomyelin and cholesterol.

  1. Synthesis, crystal structure and computational chemistry research of a Zinc(II complex: [Zn(Pt(Biim2

    Teng Fei


    Full Text Available The title metal-organic coordination complex [Zn(pt(Biim2] (pt=phthalic acid, benzene-1,2-dicarboxylate, Biim=2,2'-biimidazole 1 has been obtained by using hydrothermal synthesis and characterized by single-crystal X-ray diffraction. The complex crystallizes in monoclinic, space group P21/n with a = 8.5466(15 Å, b = 11.760(2 Å, c = 20.829(4 Å, β = 95.56(2º, V = 2083.5(6 Å3, Mr =497.78, Dc = 1.587 g/cm3, μ(MoKα = 1.226 mm−1, F(000 = 1016, Z = 4, the final R = 0.0564 and wR = 0.1851 for 3656 observed reflections (I > 2σ(I. The elemental analysis, IR, TG and the theoretical calculation were also investigated.

  2. One- and Two-photon Excited Fluorescence of Zinc(Ⅱ), Cadmium(Ⅱ) Complexes Containing Phenothiazine Ligand


    A new ligand, 10-ethylphenothiazinyl - 3 - yl - methylene thiosemicarbazon (HL) and its complexes ML2 (M=Zn2+, Cd2+), which exhibit intensive two-photon excited (TPE) fluorescence at 800 nm laser pulses in femtosecond regime, were synthesized and characterized.The measured power dependence of the fluorescence signals provided direct evidence for TPE.All of them exhibited a large two-photon absorptive cross section and, more importantly from the application point of view, high photochemical/photothermal stability.

  3. Availability of zinc and the ligands citrate and histidine to wheat: does uptake of entire complexes play a role?

    Gramlich, Anja; Tandy, Susan; Frossard, Emmanuel; Eikenberg, Jost; Schulin, Rainer


    Organic ligands in soils affect the availability of trace metals such as Zn to plants. This study investigated the effects of two of these ligands, citrate and histidine, on Zn uptake by wheat under hydroponic conditions. Uptake of (65)Zn in the presence of these ligands was compared to uptake in the presence of EDTA at the same free Zn concentration (Zn(2+) ~ 50 nM). In the presence of citrate Zn root uptake was enhanced ~3.5 times and in the presence of histidine, by a factor of ~9, compared to the EDTA treatments. Citrate uptake was slightly reduced in the treatment containing ligands and Zn compared to the treatment containing the same ligand concentration but no Zn. In addition, a higher uptake of Zn than of citrate was observed. This suggests that the enhanced Zn uptake was primarily due to increased supply of Zn(2+) by diffusion and dissociation of Zn-citrate complexes at the root surface. Histidine uptake was much higher than citrate uptake and not influenced by the presence of Zn. As histidine forms stronger complexes with Zn than citrate, the results suggest that the enhancement of Zn uptake in the presence of histidine was in part due to the uptake of undissociated Zn-histidine complexes.

  4. A Novel Two-dimensional Homochiral Zinc(II) Complex Constructed Based on In Situ Ligand Formation%A Novel Two-dimensional Homochiral Zinc(II) Complex Constructed Based on In Situ Ligand Formation

    ZHAO Xiu-Qin; GUO Chang; HUANG Rong-Yi; XU Heng; LIU Guang-Xiang; WU Gen-Hua


    A novel zinc(II) complex, Zn(IBT)2 (1, H1BT = 5-(4-((1H-imidazol-1-yl)methyl)- phenyl)-2H-tetrazole) has been synthesized with Zn(NO3)2·6H2O, 4-(imidazol-l-ylmethyl)benzonnitrile (IBN) and NaN3 by the hydrothermal method, and characterized by elemental analysis, IR and single-crystal X-ray diffraction. Crystallographic data for 1: C22H18N12Zn, Mr = 515.85, orthorhombic, Pbcn, a = 16.0567(15), b = 9.5316(9), c = 14.6107(14) A, V= 2236.1(4) A3, Z= 4, Dc = 1.532 g/cm3,μ = 1.138 mm-1, F(000) = 1056, R = 0.0350 and wR = 0.0888 for 1438 observed reflections (I 〉 2σ(I)) and the goodness-of-fit S = 1.002 on F2. The crystal structural analysis revealed that complex 1 exhibits a rare two-dimensional homochiral wave-like layer structure. In addition, the photoluminescence of complex 1 was studied in the solid state at room temperature together with its theoretical analysis.

  5. Post-synthetic modification of mesoporous zinc-adeninate framework with tris(2,2′-biprydine) ruthenium(II) complex and its electrochemiluminescence

    Park, Ji Eun; Shin, Ik Soo [Dept. of Chemistry, Soongsil University, Seoul (Korea, Republic of); Oh, Hye Jae; An, Ji Hyun [Dept. of Chemistry Education, Seoul National University, Seoul (Korea, Republic of)


    Herein we report a redox-active metal-organic framework (MOF) via post-synthetic cation exchange with tris(2,2′-biprydine) ruthenium(II) complex (Ru(bpy){sub 3}{sup 2+}). A porous anionic zinc-adeninate framework (bMOF-100) is spacious enough to easily entrap 2.43 of Ru(bpy){sub 3}{sup 2+} cations within the mesopore. The encapsulation supported the framework structure preventing any distortion from a rapid solvent evaporation under SEM observation. Ru(bpy){sub 3}{sup 2+}@bMOF-100 was then immobilized on the surface of glassy carbon electrode, and its electrocatalytic and electrochemiluminescent (ECL) properties were investigated in aqueous and organic solution. Especially, Ru(bpy){sub 3}{sup 2+}@bMOF-100 showed the excellent electrochemical properties of Ru(bpy){sub 3}{sup 2+}, but gradual decomposition of the MOF structure was observed under electrochemical measurements because of the sluggish oxidation of adeninate ligand.

  6. Unusual self-assembled 1D tape of tetramers and water-nitrate clusters trapped in a zinc(II) complex: Synthesis, characterization, luminescence and catalytic properties

    Ma, De-Yun; Guo, Hai-Fu; Dong, Ji; Xu, Jun


    Unusual tetramers and water-nitrate clusters have been observed in a mononuclear zinc(II) complex of [Zn(4-cpa)(phen)2(H2O)]·(H2O)·(NO3)] (1), (4-Hcpa = 4-chlorophenoxyacetic acid, phen = 1,10-phenanthroline), which was synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction, UV-vis absorption spectra and single-crystal X-ray diffraction. The crystal structure analysis of 1, reveals that the nitrate anions, water molecules and carboxylate oxygen atoms (O3) pack to form a one-dimensional infinite tape parallel to the c-axis. The uncoordinated carboxylate oxygen atoms (O3) of 4-cpa ligands, water molecules and nitrate anions interact via hydrogen bonds and extend 1 into a water-anion-cation tape, which are finally connected into a 3D supramolecular structure via π⋯π stacking interactions. Excitation (λex = 310 nm) and luminescence data observed at room temperature show that 1 emits bright blue fluorescence. Moreover, 1 has a remarkable activity for degradation of methyl orange in a photo-assisted Fenton-like process.

  7. Syntheses, spectral, electrochemical and thermal studies of mononuclear manganese(III) complexes with ligands derived from 1,2-propanediamine and 2-hydroxy-3 or 5-methoxybenzaldehyde: Self-assembled monolayer formation on nanostructure zinc oxide thin film

    Habibi, Mohammad Hossein; Askari, Elham; Amirnasr, Mehdi; Amiri, Ahmad; Yamane, Yuki; Suzuki, Takayoshi


    Mononuclear Mn(III) complexes have been prepared via the Mn(II) reaction of an equimolar of Schiff-bases derived from reaction of 2-hydroxy-3-methoxybenzaldehyde or 2-hydroxy-5-methoxybenzaldehyde with 1,2-diaminopropane. Axial ligands L include: pyridine (py) and H 2O. The resulting complexes have been characterized by FT-IR and UV-vis spectroscopy. The crystal structures of the complexes were determined and indicate that in the solid state the complex adopts a slightly distorted octahedral environment of the imine N and hydroxo O with the two axial ligands. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Mn III-Mn II is electrochemically quasi-reversible. Thermal stability of these complexes was determined by TG and DTG. Layers of these complexes were formed on nanostructure zinc oxide thin film and a red shift was observed when zinc oxide thin film is modified by complex.

  8. The biological inorganic chemistry of zinc ions.

    Krężel, Artur; Maret, Wolfgang


    The solution and complexation chemistry of zinc ions is the basis for zinc biology. In living organisms, zinc is redox-inert and has only one valence state: Zn(II). Its coordination environment in proteins is limited by oxygen, nitrogen, and sulfur donors from the side chains of a few amino acids. In an estimated 10% of all human proteins, zinc has a catalytic or structural function and remains bound during the lifetime of the protein. However, in other proteins zinc ions bind reversibly with dissociation and association rates commensurate with the requirements in regulation, transport, transfer, sensing, signalling, and storage. In contrast to the extensive knowledge about zinc proteins, the coordination chemistry of the "mobile" zinc ions in these processes, i.e. when not bound to proteins, is virtually unexplored and the mechanisms of ligand exchange are poorly understood. Knowledge of the biological inorganic chemistry of zinc ions is essential for understanding its cellular biology and for designing complexes that deliver zinc to proteins and chelating agents that remove zinc from proteins, for detecting zinc ion species by qualitative and quantitative analysis, and for proper planning and execution of experiments involving zinc ions and nanoparticles such as zinc oxide (ZnO). In most investigations, reference is made to zinc or Zn(2+) without full appreciation of how biological zinc ions are buffered and how the d-block cation Zn(2+) differs from s-block cations such as Ca(2+) with regard to significantly higher affinity for ligands, preference for the donor atoms of ligands, and coordination dynamics. Zinc needs to be tightly controlled. The interaction with low molecular weight ligands such as water and inorganic and organic anions is highly relevant to its biology but in contrast to its coordination in proteins has not been discussed in the biochemical literature. From the discussion in this article, it is becoming evident that zinc ion speciation is

  9. Self-assembled nanostructures of amphiphilic zinc(II) salophen complexes: role of the solvent on their structure and morphology.

    Oliveri, Ivan Pietro; Malandrino, Graziella; Di Bella, Santo


    This contribution explores the effect of several solvent properties, such as volatility, polarity, and Lewis basicity on the formation of molecular self-assembled nanostructures in the solid state, obtained either by casting of related solutions or by complete solvent evaporation, using seven solvents representative of common classes of coordinating organic solvents, of an amphiphilic Zn(II) Schiff-base complex. In all cases, the existence of well-defined X-ray diffraction patterns, for both the cast and powder samples, indicates a strong tendency towards the molecular self-assembly of such complexes. While nanostructures formed in acetone, THF, pyridine, and DMF have a lamellar organization, those formed in ACN, ethanol, and DMSO exhibit a 2D columnar square structure. Field emission scanning electron microscopy analysis indicates that nanostructures formed in volatile acetone, THF, ACN, and ethanol solvents show a fibrous morphology, while those formed in less volatile pyridine, DMF, and DMSO have a ribbon appearance. Overall, the results indicate that while the formation of such nanostructures is independent of the Lewis basicity of the solvent, the solvent polarity affects their structure - more polar solvents favour higher symmetry structures - and the solvent volatility influences their morphology and ordering in the cast films - lower volatility of the solvent parallels the formation of much more ordered structures. Therefore, the appropriate choice of solvent allows control of the structure, morphology, and ordering of these molecular assemblies.

  10. Structural study of the zinc and cadmium complexes of a type 2 plant (Quercus suber) metallothionein: insights by vibrational spectroscopy.

    Domènech, Jordi; Tinti, Anna; Capdevila, Mercè; Atrian, Silvia; Torreggiani, Armida


    Zn- and Cd-complexes of Quercus suber metallothionein (QsMT) were obtained by in vivo-synthesis, in order to obtain physiologically representative aggregates, and characterized by spectrometric and spectroscopic methods. The secondary structure elements and the coordination environments of the metal binding sites of the two aggregates were determined, as well as the main metal-containing species formed. The results obtained from the analysis of the Raman and IR spectra reveal that these metal-MT complexes predominantly contain beta-sheet elements (about 60%), whereas they lack alpha-helices. These structural features slightly depend on the divalent metal bound. In particular, Cd(II) binding to QsMT induces a slight increase of the beta-sheet percentage, as well as a decrease in beta-turn elements with respect to Zn(II) binding. Conversely, the in vivo capability of QsMT to inglobe metal and sulfide ions is metal-depending. Spectroscopic vibrational data also confirm the presence of sulfide ligands in the metal clusters of both Zn- and Cd-QsMT, while the participation of the spacer His residue in metal coordination was only found in Cd-QsMT, in agreement with the CD results. Overall data suggest different coordination environments for Zn(II) and Cd(II) ions in QsMT.

  11. First total synthesis of a guanidine alkaloid Nitensidine D using immobilized ionic liquid, microwaves and formamidinesulfinic acid

    Shallu; M L Sharma; Jasvinder Singh


    An efficient first total synthesis of a naturally occurring guanidine alkaloid, Nitensidine D isolated from ethanol extract of Pterogyne nitens has been described. Geraniol has been used as the starting material. N-alkylation of phthalimide has been achieved using immobilized ionic liquid and formamidinesulfinic acid acts as the guanylating reagent.

  12. Electrochemical reduction of nitrogen in the presence of the titanium (III)-molybdenum (III)-guanidine hydrochloride system

    Nikolaeva, G.V.; Efimov, O.N.; Kulakovskaya, S.I.; Shilov, A.E.


    Conditions of stable work of the electrocatalytic nitrogen-fixing system Ti(III)-Mo(III)- guanidine hydrochloride were found. At an alkali content less than 0.65 M, the rate of formation of hydrazine depends on the potential of the cathode; at a higher alkali content, water must be introduced to maintain a constant reaction rate.

  13. Synthesis of N-doped TiO2 Using Guanidine Nitrate: An Excellent Visible Light Photocatalyst

    An excellent visible light active nitrogen-rich TiO2 photocatalyst have been synthesized by using guanidine nitrate as the doping material. The catalytic efficiency of the catalyst has been demonstrated by the decomposition of the dye, methyl orange (MO), and the pollutant, 2,4 d...




    Full Text Available Five new molybdato (four and hydrogenomolybdato (one adducts and complexes have been synthesized and studied by infrared spectroscopy. The suggested structures are all discrete, the molybdate anion behaving as a trichelating, a monochelating, a bridging, a tetrachelating and a bichelating ligand. The environment around Zn, Co, Cd is tetrahedral or trigonal bipyramidal also for Zn - while being octahedral for Sb. The Cd pentanuclear adduct has a two metallic components structure, a tetranuclear anionic one with a tetrachelating molybdate, the second being a neutral dehydrated adduct component. The suggested structure for the hydrogenomolybdato adduct is discrete, the hydrogenomolybdate being present as a hydrogen bonded dimer behaves as a bridging bidentate ligand. The water molecules can be considered as a coordinating ligand or lattice. When secondary interactions through hydrogen bonds involving the water molecules are considered supramolecular architectures are obtained.

  15. Experimental research on ore dressing of one complex copper and zinc polymetallic ore from Inner Mongolia%内蒙古某铜锌复杂多金属矿石选矿试验研究

    刘先鹏; 刁玉东; 董丽梅


    A flotation experimental research is carried out according to the property of the ores from one complex copper and zinc polymetallic mine in Inner Mongolia.Through a preferential flotation flowsheet,that is to recover cop-per prior to zinc,a fairly good closed circuit test index is obtained:the copper grade in copper concentrate is 26.98%with the recovery rate of 83 .56%;the zinc grade in zinc concentrate is 50 .59%with the recovery rate of 76 .84%.%针对内蒙古某铜锌复杂多金属矿矿石性质,进行了浮选试验研究。通过采用优先浮选流程,即先选铜,再选锌,获得了较好的试验指标:铜精矿铜品位26.98%、铜回收率83.56%,锌精矿锌品位50.59%、锌回收率76.84%。

  16. Zinc-bromine battery development

    Richards, Lew; Vanschalwijk, Walter; Albert, George; Tarjanyi, Mike; Leo, Anthony; Lott, Stephen


    This report describes development activities on the zinc-bromine battery system conducted by Energy Research Corporation (ERC). The project was a cost-shared program supported by the U.S. Department of Energy and managed through Sandia. The project began in September 1985 and ran through January 1990. The zinc-bromine battery has been identified as a promising alternative to conventional energy storage options for many applications. The low cost of the battery reactants and the potential for long life make the system an attractive candidate for bulk energy storage applications, such as utility load leveling. The battery stores energy by the electrolysis of an aqueous zinc bromide salt to zinc metal and dissolved bromine. Zinc is plated as a layer on the electrode surface while bromine is dissolved in the electrolyte and carried out of the stack. The bromine is then extracted from the electrolyte with an organic complexing agent in the positive electrolyte storage tank. On discharge the zinc and bromine are consumed, regenerating the zinc bromide salt.

  17. Thermal, Spectral, Fluorescence, and Antimicrobial Studies of Cobalt, Nickel, Copper, and Zinc Complexes Derived from 4-[(5-Bromo-thiophen-2-ylmethylene-amino]-3-mercapto-6-methyl-5-oxo-[1,2,4]triazine

    Kiran Singh


    Full Text Available A new series of cobalt, nickel, copper, and zinc complexes of bidentate Schiff base derived from the condensation of 5-bromothiophene-2-carboxaldehyde with 4-amino-3-mercapto-6-methyl-5-oxo-[1,2,4]triazine were synthesized. Physical (magnetic measurements, molar conductance, TG, spectral (UV-Vis, IR, 1HNMR, fluorescence, ESR, and analytical data have established the structures of synthesized Schiff base and its metal complexes. The presence of coordinated water in metal complexes was confirmed by IR and TG studies. The Schiff base exhibits a strong fluorescence emission, contrast to this partial fluorescence quenching phenomena is observed in its metal complexes. A square planar geometry for Cu(II and octahedral geometry for Co(II, Ni(II and Zn(II complexes have been proposed. The Schiff base and its metal complexes have been screened for antibacterial (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and antifungal activities (Aspergillus niger, A. flavus.

  18. Various ways to reduce zinc oxide levels in S-SBR rubber compounds

    Heideman, G.; Noordermeer, Jacobus W.M.; Datta, Rabin; van Baarle, Ben


    Because of environmental concerns, the zinc content in rubber compounds has come under scrutiny. The research described in this article encompasses zinc-oxide, various zinc-complexes and alternative metal oxides as activators for sulphur vulcanisation. Regarding zinc complexes, it can be concluded

  19. Rapid Isolation and Determination of Flavones in Biological Samples Using Zinc Complexation Coupled with High-Performance Liquid Chromatography

    Chenghe Sun


    Full Text Available Chlorophyll-type contaminants are commonly encountered in the isolation and determination of flavones of plant aerial plant parts. Heme is also a difficult background substance in whole blood analysis. Both chlorophyll and heme are porphyrin type compounds. In this study, a rapid method for isolating flavones with 5-hydroxyl or ortho-hydroxyl groups from biological samples was developed based on the different solubilities of porphyrin-metal and flavone-metal complexes. It is important that other background substances, e.g., proteins and lipids, are also removed from flavones without an additional processing. The recoveries of scutellarin, baicalin, baicalein, wogonoside and wogonin, which are the primary constituents of Scutellaria baicalensis (skullcaps were 99.65% ± 1.02%, 98.98% ± 0.73%, 99.65% ± 0.03%, 97.59% ± 0.09% and 95.19% ± 0.47%, respectively. As a sample pretreatment procedure, this method was coupled to high-performance liquid chromatography (HPLC with good separation, sensitivity and linearity and was applied to determine the flavone content in different aerial parts of S. baicalensis and in dried blood spot samples.

  20. Determination of Diethyl Phthalate and Polyhexamethylene Guanidine in Surrogate Alcohol from Russia

    Yulia B. Monakhova


    Full Text Available Analytical methods based on spectroscopic techniques were developed and validated for the determination of diethyl phthalate (DEP and polyhexamethylene guanidine (PHMG, which may occur in unrecorded alcohol. Analysis for PHMG was based on UV-VIS spectrophotometry after derivatization with Eosin Y and 1H NMR spectroscopy of the DMSO extract. Analysis of DEP was performed with direct UV-VIS and 1H NMR methods. Multivariate curve resolution and spectra computation methods were used to confirm the presence of PHMG and DEP in the investigated beverages. Of 22 analysed alcohol samples, two contained DEP or PHMG. 1H NMR analysis also revealed the presence of signals of hawthorn extract in three medicinal alcohols used as surrogate alcohol. The simple and cheap UV-VIS methods can be used for rapid screening of surrogate alcohol samples for impurities, while 1H NMR is recommended for specific confirmatory analysis if required.

  1. 复合氨基酸络合铁、锌对肥育猪铁、锌吸收代谢的影响%Effects of Iron and Zinc Complex Amino Acid Chelate on Absorption Metabolism of Iron and Zinc of Finishing Pigs

    詹康; 占今舜; 赵国琦; 霍永久


    本试验旨在研究复合氨基酸络合铁、锌对肥育猪血液生化指标,血清中免疫球蛋白含量,毛发中铁、锌含量及铁、锌表观消化率的影响。选择体重[(55.63±1.33)kg]相近的“杜×长×大”肥育猪36头,随机分至对照组和2个试验组,每组3个重复,每个重复4头猪。对照组饲喂铁、锌含量均为100 mg/kg(由硫酸亚铁、硫酸锌提供)的基础饲粮,试验1组饲喂铁、锌含量均为50 mg/kg(由硫酸亚铁、硫酸锌提供)+50 mg/kg(由复合氨基酸络合铁、锌提供)的基础饲粮,试验2组饲喂铁、锌含量均为100 mg/kg(由复合氨基酸络合铁、锌提供)的基础饲粮。结果表明:1)3组间的红细胞数量、血细胞压积、血清免疫球蛋白A和免疫球蛋白M含量无显著差异( P>0.05)。2)试验2组的血红蛋白含量和血清免疫球蛋白 G含量显著高于对照组( P<0.05)。3)试验2组毛发中铁含量显著高于对照组( P<0.05),试验2组毛发中锌含量显著高于试验1组和对照组( P<0.05);4)试验2组粪中铁含量和试验2组、试验1组粪中锌含量显著低于对照组( P<0.05);3组间铁和锌表观消化率无显著差异( P>0.05)。由此可见,添加复合氨基酸络合铁、锌可显著增加肥育猪血红蛋白、血清免疫球蛋白G含量及毛发中铁、锌含量,显著降低粪中铁、锌含量。%To study the effects of iron and zinc complex amino acid chelate on blood biochemical indexes,im-munoglobulin content in serum,iron and zinc contents in hair and apparent digestibility of iron and zinc of fin-ishing pigs,thirty-six finishing pigs( Duroc × Landrace × Yorkshire ) with an average initial body weight of (55.63±1.33)kg were selected and randomly allotted to three groups. There were three replicates per group and four pigs in each replicate. Pigs of the control group fed a basal diet with 100 mg

  2. Dinuclear cadmium(II), zinc(II), and manganese(II), trinuclear nickel(II), and pentanuclear copper(II) complexes with novel macrocyclic and acyclic Schiff-base ligands having enantiopure or racemic camphoric diamine components.

    Jiang, Jue-Chao; Chu, Zhao-Lian; Huang, Wei; Wang, Gang; You, Xiao-Zeng


    Four novel [3 + 3] Schiff-base macrocyclic ligands I-IV condensed from 2,6-diformyl-4-substituted phenols (R = CH(3) or Cl) and enantiopure or racemic camphoric diamines have been synthesized and characterized. Metal-ion complexations of these enantiopure and racemic [3 + 3] macrocyclic ligands with different cadmium(II), zinc(II), manganese(II), nickel(II), and copper(II) salts lead to the cleavage of Schiff-base C horizontal lineN double bonds and subsequent ring contraction of the macrocyclic ligands due to the size effects and the spatial restrictions of the coordination geometry of the central metals, the steric hindrance of ligands, and the counterions used. As a result, five [2 + 2] and one [1 + 2] dinuclear cadmium(II) complexes (1-6), two [2 + 2] dinuclear zinc(II) (7 and 8), and two [2 + 2] dinuclear manganese(II) (9 and 10) complexes together with one [1 + 1] trinuclear nickel(II) complex (11) and one [1 + 2] pentanuclear copper(II) complex (12), bearing enantiopure or racemic ligands, different substituent groups in the phenyl rings, and different anionic ligands (Cl(-), Br(-), OAc(-), and SCN(-)), have been obtained in which the chiral carbon atoms in the camphoric backbones are arranged in different ways (RRSS for the enantiopure ligands in 1, 2, 4, 5, and 7-10 and RSRS for the racemic ligands in 3, 6, 11, and 12). The steric hindrance effects of the methyl group bonded to one of the chiral carbon atoms of camphoric diamine units are believed to play important roles in the formation of the acyclic [1 + 1] trinuclear complex 11 and [1 + 2] dinuclear and pentanuclear complexes 6 and 12. In dinuclear cadmium(II), zinc(II), and manganese(II) complexes 1-10, the sequence of separations between the metal centers is consistent with that of the ionic radii shortened from cadmium(II) to manganese(II) to zinc(II) ions. Furthermore, UV-vis, circular dichroism, (1)H NMR, and fluorescence spectra have been used to characterize and compare the structural

  3. Copper(II) and zinc(II) complexes of the peptides Ac-HisValHis-NH2 and Ac-HisValGlyAsp-NH2 related to the active site of the enzyme CuZnSOD.

    Bóka, Beáta; Myari, Alexandra; Sóvágó, Imre; Hadjiliadis, Nick


    Copper(II) and zinc(II) complexes of the peptides Ac-HisValHis-NH2 and Ac-HisValGlyAsp-NH2 related to the active site of the enzyme CuZnSOD were studied by potentiometric and spectroscopic (UV-Vis, CD and EPR) techniques. The results reveal that both ligands have effective metal binding sites, but the tripeptide is a much stronger complexing agent than the tetrapeptide. The formation of a macrochelate via the coordination of the imidazolyl residues is suggested in the copper(II)-Ac-HisValHis-NH2 system in the acidic pH range, while a 4N complex predominates at physiological pH. The interaction of Ac-HisValHis-NH2 with zinc(II) results in the formation of a precipitate indicating polynuclear complex formation. Both copper(II)-Ac-HisValHis-NH2 and copper(II)-HisValHis systems exhibit catalytic activity toward the dismutation of superoxide anion at physiological pH, but the saturated coordination sphere of the metal ions in both systems results in low reactivity as compared to the native enzyme.

  4. Preparation of Zinc (II and Cadmium (II Complexes of the Tetradentate Schiff Base Ligand 2-((E-(2-(2-(pyridine-2-yl- ethylthioethyliminomethyl-4-bromophenol (PytBrsalH

    Roya Kabiri


    Full Text Available We describe the synthesis and characterization of two new zinc (II andcadmium (II complexes of the tetradentate dissymmetric Schiff base ligand 2-((E-(2-(2-(pyridine-2-ylethylthioethyliminomethyl-4-bromophenol (PytBrsalH, prepared from 1-(2-pyridyl-3-thia-5-aminopentane (pyta and 5-bromosalicylaldehyde. The complexeswere synthesized by treating an ethanolic solution of the ligand with equimolar amounts ofappropriate metal salts in 1 M methanolic solution of NaOH or alternatively, by a moredirect route in which the two reactants are added to a solution of the ligand immediatelyafter formation of the latter and prior to any isolation. The complexes were characterizedby elemental analysis, FTIR, 1H-NMR, electronic spectra and molar conductivity.According to obtained data, the probable coordination geometries of zinc and cadmium inthese complexes with mixed N, S and O donor atoms are tetrahedral- and octahedral-like,respectively. Both complexes were found to be 1:1 electrolyte systems in acetonitrile.

  5. DNA- and BSA-binding studies and anticancer activity against human breast cancer cells (MCF-7) of the zinc(II) complex coordinated by 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine

    Anjomshoa, Marzieh; Fatemi, Seyed Jamilaldin; Torkzadeh-Mahani, Masoud; Hadadzadeh, Hassan


    Binding studies of a mononuclear zinc(II) complex, [Zn(dppt)2Cl2] (dppt is 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine), with DNA and bovine serum albumin (BSA) have been investigated under physiological conditions. The binding properties of the complex with fish sperm DNA (FS-DNA) have been investigated by UV-Vis absorption, thermal denaturation, competitive DNA-binding studies with ethidium bromide (EB) by fluorescence, and gel electrophoresis techniques. The competitive study with (EB) shows that the complex can displace EB from the DNA-EB system and compete for the DNA-binding sites with EB, which is usually characteristic of the intercalative interaction of compounds with DNA. The value of the fluorescence quenching constant (Ksv) was obtained as 3.1 × 104 M-1, indicating that this complex shows a high quenching efficiency and a significant degree of binding to DNA. Moreover, the intercalative binding mode has also been verified by the results of UV-Vis absorption, thermal denaturation and gel electrophoresis. The value of Kb at room temperature was calculated to be 1.97 × 105 M-1, indicating that the complex possesses strong tendency to bind with DNA. This value is very greater than to the values obtained for other zinc(II) complexes. The interaction of the complex with BSA has been studied by UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopic techniques. The results indicate that the complex has a quite strong ability to quench the fluorescence of BSA and the binding reaction is mainly a static quenching process. The quenching constants (KSV), the binding constants (Kb), the number of binding sites at different temperatures, the binding distance between BSA and the complex (r), and the thermodynamic parameters (ΔHo, ΔSo and ΔGo) between BSA and the complex were calculated. The complex exhibits good binding propensity to BSA showing relatively high binding constant values. The positive ΔHo and ΔSo values indicate that the

  6. DNA- and BSA-binding studies and anticancer activity against human breast cancer cells (MCF-7) of the zinc(II) complex coordinated by 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine.

    Anjomshoa, Marzieh; Fatemi, Seyed Jamilaldin; Torkzadeh-Mahani, Masoud; Hadadzadeh, Hassan


    Binding studies of a mononuclear zinc(II) complex, [Zn(dppt)2Cl2] (dppt is 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine), with DNA and bovine serum albumin (BSA) have been investigated under physiological conditions. The binding properties of the complex with fish sperm DNA (FS-DNA) have been investigated by UV-Vis absorption, thermal denaturation, competitive DNA-binding studies with ethidium bromide (EB) by fluorescence, and gel electrophoresis techniques. The competitive study with (EB) shows that the complex can displace EB from the DNA-EB system and compete for the DNA-binding sites with EB, which is usually characteristic of the intercalative interaction of compounds with DNA. The value of the fluorescence quenching constant (Ksv) was obtained as 3.1×10(4)M(-1), indicating that this complex shows a high quenching efficiency and a significant degree of binding to DNA. Moreover, the intercalative binding mode has also been verified by the results of UV-Vis absorption, thermal denaturation and gel electrophoresis. The value of Kb at room temperature was calculated to be 1.97×10(5)M(-1), indicating that the complex possesses strong tendency to bind with DNA. This value is very greater than to the values obtained for other zinc(II) complexes. The interaction of the complex with BSA has been studied by UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopic techniques. The results indicate that the complex has a quite strong ability to quench the fluorescence of BSA and the binding reaction is mainly a static quenching process. The quenching constants (KSV), the binding constants (Kb), the number of binding sites at different temperatures, the binding distance between BSA and the complex (r), and the thermodynamic parameters (ΔH(o), ΔS(o) and ΔG(o)) between BSA and the complex were calculated. The complex exhibits good binding propensity to BSA showing relatively high binding constant values. The positive ΔH(o) and ΔS(o) values indicate that

  7. Transcriptional activation is a conserved feature of the early embryonic factor Zelda that requires a cluster of four zinc fingers for DNA binding and a low-complexity activation domain.

