Flow injection analysis of zinc pyrithione in hair care products on a cobalt phthalocyanine modified screen-printed carbon electrode

Zinc pyrithione (ZPT) is an antibacterial and antifungal reagent that is often utilized for the antidandruff activity in hair-care shampoos with a composition level up to 1% in the formulation. It has some adverse effects to human and animal if consumed orally. A disposable type of cobalt phthalocyanide modified screen-printed carbon electrode (CoPc/SPE) in couple with flow injection analysis (FIA) was developed for easy and selective analysis of ZPT in commercial hair-care products. Under the optimized FIA conditions, the CoPc/SPE yielded a linear calibration plot in the window of 6–576 μM with sensitivity and detection limit of 1.65 nA μM⁻¹ and 0.9 μM (i.e. 1.42 pg in 5 μl sample loop), respectively, in 0.1 M KOH solution at an applied potential of 0.3 V versus Ag/AgCl. Since the approach is simple, easy, selective, and inexpensive, it offers a potential application of daily ZPT analysis in hair-care products.     

The interaction of zinc pyrithione with mitochondria from rat liver and a study of the mechanism of inhibition of ATP synthesis

The interactions of zinc pyrithione (ZnPT) with rat liver mitochondria were investigated. Since most of the organometals, principally the triorganotin compounds, induce the inhibition of ATP synthesis in rat liver mitochondria, the efficiency of the ATP synthesis was measured in the presence of ZnPT. The results indicate that ZnPT inhibits ATP synthesis. In order to individuate the molecular mechanism responsible for a failure in ATP synthesis, all of the steps involved in ATP synthesis or in its inhibition were investigated separately, i.e. the respiratory chain, the uncoupling effect, the ATPase and the opening of a permeability pore. All of the steps are inhibited by ZnPT, but the crucial one, the one responsible for the inhibition of ATP synthesis, seems to be the opening of a small‐size cyclosporine‐sensitive pore. The results are different from those obtained using other organometallic compounds, but are similar to those obtained when using methylmercury and Zn²⁺, both of which also induce the opening of a cyclosporine‐sensitive pore. However, although Hg²⁺ and Zn²⁺ would seem to induce the opening of large‐size pores, in the case of ZnPT the pores involved are of a small size. This action mechanism seems to exclude the possibility that ZnPT is a deliverer of Zn²⁺. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis of perfluoroalkyl-containing multifunctional groups compounds for textile finishing

A new kind of perfluoroalkyl-containing multifunctional groups compound was designed. Treatment of 1H,1H,2H,2H-perfluorooctyltrichlorosilane (4) with allylmagnesium bromide provided key intermediate 1H,1H,2H,2H-perfluorooctyltriallylsilane (2). Hydroboration followed by oxidation, epoxidation and dihydroxylation of 2 gave perfluoroalkyl-containing multifunctional groups compound 1a, 1b and 1c, respectively.     

Synthesis and antimicrobial activity of a perfluoroalkyl-containing quaternary ammonium salt

A novel perfluoroalkyl-containing quaternary ammonium salt 5 was designed and synthesized. Consequently, the antimicrobial activities of compound 5 were measured with Escherichia coli 8099 as a Gram-negative strain and Staphylococcus aureus ATCC 6538 as a Gram-positive strain. Both the minimum inhibitory concentration (MIC, the lowest concentration of compound 5 that inhibits microbial growth) values of quaternary ammonium salt 5 against Escherichia coli 8099 and Staphylococcus aureus ATCC 6538 were 7.8 μg/ml.     