    Hamm, Danielle C; Bondra, Eliana R; Harrison, Melissa M


    Delayed transcriptional activation of the zygotic genome is a nearly universal phenomenon in metazoans. Immediately following fertilization, development is controlled by maternally deposited products, and it is not until later stages that widespread activation of the zygotic genome occurs. Although the mechanisms driving this genome activation are currently unknown, the transcriptional activator Zelda (ZLD) has been shown to be instrumental in driving this process in Drosophila melanogaster. Here we define functional domains of ZLD required for both DNA binding and transcriptional activation. We show that the C-terminal cluster of four zinc fingers mediates binding to TAGteam DNA elements in the promoters of early expressed genes. All four zinc fingers are required for this activity, and splice isoforms lacking three of the four zinc fingers fail to activate transcription. These truncated splice isoforms dominantly suppress activation by the full-length, embryonically expressed isoform. We map the transcriptional activation domain of ZLD to a central region characterized by low complexity. Despite relatively little sequence conservation within this domain, ZLD orthologs from Drosophila virilis, Anopheles gambiae, and Nasonia vitripennis activate transcription in D. melanogaster cells. Transcriptional activation by these ZLD orthologs suggests that ZLD functions through conserved interactions with a protein cofactor(s). We have identified distinct DNA-binding and activation domains within the critical transcription factor ZLD that controls the initial activation of the zygotic genome.

  8. Small Cause, Great Impact: Modification of the Guanidine Group in the RGD Motif Controls Integrin Subtype Selectivity.

    Kapp, Tobias G; Fottner, Maximilian; Maltsev, Oleg V; Kessler, Horst


    Due to its unique role as a hydrogen-bond donor and its positive charge, the guanidine group is an important pharmacophoric group and often used in synthetic ligands. The chemical modification of the guanidine group is often considered to destroy its function. Herein, we show that the N-methylation, N-alkylation, or N-acylation of the guanidine group can be used to modify the receptor subtype specificity of the integrin ligand cilengitide. Using the αvβ6/α5β1-biselective ligand c(isoDGRkphg) and the αvβ6-specific ligand c(FRGDLAFp(NMe)K(Ac) as examples, we show that the binding affinities of the ligands can be fine-tuned by this method to enhance the selectivity for αvβ6. Furthermore, we describe a new strategy for the functionalization of integrin ligands. By introducing longer N-alkylguanidine and N-acylguanidine groups, we are able to simultaneously identify a hitherto unknown anchoring point and enhance the subtype selectivity of the ligand.

  9. Further Aspects of Ochratoxin A-Cation Interactions: Complex Formation with Zinc Ions and a Novel Analytical Application of Ochratoxin A-Magnesium Interaction in the HPLC-FLD System

    Miklós Poór


    Full Text Available Ochratoxin A (OTA is a mycotoxin produced by different Aspergillus and Penicillium species. Since its mechanism of action is not fully understood yet, it is important to gain further insight into different interactions of OTA at the molecular level. OTA is found worldwide in many foods and drinks. Moreover, it can also be detected in human and animal tissues and body fluids, as well. Therefore, the development of highly sensitive quantitative methods for the determination of OTA is of utmost importance. OTA most likely forms complexes with divalent cations, both in cells and body fluids. In the present study, the OTA-zinc interaction was investigated and compared to OTA-magnesium complex formation using fluorescence spectroscopy and molecular modeling. Our results show that zinc(II ion forms a two-fold higher stable complex with OTA than magnesium(II ion. In addition, based on the enhanced fluorescence emission of OTA in its magnesium-bound form, a novel RP-HPLC-fluorescence detector (FLD method was also established. Our results highlight that the application of magnesium chloride in alkaline eluents results in an approximately two-fold increase in sensitivity using the HPLC-FLD technique.

  10. Synthesis and characterization of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with Schiff base derived from 4-amino-3-mercapto-6-methyl-5-oxo-1,2,4-triazine.

    Singh, Kiran; Barwa, Manjeet Singh; Tyagi, Parikshit


    A few (1:1) and (1:2) metal complexes of cobalt(II), nickel(II), copper(II) and zinc(II) have been isolated with ligand derived from the condensation of 4-amino-3-mercapto-6-methyl-5-oxo-1,2,4-triazine with 2-acetylpyridine (L(1)) and characterized by elemental analysis, conductivity measurements, infrared, electronic, (1)H NMR spectral data, magnetic and thermogravimetric analyses. Due to insolubility in water and most of the common organic solvents and infusibility at higher temperatures, all the complexes are thought to be polymeric in nature. A square-planar geometry was suggested for copper(II) and octahedral proposed for cobalt(II), nickel(II) and zinc(II). Some of the chemically synthesized compounds have been screened in vitro against the three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and two Gram-negative (Salmonella typhi and Escherichia coli) organisms. It is observed that the coordination of metal ion has pronounced effect on the microbial activities of the ligand. The metal complexes have higher antimicrobial effect than the free ligands.


    Dr.Nilima Thosar*, Dr. Manoj Chandak, Dr.Manohar Bhat, Dr.Silpi Basak


    Background: Endodontic treatment of primary teeth is required to eliminate microorganisms from the infected root canals having complex root canal anatomy. Objectives: To assess the antifungal effect of zinc oxide paste with tea tree oil, thyme oil, peppermint oil on candida albicans and to compare it with zinc oxide eugenol paste. Materials and methods: Zinc oxide pastes containing essential oils used in the present study were zinc oxide tea tree oil paste (ZOT); zinc oxide thyme oil ...

  12. Lessons from a “Failed” Experiment: Zinc Silicates with Complex Morphology by Reaction of Zinc Acetate, the Ionic Liquid Precursor (ILP Tetrabutylammonium Hydroxide (TBAH, and Glass

    Andreas Taubert


    Full Text Available At elevated temperatures, the ionic liquid precursor (ILP tetrabutylammonium hydroxide reacts with zinc acetate and the glass wall of the reaction vessel. While the reaction of OH- with the glass wall is not surprising as such and could be considered a failed experiment, the resulting materials are interesting for a variety of applications. If done on purpose and under controlled conditions, the reaction with the glass wall results in uniform, well-defined hemimorphite Zn4Si2O7(OH2·nH2O and willemite Zn2SiO4 microcrystals and films. Their morphology can be adjusted by variation of the reaction time and reaction temperature. The hemimorphite can be transformed to Zn2SiO4 via calcination. The process is therefore a viable approach for the fabrication of porous films on glass surfaces with potential applications as catalyst support, among others.

  13. Integrated criteria document Zinc

    Cleven RFMJ; Janus JA; Annema JA; Slooff W


    This report contains information on zinc and zinc compounds concerning standards, emissions, exposure levels and effect levels. It includes a risk evaluation and presents proposals for maximum permissible concentrations of zinc in the environment. This study indicates that the concentration of zinc

  14. Cobalt(II), nickel(II), copper(II), zinc(II) and hafnium(IV) complexes of N'-(furan-3-ylmethylene)-2-(4-methoxyphenylamino)acetohydrazide.

    Emam, Sanaa M; El-Saied, Fathy A; Abou El-Enein, Saeyda A; El-Shater, Heba A


    Cobalt(II), nickel(II), copper(II), zinc(II) and hafnium(IV) complexes of furan-2-carbaldehyde 4-methoxy-N-anilinoacetohydrazone were synthesized and characterized by elemental and thermal (TG and DTA) analyses, IR, UV-vis and (1)H NMR spectra as well as magnetic moment and molar conductivity. Mononuclear complexes are obtained with 1:1 molar ratio except complexes 3 and 9 which are obtained with 1:2 molar ratios. The IR spectra of ligand and metal complexes reveal various modes of chelation. The ligand behaves as a neutral bidentate one and coordination occurs via the carbonyl oxygen atom and azomethine nitrogen atom. The ligand behaves also as a monobasic tridentate one and coordination occurs through the enolic oxygen atom, azomethine nitrogen atom and the oxygen atom of furan ring. Moreover, the ligand behaves as a neutral tridentate and coordination occurs via the carbonyl oxygen, azomethine nitrogen and furan oxygen atoms as well as a monobasic bidentate and coordination occurs via the enolic oxygen atom and azomethine nitrogen atom. The electronic spectra and magnetic moment measurements reveal that all complexes possess octahedral geometry except the copper complex 10 possesses a square planar geometry. The thermal studies showed the type of water molecules involved in metal complexes as well as the thermal decomposition of some metal complexes.

  15. Update on zinc biology.

    Solomons, Noel W


    Zinc has become a prominent nutrient of clinical and public health interest in the new millennium. Functions and actions for zinc emerge as increasingly ubiquitous in mammalian anatomy, physiology and metabolism. There is undoubtedly an underpinning in fundamental biology for all of the aspects of zinc in human health (clinical and epidemiological) in pediatric and public health practice. Unfortunately, basic science research may not have achieved a full understanding as yet. As a complement to the applied themes in the companion articles, a selection of recent advances in the domains homeostatic regulation and transport of zinc is presented; they are integrated, in turn, with findings on genetic expression, intracellular signaling, immunity and host defense, and bone growth. The elements include ionic zinc, zinc transporters, metallothioneins, zinc metalloenzymes and zinc finger proteins. In emerging basic research, we find some plausible mechanistic explanations for delayed linear growth with zinc deficiency and increased infectious disease resistance with zinc supplementation. Copyright © 2013 S. Karger AG, Basel.

  16. Synthesis and characterization of azo-guanidine based alcoholic media naked eye DNA sensor

    Hashmat, Uzma; Yousaf, Muhammad; Lal, Bhajan; Ullah, Shafiq; Holder, Alvin A.; Badshah, Amin


    DNA sensing always has an open meadow of curiosity for biotechnologists and other researchers. Recently, in this field, we have introduced an emerging class of molecules containing azo and guanidine functionalities. In this study, we have synthesized three new compounds (UA1, UA6 and UA7) for potential application in DNA sensing in alcoholic medium. The synthesized materials were characterized by elemental analysis, FTIR, UV-visible, 1H NMR and 13C NMR spectroscopies. Their DNA sensing potential were investigated by UV-visible spectroscopy. The insight of interaction with DNA was further investigated by electrochemical (cyclic voltammetry) and hydrodynamic (viscosity) studies. The results showed that compounds have moderate DNA binding properties, with the binding constants range being 7.2 × 103, 2.4 × 103 and 0.2 × 103 M−1, for UA1, UA6 and UA7, respectively. Upon binding with DNA, there was a change in colour (a blue shift in the λmax value) which was observable with a naked eye. These results indicated the potential of synthesized compounds as DNA sensors with detection limit 1.8, 5.8 and 4.0 ng µl−1 for UA1, UA6 and UA7, respectively. PMID:28018613

  17. Sequential conformation change and activation of chicken liver dihydrofolate reductase in low concentration of guanidine hydrochloride

    范映辛; 朱笠; 周筠梅; 邹承鲁


    The conformation changes of dihydrofolate reductase (DHFR) from chicken liver in guanidine hy-drochloride were monitored by protein intrinsic fluorescence, hydrophobic fluorescence probe TNS and limited proteol-ysis by proteinase K. The kinetics of the enzyme denaturation were also studied and compared with its activity changes. It was indicated by the enhanced fluorescence of 2-p-toluidinylnaphthalene (TNS) that a subtle conforma-tional change of the enzyme in dilute GuHCl parallels GuHCl-induced activation. At GuHCl concentration higher than 0.75 mol/L, the conformational change can be detected by increased susceptibility of the enzyme to proteinase K, but no significant gross conformational change of the enzyme molecule is observed by intrinsic fluorescence up to a GuHCl concentration of 1.2 mol/L. The results suggest that the denaturation of DHFR by GuHCl does not follow strictly the two-state model. The enzyme seems to open up sequentially with increasing concentrations of denaturants, mainly at th

  18. Synthesis, Characterization, and Bactericidal Evaluation of Chitosan/Guanidine Functionalized Graphene Oxide Composites.

    Li, Ping; Gao, Yangyang; Sun, Zijia; Chang, Dan; Gao, Ge; Dong, Alideertu


    In response to the wide spread of microbial contamination induced by bacterial pathogens, the development of novel materials with excellent antibacterial activity is of great interest. In this study, novel antibacterial chitosan (CS) and polyhexamethylene guanidine hydrochloride (PHGC) dual-polymer-functionalized graphene oxide (GO) (GO-CS-PHGC) composites were designed and easily fabricated. The as-prepared materials were characterized by Fourier transform infrared (FTIR), X-ray photoelectron spectrometer (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and Raman spectroscopy. Their antibacterial capability towards bacterial strains was also studied by incubating both Gram-negative bacteria and Gram-positive bacteria in their presence. More significantly, the synergistic antibacterial action of the three components was assayed, and the findings implied that the as-prepared GO-CS-PHGC shows enhanced antibacterial activity when compared to its single components (GO, CS, PHGC or CS-PHGC) and the mixture of individual components. Not only Gram-negative bacteria but also Gram-positive bacteria are greatly inhibited by GO-CS-PHGC composites. The minimum inhibitory concentration (MIC) value of GO-CS-PHGC against E. coli was 32 μg/mL. With the powerful antibacterial activity as well as its low cost and facile preparation, GO-CS-PHGC has potential applications as a novel antibacterial agent in a wide range of biomedical uses.

  19. Synthesis, Characterization, and Bactericidal Evaluation of Chitosan/Guanidine Functionalized Graphene Oxide Composites

    Ping Li


    Full Text Available In response to the wide spread of microbial contamination induced by bacterial pathogens, the development of novel materials with excellent antibacterial activity is of great interest. In this study, novel antibacterial chitosan (CS and polyhexamethylene guanidine hydrochloride (PHGC dual-polymer-functionalized graphene oxide (GO (GO-CS-PHGC composites were designed and easily fabricated. The as-prepared materials were characterized by Fourier transform infrared (FTIR, X-ray photoelectron spectrometer (XPS, field emission scanning electron microscopy (FE-SEM, transmission electron microscope (TEM, thermogravimetric analysis (TGA and Raman spectroscopy. Their antibacterial capability towards bacterial strains was also studied by incubating both Gram-negative bacteria and Gram-positive bacteria in their presence. More significantly, the synergistic antibacterial action of the three components was assayed, and the findings implied that the as-prepared GO-CS-PHGC shows enhanced antibacterial activity when compared to its single components (GO, CS, PHGC or CS-PHGC and the mixture of individual components. Not only Gram-negative bacteria but also Gram-positive bacteria are greatly inhibited by GO-CS-PHGC composites. The minimum inhibitory concentration (MIC value of GO-CS-PHGC against E. coli was 32 μg/mL. With the powerful antibacterial activity as well as its low cost and facile preparation, GO-CS-PHGC has potential applications as a novel antibacterial agent in a wide range of biomedical uses.

  20. Flame Retardancy of PA6 Using a Guanidine Sulfamate/Melamine Polyphosphate Mixture

    Mathieu Coquelle


    Full Text Available Polyamide 6 (PA6 is a widely-used polymer that could find applications in various sectors, including home textiles, transportation or construction. However, due to its organic nature, PA6 is flammable, and flame-retardant formulations have to be developed to comply with fire safety standards. Recently, it was proposed to use ammonium sulfamate as an effective flame retardant for PA6, even at low loading content. However, processing issues could occur with this additive considering large-scale production. This paper thus studies the use of another sulfamate salt—guanidine sulfamate (GAS—and evidences its high efficiency when combined with melamine polyphosphate (MPP as a flame retardant for PA6. A decrease of the peak of the heat release rate by 30% compared to pure PA6 was obtained using only 5 wt% of a GAS/MPP mixture in a microscale calorimeter. Moreover, PA6 containing the mixture GAS/MPP exhibits a Limiting Oxygen Index (LOI of 37 vol% and is rated V0 for the UL 94 test (Vertical Burning Test; ASTM D 3801. The mechanisms of degradation were investigated analyzing the gas phase and solid phase when the material degrades. It was proposed that MPP and GAS modify the degradation pathway of PA6, leading to the formation of nitrile end-group-containing molecules. Moreover, the formation of a polyaromatic structure by the reaction of MPP and PA6 was also shown.

  1. DSC study of cold and heat denaturation processes of β-lactoglobulin A with guanidine hydrochloride

    王邦宁; 谈夫


    The cold and heat denaturations of bovine β-lactoglobuhn A (β-lg A) has been studied in solutions of guanidine hydrochloride (GuHCl) by differential scanning calorimelry (DSC) The experimental results are presented and discussed.It is shown that the number of protons bound by the monomeric molecules of β-lg A was unchanged before and after its heat denaturation below pH 3,and that the activation energy of the heat denaturation was depressed owing to the presence of GuHCl.In the solutions with 2.50 and 3.06 mol/L of GuHCl,both the cold and heat denat-urations of β-lg A were observed.In comparison with the heat denaturation,the activation energy of cold denaturation was far lower and the number of GuHCl molecules bound by the unfolded polypeptide chains after cold denaturation increased a lot.The absolute value of the enthalpy of cold denaturation was larger than that of heat denaturation It was found by the analysis that the contribution to the total denaturational enthalpy of conformational change i

  2. Denaturing Effects of Urea and Guanidine Hydrochloride on Hyperthermophilic Esterase from Aeropyrum pernix K1


    The changes in the activity and the conformation of the hyperthermophilic esterase derived from aerobic thermophilic Aeropyrumpernix K1 (APE1547) were studied during denaturation by guanidine hydrochloride (GdnHCl)and urea. The denaturation course of APE1547 was followed by the steady-state and time resolved fluorescence methods. An increase in the denaturant concentration in the denatured system can significantly enhance the inactivation and unfolding of APE1547. The enzyme can be completely inactivated with a urea concentration of 2. 7 mol/L or a GdnHCl concentration of 7.5 mol/L. The fluorescence emission maximum of the enzyme protein red shifts in magnitude to a maximum value(355 nm) when the concentration of GdnHCl is 5.1 mol/L. The experimental results indicate that APE1547 has a high resistance to urea. Unfolding of APE1547 in GdnHCl(4.2-6.0 mol/L) was shown to be an irreversible process. The present results indicate that the ion pairs in this protein may be a key factor for the stability of this esterase.

  3. Probing conformational stability and dynamics of erythroid and nonerythroid spectrin: effects of urea and guanidine hydrochloride.

    Malay Patra

    Full Text Available We have studied the conformational stability of the two homologous membrane skeletal proteins, the erythroid and non-erythroid spectrins, in their dimeric and tetrameric forms respectively during unfolding in the presence of urea and guanidine hydrochloride (GuHCl. Fluorescence and circular dichroism (CD spectroscopy have been used to study the changes of intrinsic tryptophan fluorescence, anisotropy, far UV-CD and extrinsic fluorescence of bound 1-anilinonapthalene-8-sulfonic acid (ANS. Chemical unfolding of both proteins were reversible and could be described as a two state transition. The folded erythroid spectrin and non-erythroid spectrin were directly converted to unfolded monomer without formation of any intermediate. Fluorescence quenching, anisotropy, ANS binding and dynamic light scattering data suggest that in presence of low concentrations of the denaturants (up-to 1M hydrogen bonding network and van der Waals interaction play a role inducing changes in quaternary as well as tertiary structures without complete dissociation of the subunits. This is the first report of two large worm like, multi-domain proteins obeying twofold rule which is commonly found in small globular proteins. The free energy of stabilization (ΔGuH20 for the dimeric spectrin has been 20 kcal/mol lesser than the tetrameric from.

  4. Probing Conformational Stability and Dynamics of Erythroid and Nonerythroid Spectrin: Effects of Urea and Guanidine Hydrochloride

    Patra, Malay; Mukhopadhyay, Chaitali; Chakrabarti, Abhijit


    We have studied the conformational stability of the two homologous membrane skeletal proteins, the erythroid and non-erythroid spectrins, in their dimeric and tetrameric forms respectively during unfolding in the presence of urea and guanidine hydrochloride (GuHCl). Fluorescence and circular dichroism (CD) spectroscopy have been used to study the changes of intrinsic tryptophan fluorescence, anisotropy, far UV-CD and extrinsic fluorescence of bound 1-anilinonapthalene-8-sulfonic acid (ANS). Chemical unfolding of both proteins were reversible and could be described as a two state transition. The folded erythroid spectrin and non-erythroid spectrin were directly converted to unfolded monomer without formation of any intermediate. Fluorescence quenching, anisotropy, ANS binding and dynamic light scattering data suggest that in presence of low concentrations of the denaturants (up-to 1M) hydrogen bonding network and van der Waals interaction play a role inducing changes in quaternary as well as tertiary structures without complete dissociation of the subunits. This is the first report of two large worm like, multi-domain proteins obeying twofold rule which is commonly found in small globular proteins. The free energy of stabilization (ΔGuH20) for the dimeric spectrin has been 20 kcal/mol lesser than the tetrameric from. PMID:25617632

  5. Hemimorphite Ores: A Review of Processing Technologies for Zinc Extraction

    Chen, Ailiang; Li, Mengchun; Qian, Zhen; Ma, Yutian; Che, Jianyong; Ma, Yalin


    With the gradual depletion of zinc sulfide ores, exploration of zinc oxide ores is becoming more and more important. Hemimorphite is a major zinc oxide ore, attracting much attention in the field of zinc metallurgy although it is not the major zinc mineral. This paper presents a critical review of the treatment for extraction of zinc with emphasis on flotation, pyrometallurgical and hydrometallurgical methods based on the properties of hemimorphite. The three-dimensional framework structure of hemimorphite with complex linkage of its structural units lead to difficult desilicification before extracting zinc in the many metallurgical technologies. It is found that the flotation method is generally effective in enriching zinc minerals from hemimorphite ores into a high-grade concentrate for recovery of zinc. Pure zinc can be produced from hemimorphite or/and willemite with a reducing reagent, like methane or carbon. Leaching reagents, such as acid and alkali, can break the complex structure of hemimorphite to release zinc in the leached solution without generation of silica gel in the hydrometallurgical process. For optimal zinc extraction, combing flotation with pyrometallurgical or hydrometallurgical methods may be required.

  6. Stepwise preparation and characterization of molecular wires made of zinc octaethylporphyrin complexes bridged by 4, 4'-bipyridine on HOPG

    Ferreira, Quirina; Alcacer, LuIs; Morgado, Jorge, E-mail:, E-mail:, E-mail: [Instituto de Telecomunicacoes, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisboa (Portugal)


    Molecular-scale devices can be made using a step-by-step procedure, in a controllable and highly versatile way. In this report, we describe the growth of molecular wires (MW) from zinc (II) octaethylporphyrin (ZnOEP) assembled on highly oriented pyrolytic graphite (HOPG) by a step-by-step approach using 4, 4'-bipyridine (BP) to bridge the porphyrin units, via coordination of the nitrogen atom to zinc. In order to gain an insight into the molecular self-organization of these wires, we carried out a detailed scanning tunnelling microscopy (STM) analysis of each monolayer, using a solid/liquid interface technique, up to a complete ZnOEP/BP/ZnOEP/BP/ZnOEP-assembled structure. The electrical properties of the MWs were assessed by scanning tunnelling spectroscopy (STS) and by current-sensing atomic force microscopy (CS-AFM), showing an increase of electrical resistance with the length of the MW.

  7. Mixed effect of the supporting electrolyte and the zinc anode in the electrochemical homocoupling of 2-bromopyridines catalyzed by nickel complexes in an undivided cell.

    de França, Kelnner W R; Oliveira, Jadson de Lira; Florêncio, Tupolevck; da Silva, Aderivaldo P; Navarro, Marcelo; Léonel, Eric; Nédélec, Jean-Yves


    [reactions: see text] Nickel-catalyzed electroreductive homocoupling of 2-bromomethylpyridines and 2-bromopyridine has been investigated in an undivided cell in the presence of a zinc sacrificial anode. A series of reactions were performed with various types and concentrations of supporting electrolyte. It was observed that a key step in this process is the formation of an arylzinc through a nickel-zinc transmetalation. This intermediate can be transformed back to the reactive arylnickel species to afford the homocoupling as the final product. The back process from the arylzinc intermediate is, however, suppressed in the presence of high concentration (0.2 M) of tetraalkylammonium salts. On the contrary, with NaI, the formation of the dimer is not prevented, whatever the NaI concentration.

  8. 2-氨甲基吡啶配体锌配合物的合成、晶体结构及催化性能%Synthesis, Crystal Structure and Catalytic Performance of Zinc Complex Containing 2-(Aminomethyl) pyridine Ligand

    刘超; 卓馨; 张虎; 刘新华


    以2-氨甲基吡啶为配体与醋酸锌反应合成了一种新型锌金属配合物[Zn( AMPy)2(OAc)]2·[ Zn( OAc)4]( AMPy=2-氨甲基吡啶),通过核磁共振谱、红外光谱、元素分析和X射线单晶衍射对其结构进行了表征.晶体结构显示,该配合物属于三斜晶系,空间群为 P1,晶胞参数为 a=1.07360(19) nm, b=1.2491(2) nm, c=1.8976(3) nm,α=83.809(2)°,β=89.595(2)°,γ=65.708(2)°, V=2.3039(7) nm3, Z=2;配合物分子由3个不同的配位Zn离子通过分子内氢键连成一个完整的分子,分子间氢键再将其连成一个二维网状结构.研究了该金属配合物在Henry催化反应方面的性能,并优化出最佳催化条件.%A novel zinc metal complex [ Zn ( AMPy ) 2 ( OAc ) ] 2 [ Zn ( OAc ) 4 ] [ AMPy=2-( aminomethyl ) pyridine] was synthesized by the reaction of zinc acetate to 2-( aminomethyl) pyridine ligand. The structure of the complex was characterized by 1 H NMR, IR, elemental analysis and X-ray single crystal diffraction. The crystal structural analyses show that the complex belongs to triclinic system, space group is P1 with a=1. 07360(19) nm, b=1. 2491(2) nm, c=1. 8976(3) nm, α=83. 809(2)°, β=89. 595(2)°, γ=65. 708(2)°, V=2. 3039(7) nm3, Z=2. The complex molecular consists of three different coordinated zinc ions which are connected by intramolecular hydrogen bonds into a total molecular, and 2D network structure is further formed by intermolecular hydrogen bonds. The catalytic performance of the metal complex in Henry reaction was studied, and the optimum catalytic conditions were obtained. The results show that the complex exhibits a high catalytic performance with 9%( molar fraction) of catalyst loading, methanol as solvent and reaction at room temperature for 20 h.

  9. ErbB2-Driven Breast Cancer Cell Invasion Depends on a Complex Signaling Network Activating Myeloid Zinc Finger-1-Dependent Cathepsin B Expression

    Rafn, Bo; Nielsen, Christian Thomas Friberg; Andersen, Sofie Hagel;


    signaling network activates the transcription of cathepsin B gene (CTSB) via myeloid zinc finger-1 transcription factor that binds to an ErbB2-responsive enhancer element in the first intron of CTSB. This work provides a model system for ErbB2-induced breast cancer cell invasiveness, reveals a signaling...... network that is crucial for invasion in vitro, and defines a specific role and targets for the identified serine-threonine kinases....

  10. Structural, MALDI-TOF-MS, magnetic and spectroscopic studies of new dinuclear copper(II), cobalt(II) and zinc(II) complexes containing a biomimicking μ-OH bridge.

    Núñez, Cristina; Bastida, Rufina; Macías, Alejandro; Valencia, Laura; Neuman, Nicolás I; Rizzi, Alberto C; Brondino, Carlos D; González, Pablo J; Capelo, José Luis; Lodeiro, Carlos


    The Py(2)N(4)S(2) octadentate coordinating ligand afforded dinuclear cobalt, copper and zinc complexes and the corresponding mixed metal compounds. The overall geometry and bonding modes have been deduced on the basis of elemental analysis data, MALDI-TOF-MS, IR, UV-vis and EPR spectroscopies, single-crystal X-Ray diffraction, conductivity and magnetic susceptibility measurements. In the copper and zinc complexes, a μ-hydroxo bridge links the two metal ions. In both cases, the coordination geometry is distorted octahedral. Magnetic and EPR data reveal weakly antiferromagnetic high spin Co(II) ions, compatible with a dinuclear structure. The magnetic characterization of the dinuclear Cu(II) compound indicates a ferromagnetically coupled dimer with weak antiferromagnetic intermolecular interactions. The intra-dimer ferromagnetic behaviour was unexpected for a Cu(II) dimer with such μ-hydroxo bridging topology. We discuss the influence on the magnetic properties of non-covalent interactions between the bridging moiety and the lattice free water molecules.

  11. Method of capturing or trapping zinc using zinc getter materials

    Hunyadi Murph, Simona E.; Korinko, Paul S.


    A method of trapping or capturing zinc is disclosed. In particular, the method comprises a step of contacting a zinc vapor with a zinc getter material. The zinc getter material comprises nanoparticles and a metal substrate.

  12. Zinc: the neglected nutrient.

    Shambaugh, G E


    Zinc was first recognized as essential for animals at the University of Illinois School of Agriculture in 1916, when it was found that zinc-deficient baby pigs were runty, developed dermatitis on their legs, and were sterile. Zinc deficiency was first recognized in man by Dr. Ananda Prasad of Detroit 26 years ago when he measured serum and hair zinc levels in young male Egyptian dwarfs who had failed to mature and were small in stature. By simply adding zinc to their regular diet, they grew in height and became sexually mature. It is now recognized that dwarfism in males is frequent around the Mediterranean, where wheat is the staple of life and has been grown for 4,000 years on the same soil, thereby resulting in the depletion of zinc. Professor Robert Henkin first suggested that zinc deficiency might cause hearing-nerve impairment. Assay of the soft tissues of the cochlea and vestibule revealed a zinc level higher than that of any other part of the body. Previously, the eye was considered to have the highest level of zinc of any organ. To diagnose zinc deficiency clinically, we use serum zinc assays made at the Mayo Clinic Trace Element Laboratory. With zinc supplementation in patients who are marginally zinc deficient, there has been improvement in tinnitus and sensorineural hearing loss in about one-third of elderly adults. We believe zinc deficiency is one causation of presbycusis; by recognizing and correcting it, a progressive hearing loss can be arrested.

  13. Dynamic equilibrium unfolding pathway of human tumor necrosis factor-alpha induced by guanidine hydrochloride.

    Kim, Y R; Hahn, J S; Hong, H; Jeong, W; Song, N W; Shin, H C; Kim, D


    The dynamic equilibrium unfolding pathway of human tumor necrosis factor-alpha (TNF-alpha) during denaturation at different guanidine hydrochloride (GdnHCl) concentrations (0-4.2 M) was investigated by steady-state fluorescence spectroscopy, potassium iodide (KI) fluorescence quenching, far-UV circular dichroism (CD), picosecond time-resolved fluorescence lifetime, and anisotropy decay measurements. We utilized the intrinsic fluorescence of Trp-28 and Trp-114 to characterize the conformational changes involved in the equilibrium unfolding pathway. The detailed unfolding pathway under equilibrium conditions was discussed with respect to motional dynamics and partially folded structures. At 0-0.9 M [GdnHCl], the rotational correlation times of 22-25 ns were obtained from fluorescence anisotropy decay measurements and assigned to those of trimeric states by hydrodynamic calculation. In this range, the solvent accessibility of Trp residues increased with increasing [GdnHCl], suggesting the slight expansion of the trimeric structure. At 1.2-2.1 M [GdnHCl], the enhanced solvent accessibility and the rotational degree of freedom of Trp residues were observed, implying the loosening of the internal structure. In this [GdnHCl] region, TNF-alpha was thought to be in soluble aggregates having distinct conformational characteristics from a native (N) or fully unfolded state (U). At 4.2 M [GdnHCl], TNF-alpha unfolded to a U-state. From these results, the equilibrium unfolding pathway of TNF-alpha, trimeric and all beta-sheet protein, could not be viewed from the simple two state model (N-->U).

  14. Unfolding of C2A Domain of Synaptotagmin I in the Presence of Guanidine Hydrochloride

    孟凡国; 惠恩夫; 周海梦


    The C2 domain originally referred to the second of four constant structural motifs in protein kinase C (PKC).Now this domain represents a large structural family sharing a homologous dimensional structure in many proteins that play important roles in many organisms.The C2A domain is one of the two C2 domains of synaptotagmin I involved in the Ca2+ regulation of exocytosis.This domain is mostly composed of β-sheet except for a small fraction of α-helix, and therefore provides an ideal model for a protein folding study.In this report, the unfolding equilibrium of the C2A domain in guanidine hydrochloride (GdnHCl) containing solutions has been studied using ultraviolet (UV) difference spectrum, fluorescence spectrum, size exclusion chromatography (SEC), and circular dichroism (CD) spectrum.The results suggest that unfolding of the C2A domain occurs as a two-state process during GdnHCl titration.By examining the changes of both tertiary structure and secondary structure, no intermediates could be detected during this unfolding study.However, it has been found that the native state of the C2A domain has a large hydrophobic surface.This result suggests that as a fragment of a protein, the C2A domain itself may exist in a state with large hydrophobic surface.This hydrophobic surface may be the molecular basis for interaction between domains in the whole protein.Furthermore, the hydrophobic behavior may play a role during the oligomerization of synaptotagmin.

  15. Meta-iodobenzyl guanidine for detection and staging of neuroendocrine tumors

    Pryma, Daniel [Nuclear Medicine and Clinical Molecular Imaging Division, University of Pennsylvania, Philadelphia, PA 19105 (United States); Divgi, Chaitanya [Nuclear Medicine and Clinical Molecular Imaging Division, University of Pennsylvania, Philadelphia, PA 19105 (United States)], E-mail:


    Gastroenteropancreatic neuroendocrine tumors (GEP-NET) are slow-growing neoplasms that arise from the neuroendocrine system of the gastrointestinal tract and pancreas. These may be classified based on location into the following: pheochromocytomas and parangangliomas; carcinoids; and pancreatic endocrine tumors. The majority of these tumors are nonfunctional, and thus, molecular imaging methods are critical in detection and staging of disease. Meta-iodobenzyl guanidine (MIBG) is a norepinephrine analog taken up by norepinephrine transporters that are overexpressed in the majority of GEP-NET. Radioactive MIBG can be used to image GEP-NET. The isotopes suitable for imaging include iodine-123 and iodine-131, using single-photon cameras, and iodine-124, using positron emission tomography (PET). Imaging is usually carried out a day or more after administration of the radiotracer, and serial and tomographic imaging may be necessary for optimal delineation. MIBG imaging is more useful for detecting pheochromocytoma, with reported accuracies greater than 80%, than for detecting carcinoid tumors, where the accuracy has been {approx}70% and is reportedly higher in mid-gut tumors. MIBG imaging has been invaluable in the accurate staging of children with neuroblastoma, a lethal childhood tumor of the sympathetic nervous system. An important application of MIBG imaging is to demonstrate targeting of therapeutic I-131 MIBG. Imaging is thus useful in the detection of disease as well as in the demonstration of adequate targeting for therapy - either qualitatively or quantitatively with dosimetry. The latter will probably be feasible with PET using isotopes like iodine-124, and perhaps with single photon emission computed tomography/computed tomography. Imaging with MIBG will continue to be the mainstay for detection and staging of GEP-NET. More importantly, perhaps, imaging with MIBG will form part of an imaging continuum, including assessment of glycolytic rate and somatostatin

  16. Kinetics of the dissolution of zinc sulfide in an oxidizing slag

    Gupta, Suresh K.


    A new concept has been developed for the production of zinc from zinc and complex zinc concentrates. It is a two-stage process involving oxidation of zinc sulfide to oxide and dissolution into slag and the fuming of zinc from the slag by injecting carbonaceous materials into it to produce zinc vapors which can be subsequently condensed in a lead-splash condenser such as those used in the Imperial Smelting Process (ISP). In this paper, the effects of the quantity of air, temperature, and concentrate feed rate have been discussed on the production of zinc-rich slag, which is the first stage of the proposed process.

  17. Effect of 2-Amino-Benzothiazole Zinc Complex on the Growth and Development of Cotton Bollworm%2-氨基苯并噻唑锌配合物对棉铃虫生长发育的影响

    张海玲; 王树芳; 张优优; 王玉平; 柴连琴


    选取数百条正常三龄棉铃虫,分成5组,分别饲喂含不同剂量的2-氨基苯并噻唑锌配合物的人工配制饲料,期间测量每条虫的体重,直至生长到六龄使用血细胞计数板对血细胞进行计数,再测定血浆中的T-SOD活性.结果显示:与对照组相比,饲喂含低剂量2-氨基苯并噻唑锌配合物饲料的棉铃虫的血细胞数目较多,T-SOD活力较强;饲喂含高剂量配合物饲料的棉铃虫受到严重抑制,几乎处于不生长状态.以上结果表明低剂量2-氨基苯并噻唑锌配合物对棉铃虫生长发育有促进作用,而高剂量的则有抑制作用.%Hundreds of normal third instar cotton bollworms were selected and divided into five groups. They were fed with the artificial feed with different doses of 2-amino benzothiazole zinc complex solution. During the period, the weight of each cotton bollworm was measured. The number of the blood cells was calculated, using the blood cell counting plate. Then the activity of the T-SOD was determinated. Compared with the control group, the cotton bollworms fed with low dose of 2-amino benzothiazole zinc complex feed have more blood cells and a higher activity of T-SOD. Cotton bollworms fed with high dose of the complex were seriously inhibited and almost no growth in the state was shown. It suggested that low dose of 2-amino benzothiazole zinc complex promoted the growth and development of cotton bollworms, while high dose inhibited that.

  18. Partial substitution, with their chelated complexes, of the inorganic zinc, copper and manganese in sow diets reduced the laminitic lesions in the claws and improved the morphometric characteristics of the hoof horn of sows from three Greek herds.

    Varagka, Nikoleta; Lisgara, Marina; Skampardonis, Vassilis; Psychas, Vassilis; Leontides, Leonidas


    Hoof lesions in sows have been associated with lameness and poor hoof horn quality. The mechanical strength and quality of hoof horn is determined by the density and diameter of horn tubules, which were recently associated with the severity of lesions on the hoof wall of sows. Histologic changes that have previously been described in cases of bovine laminitis, have also been observed in the dermis and epidermis of the sows' claws. Trace elements, particularly zinc, copper and manganese, occupy important roles as enzyme catalysts in the process of keratin synthesis which determines the quality and the integrity of the hoof epidermis. Therefore, the objective of this study was to investigate the effect of diet supplementation with chelated zinc, copper and manganese, partially substituting their inorganic form, on sow claw health and hoof horn quality assessed by macroscopic, histologic and morphometric examination. Clinically, the total claw lesion score was significantly lower in claws of sows which received the "organic" diet compared to those of sows on the "inorganic" diet. Histologically, lamellar hyperplasia was the most frequently recorded change in the epidermis of the sows' claws regardless of the diet's mineral source. The claws of the sows which received the organic diet were more likely to have none or less histologic changes than at least one or more, respectively, compared to those of the sows on the "inorganic" diet. Morphometrically, the density and vertical and horizontal diameters of the horn tubules was significantly higher and smaller, respectively, in the hoof horn of sows which received the "organic" compared to those which received the "inorganic" source diet. Partial substitution of the inorganic zinc, copper and manganese in sows' diet with their chelated complexes, provided a comparative advantage against a conventional, inorganic mineral source diet, at least under the conditions examined in the current study, in terms of macroscopic

  19. Crosstalk between Zinc Status and Giardia Infection: A New Approach

    Humberto Astiazarán-García


    Full Text Available Zinc supplementation has been shown to reduce the incidence and prevalence of diarrhea; however, its anti-diarrheal effect remains only partially understood. There is now growing evidence that zinc can have pathogen-specific protective effects. Giardiasis is a common yet neglected cause of acute-chronic diarrheal illness worldwide which causes disturbances in zinc metabolism of infected children, representing a risk factor for zinc deficiency. How zinc metabolism is compromised by Giardia is not well understood; zinc status could be altered by intestinal malabsorption, organ redistribution or host-pathogen competition. The potential metal-binding properties of Giardia suggest unusual ways that the parasite may interact with its host. Zinc supplementation was recently found to reduce the rate of diarrhea caused by Giardia in children and to upregulate humoral immune response in Giardia-infected mice; in vitro and in vivo, zinc-salts enhanced the activity of bacitracin in a zinc-dose-dependent way, and this was not due to zinc toxicity. These findings reflect biological effect of zinc that may impact significantly public health in endemic areas of infection. In this paper, we shall explore one direction of this complex interaction, discussing recent information regarding zinc status and its possible contribution to the outcome of the encounter between the host and Giardia.

  20. Prediction of DNA-binding specificity in zinc finger proteins

    Sumedha Roy; Shayoni Dutta; Kanika Khanna; Shruti Singla; Durai Sundar


    Zinc finger proteins interact via their individual fingers to three base pair subsites on the target DNA. The four key residue positions −1, 2, 3 and 6 on the alpha-helix of the zinc fingers have hydrogen bond interactions with the DNA. Mutating these key residues enables generation of a plethora of combinatorial possibilities that can bind to any DNA stretch of interest. Exploiting the binding specificity and affinity of the interaction between the zinc fingers and the respective DNA can help to generate engineered zinc fingers for therapeutic purposes involving genome targeting. Exploring the structure–function relationships of the existing zinc finger–DNA complexes can aid in predicting the probable zinc fingers that could bind to any target DNA. Computational tools ease the prediction of such engineered zinc fingers by effectively utilizing information from the available experimental data. A study of literature reveals many approaches for predicting DNA-binding specificity in zinc finger proteins. However, an alternative approach that looks into the physico-chemical properties of these complexes would do away with the difficulties of designing unbiased zinc fingers with the desired affinity and specificity. We present a physico-chemical approach that exploits the relative strengths of hydrogen bonding between the target DNA and all combinatorially possible zinc fingers to select the most optimum zinc finger protein candidate.

  1. Synthesis, crystal structure and investigation of mononuclear copper(II) and zinc(II) complexes of a new carboxylate rich tripodal ligand and their interaction with carbohydrates in alkaline aqueous solution.

    Stewart, Christopher D; Pedraza, Mayra; Arman, Hadi; Fan, Hua-Jun; Schilling, Eduardo Luiz; Szpoganicz, Bruno; Musie, Ghezai T


    A new carboxylate rich asymmetric tripodal ligand, N-[2-carboxybenzomethyl]-N-[carboxymethyl]-β-alanine (H3camb), and its di-copper(II), (NH4)2[1]2, and di-zinc(II), ((CH3)4N)2[2]2, complexes have been synthesized as carbohydrate binding models in aqueous solutions. The ligand and complexes have been fully characterized using several techniques, including single crystal X-ray diffraction. The interactions of (NH4)2[1]2 and ((CH3)4N)2[2]2 with D-glucose, D-mannose, D-xylose and xylitol in aqueous alkaline media were investigated using UV-Vis and (13)C-NMR spectroscopic techniques, respectively. The molar conductance, NMR and ESI-MS studies indicate that the complexes dissociate in solution to produce the respective complex anions, 1(-) and 2(-). Complexes 1(-) and 2(-) showed chelating ability towards the naturally abundant and biologically relevant sugars, D-glucose, D-mannose, D-xylose, and xylitol. The complex ions bind to one molar equivalent of the sugars, even in the presence of stoichiometric excess of the substrates, in solution. Experimentally obtained spectroscopic data and computational results suggest that the substrates bind to the metal center in a bidentate fashion. Apparent binding constant values, pK(app), between the complexes and the substrates were determined and a specific mode of substrate binding is proposed. The pK(app) and relativistic density functional theory (DFT) calculated Gibbs free energy values indicate that D-mannose displayed the strongest interaction with the complexes. Syntheses, characterizations, detailed substrate binding studies using spectroscopic techniques, single crystal X-ray diffraction and geometry optimizations of the complex-substrates with DFT calculations are also reported.

  2. Zinc oxide overdose

    Zinc oxide is an ingredient in many products. Some of these are certain creams and ointments used ... prevent or treat minor skin burns and irritation. Zinc oxide overdose occurs when someone eats one of ...


    Marek Pająk


    Full Text Available The research was carried out in the Świerklaniec Forest District, the Brynica sub-district, which is located in the immediate vicinity of a metallurgical plant, a zinc mine named Huta Cynku "Miasteczko Śląskie" (HCMŚ. In autumn 2008, in the area in question, 31 permanent trial plots were established, aligned within a regular net of squares, with dimensions of 1500×1500 m. The trial plots were located to the north-east and to the east of the emitter (the HCMŚ zinc mine, accordingly with the direction of prevailing winds. In September 2013, and September and October 2014, sporocarps of bay bolete (Xerocomus badius (Fr. E. were collected from the trial plots. The analyses performed for the material gathered covered a determination of heavy metal content in mushrooms (Zn, Pb and Cd, using a method of inductively coupled plasma atomic emission spectroscopy ICP-AES. This paper aimed to establish the accumulation levels of selected heavy metals (Zn, Pb and Cd in bay bolete growing in forests of the Brynica sub-district, in the Świerklaniec Forest District, and the correlation between their content in soil and in the mushrooms under scrutiny. The analyses revealed that the contamination degree in the investigated species was extremely high. The content of toxic elements in bay bolete significantly exceeded the acceptable standards referring to the maximum content of heavy metals in mushrooms, which was particularly true for cadmium.

  4. Influence of structural factors on the thermal stability of zinc{sup (II)} and boron{sup (III)} complexes with iodo- and bromosubstituted 2,2′-dipyrrines

    Guseva, G.B., E-mail:; Antina, E.V.; Nuraneeva, E.N.


    Highlights: • Halogenated zinc{sup (II)} and boron{sup (III)} dipyrrinates are thermal stable up to 179–266 °C in argon. • Intramolecular red-ox-reactions are the main cause of the lowering of stability complexes. • Stability of complexes is increased when passing from I- to Br-substituted dipyrrinates. • The obtained results are interest in the development of laser dyes and sensors for PDT. - Abstract: The results of the analysis of thermal stability for zinc {sup (II)} and boron {sup (III)} complexes with 3,3′,5,5′-tetramethyl-4-ethyl-4′-iodo-2,2-dipyrrin [HL{sup 1}], 3,3′-diamyl-4,4′-dimethyl-5,5′-dibromo-2,2′-dipyrrin [HL{sup 2}] and 3,3′,5,5′-tetramethyl-4,4′-dibromo-2,2′-dipyrrin [HL{sup 3}] of the composition [Zn(L{sup 1}){sub 2}]–[Zn(L{sup 3}){sub 2}] and [BF{sub 2}L{sup 1}]–[BF{sub 2}L{sup 3}] are presented. The influence of halogenation of dipyrrin ligand is manifested in decreasing thermal stability of [Zn(L){sub 2}] and [BF{sub 2}L] when replacing 4,4′-dibromosubstituted dipyrrin on 5,5′-dibromo- or 4-monoiodosubstituted ligand. Intramolecular red-ox-reactions with participation of halogen atoms are the main cause of thermal stability lowering of dipyrrinates [Zn(L){sub 2}] and [BF{sub 2}L] compared with alkylsubstituted analogs. The obtained results are interesting for the development of laser dyes and sensors for PDT.

  5. Complexation and toxicity of copper in higher plants. II. Different mechanisms for copper versus cadmium detoxification in the copper-sensitive cadmium/zinc hyperaccumulator Thlaspi caerulescens (Ganges Ecotype).

    Mijovilovich, Ana; Leitenmaier, Barbara; Meyer-Klaucke, Wolfram; Kroneck, Peter M H; Götz, Birgit; Küpper, Hendrik


    The cadmium/zinc hyperaccumulator Thlaspi caerulescens is sensitive toward copper (Cu) toxicity, which is a problem for phytoremediation of soils with mixed contamination. Cu levels in T. caerulescens grown with 10 microm Cu(2+) remained in the nonaccumulator range (hyperaccumulation and metal resistance are highly metal specific. Cu-induced inhibition of photosynthesis followed the "sun reaction" type of damage, with inhibition of the photosystem II reaction center charge separation and the water-splitting complex. A few individuals of T. caerulescens were more Cu resistant. Compared with Cu-sensitive individuals, they recovered faster from inhibition, at least partially by enhanced repair of chlorophyll-protein complexes but not by exclusion, since the content of Cu in their shoots was increased by about 25%. Extended x-ray absorption fine structure (EXAFS) measurements on frozen-hydrated leaf samples revealed that a large proportion of Cu in T. caerulescens is bound by sulfur ligands. This is in contrast to the known binding environment of cadmium and zinc in the same species, which is dominated by oxygen ligands. Clearly, hyperaccumulators detoxify hyperaccumulated metals differently compared with nonaccumulated metals. Furthermore, strong features in the Cu-EXAFS spectra ascribed to metal-metal contributions were found, in particular in the Cu-resistant specimens. Some of these features may be due to Cu binding to metallothioneins, but a larger proportion seems to result from biomineralization, most likely Cu(II) oxalate and Cu(II) oxides. Additional contributions in the EXAFS spectra indicate complexation of Cu(II) by the nonproteogenic amino acid nicotianamine, which has a very high affinity for Cu(II) as further characterized here.

  6. 微波固相法合成邻苯二甲酸锌、铜配合物%Synthesis of Zinc( Ⅱ ) and Copper( Ⅱ ) Complexes with Phthalic Acid Ligand by Microwave Solid-State Method

    张艳; 钟国清; 熊鑫; 蒋琪英


    以邻苯二甲酸( H2phth)、乙酸锌或乙酸铜为原料,通过微波固相法合成了邻苯二甲酸锌、铜配合物Zn(phth)·2H2O和Cu (phth)·H2O,用化学分析、元素分析、傅里叶变换红外光谱、X射线粉末衍射、热分析对配合物的组成和结构进行了表征.结果表明,邻苯二甲酸配体中的羧基以双齿桥式与Zn(Ⅱ)或Cu(Ⅱ)结合形成配合物,其热分解包括失水、配体的氧化分解过程,最后完全分解为金属氧化物.%Zinc ( II ) and copper ( II ) complexes of o-phthalic acid (H2phth) were synthesized by microwave solid-state method with o-phthalic acid, zinc acetate or copper acetate as raw materials. Chemical and elemental analysis, fourier transformed infrared spectra (FTIR) , X-ray powder diffraction (XRD) and thermogravimetry-derivative thermogravimetry(TG-DTG) were applied to characterize the composition and structure of the compounds. The results show that the compositions of the complexes are Zn(phth) ? 2H2O and Cu(phth) ? H2O,and the ligand is coordinated simultaneously with Zn (II) or Cu ( II ) via the carboxyl group of o-phthalic acid to form bidentate chelates. Thermal decomposition processes of the complexes include dehydration, oxidation and pyrolysis of the ligand, and finally as metallic oxide.

  7. Synthesis and characterization of zinc(II, palladium(II and platinum(II complex with 2’-[1-(2-pyridinylethylidene] oxamohydrazide. The crystal structure of bis{2’-[1-(2-pyridinylethylidene]oxamohydrazido}zinc(II trihydrate



    Full Text Available Complexes of Zn(II, Pd(II and Pt(II with 2’-[1-(2-pyridinylethylidene]oxamohydrazide (Hapsox were synthesized and their structures were determined. All the complexes are of a neutral type with two apsox ligands coordinated to Zn(II and one apsox ligand coordinated to Pd(II or Pt(II. In each case, the polydentate was coordinated via pyridine and hydrazone nitrogens and a-oxyazine oxygen, forming an octahedral geometry around Zn(II, and a square planar one around Pd(II and Pt(II. The structure determination was performed by IR, 1H-NMR and 13C-NMR spectroscopy, and for the Zn(II complex by X-ray structure analysis.

  8. Synthesis, Structure and Biological Activities of Some Novel N-(4,6-Disubstituted-pyrimidin-2-yl)-N'-(trifluoromethylphenyl)-guanidine Derivatives

    HE Feng-Qi; LIU Xing-Hai; WANG Bao-Lei; LI Yong-Hong; LI Zheng-Ming


    A novel series of guanidine derivatives were designed, synthesized and confirmed by FTIR, MS, 1H NMR and elemental analysis. The single crystal structure of 11b was determined by X-ray diffraction. Herbicidal activities of these guanidine derivatives were evaluated through barnyardgrass and rape cup tests, among which compounds lla, lib, and lie against Brassica campestris reached 71.2%, 86.7%, and 86.9% at 100 μg·mL-1 respectively. The preliminary ketol-acid reductoisomerase test showed that the synthesized compounds had weak activities.

  9. Horse Liver Alcohol Dehydrogenase: Zinc Coordination and Catalysis

    Plapp, Bryce V.; Savarimuthu, Baskar Raj; Ferraro, Daniel J.; Rubach, Jon K.; Brown, Eric N.; Ramaswamy, S. (Iowa)


    During catalysis by liver alcohol dehydrogenase (ADH), a water bound to the catalytic zinc is replaced by the oxygen of the substrates. The mechanism might involve a pentacoordinated zinc or a double-displacement reaction with participation by a nearby glutamate residue, as suggested by studies of human ADH3, yeast ADH1, and some other tetrameric ADHs. Zinc coordination and participation of water in the enzyme mechanism were investigated by X-ray crystallography. The apoenzyme and its complex with adenosine 5'-diphosphoribose have an open protein conformation with the catalytic zinc in one position, tetracoordinated by Cys-46, His-67, Cys-174, and a water molecule. The bidentate chelators 2,2'-bipyridine and 1,10-phenanthroline displace the water and form a pentacoordinated zinc. The enzyme–NADH complex has a closed conformation similar to that of ternary complexes with coenzyme and substrate analogues; the coordination of the catalytic zinc is similar to that found in the apoenzyme, except that a minor, alternative position for the catalytic zinc is ~1.3 Å from the major position and closer to Glu-68, which could form the alternative coordination to the catalytic zinc. Complexes with NADH and N-1-methylhexylformamide or N-benzylformamide (or with NAD+ and fluoro alcohols) have the classical tetracoordinated zinc, and no water is bound to the zinc or the nicotinamide rings. The major forms of the enzyme in the mechanism have a tetracoordinated zinc, where the carboxylate group of Glu-68 could participate in the exchange of water and substrates on the zinc. Hydride transfer in the Michaelis complexes does not involve a nearby water.

  10. Horse Liver Alcohol Dehydrogenase: Zinc Coordination and Catalysis.

    Plapp, Bryce V; Savarimuthu, Baskar Raj; Ferraro, Daniel J; Rubach, Jon K; Brown, Eric N; Ramaswamy, S


    During catalysis by liver alcohol dehydrogenase (ADH), a water bound to the catalytic zinc is replaced by the oxygen of the substrates. The mechanism might involve a pentacoordinated zinc or a double-displacement reaction with participation by a nearby glutamate residue, as suggested by studies of human ADH3, yeast ADH1, and some other tetrameric ADHs. Zinc coordination and participation of water in the enzyme mechanism were investigated by X-ray crystallography. The apoenzyme and its complex with adenosine 5'-diphosphoribose have an open protein conformation with the catalytic zinc in one position, tetracoordinated by Cys-46, His-67, Cys-174, and a water molecule. The bidentate chelators 2,2'-bipyridine and 1,10-phenanthroline displace the water and form a pentacoordinated zinc. The enzyme-NADH complex has a closed conformation similar to that of ternary complexes with coenzyme and substrate analogues; the coordination of the catalytic zinc is similar to that found in the apoenzyme, except that a minor, alternative position for the catalytic zinc is ∼1.3 Å from the major position and closer to Glu-68, which could form the alternative coordination to the catalytic zinc. Complexes with NADH and N-1-methylhexylformamide or N-benzylformamide (or with NAD(+) and fluoro alcohols) have the classical tetracoordinated zinc, and no water is bound to the zinc or the nicotinamide rings. The major forms of the enzyme in the mechanism have a tetracoordinated zinc, where the carboxylate group of Glu-68 could participate in the exchange of water and substrates on the zinc. Hydride transfer in the Michaelis complexes does not involve a nearby water.

  11. Zinc(II and copper(II complexes with pheophytin and mesoporphyrin and their stability to UV-B irradiation: Vis spectroscopy studies

    Zvezdanović Jelena B.


    Full Text Available Stability of Zn(II and Cu(II complexes of porphyrin derivatives (pheophytin and mesoporphyrin to UV-B -irradiation has been studied by absorbance spectroscopy in 95% ethanol. The chosen porphyrins as well as their heavy metal complexes undergo photochemical decomposition obeying first-order kinetics. In general, pheophytin is more stable than mesoporphyrin to UV-B irradiation. On the other hand, stability of Zn(II-complex is smaller than Cu(II-complex both for pheophytin and mesoporphyrin; however while Cu(II-complex with pheophytin is more stable than the one with mesoporphyrin, with Zn(II-complex the situation is vice versa.

  12. Zinc and cadmium monosalicylates

    Kharitonov, Yu.Ya.; Tujebakhova, Z.K. (Moskovskij Khimiko-Tekhnologicheskij Inst. (USSR))


    Zinc and cadmium monosalicylates of the composition MSal, where M-Zn or Cd, Sal - twice deprotonated residue of salicylic acid O-HOC/sub 6/H/sub 4/COOH (H/sub 2/Sal), are singled out and characterized. When studying thermograms, thermogravigrams, IR absorption spectra, roentgenograms of cadmium salicylate compounds (Cd(OC/sub 6/H/sub 4/COO) and products of their thermal transformations, the processes of thermal decomposition of the compounds have been characterized. The process of cadmium monosalicylate decomposition takes place in one stage. Complete loss of salicylate acido group occurs in the range of 320-460 deg. At this decomposition stage cadmium oxide is formed. A supposition is made that cadmium complex has tetrahedral configuration, at that, each salicylate group plays the role of tetradentate-bridge ligand. The compound evidently has a polymer structure.

  13. On the Lewis acidic character of bis(salicylaldiminato)zinc(ii) Schiff-base complexes: a computational and experimental investigation on a series of compounds varying the bridging diimine.

    Forte, Giuseppe; Oliveri, Ivan Pietro; Consiglio, Giuseppe; Failla, Salvatore; Di Bella, Santo


    This contribution explores the effect of the 1,2-diimine bridge upon the Lewis acidic character of a series of bis(salicylaldiminato)zinc(ii), ZnL, Schiff-base complexes. The structure of the monomeric and dimeric ZnL complexes, and of the 1 : 1 adducts with pyridine, ZnL·py, is fully optimized by means of DFT calculations. The Gibbs free energy for the dimerization of ZnL complexes and for the formation of ZnL·py adducts is evaluated by accurate composite calculations. It accounts for their spontaneous dimerization and for the greater stability of the ZnL·py adducts with respect to the dimers. Calculated binding constants for the formation ZnL·py adducts are in excellent agreement with experimentally derived values, thus allowing establishing a relative Lewis acidity scale within this series. While the complex derived from the non-conjugated ethylenediamine reveals the lowest Lewis acidity, the complex derived from the diaminomaleonitrile represents the stronger Lewis acidic species. These findings are in good agreement with the greater catalytic activity observed for ZnL Schiff-base complexes derived from conjugated 1,2-diamines in comparison to the non-conjugated analogues. Both in ZnL dimers as well as in ZnL·py adducts the geometry of the coordination sphere seems to be a relevant feature to assess their relative stability. Thus, while the quasi-planarity of ZnL monomers of the conjugated diimines is an unfavourable feature in the dimerization process, it represents an important aspect in stabilizing ZnL·py adducts in a nearly perfect square-pyramidal coordination. These features are relevant for the sensing and catalytic properties of these complexes.

  14. Fluorescence studies of the effect of pH, guanidine hydrochloride and urea on equinatoxin II conformation.

    Malavasic, M; Poklar, N; Macek, P; Vesnaver, G


    The solvent denaturation of equinatoxin II (EqTxII) in aqueous solutions of urea, guanidine hydrochloride (Gu-HCl) and at various pH values was examined by monitoring changes in the protein intrinsic emission fluorescence spectra and in the fluorescence spectra of the added external probe ANS. It has been observed that EqTxII denaturation is reflected in a strong red shift of intrinsic fluorescence emission maxima accompanied by a simultaneous decrease in fluorescence intensity and that guanidine hydrochloride is significantly more powerful denaturant than urea or changing of pH. Comparison of intrinsic fluorescence spectra of EqTxII denatured by one of the three denaturing agents has shown that the fully denatured states of the protein in Gu-HCl and urea are similar and substantially different from those induced by changing of pH. Furthermore, according to the measurements of the ANS-fluorescence in EqTxII solutions as a function of pH the protein exists at pH values below 2.0 in an acid-denatured compact state.

  15. Docking Based 3D-QSAR Study of Tricyclic Guanidine Analogues of Batzelladine K as anti-malarial agents

    Ahmed, Nafees; Anwar, Sirajudheen; Thet Htar, Thet


    The Plasmodium falciparum Lactate Dehydrogenase enzyme (PfLDH) catalyzes inter-conversion of pyruvate to lactate during glycolysis producing the energy required for parasitic growth. The PfLDH has been studied as a potential molecular target for development of anti-malarial agents. In an attempt to find the potent inhibitor of PfLDH, we have used Discovery studio to perform molecular docking in the active binding pocket of PfLDH by CDOCKER, followed by three-dimensional quantitative structure-activity relationship (3D-QSAR) studies of tricyclic guanidine batzelladine compounds, which were previously synthesized in our laboratory. Docking studies showed that there is a very strong correlation between in silico and in vitro results. Based on docking results, a highly predictive 3D-QSAR model was developed with q2 of 0.516. The model has predicted r2 of 0.91 showing that predicted IC50 values are in good agreement with experimental IC50 values. The results obtained from this study revealed the developed model can be used to design new anti-malarial compounds based on tricyclic guanidine derivatives and to predict activities of new inhibitors.

  16. Cadmium and zinc relationships

    Elinder, C.; Piscator, M.


    Higher mammals, such as homo sapiens, accumulate zinc in kidney cortex almost equimolarly with cadmium. A different pattern seems to be present in liverthere is a limited increase of zinc in two species of large farm animals compared with a marked increase in the laboratory. In large farm animals, an equimolar increase of zinc with cadmium in renal cortex seems to indicate that the form of metallothionein that binds equal amounts of cadmium and zinc in present. Differences in cadmium and zinc relationships in large animals and humans compared with laboratory animals must be carefully considered. (4 graphs, 26 references)

  17. Flotation Experiment Study on a Copper-Lead-Zinc Complex Polymetallic Ore in Inner Mongolia%内蒙古某铜铅锌复杂多金属矿的浮选试验研究

    宋涛; 洪家薇; 刘宸婷


    试验矿样取自内蒙古某地的铜铅锌复杂多金属矿,原矿含Cu 0.25%、Pb 2.53%、Zn 4.47%,并且伴生Ag 92.5 g/t、In 42.5 g/t,研究了该矿石的浮选工艺以及在浮选过程中各种药剂的用量,最终得到铜精矿中含Cu 17.62%、回收率达到58.26%;铅精矿含Pb 66.55%、回收率高达90.39%;锌精矿含Zn 48.12%,回收率90.29%;与此同时,铅精矿含Ag达到1 642.0 g/t、回收率60.3%,锌精矿含In达到248.7 g/t、回收率达到53.5%.结果表明,此浮选工艺可有效处理该复杂多金属矿.%The experiment sample is taken from a copper-lead-zinc complex polymetallic deposit in Inner Mongolia, there are 0. 25 % Cu, 2. 53 % Pb, 4.47% Zn in the raw ore, and it also associated with 92. 5 g/t Ag and 42. 5 g/t In, the flotation process of this ore and also the dosage of agents which used in the flotation process is researched, the copper concentrate contents Cu 17.6% , and the recovery can be reached to 58. 26% ; the lead concentrate contents Pb 66. 55% , the recovery reach up to 90. 39% ; the zinc concentrate contents Ag 1 642.0 g/t, the recovery is 60. 3% ; the zinc concentrate contents In 248. 7 g/t, the recovery is 53.5%. The results showed that this flotation process can treat this complex polymetallic ore effectively.

  18. Zinc Binding by Lactic Acid Bacteria

    Jasna Mrvčić


    Full Text Available Zinc is an essential trace element in all organisms. A common method for the prevention of zinc deficiency is pharmacological supplementation, especially in a highly available form of a metalloprotein complex. The potential of different microbes to bind essential and toxic heavy metals has recently been recognized. In this work, biosorption of zinc by lactic acid bacteria (LAB has been investigated. Specific LAB were assessed for their ability to bind zinc from a water solution. Significant amount of zinc ions was bound, and this binding was found to be LAB species-specific. Differences among the species in binding performance at a concentration range between 10–90 mg/L were evaluated with Langmuir model for biosorption. Binding of zinc was a fast process, strongly influenced by ionic strength, pH, biomass concentration, and temperature. The most effective metal-binding LAB species was Leuconostoc mesenteroides (27.10 mg of Zn2+ per gram of dry mass bound at pH=5 and 32 °C, during 24 h. FT-IR spectroscopy analysis and electron microscopy demonstrated that passive adsorption and active uptake of the zinc ions were involved.

  19. Zinc and skin biology.

    Ogawa, Youichi; Kawamura, Tatsuyoshi; Shimada, Shinji


    Of all tissues, the skin has the third highest abundance of zinc in the body. In the skin, the zinc concentration is higher in the epidermis than in the dermis, owing to a zinc requirement for the active proliferation and differentiation of epidermal keratinocytes. Here we review the dynamics and functions of zinc in the skin as well as skin disorders associated with zinc deficiency, zinc finger domain-containing proteins, and zinc transporters. Among skin disorders associated with zinc deficiency, acrodermatitis enteropathica is a disorder caused by mutations in the ZIP4 transporter and subsequent zinc deficiency. The triad acrodermatitis enteropathica is characterized by alopecia, diarrhea, and skin lesions in acral, periorificial, and anogenital areas. We highlight the underlying mechanism of the development of acrodermatitis because of zinc deficiency by describing our new findings. We also discuss the accumulating evidence on zinc deficiency in alopecia and necrolytic migratory erythema, which is typically associated with glucagonomas. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Cadmium and zinc relationships.

    Elinder, C G; Piscator, M


    Cadmium and zinc concentrations in kidney and liver have been measured under different exposure situations in different species including man. The results show that zinc increases almost equimolarly with cadmium in kidney after long-term low-level exposure to cadmium, e.g., in man, horse, pig, and lamb. In contrast, the increase of zinc follows that of cadmium to only a limited extent, e.g., in guinea pig, rabbit, rat, mouse, and chicks. In liver, the cadmium--zinc relationship seems to be reversed in such a way that zinc increases with cadmium more markedly in laboratory animals than in higher mammals. These differences between cadmium and zinc relationships in humans and large farm animals and those in commonly used laboratory animals must be considered carefully before experimental data on cadmium and zinc relationships in laboratory animals can be extrapolated to humans.

  1. DFT/TD-DFT study on spectroscopic properties of zinc(II, nickel(II, and palladium(II metal complexes with a thiourea derivative

    Wang Xin


    Full Text Available The geometries, electronic structures, and spectral properties of three metal complexes Zn(C10H12N3OS2 (1, Ni(C10H12N3OS2 (2, and Pd(C10H12N3OS2 (3 with N-(2-pyridinylmorpholine-4-carbothioamide as a ligand are investigated by means of DFT (density functional theory and TD-DFT (time-dependent density functional theory methods. Complex 1 is a distorted tetrahedral geometry, while complexes 2 and 3 present a distorted square-planar coordination environment. In the simulated range, the spectrum of complex 1 has five obvious absorption peaks and one of them has the strongest intensity. The latter two complexes have one more absorption peak and shoulder peak with the similar intensity. Moreover, the strongest peaks of complexes 2.

  2. 速溶胍胶压裂液体系性能评价与应用%Laboratory Performance Evaluation and the Application of Instant Guanidine Gumfracturing Fluid



    针对新型速溶胍胶压裂液体系进行系统评价,并与常规胍胶体系性能对比,针对地层特点进行配方优化并投入现场使用验证。新型速溶胍胶压裂液体系溶胀时间快,耐温性能好,水不溶物是常规胍胶的一半,破胶液残渣较普通胍胶降低64%以上,破胶时间可控性强。%According to the new instant guanidine gum fracturing fluid system of evaluation system, and with the conventional guanidine gum system performance comparison, the characteristics of the strata formulation optimization was studied and used on the spot verification. Swelling time of new instant guanidine gum fracturing fluid system was fast, with good performance of temperature, water insoluble matter was half of the conventional guanidine gum, broken glue residue decreased more than 64% compared with ordinary guar gum, breaking gel time had strong controllability.

  3. Synthesis of a chiral quaternary carbon center bearing a fluorine atom: enantio- and diastereoselective guanidine-catalyzed addition of fluorocarbon nucleophiles.

    Jiang, Zhiyong; Pan, Yuanhang; Zhao, Yujun; Ma, Ting; Lee, Richmond; Yang, Yuanyong; Huang, Kuo-Wei; Wong, Ming Wah; Tan, Choon-Hong


    The perfect combination: The title reaction provides adducts having quaternary carbon centers bearing a fluorine atom with high ee and d.r. values (see scheme). The mechanism and origin of stereoselectivity were elucidated by DFT calculations. The bifunctional mode of the guanidine catalysis was demonstrated in the transition states resulting from the DFT results.

  4. Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

    Tatyana E. Shubina


    Full Text Available A new guanidine-thiourea organocatalyst has been developed and applied as bifunctional organocatalyst in the Michael addition reaction of diethyl malonate to trans-β-nitrostyrene. Extensive DFT calculations, including solvent effects and dispersion corrections, as well as ab initio calculations provide a plausible description of the reaction mechanism.

  5. [Zinc and type 2 diabetes].

    Fukunaka, Ayako; Fujitani, Yoshio


    Pancreatic β cells contain the highest amount of zinc among cells within the human body, and hence, the relationship between zinc and diabetes has been a topic of great interest. While many studies demonstrating possible involvement of zinc deficiency in diabetes have been reported, precise mechanisms how zinc regulates glucose metabolism are still far from understood. Recent studies revealed that zinc can transmit signals that are driven by a variety of zinc transporters in a tissue and cell-type specific manner and deficiency in some zinc transporters may cause human diseases. Here, we review the role of zinc in metabolism particularly focusing on the emerging role of zinc transporters in diabetes.

  6. Root-secreted nicotianamine from Arabidopsis halleri facilitates zinc hypertolerance by regulating zinc bioavailability.

    Tsednee, Munkhtsetseg; Yang, Shun-Chung; Lee, Der-Chuen; Yeh, Kuo-Chen


    Hyperaccumulators tolerate and accumulate extraordinarily high concentrations of heavy metals. Content of the metal chelator nicotianamine (NA) in the root of zinc hyperaccumulator Arabidopsis halleri is elevated compared with nonhyperaccumulators, a trait that is considered to be one of the markers of a hyperaccumulator. Using metabolite-profiling analysis of root secretions, we found that excess zinc treatment induced secretion of NA in A. halleri roots compared with the nonhyperaccumulator Arabidopsis thaliana. Metal speciation analysis further revealed that the secreted NA forms a stable complex with Zn(II). Supplying NA to a nonhyperaccumulator species markedly increased plant zinc tolerance by decreasing zinc uptake. Therefore, NA secretion from A. halleri roots facilitates zinc hypertolerance through forming a Zn(II)-NA complex outside the roots to achieve a coordinated zinc uptake rate into roots. Secretion of NA was also found to be responsible for the maintenance of iron homeostasis under excess zinc. Together our results reveal root-secretion mechanisms associated with hypertolerance and hyperaccumulation. © 2014 American Society of Plant Biologists. All Rights Reserved.

  7. Complexity

    Gershenson, Carlos


    The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.

  8. Synthesis, structural, optical band gap and biological studies on iron (III), nickel (II), zinc (II) and mercury (II) complexes of benzyl α-monoxime pyridyl thiosemicarbazone

    Bedier, R. A.; Yousef, T. A.; Abu El-Reash, G. M.; El-Gammal, O. A.


    New ligand, (E)-2-((E)-2-(hydroxyimino)-1,2-diphenylethylidene)-N-(pyridin-2 yl) hydrazinecarbothioamide (H2DPPT) and its complexes [Fe(DPPT)Cl(H2O)], [Ni(H2DPPT)2Cl2], [Zn(HDPPT)(OAc)] and [Hg(HDPPT)Cl](H2O)4 were isolated and characterized by various of physico-chemical techniques. IR spectra show that H2DPPT coordinates to the metal ions as neutral NN bidentate, mononegative NNS tridentate and binegative NNSN tetradentate, respectively. From the modeling studies, the bond length, bond angle, HOMO, LUMO and dipole moment had been calculated to confirm the geometry of the ligands and their investigated complexes. The thermal studies showed the type of water molecules involved in metal complexes Furthermore, the kinetic and thermodynamic parameters for the different decomposition steps were calculated using the Coats-Redfern and Horowitz-Metzger methods. Also, the optical band gap (Eg) has been calculated to elucidate the conductivity of the isolated complexes. The optical transition energy (Eg) is direct and equals 3.34 and 3.44 ev for Ni and Fe complexes, respectively. The ligand and their metal complexes were screened for antibacterial activity against the following bacterial species, Bacillus thuringiensis, Staphylococcus aureus, Pseudomonas aeuroginosa and Escherichia coli. The results revealed that the metal complexes have more potent antibacterial compared with the ligand. Also, the degradation effect of the investigated compounds was tested showing that, Ni complex exhibited powerful and complete degradation effect on DNA.


    Jing-shu Wu; Min Xiao; Hu He; Shuan-jin Wang; Dong-mei Han; Yue-zhong Meng


    Using supported multi-component zinc dicarboxylate catalyst,poly(1,2-propylene carbonate-co-l,2-cyclohexylene carbonate) (PPCHC) was successfully synthesized from carbon dioxide (CO2) with propylene oxide (PO) and cyclohexene oxide (CHO).The conversion of epoxides dramatically increased up to 89.7% (yield:384.2 g of polymer per g of Zn) with increasing reaction temperature from 60℃ to 80℃.The optimized reaction temperature is 80℃.The chemical structure,the molecular weight,as well as thermal and mechanical properties of the resulting terpolymers were investigated extensively.When CHO feed content (mol%) is lower than 10%,the PPCHC terpolymers have number average molecular weight (Mn)ranging from 102 × 103 to 202 × 103 and molecular weight distribution (MWD) values ranging from 2.8 to 3.5.In contrast to poly(propylene carbonate) (PPC),the introduction of small amount of CHO leads to increase in the glass transition temperature from 38.0℃ to 42.6℃.Similarly,the mechanical strength of the synthesized terpolymer is greatly enhanced due to the incorporation of CHO.These improvements in mechanical and thermal properties are of importance for the practical application of PPC.

  10. Effect of Complex Ion Concentration on the Particle Size of Nano Zinc Aluminium Oxide(ZAO)%络离子浓度对掺铝氧化锌(ZAO)纳米粉体粒径的影响

    颜东亮; 陈林; 宋杰光


    Zinc aluminium oxide (ZAO) nanoparticles were prepared by complex salt method. A new complex salt crystal, ( NH4 ) 1.95 ( Zn0.95 Al0.05 ) ( SO4 ) 2·6H2O, was synthesized in the experiment, which proved the formation of complex ion in the initial reaction solution. The influence of complex ion concentration on the particle size of ZAO powder was researched by adjusting the addition of (NH4 )2SO4. ZAO powders were characterized by XRD, SEM and laser particle size analyzer. The results indicated that the existing of complex ion decreased the concentration of dissociative metal ion and increased the controllability of primary particle size, which was in favor of the preparation of ZAO nanometer powder.%采用络盐法制备了掺铝氧化锌(ZAO)纳米粉体.通过新复合络盐晶体-(NH4)1.95(Zn0.95Al0.05)(SO4)2·6H2O的合成证实了反应初始溶液中形成了络离子.通过改变(NH4)2SO4的加入量研究了络离子浓度对ZAO粒径的影响.通过XRD、SEM和激光粒度仪对ZAO粉体进行了表征.结果表明:络离子的存在,降低了反应初始溶液中游离金属离子的浓度,使得产物的一次粒径的可调控性增强,有利于纳米级ZAO粉体的制备.

  11. 三元络合碱性电沉积锌镍合金的抗腐蚀性能研究%Research on Corrosion Resistance of Ternary Complexation Alkaline Electrodeposition Zinc-nickel Alloy

    张秀; 王少龙; 龙晋明; 裴和中; 由劲博


    The zinc-nickel alloy coating of electrodeposition preparation was made by the alkaline zinc-nickel alloy plating bath which is composed of tetraethylenepentamine (TEPA),potassium sodium tartrate and triethanolamine (TEA) ternary mixture as nickel ions complexing agent on low carbon steel substrate.The effect of different electrodeposition parameters (the current density and the relative content of nickel ions) on the corrosion electrochemical behavior of zinc-nickel alloy coating in 3.5 % NaCl solutions was investigated by polarization curve and electrochemical impedance spectroscopy.The results indicate that the coating on the substrate has an optimal protective effect when nickel content of the bath within a broad range (n (Ni2 +)/n (Ni2 + + Zn2 +) =15 %-30 %) changes.The coating corrosion resistance is the strongest when the current density within 2-3 A/dm2.However,the current density is too low and too high will decrease the corrosion resistance of the coating.%采用四乙烯五胺(TEPA)、酒石酸钾钠和三乙醇胺(TEA)三元混合物作为镍离子络合剂配制碱性锌镍合金镀液,在低碳钢基材上电沉积制备锌镍合金镀层.利用电化学工作站测试了镀层在3.5% NaCl溶液中的极化曲线和电化学阻抗谱,考察不同电沉积条件参数(电流密度和镍离子相对含量)对锌镍合金镀层的腐蚀电化学行为的影响.结果表明:当镀液的镍含量在较宽范围内(n(Ni2+)/n(Ni2+ +Zn2+) =15%~30%)变化时,所得镀层对基体都有很好的防护作用;当电流密度为2~3 A/dm2时得到的镀层抗腐蚀能力最强,而当电流密度过低和过高时都会使镀层的耐蚀性有所降低.

  12. Improved zinc electrode and rechargeable zinc-air battery

    Ross, P.N. Jr.


    The invention comprises an improved rechargeable zinc-air cell/battery having recirculating alkaline electrolyte and a zinc electrode comprising a porous foam support material which carries the active zinc electrode material. 5 figs.

  13. Zinc stannate nanostructures: hydrothermal synthesis

    Sunandan Baruah and Joydeep Dutta


    Full Text Available Nanostructured binary semiconducting metal oxides have received much attention in the last decade owing to their unique properties rendering them suitable for a wide range of applications. In the quest to further improve the physical and chemical properties, an interest in ternary complex oxides has become noticeable in recent times. Zinc stannate or zinc tin oxide (ZTO is a class of ternary oxides that are known for their stable properties under extreme conditions, higher electron mobility compared to its binary counterparts and other interesting optical properties. The material is thus ideal for applications from solar cells and sensors to photocatalysts. Among the different methods of synthesizing ZTO nanostructures, the hydrothermal method is an attractive green process that is carried out at low temperatures. In this review, we summarize the conditions leading to the growth of different ZTO nanostructures using the hydrothermal method and delve into a few of its applications reported in the literature.

  14. Preparation of zinc oxide coatings by using newly designed metal–organic complexes of Zn: Effect of molecular structure of the precursor and surfactant over the crystallization, growth and luminescence

    Brahma, Sanjaya, E-mail: [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Shivashankar, S.A. [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012 (India)


    Graphical abstract: ZnO coating comprised of tapered ZnO nanorods using Zn(acac){sub 2} bipy as the precursor. Highlights: • Newly designed precursors were used for the fabrication of ZnO coating. • ZnO coatings (1.5–2 μm) were achieved quickly (1–5 min) by a simple microwave process. • The coatings are uniform having high density of nucleation and excellent growth rate. • Luminescence could be tuned by varying molecular structure of the precursor. • Possible growth mechanism is described in detail. -- Abstract: We report large scale deposition of tapered zinc oxide (ZnO) nanorods on Si(1 0 0) substrate by using newly designed metal–organic complex of zinc (Zn) as the precursor, and microwave irradiation assisted chemical synthesis as a process. The coatings are uniform and high density ZnO nanorods (∼1.5 μm length) grow over the entire area (625 mm{sup 2}) of the substrate within 1–5 min of microwave irradiation. ZnO coatings obtained by solution phase deposition yield strong UV emission. Variation of the molecular structure/molecular weight of the precursors and surfactants influence the crystallinity, morphology, and optical properties of ZnO coatings. The precursors in addition with the surfactant and the solvent are widely used to obtain desired coating on any substrate. The growth mechanism and the schematics of the growth process of ZnO coatings on Si(1 0 0) are discussed.

  15. Zinc composite anode for batteries with solid electrolyte

    Tedjar, F.; Melki, T.; Zerroual, L.

    A new negative composite anode for batteries with a solid electrolyte is studied. Using a complex of zinc ammonium chloride mixed with zinc metal powder, the advantage of the Zn/Zn 2+ electrode ( e = -760 mV) is kept while the energy density and the shelf-life of the battery are increased.

  16. Zinc composite anode for batteries with solid electrolyte

    Tedjar, F.; Melki, T.; Zerroual, L. (Setif Univ. (Algeria). Unite de Recherche Electrochimie)


    A new negative composite anode for batteries with a solid electrolyte is studied. Using a complex of zinc ammonium chloride mixed with zinc metal powder, the advantage of the Zn/Zn[sup 2+] electrode (e = -760 mV) is kept while the energy density and the shelf-life of the battery are increased. (orig.).

  17. Novel zinc complexes of a non-steroidal anti-inflammatory drug, niflumic acid: Structural characterization, human-DNA and albumin binding properties.

    Smolková, Romana; Zeleňák, Vladimír; Smolko, Lukáš; Kuchár, Juraj; Rabajdová, Miroslava; Ferenčáková, Michaela; Mareková, Mária


    Three novel Zn(II) complexes of NSAID niflumic acid (Hnif) were prepared and studied, namely; [Zn(MeOH)4(nif)2] (1), [Zn(cyclam)(nif)2] (2) and [Zn(nif)2(tmen)] (3), where nif is deprotonated niflumic acid, cyclam is 1,4,8,11-Tetraazacyclotetradecane and tmen is N,N,N',N'-Tetramethylethylenediamine. The complexes have been characterized by infrared spectroscopy, elemental and thermal analysis and single-crystal X-ray structure analysis. All three complexes contain two deprotonated niflumato anions monodentately coordinated via carboxylato groups. Furthermore, fluorescence binding studies of the prepared compounds with human genomic DNA-EB (ethidium bromide) were carried out, which suggest that all complexes are able to bind to DNA via intercalation. Moreover, from the obtained results it followed that complexes 2 and 3 bind to DNA from the tissue with aortic aneurysm (aDNA) and control (cDNA) with a different strength. Additionally, complexes 1-3 exhibit good binding affinity to human serum albumin with high binding constant. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  18. The guanidine hydrochloride-induced denaturation of CP43 and CP47 studied by terahertz time-domain spectroscopy

    QU YuanGang; CHEN Hua; QIN XiaoChun; WANG Li; LI LiangBi; KUANG TingYun


    Terahertz time-domain spectroscopy (THz-TDS) is a new technique in studying the conformational state of a molecule in recent years. In this work, we reported the first use of THz-TDS to examine the denaturation of two photosynthesis membrane proteins: CP43 and CP47. THz-TDS was proven to be useful in discriminating the different conformational states of given proteins with similar structure and in monitoring the denaturation process of proteins. Upon treatment with guanidine hydrochloride (GuHCI),a 1.8 THz peak appeared for CP47 and free chlorophyll a (Chi a). This peak was deemed to originate from the interaction between Chli a and GuHCI molecules. The Chl a molecules in CP47 interacted with GuHCI more easily than those in CP43.

  19. The guanidine hydrochloride-induced denaturation of CP43 and CP47 studied by terahertz time-domain spectroscopy


    Terahertz time-domain spectroscopy (THz-TDS) is a new technique in studying the conformational state of a molecule in recent years. In this work, we reported the first use of THz-TDS to examine the dena- turation of two photosynthesis membrane proteins: CP43 and CP47. THz-TDS was proven to be useful in discriminating the different conformational states of given proteins with similar structure and in monitoring the denaturation process of proteins. Upon treatment with guanidine hydrochloride (GuHCl), a 1.8 THz peak appeared for CP47 and free chlorophyll a (Chl a). This peak was deemed to originate from the interaction between Chl a and GuHCl molecules. The Chl a molecules in CP47 interacted with GuHCl more easily than those in CP43.

  20. Synthesis of Conformationally Preorganized and Cell-Permeable Guanidine-Based γ-Peptide Nucleic Acids (γGPNAs)

    Sahu, Bichismita; Chenna, Venugopal; Lathrop, Kira L.; Thomas, Sufi M.; Zon, Gerald; Livak, Kenneth J.; Ly, Danith H.


    A general method for preparing optically-pure guanidine-based γ-peptide nucleic acid (γGPNA) monomers for all four natural nucleobases (A, C, G and T) is described. These second-generation γGPNAs differ from the first in that the guanidinium group is installed at the γ-instead of the α-position of the N-(2-aminoethyl)glycine backbone unit. This positional switch enables GPNAs to be synthesized from relatively cheap L- as opposed to D-amino acids. Unlike their α-predecessors, which are randomly-folded, γGPNAs prepared from L-amino acids are preorganized into a right-handed helix and bind to DNA and RNA with exceptionally high affinity and sequence selectivity, and are readily taken up by mammalian cells. PMID:19161276

  1. Moessbauer spectroscopic evidence on the heme binding to the proximal histidine in unfolded carbonmonoxy myoglobin by guanidine hydrochloride

    Harami, Taikan, E-mail: [Japan Atomic Energy Agency (Japan); Kitao, Shinji; Kobayashi, Yasuhiro [Kyoto University, Research Reactor Institute (Japan); Mitsui, Takaya [Japan Atomic Energy Agency (Japan)


    The unfolded heme structure in myoglobin is controversial because of no chance of direct X-ray structure analyses. The unfolding of carbonmonoxy myoglobin (MbCO) by guanidine hydrochloride (GdnHCl) was studied by the Moessbauer spectroscopy. The spectra show the presence of a sort of spectrum in the unfolded MbCO, independent on the concentration of GdnHCl from 1 to 6 M and the increase of the fraction of unfolded MbCO, depending on the GdnHCl concentration. The isomer shift of the iron of heme in the unfolded MbCO was identified to be different from that of the native MbCO as the globin structure in Mb collapses under the unfolded conditions. This result and the existing related Moessbauer data proved that the heme in the unfolded MbCO may remain coordinated to the proximal histidine.

  2. The effect of polyhexamethylene guanidine hydrochloride (PHMG) derivatives introduced into polylactide (PLA) on the activity of bacterial enzymes.

    Walczak, Maciej; Richert, Agnieszka; Burkowska-But, Aleksandra


    The present study was aimed at investigating bactericidal properties of polylactide (PLA) films containing three different polyhexamethylene guanidine hydrochloride (PHMG) derivatives and effect of the derivatives on extracellular hydrolytic enzymes and intracellular dehydrogenases. All PHMG derivatives had a slightly stronger bactericidal effect on Staphylococcus aureus than on E. coli but only PHMG granular polyethylene wax (at the concentration of at least 0.6 %) has a bactericidal effect. PHMG derivatives introduced into PLA affected the activity of microbial hydrolases to a small extent. This means that the introduction of PHMG derivatives into PLA will not reduce its enzymatic biodegradation significantly. On the other hand, PHMG derivatives introduced into PLA strongly affected dehydrogenases activity in S. aureus than in E. coli.

  3. Analgesic and Anti-Inflammatory Activities of Salicylaldehyde 2-Chlorobenzoyl Hydrazone (H2LASSBio-466, Salicylaldehyde 4-Chlorobenzoyl Hydrazone (H2LASSBio-1064 and Their Zinc(II Complexes

    Eliezer J. Barreiro


    Full Text Available Salicylaldehyde 2-chlorobenzoyl hydrazone (H2LASSBio-466, salicylaldehyde 4-chlorobenzoyl hydrazone (H2LASSBio-1064 and their complexes [Zn(LASSBio-466H2O]2 (1 and [Zn(HLASSBio-1064Cl]2 (2 were evaluated in animal models of peripheral and central nociception, and acute inflammation. All studied compounds significantly inhibited acetic acid-induced writhing response. Upon coordination the anti-nociceptive activity was favored in the complex 1. H2LASSBio-466 inhibited only the first phase of the formalin test, while 1 was active in the second phase, like indomethacin, indicating its ability to inhibit nociception associated with the inflammatory response. Hence coordination to zinc(II altered the pharmacological profile of H2LASSBio-466. H2LASSBio-1064 inhibited both phases but this effect was not improved by coordination. The studied compounds did not increase the latency of response in the hot plate model, indicating their lack of central anti-nociceptive activity. All compounds showed levels of inhibition of zymosan-induced peritonitis comparable or superior to indomethacin, indicating an expressive anti-inflammatory profile.

  4. Akwaton, polyhexamethylene-guanidine hydrochloride-based sporicidal disinfectant: a novel tool to fight bacterial spores and nosocomial infections.

    Oulé, Mathias K; Quinn, Kelsi; Dickman, Michael; Bernier, Anne-Marie; Rondeau, Sylvie; De Moissac, Danielle; Boisvert, Aurèle; Diop, Lamine


    Bacterial spores are of continuing interest to the food and medical industries. In efforts to eliminate bacterial spore contamination, a number of sporicidal agents have been developed. Most of these compounds must be used carefully in very specific circumstances as they are toxic to humans. The sporicidal activity of Akwaton, a polyhexamethylene-guanidine hydrochloride (PHMGH)-based disinfectant, was tested against Bacillus subtilis spores. PHMGH is a colourless, odourless, non-corrosive and non-irritating antimicrobial biocide of the guanidine family. Spores suspended in distilled water and spores placed on solid surfaces (stainless steel and glass) were used to determine the log(10) reduction after exposure to varying concentrations of Akwaton. The minimum sporostatic concentration, the minimum sporicidal concentration and the time required for sporicidal activity corresponded to 0.06% (w/v), 0.08 % (w/v) and 8.5 min, respectively. Disinfectant concentrations of 0.24 % (w/v) and 0.44 % (w/v) killed all spores suspended in distilled water within 3 min and 90 s, respectively. The sporicidal activity against suspended spores was linearly dependent with respect to the concentration of PHMGH and contact time (y(3 min) = 40x-1.6 and y(90 s) = 20x-0.8 thus y(3 min) = 2y(90 s)). Spores placed on surfaces were more resistant to the effect of the disinfectant and the positive linear correlation between the sporicidal activity and concentration was not observed. The concentration required to kill all spores placed on a surface (stainless steel or glass) corresponded to 0.52 % (w/v) for 90 s of contact and 0.36 % (w/v) for 3 min. This study demonstrated that PHMGH is an effective sporicidal disinfectant with great potential for use in hospitals, laboratories, food industries and households.

  5. Developing of a novel antibacterial agent by functionalization of graphene oxide with guanidine polymer with enhanced antibacterial activity

    Li, Ping [College of Chemistry, Jilin University and MacDiarmid Laboratory, Changchun 130021 (China); Sun, Shiyu [Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, Jilin University, Changchun 130012 (China); Dong, Alideertu [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Hao, Yanping; Shi, Shuangqiang; Sun, Zijia [College of Chemistry, Jilin University and MacDiarmid Laboratory, Changchun 130021 (China); Gao, Ge, E-mail: [College of Chemistry, Jilin University and MacDiarmid Laboratory, Changchun 130021 (China); Chen, Yuxin, E-mail: [Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, Jilin University, Changchun 130012 (China)


    Graphical abstract: - Highlights: • A novel antibacterial material, polyethylene glycol (PEG) and polyhexamethylene guanidine hydrochloride (PHGC) dual-polymer-functionalized graphene oxide (GO) (GO-PEG-PHGC), was synthesized. • GO-PEG-PHGC had excellent antibacterial activity against E. coli and S. aureus. • GO-PEG-PHGC shows enhanced antibacterial activity when compared to GO, GO-PEG or GO-PHGC alone, which was described to be related to a better dispersion of GO-PEG-PHGC in the presence of PEG. - Abstract: New materials with excellent antibacterial activity attract numerous research interests. Herein, a facile synthetic method of polyethylene glycol (PEG) and polyhexamethylene guanidine hydrochloride (PHGC) dual-polymer-functionalized graphene oxide (GO) (GO-PEG-PHGC), a novel antibacterial material, was reported. The as-prepared products were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray pattern (XRD) and elemental analysis. The antibacterial effect on the bacterial strain was investigated by incubating both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus). The results show that GO-PEG-PHGC has enhanced antibacterial activity when compared to GO, GO-PEG or GO-PHGC alone. The improved antibacterial activity was described to be related to a better dispersion of GO-PEG-PHGC in the presence of PEG. This better dispersion leads to a greater contact between the bacteria membrane and nanomaterials, therefore leading to greater cell damage. Not only Gram-negative bacteria but also Gram-positive bacteria are greatly inhibited by this antibacterial agent. With the powerful antibacterial activity as well as its low cost and facile preparation, the GO-PEG-PHGC as a novel antibacterial agent can find potential application in the areas of healthcare and environmental engineering.

  6. Complex


    Schiff bases and their complex compounds have been studied for their .... establishing coordination of the N–(2 – hydroxybenzyl) - L - α - valine Schiff base ..... (1967); “Spectrophotometric Identification of Organic Compounds”, Willey, New.

  7. Chelators for investigating zinc metalloneurochemistry.

    Radford, Robert J; Lippard, Stephen J


    The physiology and pathology of mobile zinc signaling has become an important topic in metalloneurochemistry. To study the action of mobile zinc effectively, specialized tools are required that probe the temporal and positional changes of zinc ions within live tissue and cells. In the present article we describe the design and implementation of selective zinc chelators as antagonists to interrogate the function of mobile zinc, with an emphasis on the pools of vesicular zinc in the terminals of hippocampal mossy fiber buttons.

  8. Zinc coordination spheres in protein structures.

    Laitaoja, Mikko; Valjakka, Jarkko; Jänis, Janne


    Zinc metalloproteins are one of the most abundant and structurally diverse proteins in nature. In these proteins, the Zn(II) ion possesses a multifunctional role as it stabilizes the fold of small zinc fingers, catalyzes essential reactions in enzymes of all six classes, or assists in the formation of biological oligomers. Previously, a number of database surveys have been conducted on zinc proteins to gain broader insights into their rich coordination chemistry. However, many of these surveys suffer from severe flaws and misinterpretations or are otherwise limited. To provide a more comprehensive, up-to-date picture on zinc coordination environments in proteins, zinc containing protein structures deposited in the Protein Data Bank (PDB) were analyzed in detail. A statistical analysis in terms of zinc coordinating amino acids, metal-to-ligand bond lengths, coordination number, and structural classification was performed, revealing coordination spheres from classical tetrahedral cysteine/histidine binding sites to more complex binuclear sites with carboxylated lysine residues. According to the results, coordination spheres of hundreds of crystal structures in the PDB could be misinterpreted due to symmetry-related molecules or missing electron densities for ligands. The analysis also revealed increasing average metal-to-ligand bond length as a function of crystallographic resolution, which should be taken into account when interrogating metal ion binding sites. Moreover, one-third of the zinc ions present in crystal structures are artifacts, merely aiding crystal formation and packing with no biological significance. Our analysis provides solid evidence that a minimal stable zinc coordination sphere is made up by four ligands and adopts a tetrahedral coordination geometry.

  9. Determination of Constant-Volume Combustion Energy for the Complexes of Zinc Nitrate with Four Amino Acids%硝酸锌与四种α-氨基酸配合物的恒容燃烧能测定

    谢钢; 杨旭武; 陈三平; 高胜利; 史启祯


    Ten solid complexes of zinc nitrate with L-α-leucine(Leu), L-α-valine(Val), L-α-tryptophan(Try) andL-α-threonine(Thr) were prepared in water. The compositions of these complexes are determined by chemicalanalysis and elemental analysis, which are identified as Zn (Leu) (NO3) 2 @ 2H2O (A), Zn (Leu)2 (NO3)2 @ H2O (B),Zn(Val) (NO3)2 @ 2H2O(C), Zn(Val) 2(NO3)2 @ H2O(D), Zn(Val) 3(NO3) 2 @ H2O(E), Zn(Try) (NO3)2 @ 2H2O(F), Zn(Try)2(NO3)2 @ H2O(G), Zn(Thr) (NO3)2 @ 2H2O(H), Zn(Thr) 2(NO3)2 @ H2O(I) and Zn(Thr) 3(NO3)@ H2O(J) . The constant-volume combustion energies of the complexes, Δc U(complex), were determined by aprecise rotating bomb calorimeter at 298.15K. Standard enthalpies of combustion, ΔcH-m(complex, s, 298. 15K),and standard enthalpies of formation, ΔfH-m (complex, s, 298. 15K) for these complexes were calculated as(4523.22 ± 2.08), (7208.86 ± 4.28), (3442.21 ± 1.85), (5971.21 ±3.32), (9007.26 ± 4.24),(5802.35±2.14), (10891.58±3.01), (2147.40±1.28), (4120.83±0.99), (6444.68±3.85)kJ@mol-1and (615.67±2.27), (1863.16±4.60), (1017.34±2.00), (1742.93±3.61), (2245.70±4.73),(1161.18±2.61), (1829.71±4.20), (1632.82±1.43), (1885.55±1.50), (2770. 25 ± 4. 21) kJ @ mol-1,respectively.

  10. Synthesis, spectroscopic and thermal characterization of sulpiride complexes of iron, manganese, copper, cobalt, nickel, and zinc salts. Antibacterial and antifungal activity

    Mohamed, Gehad G.; Soliman, Madiha H.


    Sulpiride (SPR; L) is a substituted benzamide antipsychotic which is reported to be a selective antagonist of central dopamine receptors and claimed to have mood-elevating properties. The ligation behaviour of SPR drug is studied in order to give an idea about its potentiality towards some transition metals in vitro systems. Metal complexes of SPR have been synthesized by reaction with different metal chlorides. The metal complexes of SPR with the formula [MCl 2(L) 2(H 2O) 2]· nH 2O [M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); n = 0-2] and [FeCl 2(HL)(H 2O) 3]Cl·H 2O have been synthesized and characterized using elemental analysis (CHN), electronic (infrared, solid reflectance and 1H NMR spectra) and thermal analyses (TG and DTA). The molar conductance data reveal that the bivalent metal chelates are non-electrolytes while Fe(III) complex is 1:1 electrolyte. IR spectra show that SPR is coordinated to the metal ions in a neutral monodentate manner with the amide O. From the magnetic and solid reflectance spectra, octahedral geometry is suggested. The thermal decomposition processes of these complexes were discussed. The correlation coefficient, the activation energies, E*, the pre-exponential factor, A, and the entropies, Δ S*, enthalpies, Δ H*, Gibbs free energies, Δ G*, of the thermal decomposition reactions have been derived from thermogravimetric (TG) and differential thermogravimetric (DTG) curves. The synthesized ligand and its metal complexes were also screened for their antibacterial and antifungal activity against bacterial species ( Escherichia coli and Staphylococcus aureus) and fungi ( Aspergillus flavus and Candida albicans). The activity data show that the metal complexes are found to have antibacterial and antifungal activity than the parent drug and less than the standard.

  11. Synthesis, spectroscopic and thermal characterization of sulpiride complexes of iron, manganese, copper, cobalt, nickel, and zinc salts. Antibacterial and antifungal activity.

    Mohamed, Gehad G; Soliman, Madiha H


    Sulpiride (SPR; L) is a substituted benzamide antipsychotic which is reported to be a selective antagonist of central dopamine receptors and claimed to have mood-elevating properties. The ligation behaviour of SPR drug is studied in order to give an idea about its potentiality towards some transition metals in vitro systems. Metal complexes of SPR have been synthesized by reaction with different metal chlorides. The metal complexes of SPR with the formula [MCl(2)(L)(2)(H(2)O)(2)].nH(2)O [M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); n=0-2] and [FeCl(2)(HL)(H(2)O)(3)]Cl.H(2)O have been synthesized and characterized using elemental analysis (CHN), electronic (infrared, solid reflectance and (1)H NMR spectra) and thermal analyses (TG and DTA). The molar conductance data reveal that the bivalent metal chelates are non-electrolytes while Fe(III) complex is 1:1 electrolyte. IR spectra show that SPR is coordinated to the metal ions in a neutral monodentate manner with the amide O. From the magnetic and solid reflectance spectra, octahedral geometry is suggested. The thermal decomposition processes of these complexes were discussed. The correlation coefficient, the activation energies, E*, the pre-exponential factor, A, and the entropies, DeltaS*, enthalpies, DeltaH*, Gibbs free energies, DeltaG*, of the thermal decomposition reactions have been derived from thermogravimetric (TG) and differential thermogravimetric (DTG) curves. The synthesized ligand and its metal complexes were also screened for their antibacterial and antifungal activity against bacterial species (Escherichia coli and Staphylococcus aureus) and fungi (Aspergillus flavus and Candida albicans). The activity data show that the metal complexes are found to have antibacterial and antifungal activity than the parent drug and less than the standard.

  12. Examination of nanoformulated crosslinked polymers complexed with copper/zinc superoxide dismutase as a therapeutic strategy for angiotensin II-mediated hypertension

    Savalia, Krupa

    Excessive generation of superoxide (O2·-) has been extensively implicated as a signaling molecule in cardiovascular pathologies, including hypertension. As a major risk factor for myocardial infarction, stroke, and heart failure, the morbidity and mortality associated with hypertension is a worldwide epidemic. Although there are several standard therapies that effectively lower blood pressure, many hypertensive patients have uncontrolled blood pressure despite taking available medications. Thus, there is a necessity to develop new pharmacotherapies that target novel molecular effectors (e.g. O2·-) that have been implicated to be integral in the pathogenesis of hypertension. To overcome the failed therapeutic impact of currently available antioxidants in cardiovascular disease, we developed a nanomedicine-based delivery system for the O2 ·- scavenging enzyme, copper/zinc superoxide dismutase (CuZnSOD), in which CuZnSOD protein is electrostatically bound to poly-L-lysine (PLL 50)-polyethylene glycol (PEG) block co-polymer to form CuZnSOD nanozyme. Different formulations of CuZnSOD nanozyme are covalently stabilized by either reducible or non-reducible crosslinked bonds between the PLL50-PEG polymers. Herein, we tested the overall hypothesis that PLL50-PEG CuZnSOD nanozyme delivers active CuZnSOD protein to neurons and decreases blood pressure in a model of Angll-dependent hypertension. As determined by electron paramagnetic resonance (EPR) spectroscopy, nanozymes retain full SOD enzymatic activity. Furthermore, non-reducible crosslinked nanozyme delivers active CuZnSOD protein to central neurons in culture (CATH.a neurons) without inducing significant neuronal toxicity. In vivo studies conducted in Angll-mediated hypertensive adult male C57BL/6 mice demonstrate that the non-reducible crosslinked nanozyme significantly attenuates blood pressure when given directly into the brain and prevents the further increase in hypertension when intravenously (IV) administered

  13. Binding of free and protein-associated zinc to rat spermatozoa.

    Sansone, G; Martino, M; Abrescia, P


    1. The zinc content of rat spermatozoa increases, upon ejaculation, from 0.035 to 1.055 micrograms/10(6) cells. 2. The rat seminal plasma holds zinc both as free ion and as protein-bound forms. 3. Zinc-free ions bind in vitro to rat epididymal spermatozoa. 4. Zinc-protein complexes can be isolated, by a chromatographic procedure, from the dorsolateral lobe of rat prostate. 5. The isolated zinc-protein complexes bind in vitro to rat epididymal spermatozoa.

  14. 席夫碱大环双核锌配合物的合成与表征%Synthesis and crystal structure of macrocyclic Schiff base binuclear zinc( Ⅱ )complex

    康海霞; 马宁; 傅玉琴; 李森兰


    A tetraaza macrocyclic Schiff base was synthesized through the reaction of acetone and ethylenediamine by the catalysis of perchloric acid. The Schiff base reacted with ZnO and NaN3 to form a binuclear zinc ( Ⅱ ) macrocyclic complex. The complex was characterized by infrared spectrum and X-Ray single crystal diffraction. It belongs to monoclinic system with space groupC2/c,α = 2.4914(2)nm,b = 1.4 9748(13)nm,c=1.26800(11)nm;β=l02. 1900( 10)°;v=4. 6240(7)nm3 ,Z=4,Dc = 1.482 Mg/m\\Mr = 1032.03 ,F(000)= 2160,final R=0.0506,wR = 0. 1434. The Zinc atom is five-coordinated by five nitrogen atoms(four nitrogen atoms come from the Schiff base and one nitrogen atom comes from the azido anion). As a result, a slightly distorted triangle double-cone geometry forms.%本文用丙酮和乙二胺在高氯酸催化下合成了四氮杂十四环席夫碱(1),并用此化合物(1)与氧化锌和叠氮化钠反应,生成锌的双核大环配合物.通过X-射线单晶衍射和红外光谱对其进行了结构表征.该配合物属单斜晶系,C2/c空间群,晶胞参数为a=2.4914 (2) nm,b=1.4 9748 (13) nm,c=1.26800( 11 )nm;β=102.1900(10)°;v=4.6240(7) nm3,Z=4,Dc=1.482Mg/m3,Mr=1032.03,F(000)=2160,最终R=0.0506,wR=0.1434.该配合物中锌原子是五配位,它们分别和大环配体上的4个氮原子及叠氮根负离子两端的氮原子配位形成畸变的三角双锥构型.

  15. Deletion of the zupT gene for a zinc importer influences zinc pools in Cupriavidus metallidurans CH34.

    Herzberg, M; Bauer, L; Nies, D H


    complex, and to the loss of metal resistance. This phenomenon occurred only if the ΔzupT cells had been cultivated for several transfers in solid culture medium, which generated severe zinc starvation. Thus, two zinc pools appear to exist in C. metallidurans: one pool of at least 20,000 tightly bound Zn(II) ions, in addition to a second pool of up to 200,000 cations bound loosely and with low substrate specificity.

  16. Synthesis and crystal structure of nickel(II) and zinc(II) complexes with 2,4-bis(3,5-dimethylpyrazol-1-yl)-6-methoxyl- 1,3,5-triazine

    YANG; Chi


    synthesis, crystal and molecular structure of terpy and bis(terpy)nickel(II) chloride decahydrate, Inorg. Chim. Acta, 1990, 178: 47.[10]Bhattacharyya, S., Kumar, S. B., Dutta, S. K. Et al., Zinc(II) and copper (II) complexes of pentacoordinating ligands with pyrazolyl arms: synthesis, structure, redox and spectroscopic properties, Inorg. Chem., 1996, 35: 1967.

  17. Interaction of zinc and cobalt with dipeptides and their DNA binding studies

    P Rabindra Reddy; M Radhika; K Srinivas Rao


    Interactions of zinc and cobalt with peptides cysteinylglycine and histidylglycine have been studied. The binding modes were identified and geometry assigned. Stabilities of these complexes and their ability to bind DNA have been investigated. It is demonstrated that only zinc complexes bind DNA as compared to cobalt complexes.

  18. Copper(II), cobalt(II), nickel(II) and zinc(II) complexes of Schiff base derived from benzil-2,4-dinitrophenylhydrazone with aniline

    N Raman; S Ravichandran; C Thangaraja


    New Schiff base chelates of Cu(II), Co(II), Ni(II) and Zn(II) derived from benzil-2,4-dinitrophenylhydrazone with aniline have been synthesised. Microanalytical data, molar conductance, and magnetic susceptibility values have been obtained, and IR, 1H NMR, 13C NMR, UV-Vis, CV and EPR spectral studies have been carried out to suggest tentative structures for the complexes.

  19. Palladium(II) and zinc(II) complexes of neutral [N2O2] donor Schiff bases derived from furfuraldehyde: Synthesis, characterization, fluorescence and corrosion inhibitors of ligands

    Ali, Omyma A. M.


    Metal complexes of Schiff bases derived from furfuraldehyde and 4,5-dimethyl-1,2-phenylendiamine (L1) or 4,5-dichloro-1,2-phenylendiamine (L2) have been reported and characterized based on elemental analyses, IR, 1H NMR, UV-Vis, magnetic moment, molar conductance and thermal analysis. The complexes are found to have the formulae [PdL1-2]Cl2 and [ZnL1-2](AcO)2·H2O. The molar conductance data reveal that Pd(II) and Zn(II) chelates are ionic in nature and are of the type 2:1 electrolytes. The spectral data are consistent with a square planar and tetrahedral geometry around Pd(II) and Zn(II), respectively, in which the ligands act as tetradentate ligands. The thermal behavior of some chelates is studied and the activation thermodynamic parameters are calculated using Coats-Redfern method. The corrosion inhibition of stainless steel types 410 and 304 in 1 M HCl using the synthesized Schiff bases as inhibitors have been studied by weight loss method. The obtained data considered these ligands as efficient corrosion inhibitors. The ligands and their metal complexes exhibited considerable antibacterial activity against Staphylococcusaureus, and Escherichiacoli and antifungal activity against Candida albicans.

  20. Potentiometric and spectrometric study: Copper(II), nickel(II) and zinc(II) complexes with potentially tridentate and monodentate ligands

    R N Patel; Nripendra Singh; R P Shrivastava; K K Shukla; P K Singh


    Equilibrium and solution structural study of mixed-metal-mixed-ligand complexes of Cu(II), Ni(II) and Zn(II) with L-cysteine, L-threonine and imidazole are conducted in aqueous solution by potentiometry and spectrophotometry. Stability constants of the binary, ternary and quaternary complexes are determined at 25 ± 1 ° C and in = 0.1 M NaClO4. The results of these two methods are made selfconsistent, then rationalized assuming an equilibrium model including the species H3A, H2A, A, BH, B, M(OH), M(OH)2, M(A), MA(OH), M(B), M(A)(B), M2(A)2(B), M2(A)2(B-H), M1M2(A)2(B) and M1M2(A)2(B-H) (where the charges of the species have been ignored for the sake of simplicity) (A = L-cysteine, L-threonine, salicylglycine, salicylvaline and BH = imidazole). Evidence of the deprotonation of BH ligand is available at alkaline H. N1H deprotonation of the bidentate coordinated imidazole ligand in the binuclear species at H > 7.0 is evident from spectral measurements. Stability constants of binary M(A), M(B) and ternary M(A)(B), complexes follow the Irving-Williams order.

  1. Metalloantibiotics: synthesis, characterization and in-vitro antibacterial studies on cobalt (II), copper (II), nickel (II) and zinc (II) complexes with cloxacillin.

    Chohan, Zahid H; Supuran, Claudiu T


    The synthesis and characterization of cloxacillin (clox) complexes with divalent metal ions [Co (II), Cu (II), Ni (II) and Zn (II)] is described. The nature of bonding of the chelated cloxacillin and the structures of the metal complexes have been elucidated on the basis of their physical and spectroscopic data. In all the complexes, the cloxacillin acts as a uninegatively charged bidentate ligand with coordination involving the carboxylate-O and endocyclic-N of the beta-lactam ring. The new compounds have been screened for in-vitro antibacterial activity against Escherichia coli (a), Klebsiella pneumonae (b), Proteus mirabilis (c), Pseudomonas aeruginosa (d), Salmonella typhi (e), Shigella dysentriae (f), Bacillus cereus (g), Corynebacterium diphtheriae (h), Staphylococcus aureus (j) and Streptococcus pyogenes (k) bacterial strains. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties. All compounds, respectively, showed a promising activity (90%) against five bacterial species at 10 microg/ml concentration and a significant activity (52%) against the same test bacteria at 25 microg/ml concentration.

  2. Palladium(II) and zinc(II) complexes of neutral [N2O2] donor Schiff bases derived from furfuraldehyde: synthesis, characterization, fluorescence and corrosion inhibitors of ligands.

    Ali, Omyma A M


    Metal complexes of Schiff bases derived from furfuraldehyde and 4,5-dimethyl-1,2-phenylendiamine (L1) or 4,5-dichloro-1,2-phenylendiamine (L2) have been reported and characterized based on elemental analyses, IR, 1H NMR, UV-Vis, magnetic moment, molar conductance and thermal analysis. The complexes are found to have the formulae [PdL1-2]Cl2 and [ZnL1-2](AcO)2·H2O. The molar conductance data reveal that Pd(II) and Zn(II) chelates are ionic in nature and are of the type 2:1 electrolytes. The spectral data are consistent with a square planar and tetrahedral geometry around Pd(II) and Zn(II), respectively, in which the ligands act as tetradentate ligands. The thermal behavior of some chelates is studied and the activation thermodynamic parameters are calculated using Coats-Redfern method. The corrosion inhibition of stainless steel types 410 and 304 in 1 M HCl using the synthesized Schiff bases as inhibitors have been studied by weight loss method. The obtained data considered these ligands as efficient corrosion inhibitors. The ligands and their metal complexes exhibited considerable antibacterial activity against Staphylococcusaureus, and Escherichiacoli and antifungal activity against Candida albicans.

  3. Chiroptical properties, binding affinity, and photostability of a conjugated zinc porphyrin dimer complexed with left-handed Z-DNA and right-handed B-DNA.

    Choi, Jung Kyu; Reed, Aisha; Balaz, Milan


    We have studied the UV-vis absorption and chiroptical properties, binding affinity and photostability of a conjugated positively charged butadiyne-linked Zn(ii) porphyrin dimer bound to DNA sequence poly(dG-dC)2. Right-handed B-DNA, spermine-induced Z-DNA and Co(iii)-induced Z-DNA have been explored. Resonance light scattering (RLS) spectra showed formation of porphyrin aggregates in the presence of all DNA forms with the largest aggregates formed with B-DNA. The porphyrin dimer gave rise to induced bisignate circular dichroism (CD) signals in the presence of the left-handed Z-DNA conformations. On the other hand, the dimer stayed nearly chiroptically silent when complexed with the B-form of poly(dG-dC)2. Our results indicated that the conjugated Zn(ii) porphyrin dimer can be used as a sensor for the chiroptical detection of Z-DNA in the visible (400-500 nm) and near-infrared region of the electromagnetic spectrum (700-800 nm). The helicity of DNA had little effect on the dimer binding affinities. The photostability of the porphyrin dimer complexed with any form of DNA was higher than that of the free molecule. The porphyrin dimer bound to Z-DNA exhibited slower photobleaching than the B-DNA dimer complex.

  4. Rapid growth of nanotubes and nanorods of würtzite ZnO through microwave-irradiation of a metalorganic complex of zinc and a surfactant in solution

    Sanjaya Brahma; Kalya Jagannatha Rao; Srinivasarao Shivashankar


    Large quantities of single-crystalline ZnO nanorods and nanotubes have been prepared by the microwave irradiation of a metalorganic complex of zinc, in the presence of a surfactant. The method is simple, fast, and inexpensive (as it uses a domestic microwave oven), and yields pure nanostructures of the hexagonal würtzite phase of ZnO in min, and requires no conventional templating. The ZnO nanotubes formed have a hollow core with inner diameter varying from 140–160 nm and a wall of thickness, 40–50 nm. The length of nanorods and nanotubes varies in the narrow range of 500–600 nm. These nanostructures have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). The ZnO nanorods and nanotubes are found by SAED to be single-crystalline. The growth process of ZnO nanorods and nanotubes has been investigated by varying the surfactant concentration and microwave irradiation time. Based on the various results obtained, a tentative and plausible mechanism for the formation of ZnO nanostructures is proposed.

  5. Hydrothermal Synthesis and Crystal Structure of a Zinc Complex: [Zn2.5(phen)(BDC)2(OH)](phen = 1,10-Phenanthroline, BDC= Benzene-1,4-dicarboxylic Acid)

    WANG Qing-Wei; LI Xiu-Mei; SHI Lin-Fang


    A metal-organic coordination polymer [Zn2.5(phen)(BDC)2(OH)]2 (phen = 1,10-phenanthroline, BDC = benzene-1,4-dicarboxylic acid)1 has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analyses and IR spectro-scopy. The complex crystallizes in the triclinic system, space group P1 with a = 11.199(2), b =11.593(2), c = 11.865(3) A, α= 99.330(1), β=111.506(1),γ = 104.804(1)°, V= 1328.4(5) A3, Dc=1.722 g/cm3, Z = 1, Mr = 1377.82, F(000) = 692, μ(MoKa) = 2.306 mm-1, S = 1.093, R = 0.0281 and wR= 0.0756 for 4179 observed reflections (Ⅰ 20(Ⅰ)). The coordination polyhedron around Zn(Ⅱ)can be described as a tetrahedron, trigonal bipyramid and octahedron. It is worth noting that the crystal structure of 1 is composed of tetranuclear zinc clusters linked by {ZnO6} units.

  6. Determination of total polyphenols in the zinc complex of polyphenol by Folin-Ciocalteu colorimetry%Folin-Ciocalteu分光光度法测定茶多酚锌配合物中多酚的含量

    王彦兵; 胥艳; 魏永春; 刘小强; 刘绣华


    A quantitative determination method for total polyphenols content in the Zinc complex of polyphenol was developed by using Folin-Ciocalteu colorimetry with gallic acid as reference compound. The results showed that the linear range of calibration curve was 0 - 8. 54 mg ·L-1. The RSD (relative standard deviation) of stability, precision, repeatability and recovery rate were in the range of 0. 39% -1. 23%. Therefore, FC method is a convenient, fast and accurate method to determine the total polyphenols of tea products.%以没食子酸为对照品,采用Folin-Ciocalteu比色法测定了茶多酚锌配合物(TP-Zn)中多酚的含量.结果表明,多酚质量浓度在0~8.54 mg ·L-1范围内与吸光度呈良好的线性关系;稳定性、精密度、重现性和回收率实验的相对标准偏差在0.39%~1.23%范围内.该法是一种简便、快速、准确测定茶叶制品中多酚含量的可靠方法.

  7. Low-cost chemiresistive sensor for volatile amines based on a 2D network of a zinc(II) Schiff-base complex

    Mirabella, S.; Oliveri, I. P.; Ruffino, F.; Maccarrone, G.; Di Bella, S.


    A marked chemiresistive behavior is revealed in a nanostructured material obtained by spin-coating a solution of a bis(salycilaldiminato)Zn(II) Schiff-base (ZnSB) complex. The resulting submicron 2D network exhibits reversible changes in absorbance and resistance under the cycles of absorption and desorption of a volatile amine. These results are explained in terms of a Lewis donor-acceptor interaction between the ZnSB (acceptor) and the chemisorbed amine (donor). The 2D network of ZnSB was employed as a sensing element to fabricate a low-cost device for the volatile amines detection, showing promising results for food spoilage detection.

  8. 铜、铁、锌-氟尿嘧啶配合物合成及其对肿瘤细胞增殖的抑制%Copper, iron, zinc-fluorouracil complexes synthesized in vitro inhibit tumor cell proliferation

    周轶平; 陈元晓; 周云; 石中正; 罗敏; 钟文远; 陈英杰


    背景:有机抗癌药与金属盐形成配合物后会形成新的结构或改变离子浓度,因此改变二者的毒性与活性而产生协同作用。目的:寻求高效低毒的新型金属-氟尿嘧啶配合物抗肿瘤药物。方法:以铜、铁、锌盐和氟尿嘧啶为原料,合成了4种配合物,分别为[Cu(5-Fu)2Cl2],[Cu(5-Fu)2(NO3)2],[Fe(5-Fu)3]SO4和[Zn(5-Fu)2Cl2]。用元素分析和质谱法分析配合物的化学结构。分别以4种配合物溶液、4种盐溶液、顺铂、氟尿嘧啶培养人白血病细胞株K562与人结肠癌细胞株HCT-116,改良MTT法测试细胞增殖。结果与结论:配合物的元素分析及摩尔电导数据初步确定了配合物的化学式,质谱结果进一步证明氟尿嘧啶确实与金属离子Cu2+、Fe2+、Zn2+配位。在0.1-100 mg/L质量浓度范围内,4种配合物对K562和HCT-116细胞增殖均有不同程度的抑制作用,4种配合物对K562和HCT-116细胞增殖的IC50值均低于氟尿嘧啶组,其细胞毒活性是氟尿嘧啶的1.5-7.8倍。表明铜盐、锌盐、铁盐与氟尿嘧啶形成配合物后有协同抑制肿瘤组织细胞增殖的作用。%BACKGROUND:Anticancer drug and organic metal complexes wil form a new structure or a change in ion concentration, thus changing both the activity and toxicity to produce a synergistic effect. OBJECTIVE:To synthesize new high-efficient and low-toxic metal-fluorouracil complexes as anticancer drugs. METHODS:Copper, zinc and iron salts and fluorouracil were used to synthesize four copper, zinc and iron-fluorouracil complexes that were [Cu(5-Fu)2Cl2], [Cu(5-Fu)2(NO3)2], [Fe(5-Fu)3]SO4 and [Zn(5-Fu)2Cl2]. Preliminary chemical structures of the four complexes were confirmed by elemental analysis and mass spectrometry. Their inhibitory activity on human cancer cells, human leukemia cellline K562 and human colon cancer cellline HCT-116, was measured by MTT colorimetric assay. RESULTS AND CONCLUSION:[Cu(5-Fu)2Cl2], [Cu

  9. Synthesis and structure-activity relationships of new carbonyl guanidine derivatives as novel dual 5-HT2B and 5-HT7 receptor antagonists.

    Moritomo, Ayako; Yamada, Hiroyoshi; Watanabe, Toshihiro; Itahana, Hirotsune; Akuzawa, Shinobu; Okada, Minoru; Ohta, Mitsuaki


    To identify potent dual 5-HT2B and 5-HT7 receptor antagonists, we synthesized a series of novel carbonyl guanidine derivatives and examined their structure-activity relationships. Among these compounds, N-(9-hydroxy-9H-fluorene-2-carbonyl)guanidine (10) had a good in vitro profile, that is, potent affinity for human 5-HT2B and 5-HT7 receptor subtypes (Ki=1.8 nM and Ki=17.6 nM, respectively) and high selectivity over 5-HT2A, 5-HT2C, α1, D2 and M1 receptors. Compound 10 also showed a suppressing effect on 5-HT-induced dural protein extravasation in guinea pigs when orally administered.

  10. The insulin secretory action of novel polycyclic guanidines: discovery through open innovation phenotypic screening, and exploration of structure-activity relationships.

    Shaghafi, Michael B; Barrett, David G; Willard, Francis S; Overman, Larry E


    We report the discovery of the glucose-dependent insulin secretogogue activity of a novel class of polycyclic guanidines through phenotypic screening as part of the Lilly Open Innovation Drug Discovery platform. Three compounds from the University of California, Irvine, 1-3, having the 3-arylhexahydropyrrolo[1,2-c]pyrimidin-1-amine scaffold acted as insulin secretagogues under high, but not low, glucose conditions. Exploration of the structure-activity relationship around the scaffold demonstrated the key role of the guanidine moiety, as well as the importance of two lipophilic regions, and led to the identification of 9h, which stimulated insulin secretion in isolated rat pancreatic islets in a glucose-dependent manner. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. Separation and quantitation of the polyamine biosynthesis inhibitor D,L-alpha-difluoromethylarginine and other guanidine-containing compounds by high-performance liquid chromatography.

    Hunter, K J; Fairlamb, A H


    The arginine decarboxylase inhibitor difluoromethylarginine (DFMA) is an important tool in the study of polyamine metabolism, particularly with respect to the human pathogen Trypanosoma cruzi. This paper demonstrates a unique method for the detection and quantitation of intracellular DFMA using the fluorogenic agent 9,10-phenanthrenequinone. After separation of cell extracts by HPLC, DFMA can be accurately and reproducibly quantified with a lower sensitivity limit of 0.1 nmol by this simple fluorometric method. This assay can also be used to detect other guanidine-containing compounds such as arginine, agmatine, creatinine, and hirudonine, but not substituted guanidines such as aminoguanidine and creatine, or the structurally related amidines such as benzamidine and pentamidine.

  12. Design and synthesis of a new terbium complex-based luminescent probe for time-resolved luminescence sensing of zinc ions.

    Ye, Zhiqiang; Xiao, Yunna; Song, Bo; Yuan, Jingli


    Luminescent probes/chemosensors based on lanthanide complexes have shown great potentials in various bioassays due to their unique long-lived luminescence property for eliminating short-lived autofluorescence with time-resolved detection mode. In this work, we designed and synthesized a new dual-chelating ligand {4'-[N,N-bis(2-picolyl)amino]methylene-2,2':6',2'-terpyridine-6,6'-diyl} bis(methylenenitrilo) tetrakis(acetic acid) (BPTTA), and investigated the performance of its Tb(3+) complex (BPTTA-Tb(3+)) for the time-resolved luminescence sensing of Zn(2+) ions in aqueous media. Weakly luminescent BPTTA-Tb(3+) can rapidly react with Zn(2+) ions to display remarkable luminescence enhancement with high sensitivity and selectivity, and such luminescence response can be realized repeatedly. Laudably, the dose-dependent luminescence enhancement shows a good linear response to the concentration of Zn(2+) ions with a detection limit of 4.1 nM. To examine the utility of the new probe for detecting intracellular Zn(2+) ions, the performance of BPTTA-Tb(3+) in the time-resolved luminescence imaging of Zn(2+) ions in living HeLa cells was investigated. The results demonstrated the applicability of BPTTA-Tb(3+) as a probe for the time-resolved luminescence sensing of intracellular Zn(2+) ions.

  13. Slow relaxation of the magnetization in an Isostructural series of Zinc-lanthanide complexes: an integrated EPR and AC susceptibility study

    Amjad, Asma; Madalan, Augustin; Andruh, Marius; Caneschi, Andrea; Sorace, Lorenzo; University of Bucharest, Faculty of Chemistry, Inorganic Chemistry Laboratory, Bucharest, Romania Collaboration


    Lanthanide based molecular complexes have shown potential to behave as single molecule magnets proficient to function above cryogenic temperatures. In this work we explore the dynamics of one such family, [Zn(LH)2Ln](NO3)3 .6H2O - (Ln = Nd3+, Dy3+, Tb3+, Ho3+, Er3+, Yb3+) . The series has a single lanthanide ion as a magnetic center in a low symmetry environment; the dynamics and energy landscape of the series is explored using X-band EPR, AC and DC susceptibility over a range of temperature, field and frequency. DC magnetic data show χT value consistent with expected behavior. EPR spectra for Er3+ and Yb3+ complexes shows EPR spectra typical for easy-plane and quasi-isotropic systems respectively, thus explaining the lack of out of phase susceptibility even in an external applied filed. However, Dy3+ derivative show slow relaxation of the magnetization in zero field up to 15 K and is, accordingly EPR silent.

  14. Synthesis and Crystal Structure of a Tetranuclear Carboxylate-bridged Lanthanum(III)-Zinc(II) Complex [La2Zn2(m-CNC6H4COO)10(Py)2(C2H5OH)2


    The title complex was prepared from self-assembly reaction of La(NO3)3×6H2O, Zn(NO3)2×6H2O, m-cyanobenzoic acid (m-CNC6H4COOH) and pyridine (Py) in refluxing ethanol and its structure was determined by single-crystal X-ray diffraction. Crystallographic data: C94H62N12La2O22Zn2, Mr = 2120.12, triclinic space group P _ 1, a = 13.2219(5), b = 13.2713(5), c = 14.1987(6) ?, a = 69.156(1), b = 84.034(1), g = 89.400(1) °, V = 2314.9(2) ?3, Z = 1, Dc = 1.521 g/cm3, F(000) = 1060, m (MoKa) = 14.94 cm-1, the final R = 0.043 and wR = 0.117 for 6381 unique reflections with I > 2s(I). Crystal structure determination shows that the neighboring lanthanum(III) and zinc(II) ions are bridged by three bidentate m-cyanobenzonate ligands in the syn-syn fashion to form a pair of dinuclear [LaZn(m-CNC6H4COO)3(Py)(C2H5OH)] subunits, being linked together by two bidentate and two tridentate m-cyanobenzonate groups in the syn-syn and syn-anti modes, respectively, to construct a tetranuclear La-Zn complex [La2Zn2(m-CNC6H4COO)10(Py)2(C2H5OH)2].

  15. Synthesis, Dimeric Crystal Structure, and Biological Activities of N-(4-Methyl-6-oxo-1,6-dihydro-pyrimidin-2-yl)-N-(2-trifluoromethyl-phenyl)-guanidine


    The title compound, N-(4-methyl-6-oxo-1,6-dihydro-pyrimidin-2-yl)-N′-(2-trifluoromethyl-phenyl)-guanidine, was synthesized and its structure was confirmed by using IR, MS, 1H NMR, and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test showed that the synthesized compound has a weak herbicidal activity.

  16. Asymmetric α-hydroxylation of tetralone-derived β-ketoesters by using a guanidine-urea bifunctional organocatalyst in the presence of cumene hydroperoxide.

    Odagi, Minami; Furukori, Kota; Watanabe, Tatsuya; Nagasawa, Kazuo


    Highly enantioselective catalytic oxidation of 1-tetralone-derived β-keto esters was achieved by using a guanidine-urea bifunctional organocatalyst in the presence of cumene hydroperoxide (CHP), a safe, commercially available oxidant. The α-hydroxylation products were obtained in 99% yield with up to 95% enantiomeric excess (ee). The present oxidation was successfully applied to synthesize a key intermediate of the anti-cancer agent daunorubicin (2).

  17. Low serum zinc level in dpression

    SA Mousavi


    Full Text Available BACKGROUND: Major Depressive Disorder (MDD is a common disorder, with a lifetime prevalence of about 15 percent, perhaps as high as 25 percent for women. The etiology of MDD is too complex to be explained totally by a single social, developmental, or biological theory. A variety of factors appear to work together to cause or precipitate depressive disorders. Various functions have been reported for trace elements such as zink in recovery or exacerbation of depression. METHODS: In this experimental study, we studied 46 patients with MDD based on DSM IV criteria, among the patients referred to mental disorders clininc of Noor Hospital. Twenty Patients were men and 26 were women. Thirty two volunteers of general population were evaluated for depression with Beck depression test who did not show any depressive symptoms with this test. A blood sample of 5cc was obtained from each person and the serum zinc concentration was measured. Data gathered and analyzed with SPSS, logistic regression and chi-squar tests. RESULTS: Serum zinc concentrations were 74 to 130 mg/dl in men and 60 to 128 mg/dl in women of control group. Serum zinc concentration was 30 to 60 mg/dl in depressive patients that it was lower in women than men. The difference between serum zinc concentrations of normal and depressive persons was meaningful (P = 0.02. CONCLUSION: In our study, the serum concentration of zinc was about half of normal value. This study replicates previous findings that major depressed subjects show significantly lowered serum zinc concentration. KEYWORDS: Depression, zinc.

  18. Review on Energetic Guanidine Ionic Compounds%胍基含能离子化合物的研究进展

    甘志勇; 柴春鹏; 罗运军; 李娜; 李国平


    The synthesis method of energetic guanidine ionic compounds with the characteristics of high enthalpy of formation, good thermal stability and environment-friendly was summarized. The effects of cation,anion,substituent group and intermolecular force on the melting point,density and energy performance of energetic guanidine ionic compounds were analyzed. The progress in the applications of energetic guanidine ionic compounds in gas generation agents, propellants and explosives was introduced and reviewed.%总结了具有生成焓高、热稳定性好、对环境友好等特点的胍基含能离子化合物合成方法,分析了阴阳离子、取代基团和分子间作用力对其熔点、密度和能量性能的影响,详述了胍基含能离子化合物在气体发生剂、推进剂和炸药方面的应用进展.

  19. Effect of electrochemical treatment in H2SO4 aqueous solution on carbon material derived from cellulose with added guanidine phosphate

    Tsubota, Toshiki; Wang, Chuanshu; Murakami, Naoya; Ohno, Teruhisa


    The electrochemical treatment in a 1 M H2SO4 aqueous solution is applied to the carbon material synthesized from cellulose mixed with guanidine phosphate. The capacitance value increased by the addition of guanidine phosphate; furthermore, the value significantly increased by the electrochemical treatment and was higher than 350 F g-1 at 50 mA g-1. The process used in this study, that is, removing the lignin from wood waste products, such as bamboo, and then mixing with guanidine phosphate before the heat treatment followed by an electrochemical treatment, should be of benefit for the synthesis of a high performance material for the electrodes of electrochemical capacitors. The significant enhancement of the capacitance value appears in the range of 1.5 V∼2.8 V vs. Ag/AgCl for the applied maximum voltage. This voltage range is consistent with the voltage for the significant enhancement of the current value in the CV curve. The change in the capacitance value should be related to the electrochemical reaction of the water electrolysis. The XPS data indicated that the concentrations of both the N atom and the O atom on the surface increased after the electrochemical process.


    S.B. Strashnova


    Full Text Available The complexes of general formula MCl2∙L1-4∙nH2O (where L1 - N-(2,4,7-trinitrofluorenilidene-9-p-dimethyl-aminoanilin, L2 - N-(2,4,5,7-tetranitrofluorenilidene-9-p-dimethylaminoaniline, L3 - N-(2,4,7-trinitrofluorenilidene-N-(p-dimethylaminophenylhydroxylamine, L4 - N-(2,4,5,7-tetranitrofluorenilidene-9-N-(p-dimethylaminophenyl-hydroxylamine; M=Cu, Co, Ni, Zn; n= 1-3 have been synthesized and investigated by different methods. Spectral criteria of co-ordination of the molecules L1 –L4 in electronic adsorption spectra were detected.

  1. 聚六亚甲基胍与表面活性剂复配研究%Study on formulation of polyhexamethylene guanidine with surfactants

    徐平如; 周明灿; 赖桂兰; 武秀文


    以聚氧乙烯脱水山梨醇油酸酯( Tween 80)和壬基酚聚氧乙烯醚(TX - 10)为增溶剂对聚六亚甲基胍(PHMG)与阴离子表面活性剂直链烷基苯磺酸钠(LAS)形成的难溶性复合物进行增溶试验.正交试验结果表明,Tween 80和TX-10在单独使用时均无显著增溶效果,但二者复配使用时则有极为显著的增溶效果;Tween 80和TX-10复配产生最佳增效作用时的添加量分别为1%和3%(质量分数),以此量添加Tween 80和TX - 10,可使PHMG加入LAS水溶液后呈均一、透明、稳定的状态.该复配物的杀菌消毒效果优于同量(质量分数1%)的PHMG原液.%Ethoxylated sorbitan monooleate (Tween 80) and ethoxylated nonylphenol (TX -10) were used as emulsifying agent for solubilizing the gel - like solid complex composed of polyhexamethylene guanidine ( PHMG) and sodium linear alkylbenze sulfonate (LAS) that is difficult to dissolve in water. Orthogonal design experimental results showed that either Tween 80 or TX - 10 displays no significant solubilization effect when it is used individually and separately. However, in case the two surfactants are used in combination with each other,very remarkable solubilization effect is displayed. Optimum dosage of Tween 80 and TX - 10 is 1% and 3% mass fraction respectively. In this case,the PHMG - LAS system becomes a uniform,transparent and stable aqueous solution. Disinfection effect of such solubilized system is better than that of the single PHMG aqueous solution with same mass fraction of 1 %.

  2. Zinc electrode and rechargeable zinc-air battery

    Ross, Jr., Philip N.


    An improved zinc electrode is disclosed for a rechargeable zinc-air battery comprising an outer frame and a porous foam electrode support within the frame which is treated prior to the deposition of zinc thereon to inhibit the formation of zinc dendrites on the external surface thereof. The outer frame is provided with passageways for circulating an alkaline electrolyte through the treated zinc-coated porous foam. A novel rechargeable zinc-air battery system is also disclosed which utilizes the improved zinc electrode and further includes an alkaline electrolyte within said battery circulating through the passageways in the zinc electrode and an external electrolyte circulation means which has an electrolyte reservoir external to the battery case including filter means to filter solids out of the electrolyte as it circulates to the external reservoir and pump means for recirculating electrolyte from the external reservoir to the zinc electrode.

  3. Zinc in diet

    ... Zinc is also needed for the senses of smell and taste. During pregnancy, infancy, and childhood the ... sense of taste Problems with the sense of smell Skin sores Slow growth Trouble seeing in the ...

  4. Zinc level and obesity

    Doaa S.E. Zaky


    Conclusion Plasma zinc concentration in obese individuals showed an inverse relationship with the waist circumference and BMI as well as serum low-density lipoprotein-cholesterol and correlated positively with high-density lipoprotein.

  5. Zinc level and obesity

    Doaa S.E Zaky; Eman A Sultan; Mahmoud F Salim; Rana S Dawod


    Background Obesity is a chronic condition that is associated with disturbances in the metabolism of zinc. Therefore, the aim of this study was to investigate the relationship between serum zinc level and different clinical and biochemical parameters in obese individuals. Patients and methods Twenty-four individuals with BMI more than 30 kg/m 2 and 14 healthy controls (BMI < 24 kg/m 2 ) were assessed for BMI and waist circumference using anthropometric measurements. Colorimetric tes...

  6. Structures and properties of 1,8,15,22-tetrasubstituted phthalocyaninato zinc and nickel complexes: substitution and axially coordination effects study based on density functional theory calculations.

    Wan, Liang; Zhang, Yuexing; Qi, Dongdong; Jiang, Jianzhuang


    On the basis of the density functional theory (DFT) calculation of ZnPc (1), Zn[Pc(alpha-OC(5)H(11))(4)] (2), Ni[Pc(alpha-OC(5)H(11))(4)] (3), and Zn[Pc(alpha-OC(5)H(11))(4)]xH(2)O (4), the effects of non-peripheral substitution, different transition metals, and axial water coordination on the molecular structure, molecular orbital, atomic charge, infrared (IR) spectrum, and electronic absorption spectrum were investigated. The calculation results reveal that bulky 3-pentyloxy groups at the non-peripheral positions of the phthalocyanine ring evince great changes in structure and properties: they deflect the isoindole units, lift the frontier molecular orbitals, alter the atomic charge distribution, shift the bands of IR and electronic absorption spectra, etc. Though the central metal can shorten or lengthen the bond length, its effect on the electronic structure and properties of the phthalocyanine complex is very limited. Axial coordination significantly enhances the non-planarity of the phthalocyanine ring and, thus, alters the electronic structure, which is important for the formation of novel dimeric supramolecular structures through intermolecular hydrogen bonds. In addition, the calculated structures of 3 as well as the simulated IR and electronic absorption spectra of 4 were compared with the experimental data and showed good agreement.

  7. Analysis of reaction and transport processes in zinc air batteries

    Schröder, Daniel


    This book contains a novel combination of experimental and model-based investigations, elucidating the complex processes inside zinc air batteries. The work presented helps to answer which battery composition and which air-composition should be adjusted to maintain stable and efficient charge/discharge cycling. In detail, electrochemical investigations and X-ray transmission tomography are applied on button cell zinc air batteries and in-house set-ups. Moreover, model-based investigations of the battery anode and the impact of relative humidity, active operation, carbon dioxide and oxygen on zinc air battery operation are presented. The techniques used in this work complement each other well and yield an unprecedented understanding of zinc air batteries. The methods applied are adaptable and can potentially be applied to gain further understanding of other metal air batteries. Contents Introduction on Zinc Air Batteries Characterizing Reaction and Transport Processes Identifying Factors for Long-Term Stable O...

  8. Anti-inflammatory activity and gastric lesions induced by zinc-tenoxicam.

    Nascimento, Jorge Willian L; Santos, Luiz Henrique; Nothenberg, Michael S; Coelho, Márcio M; Oga, Seizi; Tagliati, Carlos A


    Oral administration of tenoxicam or zinc-tenoxicam complex inhibited to a similar extent carrageenin-induced paw oedema and granulomatous tissue formation in rats as well as the acetic acid induced writhing response in mice. Gastric lesions induced by oral administration of zinc-tenoxicam were reduced in number and severity when compared with those induced by tenoxicam or the co-administration of tenoxicam and zinc acetate. However, after intraperitoneal administration, both zinc-tenoxicam and tenoxicam plus zinc acetate induced a reduced number of gastric lesions as compared with tenoxicam.

  9. Blood-brain transfer and antinociception of linear and cyclic N-methyl-guanidine and thiourea-enkephalins

    Verbeken, Mathieu; Wynendaele, Evelien; Mauchauffee, Elodie


    cyclic enkephalin analogs with a thiourea (CycS) or a N-methyl-guanidine bridge (CycNMe), and their linear counterparts (LinS and LinNMe) in mice, as well as their in vitro metabolic stability. 125I-LinS had the highest blood–brain clearance (K1 = 3.46 μL/g min), followed by 125I-LinNMe, 125I......-CycNMe, and 125I-CycS (K1 = 1.64, 0.31, and 0.11 μL/g min, respectively). Also, these peptides had a high metabolic stability (t1/2 > 1 h) in mouse serum and brain homogenate, and half-inhibition constant (Ki) values in the nanomolar range with predominantly μ-opioid receptor selectivity. The positively charged...... NMe-enkephalins showed a higher antinociceptive activity (LinNMe: 298% and CycNMe: 205%), expressed as molar-dose normalized area under the curve (AUC) relative to morphine, than the neutral S-enkephalins (CycS: 122% and LinS: 130%)....

  10. The bioavailability of four zinc oxide sources and zinc sulphate in broiler chickens

    Veldkamp, T.; Diepen, van, C.A.; Bikker, P.


    Zinc is an essential trace element for all farm animal species. It is commonly included in animal diets as zinc oxide, zinc sulphate or organically bound zinc. Umicore Zinc Chemicals developed zinc oxide products with different mean particle sizes. Umicore Zinc Chemicals requested Wageningen UR Livestock Research to determine the bioavailability of four zinc oxide sources and zinc sulphate in broiler chickens. A precise estimate of the bioavailability of zinc sources is required both for fulf...

  11. Treatment of zinc deficiency without zinc fortification

    Donald OBERLEAS; Barbara F. HARLAND


    Zinc (Zn) deficiency in animals became of interest until the 1950s. In this paper, progresses in researches on physi-ology of Zn deficiency in animals, phytate effect on bioavailability of Zn, and role of phytase in healing Zn deficiency of animals were reviewed. Several studies demonstrated that Zn is recycled via the pancreas; the problem of Zn deficiency was controlled by Zn homeostasis. The endogenous secretion of Zn is considered as an important factor influencing Zn deficiency, and the critical molar ratio is 10. Phytate (inositol hexaphosphate) constituted up to 90% of the organically bound phosphorus in seeds. Great improvement has been made in recent years on isolating and measuring phytate, and its structure is clear. Phytate is considered to reduce Zn bioavailability in animal. Phytase is the enzyme that hydrolyzes phytate and is present in yeast, rye bran, wheat bran, barley, triticale, and many bacteria and fungi. Zinc nutrition and bioavailability can be enhanced by addition of phytase to animal feeds. Therefore, using phytase as supplements, the most prevalent Zn deficiency in animals may be effectively corrected without the mining and smelting of several tons of zinc daily needed to correct this deficiency by fortification worldwide.

  12. Molecular dynamics of sialic acid analogues complex with cholera toxin and DFT optimization of ethylene glycol-mediated zinc nanocluster conjugation.

    Sharmila, D Jeya Sundara; Jino Blessy, J


    Cholera is an infectious disease caused by cholera toxin (CT) protein of bacterium Vibrio cholerae. A sequence of sialic acid (N-acetylneuraminic acid, NeuNAc or Neu5Ac) analogues modified in its C-5 position is modelled using molecular modelling techniques and docked against the CT followed by molecular dynamics simulations. Docking results suggest better binding affinity of NeuNAc analogue towards the binding site of CT. The NeuNAc analogues interact with the active site residues GLU:11, TYR:12, HIS:13, GLY:33, LYS:34, GLU:51, GLN:56, HIE:57, ILE:58, GLN:61, TRP:88, ASN:90 and LYS:91 through intermolecular hydrogen bonding. Analogues N-glycolyl-NeuNAc, N-Pentanoyl-NeuNAc and N-Propanoyl-NeuNAc show the least XPGscore (docking score) of -9.90, -9.16, and -8.91, respectively, and glide energy of -45.99, -42.14 and -41.66 kcal/mol, respectively. Stable nature of CT-N-glycolyl-NeuNAc, CT-N-Pentanoyl-NeuNAc and CT-N-Propanoyl-NeuNAc complexes was verified through molecular dynamics simulations, each for 40 ns using the software Desmond. All the nine NeuNAc analogues show better score for drug-like properties, so could be considered as suitable candidates for drug development for cholera infection. To improve the enhanced binding mode of NeuNAc analogues towards CT, the nine NeuNAc analogues are conjugated with Zn nanoclusters through ethylene glycol (EG) as carriers. The NeuNAc analogues conjugated with EG-Zn nanoclusters show better binding energy towards CT than the unconjugated nine NeuNAc analogues. The electronic structural optimization of EG-Zn nanoclusters was carried out for optimizing their performance as better delivery vehicles for NeuNAc analogues through density functional theory calculations. These sialic acid analogues may be considered as novel leads for the design of drug against cholera and the EG-Zn nanocluster may be a suitable carrier for sialic acid analogues.

  13. Morphology of ZnS Particles Produced from Various Zinc Salts by Homogeneous Precipitation


    acetato, sulfato , chloro and nitrato complexes of zinc corrected for the ionic strengths of the solutions that we used (9). Complex species involving...chloride system 8 Table I Concentration equilibrium constants for acetato, nitrato, sulfato and chloro complexes of Znz- ions found by interpolation...this conclusion. Although stability constants for acetato complexes of zinc (Table I) are very close to those for sulfato complexes, nucleation is

  14. The mouse nac1 gene, encoding a cocaine-regulated Bric-a-brac Tramtrac Broad complex/Pox virus and Zinc finger protein, is regulated by AP1.

    Mackler, S A; Homan, Y X; Korutla, L; Conti, A C; Blendy, J A


    NAC1 cDNA was identified as a novel transcript induced in the nucleus accumbens from rats chronically treated with cocaine. NAC1 is a member of the Bric-a-brac Tramtrac Broad complex/Pox virus and Zinc finger family of transcription factors and has been shown by overexpression studies to prevent the development of behavioral sensitization resulting from repeated cocaine treatment. This paper reports the cloning and characterization of the corresponding gene. The mouse Nac1 gene consist of six exons, with exon 2 containing an alternative splice donor, providing a molecular explanation of the splice variants observed in mouse and rat. Transcripts of Nac1 were ubiquitously detected in different mouse tissues with prominent expression in the brain. The mouse Nac1 gene was localized to chromosome 8, suggesting a highly plausible candidate gene to explain differences in cocaine-induced behaviors between C57BL6/J and DBA/2J mice that had previously been mapped to the area. In addition, a functional AP1 binding site has been identified in an intron 1 enhancer of the Nac1 gene that plays an essential role in the activation of the gene in differentiation of neuroblastoma cells. Co-transfection with c-jun and c-fos expression plasmids, which encode the two subunits of AP1, activated the wild type Nac1 intron 1 enhancer two-fold over basal, nearly at the level of NAC1 enhancer activity seen in differentiated N2A cells. Mutation of the AP1 site completely abrogated all activation of the NAC1 enhancer in differentiated N2A cells. Activation of immediate early genes such as c-fos and c-jun following chronic drug treatments has been well characterized. The present data describe one potential regulatory cascade involving these transcription factors and activation of NAC1. Identification of drug induced alterations in gene expression is key to understanding the types of molecular adaptations underlying addiction.

  15. Conformational changes of active site of copper zinc superoxide dismutase can be detected sensitively by electron-transfer reaction



    The electron-transfer (ET) reaction between Fe(CN)64- and copper zinc superoxide dismutase (CuZn-SOD) occurs at the active site of the enzyme. The ET parameters which are sensitive to the denaturation have been used to determine the conformational changes of the active site induced by guanidine hydrochloride and thermal denaturation. The decreases of ET rates for all the denatured enzyme samples reflect the collapse of the active cavity of enzyme in the unfolding processes. The interesting changes of ET amplitude for the enzyme denatured at different pH values suggest that electrostatic interaction plays an important role in the conformational changes of active site. From the results of the kinetic analyses, it is concluded that the conformational changes of the active site are parallel with the inactivation.

  16. Controlled Growth of ZnSe Nanocrystals by Tuning Reactivity and Amount of Zinc Precursor

    Lai-Jun Zhang


    Full Text Available Zinc selenide (ZnSe nanocrystals were synthesized via a phosphine-free route using the highly reactive alkylamine-H2Se complex as selenium precursor and zinc precursors with different reactivity. The reactivity of zinc precursor was tuned by using three kinds of zinc carboxylates with different alkyl chain lengths, including zinc acetate, zinc nonanoate, and zinc stearate. The effect of the reactivity and the amount of zinc precursor on nucleation and growth of ZnSe nanocrystals were investigated by ultraviolet-visible absorption and photoluminescence spectra. Result indicates that the growth and optical property of the resulting ZnSe nanocrystals are strongly dependent on the alkyl chain length and the amount of the zinc carboxylates and both shorter alkyl chain length, and more amount of zinc carboxylate will lead to faster growth of ZnSe nanocrystals. This allows that the controlled growth and excellent optical property of high-quality ZnSe nanocrystals can be achieved by combining the different reactivity and the used amount of zinc precursor, such as by using stoichiometric and reactive Zn precursor and Se precursor or by using larger amount of more unreactive Zn precursor relative to the highly reactive alkylamine-H2Se complex precursor.

  17. Spectrophotometric determination of micro quantities of zinc in rocks

    Huffman, C.; Lipp, H.H.; Rader, L.F.


    A chemical method is presented for the determination of microgram amounts of zinc in rocks. Zinc is absorbed on anion-exchange resin from 1.2 M hydrochloric acid and eluted with 0.01 M hydrochloric acid. A diethyldithiocarbamate separation removes traces of interfering elements from the eluate. The zinc-diethyldithiocarbamate complex is extracted into chloroform at pH 8.5 and reextracted from other elements in the chloroform solution with 0.16 M hydrochloric acid and finally determined spectrophotometrically as the zincon complex at 621 m??. The coefficient of variation of the method determined from replicate determinations of zinc on 75 selected samples of basalt, ranging in zinc content from 0.004 to 0.018 per cent, was found to be 6.3 per cent and essentially constant in the range of zinc content studied. This method of analysis has been used extensively for a study of zinc in basalts reported by Rader, Swadley, Huffman and Lipp (companion paper, 1963). ?? 1963.

  18. Microstructure and Performances of Nanocrystalline Zinc-nickel Alloy Coatings

    LI Guang-yu; LIAN Jian-she; NIU Li-yuan; JIANG Zhong-hao


    Nanocrystalline zinc-nickel alloy coatings were deposited from an alkaline zincate bath contained an organic additive that can reduce polarization and a complexing agent. SEM and TEM observations and XRD analysis were performed to examine the microstructure and phase composition of the coatings. The nickel content in deposits is 12.0~14.7% and the coating is consisted of single nanocrystalline γ-phase structure (Ni5Zn21), with grain average grain size about 15nm. The nanocrystalline zinc-nickel alloy coatings have better corrosion resistance, less brittleness and higher microhardness than the conventional zinc coatings.

  19. Microstructure and Performances of Nanocrystalline Zinc-nickel Alloy Coatings

    LIGuang-yu; LIANJian-she; NIULi-yuan; JIANGZhong-hao


    Nanocrystalline zinc-nickel alloy coatings were deposited from an alkaline zincate bath contained an organic additive that can reduce polarization and a complexing agent. SEM and TEM observations and XRD analysis were performed to examine the microstructure and phase composition of the coatings. The nickel content in deposits is 12.0-14.7% and the coating is consisted of single nanectystalline γ-phase structure (Ni5Zn21), with grain average grain size about 15nm. The nanocrystalline zinc-nickel alloy coatings have better corrosion resistance, less brittleness and higher microhardness than the conventional zinc coatings.

  20. Root-Secreted Nicotianamine from Arabidopsis halleri Facilitates Zinc Hypertolerance by Regulating Zinc Bioavailability1[W][OPEN

    Tsednee, Munkhtsetseg; Yang, Shun-Chung; Lee, Der-Chuen; Yeh, Kuo-Chen


    Hyperaccumulators tolerate and accumulate extraordinarily high concentrations of heavy metals. Content of the metal chelator nicotianamine (NA) in the root of zinc hyperaccumulator Arabidopsis halleri is elevated compared with nonhyperaccumulators, a trait that is considered to be one of the markers of a hyperaccumulator. Using metabolite-profiling analysis of root secretions, we found that excess zinc treatment induced secretion of NA in A. halleri roots compared with the nonhyperaccumulator Arabidopsis thaliana. Metal speciation analysis further revealed that the secreted NA forms a stable complex with Zn(II). Supplying NA to a nonhyperaccumulator species markedly increased plant zinc tolerance by decreasing zinc uptake. Therefore, NA secretion from A. halleri roots facilitates zinc hypertolerance through forming a Zn(II)-NA complex outside the roots to achieve a coordinated zinc uptake rate into roots. Secretion of NA was also found to be responsible for the maintenance of iron homeostasis under excess zinc. Together our results reveal root-secretion mechanisms associated with hypertolerance and hyperaccumulation. PMID:25118254

  1. Light-Controlled Release and Uptake of Zinc Ions in Solution by a Photochromic Terthiazole-Based Ligand.

    Guérin, Juliette; Léaustic, Anne; Berthet, Jérôme; Métivier, Rémi; Guillot, Régis; Delbaere, Stéphanie; Nakatani, Keitaro; Yu, Pei


    We have synthesized and fully characterized a photochromic zinc complex with a terphenylthiazole-based ligand with a salen-like cavity. The solution stability of the complex was found to be greatly dependent on the state of the photochromic ligand and an interesting photo-triggered release and uptake of zinc ions was found as well as monitored by its fluorescence. The contrasting stability difference of the zinc complex between its two isomeric states was rationalized by DFT calculations.

  2. Zinc Determination in Pleural Fluid

    Nazan DEMİR; DEMİR, Yaşar


    In this study, an enzymatic zinc determination method was applied to pleural fluid, the basis of which was the regaining of the activity of apo carbonic anhydrase by the zinc present in the sample. The method was used for pleural fluid zinc determination in order to show the application to body fluids other than serum. For this purpose, pleural fluids were obtained from 20 patients and zinc concentrations were determined. Carbonic anhydrase was purified by affinity chromatography from bovine ...

  3. The bioavailability of four zinc oxide sources and zinc sulphate in broiler chickens

    Veldkamp, T.; Diepen, van J.T.M.; Bikker, P.


    Zinc is an essential trace element for all farm animal species. It is commonly included in animal diets as zinc oxide, zinc sulphate or organically bound zinc. Umicore Zinc Chemicals developed zinc oxide products with different mean particle sizes. Umicore Zinc Chemicals requested Wageningen UR

  4. The bioavailability of four zinc oxide sources and zinc sulphate in broiler chickens

    Veldkamp, T.; Diepen, van J.T.M.; Bikker, P.


    Zinc is an essential trace element for all farm animal species. It is commonly included in animal diets as zinc oxide, zinc sulphate or organically bound zinc. Umicore Zinc Chemicals developed zinc oxide products with different mean particle sizes. Umicore Zinc Chemicals requested Wageningen UR Live

  5. Trace elements in human physiology and pathology: zinc and metallothioneins.

    Tapiero, Haim; Tew, Kenneth D


    Zinc is one of the most abundant nutritionally essential elements in the human body. It is found in all body tissues with 85% of the whole body zinc in muscle and bone, 11% in the skin and the liver and the remaining in all the other tissues. In multicellular organisms, virtually all zinc is intracellular, 30-40% is located in the nucleus, 50% in the cytoplasm, organelles and specialized vesicles (for digestive enzymes or hormone storage) and the remainder in the cell membrane. Zinc intake ranges from 107 to 231 micromol/d depending on the source, and human zinc requirement is estimated at 15 mg/d. Zinc has been shown to be essential to the structure and function of a large number of macromolecules and for over 300 enzymic reactions. It has both catalytic and structural roles in enzymes, while in zinc finger motifs, it provides a scaffold that organizes protein sub-domains for the interaction with either DNA or other proteins. It is critical for the function of a number of metalloproteins, inducing members of oxido-reductase, hydrolase ligase, lyase family and has co-activating functions with copper in superoxide dismutase or phospholipase C. The zinc ion (Zn(++)) does not participate in redox reactions, which makes it a stable ion in a biological medium whose potential is in constant flux. Zinc ions are hydrophilic and do not cross cell membranes by passive diffusion. In general, transport has been described as having both saturable and non-saturable components, depending on the Zn(II) concentrations involved. Zinc ions exist primarily in the form of complexes with proteins and nucleic acids and participate in all aspects of intermediary metabolism, transmission and regulation of the expression of genetic information, storage, synthesis and action of peptide hormones and structural maintenance of chromatin and biomembranes.

  6. Environmental risk limits for zinc

    Bodar CWM; SEC


    Environmental Riks Limits (ERLs) were derived for zinc. ERLs serve as advisory values to set environmental quality standards in the Netherlands. The ERLs for zinc closely follow the outcomes of earlier discussions on zinc within the Water Framework Directive and EC Regulation 793/93. The ERLs refer

  7. Environmental risk limits for zinc

    Bodar CWM; SEC


    Environmental Riks Limits (ERLs) were derived for zinc. ERLs serve as advisory values to set environmental quality standards in the Netherlands. The ERLs for zinc closely follow the outcomes of earlier discussions on zinc within the Water Framework Directive and EC Regulation 793/93. The ERLs ref

  8. Zinc Phosphide Poisoning

    Erdal Doğan


    Full Text Available Zinc phosphide has been used widely as a rodenticide. Upon ingestion, it gets converted to phosphine gas in the body, which is subsequently absorbed into the bloodstream through the stomach and the intestines and gets captured by the liver and the lungs. Phosphine gas produces various metabolic and nonmetabolic toxic effects. Clinical symptoms are circulatory collapse, hypotension, shock symptoms, myocarditis, pericarditis, acute pulmonary edema, and congestive heart failure. In this case presentation, we aim to present the intensive care process and treatment resistance of a patient who ingested zinc phosphide for suicide purposes.

  9. Chemistry of guanidinate-stabilised diboranes: transition-metal-catalysed dehydrocoupling and hydride abstraction.

    Wagner, Arne; Litters, Sebastian; Elias, Jana; Kaifer, Elisabeth; Himmel, Hans-Jörg


    Herein, we analyse the catalytic boron-boron dehydrocoupling reaction that leads from the base-stabilised diborane(6) [H2 B(hpp)]2 (hpp=1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate) to the base-stabilised diborane(4) [H2 B(hpp)]2 . A number of potential transition-metal precatalysts was studied, including transition-metal complexes of the product diborane(4). The synthesis and structural characterisation of two further examples of such complexes is presented. The best results for the dehydrocoupling reactions were obtained with precatalysts of Group 9 metals in the oxidation state of +I. The active catalyst is formed in situ through a multistep process that involves reduction of the precatalyst by the substrate [H2 B(hpp)]2 , and mechanistic investigations indicate that both heterogeneous and (slower) homogeneous reaction pathways play a role in the dehydrocoupling reaction. In addition, hydride abstraction from [H2 B(hpp)]2 and related diboranes is analysed and the possibility for subsequent deprotonation is discussed by probing the protic character of the cationic boron-hydrogen compounds with NMR spectroscopic analysis.

  10. pH dependence of the urea and guanidine hydrochloride denaturation of ribonuclease A and ribonuclease T1.

    Pace, C N; Laurents, D V; Thomson, J A


    To investigate the pH dependence of the conformational stability of ribonucleases A and T1, urea and guanidine hydrochloride denaturation curves have been determined over the pH range 2-10. The maximum conformational stability of both proteins is about 9 kcal/mol and occurs near pH 4.5 for ribonuclease T1 and between pH 7 and 9 for ribonuclease A. The pH dependence suggests that electrostatic interactions among the charged groups make a relatively small contribution to the conformational stability of these proteins. The dependence of delta G on urea concentration increases from about 1200 cal mol-1 M-1 at high pH to about 2400 cal mol-1 M-1 at low pH for ribonuclease A. This suggests that the unfolded conformations of RNase A become more accessible to urea as the net charge on the molecule increases. For RNase T1, the dependence of delta G on urea concentration is minimal near pH 6 and increases at both higher and lower pH. An analysis of information of this type for several proteins in terms of a model developed by Tanford [Tanford, C. (1964) J. Am. Chem. Soc. 86, 2050-2059] suggests that the unfolded states of proteins in urea and GdnHCl solutions may differ significantly in the extent of their interaction with denaturants. Thus, the conformations assumed by unfolded proteins may depend to at least some extent on the amino acid sequence of the protein.

  11. Protein denaturation with guanidine hydrochloride or urea provides a different estimate of stability depending on the contributions of electrostatic interactions.

    Monera, O. D.; Kay, C. M.; Hodges, R. S.


    The objective of this study was to address the question of whether or not urea and guanidine hydrochloride (GdnHCl) give the same estimates of the stability of a particular protein. We previously suspected that the estimates of protein stability from GdnHCl and urea denaturation data might differ depending on the electrostatic interactions stabilizing the proteins. Therefore, 4 coiled-coil analogs were designed, where the number of intrachain and interchain electrostatic attractions (A) were systematically changed to repulsions (R): 20A, 15A5R, 10A10R, and 20R. The GdnHCl denaturation data showed that the 4 coiled-coil analogs, which had electrostatic interactions ranging from 20 attractions to 20 repulsions, had very similar [GdnHCl]1/2 values (average of congruent to 3.5 M) and, as well, their delta delta Gu values were very close to 0 (0.2 kcal/mol). In contrast, urea denaturation showed that the [urea]1/2 values proportionately decreased with the stepwise change from 20 electrostatic attractions to 20 repulsions (20A, 7.4 M; 15A5R, 5.4 M; 10A10R, 3.2 M; and 20R, 1.4 M), and the delta delta Gu values correspondingly increased with the increasing differences in electrostatic interactions (20A-15A5R, 1.5 kcal/mol; 20A-10A10R, 3.7 kcal/mol; and 20A-20R, 5.8 kcal/mol). These results indicate that the ionic nature of GdnHCl masks electrostatic interactions in these model proteins, a phenomenon that was absent when the unchanged urea was used. Thus, GdnHCl and urea denaturations may give vastly different estimates of protein stability, depending on how important electrostatic interactions are to the protein. PMID:7703845

  12. Preparation and the Standard Enthalpy of Formation on 2-Amino-4, 6-dimethyl-pyrimidine and the Related Complexes of Zinc%2-氨基-4,6-二甲基嘧啶与锌盐配合物的制备及生成焓测定

    陈三平; 魏青; 焦宝娟; 高胜利


    The complexes of zinc chloride and zinc nitrate with 2-amino-4, 6-dimethyl-pyrimidine (ADMP) were preparedthrough reflux in alcohol. The compositions of the complexes Zn(ADMP)2Cl2 (b) and Zn(ADMP)2(NO3)2 @ 4H2O(c) were determined by chemical and elemental analyses. The complexes were characterized by IR, XPS, 1H NMRand TG-DTG techniques. The constant-volume combustion energies of ADMP and the complexes, △cE, weredetermined by a precise rotating bomb calorimeter at 298. 15K. They were ( -3664. 53 + 1.18) kJ @ mol-1,( - 7130. 94 + 3.69) kJ @ mol-1, and ( - 7637. 87 + 5.71 ) kJ @ mol-1. Their standard enthalpies of combustion,△chΘm, and standard enthalpies of formation, △fHΘm, were calculated. They were ( -3666.39 + 1. 18)kJ @ mol-1,(-7129.70+3.69)kJ@ mol-1, (-7632.91 ±5.71)kJ@mol-1and (19.09±1.43)kJ@mol-1, (-411.96±4.03)kJ@mol-1, (-1153.28±6.02)kJ@mol-1.

  13. Growth mechanisms of zinc oxide and zinc sulfide films by mist chemical vapor deposition

    Uno, Kazuyuki; Yamasaki, Yuichiro; Tanaka, Ichiro


    The growth mechanisms of zinc oxide and zinc sulfide films by mist chemical vapor deposition (mist-CVD) were experimentally investigated from the viewpoint of mist behaviors and chemical reactions. The proper growth model, either vaporization or the Leidenfrost model, was studied by supplying two kinds of mists with different kinds of sources, such as H2 16O and H2 18O for ZnO growth and ZnCl2 and thiourea for ZnS growth. Moreover, the origin of the oxygen atoms of ZnO was investigated using a quantitative analysis. The role of chloro complex of zinc in the growth of ZnS from aqueous solutions was also examined by systematic studies.

  14. Porous hydrogel of wool keratin prepared by a novel method: An extraction with guanidine/2-mercaptoethanol solution followed by a dialysis

    Ozaki, Yuki; Takagi, Yusuke; Mori, Hideki; Hara, Masayuki, E-mail:


    In this study, we show a novel simple method to prepare a sponge-like porous keratin hydrogel through the extraction of wool keratin in a solution containing guanidine hydrochloride and 2-mercaptoethanol followed by dialysis for both aggregation of keratin and recrosslink. The gel had a highly porous structure and a fast-swelling property in rehydration after freeze-drying. It had also high mechanical strength both in the tensile test and the measurement of dynamic viscoelasticity. Three types of animal cells, PC12 cells, HOS cells and murine embryonic fibroblasts, well attached and grew on the surface of the porous hydrogel. - Graphical abstract: We show a novel simple method to prepare a sponge-like porous keratin hydrogel (A, B) through the extraction of wool keratin in a solution containing guanidine hydrochloride and 2-mercaptoethanol followed by dialysis for both aggregation of keratin and recrosslink. The gel had a highly porous structure (B) and a fast-swelling property in rehydration after freeze-drying. It had also high mechanical strength both in the tensile test (C) and the measurement of dynamic viscoelasticity (D). Three types of animal cells, PC12 cells (E), HOS cells (F) and murine embryonic fibroblasts (MEFs) (G), well attached and grew on the surface of the porous hydrogel. - Highlights: • We prepared a sponge-like porous keratin hydrogel by a novel method. • We used guanidine with 2-mercaptoethanol to extract keratin from wool fiber. • Extracted keratin was recrosslinked to form a porous keratin hydrogel in dialysis. • The keratin hydrogel had a high mechanical strength. • Three types of cells attached on the keratin hydrogel proliferated well.

  15. Zinc fate in animal husbandry systems.

    Romeo, A; Vacchina, V; Legros, S; Doelsch, E


    Zinc (Zn) is considered in animal production systems as both an essential nutrient and a possible pollutant. While it is generally supplemented at low levels in animal diets, with less than 200 mg kg(-1) in complete feeds, it is under scrutiny due to potential accumulation in the environment. This explains why international regulations limit maximum supplementation levels in animal feeds in a stricter way. This article gives an overview of the current knowledge on the fate of zinc in animal production systems, from animal diets to animal wastes. Some analytical methods can be used for the quantification and qualification of Zn chemical forms: X-ray crystallography, electrospray tandem mass spectrometry, separation techniques, hyphenated techniques… Analysis of chelated forms issued from complex matrices, like hydrolysed proteins, remains difficult, and the speciation of Zn in diluted carriers (premix and feed) is a challenge. Our understanding of Zn absorption has made progress with recent research on ZnT/Zip families and metallothioneins. However, fine-tuned approaches towards the nutritional and metabolic interactions for Zn supplementation in farm conditions still require further studies. The speciation of zinc in pig manure and poultry litter has been a priority as monogastric animals are usually raised under intensive conditions and fed with high quantities of trace minerals, leading to high animal density and elevated quantities of zinc from animal wastes.

  16. Porous hydrogel of wool keratin prepared by a novel method: an extraction with guanidine/2-mercaptoethanol solution followed by a dialysis.

    Ozaki, Yuki; Takagi, Yusuke; Mori, Hideki; Hara, Masayuki


    In this study, we show a novel simple method to prepare a sponge-like porous keratin hydrogel through the extraction of wool keratin in a solution containing guanidine hydrochloride and 2-mercaptoethanol followed by dialysis for both aggregation of keratin and recrosslink. The gel had a highly porous structure and a fast-swelling property in rehydration after freeze-drying. It had also high mechanical strength both in the tensile test and the measurement of dynamic viscoelasticity. Three types of animal cells, PC12 cells, HOS cells and murine embryonic fibroblasts, well attached and grew on the surface of the porous hydrogel.

  17. Doped zinc oxide microspheres

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.


    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  18. Zinc in multiple sclerosis

    Bredholt, Mikkel; Fredriksen, Jette Lautrup


    In the last 35 years, zinc (Zn) has been examined for its potential role in the disease multiple sclerosis (MS). This review gives an overview of the possible role of Zn in the pathogenesis of MS as well as a meta-analysis of studies having measured Zn in serum or plasma in patients with MS...

  19. Creep Resistant Zinc Alloy

    Frank E. Goodwin


    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  20. Creep Resistant Zinc Alloy

    Frank E. Goodwin


    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  1. Zinc in Multiple Sclerosis

    Bredholt, Mikkel; Frederiksen, Jette Lautrup


    In the last 35 years, zinc (Zn) has been examined for its potential role in the disease multiple sclerosis (MS). This review gives an overview of the possible role of Zn in the pathogenesis of MS as well as a meta-analysis of studies having measured Zn in serum or plasma in patients with MS...

  2. Studies on nanocrystalline zinc coating

    H B Muralidhara; Y Arthoba Naik


    Nano zinc coatings were deposited on mild steel by electrodeposition. The effect of additive on the morphology of crystal size on zinc deposit surface and corrosion properties were investigated. Corrosion tests were performed for dull zinc deposits and bright zinc deposits in aqueous NaCl solution (3.5 wt.%) using electrochemical measurements. The results showed that addition of additive in the deposition process of zinc significantly increased the corrosion resistance. The surface morphology of the zinc deposits was studied by scanning electron microscopy (SEM). The preferred orientation and average size of the zinc electrodeposited particles were obtained by X-ray diffraction analysis. The particles size was also characterized by TEM analysis.

  3. Influence of Guanidine Hydrochloride on Dry Heat Shrinkage Behaviors of Collagen Fibers%盐酸胍对皮胶原纤维干热收缩行为的影响及其可逆性

    王芳; 汤克勇; 潘洪波


    Collagen fibers were processed in guanidine hydrochloride solutions of different concentrations, and the dry heat shrinkage behaviors of the collagen fibers were studied by thermal platform microscope. It was indicated that the dry heat shrinkage temperature of the samples was obviously decreased by the guanidine hydrochloride process. It decreased with increasing the guanidine hydrochloride concentrations to reach equilibrium, around 120cC. With increasing the guanidine hydrochloride concentration , the dry heat shrinkage ratio of collagen fibers was increased firstly, followed by a decreasing. There is no chemical reaction between collagen fibers and guanidine hydrochloride. Only a physical action exists between collagen fibers and guanidine hydrochloride. It is reversible. Guanidine hydrochloride process may destroy the original hydrogen bonds in collagen fibers and change their aggregation structure. After guanidine hydrochloride process, the collagen structure is unstable, which may help the penetration and combination of leather chemicals with the collagen fibers in leather making.%以盐酸胍为改性剂,将皮胶原纤维在不同浓度盐酸胍溶液处理不同的时间后,研究了盐酸胍处理前后皮胶原纤维的干热收缩行为及其变化规律.研究发现:盐酸胍处理后皮胶原纤维的干热收缩温度明显降低,且随所用盐酸胍浓度的增大干热收缩温度逐渐减小,直至平衡,平衡时试样的收缩温度在120℃左右;其干热收缩率则随盐酸胍浓度的增大而先增大后减小.经过盐酸胍处理后,皮胶原纤维的结构变得不稳定,可以为以后其它材料渗透到皮胶原纤维内与皮胶原纤维间发生相互作用,创造必要的条件.

  4. Synthesis and crystal structure of zinc(Ⅱ) complexe with N-[(1-methylimidazole-2-yl)methyl]-β-alanine%N-[(1-甲基-2-咪唑基)-1-亚甲基]-β-丙氨酸锌配合物的合成及晶体结构

    杨仕平; 刘文明; 张凡; 陈红梅; 余锡宾


    The dinuclear complexes [ Zn (MIMHA) ] 2 ( MIMHAH = N- [ (1-methylimidazole-2-yl) methyl ] -β-alanine ) was prepared and characterized by single-crystal X-ray analysis. Crystal data: monlclineic, space group P21/c, a =8.792(2), b = 9.267(2), c = 16.942(2)A°, β= 99.5(2), V = 1351.6(2)A°3, and Z = 2. The zinc( Ⅱ ) atom was co-ordinated in a tetrahedral geometry(N2Cl2),which positions were occupied by one nitrogen atom and one oxygen atom from the ligand and two chlorine atoms.

  5. Interaction Between Yeasts and Zinc

    Nicola, Raffaele De; Walker, Graeme

    Zinc is an essential trace element in biological systems. For example, it acts as a cellular membrane stabiliser, plays a critical role in gene expression and genome modification and activates nearly 300 enzymes, including alcohol dehydrogenase. The present chapter will be focused on the influence of zinc on cell physiology of industrial yeast strains of Saccharomyces cerevisiae, with special regard to the uptake and subsequent utilisation of this metal. Zinc uptake by yeast is metabolism-dependent, with most of the available zinc translocated very quickly into the vacuole. At cell division, zinc is distributed from mother to daughter cells and this effectively lowers the individual cellular zinc concentration, which may become zinc depleted at the onset of the fermentation. Zinc influences yeast fermentative performance and examples will be provided relating to brewing and wine fermentations. Industrial yeasts are subjected to several stresses that may impair fermentation performance. Such stresses may also impact on yeast cell zinc homeostasis. This chapter will discuss the practical implications for the correct management of zinc bioavailability for yeast-based biotechnologies aimed at improving yeast growth, viability, fermentation performance and resistance to environmental stresses

  6. Curcumin-loaded guanidine functionalized PEGylated I3ad mesoporous silica nanoparticles KIT-6: practical strategy for the breast cancer therapy.

    Ma'mani, Leila; Nikzad, Safoora; Kheiri-Manjili, Hamidreza; Al-Musawi, Sharafaldin; Saeedi, Mina; Askarlou, Sonia; Foroumadi, Alireza; Shafiee, Abbas


    In this research, we have synthesized guanidine functionalized PEGylated mesoporous silica nanoparticles as a novel and efficient drug delivery system (DDS). For this purpose, guanidine functionalized PEGylated I3ad mesoporous silica nanoparticle KIT-6 [Gu@PEGylated KIT-6] was utilized as a promising system for the effective delivery of curcumin into the breast cancer cells. The modified mesoporous silica nanoparticles (MSNs) was fully characterized by different techniques such as transmission and scanning electron microscopy (TEM & SEM), N2 adsorption-desorption measurement, thermal gravimetric analysis (TGA), X-ray powder diffraction (XRD), and dynamic light scattering (DLS). The average particle size of [Gu@PEGylated KIT-6] and curcumin loaded [Gu@PEGylated KIT-6] nanoparticles were about 60 and 70 nm, respectively. This new system exhibited high drug loading capacity, sustained drug release profile, and high and long term anticancer efficacy in human cancer cell lines. It showed pH-responsive controlled characteristics and highly programmed release of curcumin leading to the satisfactory results in in vitro breast cancer therapy. Our results depicted that the pure nanoparticles have no cytotoxicity against human breast adenocarcinoma cells (MCF-7), mouse breast cancer cells (4T1), and human mammary epithelial cells (MCF10A).

  7. Helix stability in succinylated and acetylated ovalbumins: effect of high pH, urea and guanidine hydrochloride.

    Batra, P P; Uetrecht, D


    Previous studies (Batra, P.P., Roebuck, M.A. and Uetrecht, D. (1990) J. Protein Chem. 9, 37-44) showed that succinylation or acetylation of 75% of the lysine residues has little effect on the secondary structure of ovalbumin. The acylation of the remaining 25% lysine residues, which apparently are partially buried, results in a substantial loss of the helical structure. These conformational changes may be due not only to electrostatic repulsions introduced by succinylation or acetylation of the positively charged epsilon-amino groups but also to steric hindrance, since an increase in the ionic strength failed to reverse the loss of the helical structure. An increase in pH to 12.2 results in a complete helix-to-coil transition in the maximally succinylated ovalbumin (but not in the partially succinylated or in any of the acetylated ovalbumins including the maximally acetylated derivative), perhaps because it is most expanded and its molecular interior most accessible to solvent as succinylation replaces +1 charge of epsilon-amino group with a -1 charge so that a net of -2 charge per succinyl group is placed on the protein molecule. This helix-to-coil transition in the maximally succinylated ovalbumin induced by high pH is fully reversed by increasing the ionic strength, indicating that only electrostatic effects are responsible for this disruption. Studies have also shown that although there is no loss of the helical structure until after the 75% surface lysine residues have been acylated, the helical structure does become progressively destabilized with increasing degree of modification, a conclusion drawn from urea unfolding curves. This destabilization of the helical structure is due primarily to electrostatic effects, as an increase in the ionic strength led to an increase in the urea transition mid-point. Unlike urea, the guanidine hydrochloride unfolding curves indicate that the transition mid-point for the native protein, as well as for the maximally

  8. Zinc homeostasis and neurodegenerative disorders

    Bernadeta eSzewczyk


    Full Text Available Zinc is an essential trace element, whose importance to the function of the central nervous system (CNS is increasingly being appreciated. Alterations in zinc dyshomeostasis has been suggested as a key factor in the development of several neuropsychiatric disorders. In the CNS, zinc occurs in two forms: the first being tightly bound to proteins and, secondly, the free, cytoplasmic or extracellular form found in presynaptic vesicles. Under normal conditions, zinc released from the synaptic vesicles modulates both ionotropic and metabotropic post-synaptic receptors. While under clinical conditions such as traumatic brain injury, stroke or epilepsy, the excess influx of zinc into neurons has been found to result in neurotoxicity and damage to postsynaptic neurons. On the other hand, a growing body of evidence suggests that a deficiency, rather than an excess, of zinc leads to an increased risk for the development of neurological disorders. Indeed, zinc deficiency has been shown to affect neurogenesis and increase neuronal apoptosis, which can lead to learning and memory deficits. Altered zinc homeostasis is also suggested as a risk factor for depression, Alzheimer’s disease, aging and other neurodegenerative disorders. Under normal CNS physiology, homeostatic controls are put in place to avoid the accumulation of excess zinc or its deficiency. This cellular zinc homeostasis results from the actions of a coordinated regulation effected by different proteins involved in the uptake, excretion and intracellular storage/trafficking of zinc. These proteins include membranous transporters (ZnT and Zip and metallothioneins (MT which control intracellular zinc levels. Interestingly, alterations in ZnT and MT have been recently reported in both aging and Alzheimer’s disease. This paper provides an overview of both clinical and experimental evidence that implicates a dysfunction in zinc homeostasis in the pathophysiology of depression, Alzheimer

  9. Dietary catechins and procyanidins modulate zinc homeostasis in human HepG2 cells.

    Quesada, Isabel M; Bustos, Mario; Blay, Mayte; Pujadas, Gerard; Ardèvol, Anna; Salvadó, M Josepa; Bladé, Cinta; Arola, Lluís; Fernández-Larrea, Juan


    Catechins and their polymers procyanidins are health-promoting flavonoids found in edible vegetables and fruits. They act as antioxidants by scavenging reactive oxygen species and by chelating the redox-active metals iron and copper. They also behave as signaling molecules, modulating multiple cell signalling pathways and gene expression, including that of antioxidant enzymes. This study aimed at determining whether catechins and procyanidins interact with the redox-inactive metal zinc and at assessing their effect on cellular zinc homeostasis. We found that a grape-seed procyanidin extract (GSPE) and the green tea flavonoid (-)-epigallocatechin-3-gallate (EGCG) bind zinc cations in solution with higher affinity than the zinc-specific chelator Zinquin, and dose-dependently prevent zinc-induced toxicity in the human hepatocarcinoma cell line HepG2, evaluated by the lactate dehydrogenase test. GSPE and EGCG hinder intracellular accumulation of total zinc, measured by atomic flame absorption spectrometry, concomitantly increasing the level of cytoplasmic labile zinc detectable by Zinquin fluorescence. Concurrently, GSPE and EGCG inhibit the expression, evaluated at the mRNA level by quantitative reverse transcriptase-polymerase chain reaction, of zinc-binding metallothioneins and of plasma membrane zinc exporter ZnT1 (SLC30A1), while enhancing the expression of cellular zinc importers ZIP1 (SLC39A1) and ZIP4 (SLC39A4). GSPE and EGCG also produce all these effects when HepG2 cells are stimulated to import zinc by treatment with supplemental zinc or the proinflammatory cytokine interleukin-6. We suggest that extracellular complexation of zinc cations and the elevation of cytoplasmic labile zinc may be relevant mechanisms underlying the modulation of diverse cell signaling and metabolic pathways by catechins and procyanidins.

  10. Pinacol Coupling Reactions Catalyzed by Active Zinc

    Hui ZHAO; Wei DENG; Qing Xiang GUO


    Pinacol coupling reactions catalyzed by active zinc revealed high activity and extensive suitability. The efficiency of the reaction was improved apparently owing to decreasing reductive potential of zinc. In addition, the results indicated that the zinc activity has a direct relation to the coupling reactivity compared to untreated zinc or other general active zinc.

  11. Zinc-Laccase Biofuel Cell

    Abdul Aziz Ahmad


    Full Text Available A zinc-laccase biofuel cell adapting the zinc-air cell design features is investigated. A simple cell design configuration is employed: a membraneless single chamber and a freely suspended laccase in a quasi-neutral buffer electrolyte. The cell is characterised according to its open-circuit voltage, polarization profile, power density plot and discharge capacity at constant current. The biocatalytic role of laccase is evident from the polarization profile and power output plot. Performance comparison between a single chamber and dual chamber cell design is also presented. The biofuel cell possessed an open-circuit voltage of 1.2 V and delivered a maximum power density of 0.9 mW/cm2 at current density of 2.5 mA/cm2. These characteristics are comparable to biofuel cell utilising a much more complex system design.KEY WORDS (keyword:  Biofuel cell, Bioelectrochemical cell, Zinc anode, Laccase and Oxidoreductase.ABSTRAK: Sel bio-bahan api zink-laccase dengan adaptasi daripada ciri-ciri rekabentuk sel zink-udara telah dikaji. Sel dengan konfigurasi rekabentuk yang mudah digunapakai: ruangan tunggal tanpa membran dan laccase diampaikan secara bebas di dalam elektrolit pemampan quasi-neutral. Sel dicirikan berdasarkan voltan litar terbuka, profil polarisasi, plot ketumpatan kuasa dan kapasiti discas pada arus malar. Peranan laccase sebagai bio-pemangkin adalah amat ketara daripada profil polarisasi dan plot ketumpatan kuasa. Perbandingan prestasi di antara sel dengan rekabentuk ruangan tunggal and dwi-ruangan turut diketengahkan. Seperti dijangkakan, sel dengan rekabentuk ruangan tunggal menunjukkan kuasa keluaran yang lebih rendah jika dibandingkan dengan rekabentuk dwi-ruangan kemungkinan disebabkan fenomena cas bocor. Sel bio-bahan api ini mempunyai voltan litar terbuka 1.2 V dan memberikan ketumpatan kuasa maksima 0.9 mW/cm2 pada ketumpatan arus 2.5 mA/cm2. Ciri-ciri ini adalah sebanding dengan sel bio-bahan api yang menggunapakai rekabentuk sel

  12. Gas-phase thermolysis of a guanidinate precursor of copper studied by matrix isolation, time-of-flight mass spectrometry, and computational chemistry.

    Coyle, Jason P; Johnson, Paul A; DiLabio, Gino A; Barry, Seán T; Müller, Jens


    The fragmentation of the copper(I) guanidinate [Me(2)NC(NiPr)(2)Cu](2) (1) has been investigated with time-of-flight mass spectrometry (TOF MS), matrix-isolation FTIR spectroscopy (MI FTIR spectroscopy), and density functional theory (DFT) calculations. Gas-phase thermolyses of 1 were preformed in the temperature range of 100-800 degrees C. TOF MS and MI FTIR gave consistent results, showing that precursor 1 starts to fragment at oven temperatures above 150 degrees C, with a close to complete fragmentation at 260 degrees C. Precursor 1 thermally fragments to Cu((s)), H(2)(g), and the oxidized guanidine Me(2)NC(=NiPr)(N=CMe(2)) (3). In TOF MS experiment, 3 was clearly indentified by its molecular ion at 169.2 u. Whereas H(2)(+) was detected, atomic Cu was not found in gas-phase thermolysis. In addition, the guanidine Me(2)NC(NiPr)(NHiPr) (2) was detected as a minor component among the thermolysis products. MI thermolysis experiments with precursor 1 were performed, and species evolving from the thermolysis oven were trapped in solid argon at 20 K. These species were characterized by FTIR spectroscopy. The most indicative feature of the resulting spectra from thermolysis above 150 degrees C was a set of intense and structured peaks between 1600 and 1700 cm(-1), an area where precursor 1 does not have any absorbances. The guanidine 2 was matrix-isolated, and a comparison of its FTIR spectrum with the spectra of the thermolysis of 1 indicated that species 2 was among the thermolysis products. However, the main IR bands in the range of 1600 and 1700 cm(-1) appeared at 1687.9, 1668.9, 1635.1, and 1626.6 cm(-1) and were not caused by species 2. The oxidized guanidine 3 was synthesized for the first time and characterized by (1)H NMR and FTIR spectroscopy. A comparison of an FTIR spectrum of matrix isolated 3 with spectra of the thermolysis of 1 revealed that the main IR bands in the range of 1600 and 1700 cm(-1) are due to the presence of 3. The isomers exhibit the NMe(2

  13. DMPD: Zinc in human health: effect of zinc on immune cells. [Dynamic Macrophage Pathway CSML Database

    Full Text Available 18385818 Zinc in human health: effect of zinc on immune cells. Prasad AS. Mol Med. ...2008 May-Jun;14(5-6):353-7. (.png) (.svg) (.html) (.csml) Show Zinc in human health: effect of zinc on immun...e cells. PubmedID 18385818 Title Zinc in human health: effect of zinc on immune cells. Authors Prasad AS. Pu

  14. Comparison of Hydrogen Elimination from Molecular Zinc and Magnesium Hydride Clusters

    Intemann, J.; Sirsch, Peter; Harder, Sjoerd


    In analogy to the previously reported tetranuclear magnesium hydride cluster with a bridged dianionic bis-beta-diketiminate ligand, a related zinc hydride cluster has been prepared. The crystal structures of these magnesium and zinc hydride complexes are similar: the metal atoms are situated at the

  15. The assembly of supramolecular boxes and coordination polymers based on bis-zinc-salphen building blocks

    Kuil, M.; Puijk, I.M.; Kleij, A.W.; Tooke, D.M.; Spek, A.L.; Reek, J.N.H.


    We report the assembly of supramolecular boxes and coordination polymers based on a rigid bis-zinc(II)-salphen complex and various ditopic nitrogen ligands. The use of the bis-zinc(II)-salphen building block in combination with small ditopic nitrogen ligands gave organic coordination polymers both

  16. Comparison of Hydrogen Elimination from Molecular Zinc and Magnesium Hydride Clusters

    Intemann, J.; Sirsch, Peter; Harder, Sjoerd


    In analogy to the previously reported tetranuclear magnesium hydride cluster with a bridged dianionic bis-beta-diketiminate ligand, a related zinc hydride cluster has been prepared. The crystal structures of these magnesium and zinc hydride complexes are similar: the metal atoms are situated at the

  17. Synthesis and characterization of iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of salicylidene-N-anilinoacetohydrazone (H2L1) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H2L2).

    AbouEl-Enein, S A; El-Saied, F A; Kasher, T I; El-Wardany, A H


    Salicylidene-N-anilinoacetohydrazone (H(2)L(1)) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H(2)L(2)) and their iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes have been synthesized and characterized by IR, electronic spectra, molar conductivities, magnetic susceptibilities and ESR. Mononuclear complexes are formed with molar ratios of 1:1, 1:2 and 1:3 (M:L). The IR studies reveal various modes of chelation. The electronic absorption spectra and magnetic susceptibility measurements show that the iron(III), nickel(II) and cobalt(II) complexes of H(2)L(1) have octahedral geometry. While the cobalt(II) complexes of H(2)L(2) were separated as tetrahedral structure. The copper(II) complexes have square planar stereochemistry. The ESR parameters of the copper(II) complexes at room temperature were calculated. The g values for copper(II) complexes proved that the Cu-O and Cu-N bonds are of high covalency.

  18. Alkaline battery with low mercury content in zinc anode. Alkalisk batteri

    Kuemmel, K.


    An alkaline battery comprises a manganese dioxide mercury cathode, a zinc anode and an alkaline electrolyte. The battery has a low mercury content in the zinc anode which contains an inhibitor complex containing: (a) inhibitor tensides having a hydrophilic lepophilic balance number higher than 10 and less than 20; and (b) inhibitors of the naphthylamine-sulphonic acid type and radicals. The inhibitors are added to the anode gel and used in amount 25 to 100 ppm. The anode current collector is coated with a layer of pore-less zinc of same composition as the zinc anode. (au)

  19. Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles

    Vollenweider, Pierre, E-mail: pierre.vollenweider@wsl.c [Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, 8903 Birmensdorf (Switzerland); Bernasconi, Petra [Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, 8903 Birmensdorf (Switzerland); Environmental Protection Office (AfU), Aabachstrasse 5, 6300 Zug (Switzerland); Gautschi, Hans-Peter [Centre for Microscopy and Image Analysis (CMI), University of Zurich, Gloriastrasse 30, 8006 Zuerich (Switzerland); Menard, Terry; Frey, Beat; Guenthardt-Goerg, Madeleine S. [Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, 8903 Birmensdorf (Switzerland)


    The phytoextraction potential of plants for removing heavy metals from polluted soils is determined by their capacity to store contaminants in aboveground organs and complex them safely. In this study, the metal compartmentation, elemental composition of zinc deposits and zinc complexation within leaves from poplars grown on soil with mixed metal contamination was analysed combining several histochemical and microanalytical approaches. Zinc was the only heavy metal detected and was stored in several organelles in the form of globoid deposits showing {beta}-metachromasy. It was associated to oxygen anions and different cations, noteworthy phosphorous. The deposit structure, elemental composition and element ratios indicated that zinc was chelated by phytic acid ligands. Maturation processes in vacuolar vs. cytoplasmic deposits were suggested by differences in size and amounts of complexed zinc. Hence, zinc complexation by phytate contributed to metal detoxification and accumulation in foliage but could not prevent toxicity reactions therein. - Zinc contaminants translocated to symplast of aged leaves were detoxified by phytic acid ligands.

  20. Depleted zinc: Properties, application, production.

    Borisevich, V D; Pavlov, A V; Okhotina, I A


    The addition of ZnO, depleted in the Zn-64 isotope, to the water of boiling water nuclear reactors lessens the accumulation of Co-60 on the reactor interior surfaces, reduces radioactive wastes and increases the reactor service-life because of the inhibitory action of zinc on inter-granular stress corrosion cracking. To the same effect depleted zinc in the form of acetate dihydrate is used in pressurized water reactors. Gas centrifuge isotope separation method is applied for production of depleted zinc on the industrial scale. More than 20 years of depleted zinc application history demonstrates its benefits for reduction of NPP personnel radiation exposure and combating construction materials corrosion.

  1. Chloroquine is a zinc ionophore.

    Jing Xue

    Full Text Available Chloroquine is an established antimalarial agent that has been recently tested in clinical trials for its anticancer activity. The favorable effect of chloroquine appears to be due to its ability to sensitize cancerous cells to chemotherapy, radiation therapy, and induce apoptosis. The present study investigated the interaction of zinc ions with chloroquine in a human ovarian cancer cell line (A2780. Chloroquine enhanced zinc uptake by A2780 cells in a concentration-dependent manner, as assayed using a fluorescent zinc probe. This enhancement was attenuated by TPEN, a high affinity metal-binding compound, indicating the specificity of the zinc uptake. Furthermore, addition of copper or iron ions had no effect on chloroquine-induced zinc uptake. Fluorescent microscopic examination of intracellular zinc distribution demonstrated that free zinc ions are more concentrated in the lysosomes after addition of chloroquine, which is consistent with previous reports showing that chloroquine inhibits lysosome function. The combination of chloroquine with zinc enhanced chloroquine's cytotoxicity and induced apoptosis in A2780 cells. Thus chloroquine is a zinc ionophore, a property that may contribute to chloroquine's anticancer activity.

  2. Zinc In CCl4 Toxicity


    Objective To investigate the protective effect of zinc in CCl4-induced hepatotoxicity. Methods Rats were treated with zinc acetate for four days. The zinc doses were 5 mg Zn/kg and 10 mg Zn/kg body weight respectively. Two groups of the zinc acetate-treated rats were later challenged with a single dose of CCl4 (1.5 mL/kg body weight). Results Compared to control animals, the plasma of rats treated with CCl4 showed hyperbilirubinaemia, hypoglycaemia, hypercreatinaemia and hypoproteinaemia. When the animals were however supplemented with zinc in form of zinc acetate before being dosed with CCl4, the 5 mg Zn/kg body weight of zinc acetate reversed the hypoproteinaemia induced by CCl4, whereas the 10mg Zn/kg body weight of zinc acetate reversed the hypoglycaemia, hyperbilimbinaemia and hypercreatinaemia induced by CCl4. Conclusion The 10mug Zn/kg body weight of zinc acetate is more consistent in protecting against CCl4 hepatotoxicity. The possible mechanisms of protection are highlighted.


    盛晓阳; 沈立松; 徐翀; 吴湘如; 陈宏新; 洪照毅


    Objective Observation of the effects of lower concentrations of zinc (20~400μmol/L), which is nearby the physiological concentration, on etoposide induced HL-60 cells apoptosis. Methods Using the flow cytometry , DNA extraction, electrophoresis , and fiuoresence microscopic observation. Results We demonstrated that the low concentrations of zinc also affect cells apoptosis. If zinc was added at early time, even 200μmol/L could inhibit VP16 induced HL-60 cell apoptosis completely in 4h. But at this concentration, zinc also seems to have cell toxicity, not prolong the time of protection effect. Conclusion Zinc plays multiple roles in cellular functions and in protecting cells from exogenous deleterious factors. Zinc plays a complex, dose- and time-dependent role in apoptosis.

  4. Application of zinc isotope tracer technology in tracing soil heavy metal pollution

    Norbu, Namkha; Wang, Shuguang; Xu, Yan; Yang, Jianqiang; Liu, Qiang


    Recent years the soil heavy metal pollution has become increasingly serious, especially the zinc pollution. Due to the complexity of this problem, in order to prevent and treat the soil pollution, it's crucial to accurately and quickly find out the pollution sources and control them. With the development of stable isotope tracer technology, it's able to determine the composition of zinc isotope. Based on the theory of zinc isotope tracer technique, and by means of doing some latest domestic and overseas literature research about the zinc isotope multi-receiving cups of inductively coupled plasma mass spectrometer (MC-ICP-MS) testing technology, this paper summarized the latest research results about the pollution tracer of zinc isotope, and according to the deficiencies and existing problems of previous research, made outlooks of zinc isotope fractionation mechanism, repository establishment and tracer multiple solutions.

  5. Synthesis and characterization of dinuclear macrocyclic cobalt(II), copper(II) and zinc(II) complexes derived from 2,2,2('),2(')-S,S[bis(bis-N,N-2-thiobenzimidazolyloxalato-1,2-ethane)]: DNA binding and cleavage studies.

    Arjmand, Farukh; Aziz, Mubashira


    New homodinuclear macrocyclic complexes of cobalt(II), copper(II) and zinc(II) were isolated from the newly synthesized ligand 2,2,2',2'-S,S[bis(bis-N,N-2-thiobenzimidazolyloxalato-1,2-ethane)]. The structures of the complexes were elucidated by elemental analysis, molar conductance measurements, IR, 1H NMR, 13C NMR, electronic and ESI-MS spectroscopic techniques. In complex 1, Co(II) ions possess a tetrahedral coordination environment composed of O2S2 donor atoms while its Cu(II) and Zn(II) counterparts 2 and 3, respectively, reveal a six coordinate octahedral structure, defined by the O2S2 donors from the macrocyclic ring and two chloride ions. Molar conductance and spectroscopic data also support the proposed geometry of the complexes. DNA binding properties of complexes 1-3 were investigated using electronic absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and cyclic voltammetry. The absorption spectra of complexes 2 and 3 with calf thymus DNA showed hypochromism, while complex 1 showed hyperchromism attributed to a partial intercalation and electrostatic binding modes, respectively. The intrinsic binding constant K(b) of complexes 1-3 were determined as 16.6 x 10(4) M(-1), 4.25 x 10(4) M(-1) and 3.0 x 10(4) M(-1), respectively. The decrease in the relative specific viscosity of calf thymus DNA with increasing concentration of the complexes authenticates the partial intercalation binding mode. Gel electrophoresis of complex 2 with plasmid DNA demonstrated that complex exhibits excellent "artificial" nuclease activity.

  6. Zinc acetylacetonate hydrate adducted with nitrogen donor ligands: Synthesis, spectroscopic characterization, and thermal analysis

    Brahma, Sanjaya; Shivashankar, S. A.


    We report synthesis, spectroscopic characterization, and thermal analysis of zinc acetylacetonate complex adducted by nitrogen donor ligands, such as pyridine, bipyridine, and phenanthroline. The pyridine adducted complex crystallizes to monoclinic crystal structure, whereas other two adducted complexes have orthorhombic structure. Addition of nitrogen donor ligands enhances the thermal property of these complexes as that with parent metal-organic complex. Zinc acetylacetonate adducted with pyridine shows much higher volatility (106 °C), decomposition temperature (202 °C) as that with zinc acetylacetonate (136 °C, 220 °C), and other adducted complexes. All the adducted complexes are thermally stable, highly volatile and are considered to be suitable precursors for metal organic chemical vapor deposition. The formation of these complexes is confirmed by powder X-ray diffraction, Fourier transform infrared spectroscopy, mass spectroscopy, and elemental analysis. The complexes are widely used as starting precursor materials for the synthesis of ZnO nanostructures by microwave irradiation assisted coating process.

  7. Zinc supplementation for tinnitus.

    Person, Osmar C; Puga, Maria Es; da Silva, Edina Mk; Torloni, Maria R


    Tinnitus is the perception of sound without external acoustic stimuli. Patients with severe tinnitus may have physical and psychological complaints and their tinnitus can cause deterioration in their quality of life. At present no specific therapy for tinnitus has been found to be satisfactory in all patients. In recent decades, a number of reports have suggested that oral zinc supplementation may be effective in the management of tinnitus. Since zinc has a role in cochlear physiology and in the synapses of the auditory system, there is a plausible mechanism of action for this treatment. To evaluate the effectiveness and safety of oral zinc supplementation in the management of patients with tinnitus. The Cochrane ENT Information Specialist searched the ENT Trials Register; Central Register of Controlled Trials (CENTRAL 2016, Issue 6); PubMed; EMBASE; CINAHL; Web of Science;; ICTRP and additional sources for published and unpublished trials. The date of the search was 14 July 2016. Randomised controlled trials comparing zinc supplementation versus placebo in adults (18 years and over) with tinnitus. We used the standard methodological procedures recommended by Cochrane. Our primary outcome measures were improvement in tinnitus severity and disability, measured by a validated tinnitus-specific questionnaire, and adverse effects. Secondary outcomes were quality of life, change in socioeconomic impact associated with work, change in anxiety and depression disorders, change in psychoacoustic parameters, change in tinnitus loudness, change in overall severity of tinnitus and change in thresholds on pure tone audiometry. We used GRADE to assess the quality of the evidence for each outcome; this is indicated in italics. We included three trials involving a total of 209 participants. The studies were at moderate to high risk of bias. All included studies had differences in participant selection criteria, length of follow-up and outcome measurement

  8. Interaction between nanoparticles generated by zinc chloride treatment and oxidative responses in rat liver

    Azzouz I


    Full Text Available Inès Azzouz, Hamdi Trabelsi, Amel Hanini, Soumaya Ferchichi, Olfa Tebourbi, Mohsen Sakly, Hafedh AbdelmelekLaboratory of Integrative Physiology, Faculty of Sciences of Bizerte, Carthage University, TunisiaAbstract: The aim of the present study was to investigate the interaction of zinc chloride (3 mg/kg, intraperitoneally [ip] in rat liver in terms of the biosynthesis of nanoparticles. Zinc treatment increased zinc content in rat liver. Analysis of fluorescence revealed the presence of red fluorescence in the liver following zinc treatment. Interestingly, the co-exposure to zinc (3 mg/kg, ip and selenium (0.20 mg/L, per os [by mouth] led to a higher intensity of red fluorescence compared to zinc-treated rats. In addition, X-ray diffraction measurements carried out on liver fractions of zinc-treated rats point to the biosynthesis of zinc sulfide and/or selenide nanocomplexes at nearly 51.60 nm in size. Moreover, co-exposure led to nanocomplexes of about 72.60 nm in size. The interaction of zinc with other mineral elements (S, Se generates several nanocomplexes, such as ZnS and/or ZnSe. The nanocomplex ZnX could interact directly with enzyme activity or indirectly by the disruption of mineral elements' bioavailability in cells. Subacute zinc or selenium treatment decreased malondialdehyde levels, indicating a drop in lipid peroxidation. In addition, antioxidant enzyme assays showed that treatment with zinc or co-treatment with zinc and selenium increased the activities of glutathione peroxidase, catalase, and superoxide dismutase. Consequently, zinc complexation with sulfur and/or selenium at nanoscale level could enhance antioxidative responses, which is correlated to the ratio of number of ZnX nanoparticles (X=sulfur or X=selenium to malondialdehyde level in rat liver.Keywords: nanocomplexes biosynthesis, antioxidative responses, X-ray diffraction, fluorescence microscopy, liver

  9. Inhibitory zinc-enriched terminals in mouse spinal cord

    Danscher, G; Jo, S M; Varea, E;


    The ultrastructural localization of zinc transporter-3, glutamate decarboxylase and zinc ions in zinc-enriched terminals in the mouse spinal cord was studied by zinc transporter-3 and glutamate decarboxylase immunohistochemistry and zinc selenium autometallography, respectively.The distribution...

  10. Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide.

    Wegmüller, Rita; Tay, Fabian; Zeder, Christophe; Brnic, Marica; Hurrell, Richard F


    The water-soluble zinc salts gluconate, sulfate, and acetate are commonly used as supplements in tablet or syrup form to prevent zinc deficiency and to treat diarrhea in children in combination with oral rehydration. Zinc citrate is an alternative compound with high zinc content, slightly soluble in water, which has better sensory properties in syrups but no absorption data in humans. We used the double-isotope tracer method with (67)Zn and (70)Zn to measure zinc absorption from zinc citrate given as supplements containing 10 mg of zinc to 15 healthy adults without food and compared absorption with that from zinc gluconate and zinc oxide (insoluble in water) using a randomized, double-masked, 3-way crossover design. Median (IQR) fractional absorption of zinc from zinc citrate was 61.3% (56.6-71.0) and was not different from that from zinc gluconate with 60.9% (50.6-71.7). Absorption from zinc oxide at 49.9% (40.9-57.7) was significantly lower than from both other supplements (P zinc oxide. We conclude that zinc citrate, given as a supplement without food, is as well absorbed by healthy adults as zinc gluconate and may thus be a useful alternative for preventing zinc deficiency and treating diarrhea. The more insoluble zinc oxide is less well absorbed when given as a supplement without food and may be minimally absorbed by some individuals. This trial was registered at as NCT01576627.

  11. Testicular apoptosis after dietary zinc deficiency: ultrastructural and TUNEL studies.

    Kumari, Deepa; Nair, Neena; Bedwal, Ranveer Singh


    The present study was conducted in Wistar rats to determine whether prepubertal dietary zinc deficiency causes apoptotic changes in testes. Prepubertal male Wistar rats (40-50 gm) were divided into 3 groups: zinc control (ZC), pairfed (PF), and zinc deficient (ZD). Control and pairfed groups were given a 100 ppm zinc diet while the deficient groups received 1 ppm zinc diet for 2 and 4 weeks (w), respectively. Ultrastructural studies revealed several apoptotic features such as wavy basement membrane, displaced nuclei, chromatin condensation, plasma membrane blebbing, nuclear membrane dissolution, loss of inter-Sertoli cell junctional complexes, and intercellular bridges and deformed mitochondria. A variable spectrum of sperm defects had also been visualized e.g., acrosomal deformities such as decapitation and a ring of condensed chromatin around the nuclear periphery, deformed sperm heads with a condensed nucleus, tail-elements with superfluous cytoplasm, and damage to the mitochondrial sheath and aggregation of spermatozoa within the membrane. This was further supported by TUNEL studies. Apoptotic index, epididymal sperm concentration, motility, and fertility index also revealed a significant (P zinc deficient groups (2 and 4 w) when compared with their respective control and pairfed groups. All the above findings are indicative that changes observed in the testes after dietary zinc deficiency are due to the onset of apoptosis. Increased apoptotic degeneration in testes may cause irreversible changes in the germ cells associated with decreased epididymal sperm concentration, motility, and fertility index which contributes to the low efficiency of spermatogenesis thereby indicating a possible role of zinc in fertility.

  12. α-硫辛酸合锌对痴呆模型小鼠学习记忆能力的影响%Effects of Zinc α-lipoate Complex on the Learning and Memory Abilities of Scopolamine-induced Amnesia Mice

    张迪; 李燕; 罗瑛; 田卫群; 周青山


    Objective To investigate effects of zincα-lipoate complex on the learning and memory abilities as well as the oxidative stress in scopolamine-induced amnesia mice. Methods A total of 32 mice were randomly divided into the model control group, the group with α-lipoic acid, the group with zinc sulfate, the group with zincα-lipoate complex. rats in each group were administered corresponding drugs and trained with Y-maze five hours later. After 8 days,Rats in each group received the celiac injection of the scopolamine at a dose of 5mg/kg. After half an hour, the memory ability was tested, and then the mice were decapitated. The content of GSH and protein, the activity of SOD in the cerebral tissue were determined. Results Compared with the model control group and other groups, the zincα-li-poate complex can decrease the false times and the activity of SOD (P < 0. 01) in the cerebral tissue, while increase the content of GSH (P < 0. 01) and protein (P < 0. 05). Conclusion The zinc α-lipoate complex can improve the learning and memory abilities and de-crease the level of oxidative stress in the cerebral tissue of amnesia mice.%目的 观察α-硫辛酸合锌对东莨菪碱致痴呆模型小鼠学习记忆能力及氧化应激的影响. 方法 将32只昆明小鼠随机均分成模型对照组、硫辛酸组、硫酸锌组、α-硫辛酸合锌组. 每组每天分别给予生理盐水、硫辛酸、硫酸锌和α-硫辛酸合锌,每次给药5h后进行Y迷宫训练,连续8天后各组均给予5mg/kg东莨菪碱,半小时后进行记忆能力测试. 测定小鼠匀浆后脑组织内还原型谷胱甘肽和蛋白含量及超氧化物歧化酶的活力. 结果 与模型对照组及其他各组相比,α-硫辛酸合锌组小鼠错误次数明显减少,脑组织内还原型谷胱甘肽和蛋白质含量明显升高(P<0. 05),超氧化物歧化酶活力明显降低(P<0. 01). 结论α-硫辛酸合锌可以显著提高痴呆小鼠的学习记忆能力,降低脑组织内氧化应激水平.

  13. El zinc: oligoelemento esencial

    C. Rubio

    Full Text Available En este artículo se hace una revisión exhaustiva del zinc, elemento metálico esencial para el funcionamiento del organismo. Repasamos y reflejamos aspectos relacionados con la farmacocinética, con las fuentes dietéticas más importantes, así como las IDR (Ingestas Dietéticas Recomendadas del mismo. También se hace mención a los signos y síntomas relacionados tanto con una ingesta deficiente, como con posibles efectos tóxicos, derivados de ingestas excesivas.

  14. Zinc Base Die Castings


    183 B86- 33T SAE N.J .zn Co. B86-33T 1934 SAE N.J.Zn Cc,. Zamak 3N AllO;E Cl C2 Allo~ XXI 221 Zarnak 2 .A.llo;z XXIII .Allol XXIII 202 Zamak 2 O...2 Pb ,Fe, Cd, C:’. 3 special high gra1e ?:inc. • t • • ; -J TABLE II Chemical Composition for Zinc Alloy Nuuber Zam.ak 2 Zamak 3...was alco given regarding the aging of the alloys. The a1loy3 Aupplied were: Zamak 2, Zamak 3, Zamak 3-S (Stabilized to hasten contraction which

  15. Nanostructures of zinc oxide

    Zhong Lin Wang


    Full Text Available Zinc oxide (ZnO is a unique material that exhibits semiconducting, piezoelectric, and pyroelectric multiple properties. Using a solid-vapor phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobows, nanobelts, nanowires, and nanocages of ZnO have been synthesized under specific growth conditions. These unique nanostructures unambiguously demonstrate that ZnO is probably the richest family of nanostructures among all materials, both in structures and properties. The nanostructures could have novel applications in optoelectronics, sensors, transducers, and biomedical science because it is bio-safe.

  16. Danxia Zinc Smelter started construction


    <正>Zinc smelting project of Danxia Smelting Plant has a total investment of about RMB 4 billion, which is designed by Changsha Engineering & Research Institute of Nonferrous Metallurgy and planned to be implemented in three stages. The first stage 100,000 tons of electrolytic zinc improvement work is planned to be completed by the end of 2008. The second and third stages

  17. The use of bis (-2-ethylhexyl) phosphoric acid for the extraction of zinc from concentrated ammonium chloride solutions

    Amer, S.; Luis, A.; Cuadra, A. de la; Caravaca, C.


    The extraction of zinc from concentrated ammonium chloride solutions by means of the bis(-2-ethylhexyl) phosphoric acid is studied. Mass balances and chemical equilibria relating the different chemical species in both phases are presented in order to establish a model describing the behaviour of the different species. Good agreement between experimental data and theoretical curves is obtained. A comparison of the zinc extraction from a strong complexing medium as that of concentrated ammonium chloride solutions with an uncomplexing zinc perchlorate solution is made, in order to see the influence of the complexing effect of the aqueous phase on zinc extraction. (Author) 36 p.

  18. Automation of dimethylation after guanidination labeling chemistry and its compatibility with common buffers and surfactants for mass spectrometry-based shotgun quantitative proteome analysis

    Lo, Andy; Tang, Yanan; Chen, Lu; Li, Liang, E-mail:


    Graphical abstract: -- Highlights: •Dimethylation after guanidination (2MEGA) uses inexpensive reagents for isotopic labeling of peptides. •2MEGA can be optimized and automated for labeling peptides with high efficiency. •2MEGA is compatible with several commonly used cell lysis and protein solubilization reagents. •The automated 2MEGA labeling method can be used to handle a variety of protein samples for relative proteome quantification. -- Abstract: Isotope labeling liquid chromatography–mass spectrometry (LC–MS) is a major analytical platform for quantitative proteome analysis. Incorporation of isotopes used to distinguish samples plays a critical role in the success of this strategy. In this work, we optimized and automated a chemical derivatization protocol (dimethylation after guanidination, 2MEGA) to increase the labeling reproducibility and reduce human intervention. We also evaluated the reagent compatibility of this protocol to handle biological samples in different types of buffers and surfactants. A commercially available liquid handler was used for reagent dispensation to minimize analyst intervention and at least twenty protein digest samples could be prepared in a single run. Different front-end sample preparation methods for protein solubilization (SDS, urea, Rapigest™, and ProteaseMAX™) and two commercially available cell lysis buffers were evaluated for compatibility with the automated protocol. It was found that better than 94% desired labeling could be obtained in all conditions studied except urea, where the rate was reduced to about 92% due to carbamylation on the peptide amines. This work illustrates the automated 2MEGA labeling process can be used to handle a wide range of protein samples containing various reagents that are often encountered in protein sample preparation for quantitative proteome analysis.

  19. 锌铋复杂氧化物Bi2Zn5O8的合成及其晶体生长特性%Synthesis and Crystal Growth Characteristic of Zinc Bismuth Complex Oxide Bi2Zn5O8



    The zinc bismuth complex oxides were prepared from zinc sulfate, bismuth nitrate and sodium hydroxide under ultrasonic irradiation.The effects of feed order and feed molar ratio on the final product were studied.The properties of the product were characterized by TG-DTA, SEM and TEM.The chemical composition was defined by means of X-ray fluorescence and continuous titration.The TEM and SEM images showed the dendrite crystal was formed.%利用硫酸锌、硝酸铋、氢氧化钠为原料在超声体系中反应合成锌铋复杂氧化物,考察了反应物料比和加料顺序对产物组成的影响.经X射线荧光及化学滴定确定了产物的分子式为Bi2Zn5O8,并由TEM、SEM和TG-DTA等方法对所得产物进行表征.TEM和SEM结果显示晶体呈枝蔓晶生长.

  20. A simple liposome assay for the screening of zinc ionophore activity of polyphenols.

    Clergeaud, Gael; Dabbagh-Bazarbachi, Husam; Ortiz, Mayreli; Fernández-Larrea, Juan B; O'Sullivan, Ciara K


    An efficient liposomal system for screening the zinc ionophore activity of a selected library consisting of the most relevant dietary polyphenols is presented. The zinc ionophore activity was demonstrated by exploring the use of zinc-specific fluorophore FluoZin-3 loaded liposomes as simple membrane tools that mimic the cell membrane. The zinc ionophore activity was demonstrated as the capacity of polyphenols to transport zinc cations across the liposome membrane and increase the zinc-specific fluorescence of the encapsulated fluorophore FluoZin-3. In addition, the zinc chelation strength of the polyphenols was also tested in a competition assay based on the fluorescence quenching of zinc-dependent fluorescence emitted by zinc-FluoZin-3 complex. Finally, the correlation between the chelation capacity and ionophore activity is demonstrated, thus underlining the sequestering or ionophoric activity that the phenolic compounds can display, thus, providing better knowledge of the importance of the structural conformation versus their biological activity. Furthermore, the assays developed can be used as tools for rapid, high-throughput screening of families of polyphenols towards different biometals.