Synthesis of novel perfluoroalkyl-containing polyethers

The synthesis of iodo(perfluoroalkyl)epoxides by radical addition of perfluoroalkyl iodides to allyl glycidyl ether and 1,2-epoxydec-9-ene is described. Dehydroiodination of additional products upon treatment with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) gives unsaturated products. The use of Bu₃SnH/Bz₂O₂ as a reduction reagent of iodo(perfluoroalkyl)allyl glycidyl ethers allows to save oxirane ring. Cationic polymerization of saturated or functional (with iodine or double bond) fluoroalkyl oxiranes under action of catalytic amount of BF₃^.Et₂O proceeds only on epoxide group. In case of poly(9-iod-10-(perfluoroalkyl)-1,2-epoxyalkane) iodine atoms are removed by standard zinc reduction.     

Hydrothermal synthesis and structures of two zero-dimensional zinc phosphate polymorphs

Two polymorphs of zero-dimensional zinc phosphate with the formula, ⁰_∞[Zn(2,2′-bipy)(H₂PO₄)₂], have been synthesized employing hydrothermal technique and their structure determined by single crystal X-ray diffraction. Both the structures consists of ZnO₃N₂ distorted trigonal-bipyramidal and PO₂(OH)₂ tetrahedral units linked through their vertices giving rise to a zero-dimensional molecular zinc phosphate. The structures are stabilized by extensive hydrogen bond interactions between zero-dimensional monomers. The structures display subtle differences in their packing created by hydrogen bond interactions. Crystal data: polymorph I, triclinic, space group (No. 2), , , , α=67.32(3)°, β=81.67(3)°, γ=69.29(3)°, , Z=2; polymorph II, triclinic, space group (No. 2), , , , α=97.37(2)°, β=100.54(2)°, γ=100.98(2)°, , Z=2.     

A mass spectrometry and DFT study of pyrithione complexes with transition metals in the gas phase

2‐Mercaptopyridine N ‐oxide (pyrithione, PTOH) along with several transition metal ions forms coordination compounds displaying notable biological activities. Gas‐phase complexes formed between pyrithione and manganese (II), cobalt (II), nickel (II), copper (II), and zinc (II) were investigated by infusion in the electrospray source of a quadrupole‐time of flight mass spectrometer. Remarkably, positive ion mode spectra displayed the singly charged metal adduct ion [C₁₀H₈MN₂O₂S₂]²⁺ ([M(PTO)₂]^+• or [M(DPTO)]^+•), where DPTO is dipyrithione, 2,2′‐dithiobis(pyridine N ‐oxide), among the most abundant peaks, implying a change in the oxidation state of whether the metal ion or the ligands. In addition, doubly charged ions were recognized as metal adduct ions containing DPTO ligands, [M(DPTO)_n]²⁺. Generation of [M(PTO)₂]^+• / [M(DPTO)]^+• could be traced by CID of [M(DPTO)₂]²⁺, by observation of the sequential losses of a charged (PTO⁺) and a radical (PTO^•) deprotonated pyrithione ligand. The fragmentation pathways of [M(PTO)₂]^+• / [M(DPTO)]^+• were compared among the different metal ions, and some common features were noticed. Density functional theory (DFT) calculations were employed to study the structures of the observed adduct ions, and especially, to decide in the adduct ion [M(PTO)₂]^+• / [M(DPTO)]^+• whether the ligands are 2 deprotonated pyrithiones or a single dipyrithione as well as the oxidation state of the metal ion in the complex. Characterization of gas‐phase pyrithione metal ion complexes becomes important, especially taking into account the presence of a redox‐active ligand in the complexes, because redox state changes that produce new species can have a marked effect on the overall toxicological/biological response elicited by the metal system.     

Hydrothermal synthesis and crystal structure of a new two-dimensional zinc citrate complex

A new two-dimensional compound C₁₂H₁₄O₁₆Zn₃ (1), containing seven-coordinate zinc atoms was prepared by the hydrothermal technique. The compound obtained was characterized by TG-DTA, single crystal X-ray diffraction, elemental analysis and FT-IR analysis. Single-crystal X-ray diffraction analysis shows that compound 1 crystallizes with monoclinic symmetry in the space group P2₁/c, a?=?6.1552(13)?Å, b?=?14.546(3)?Å, c?=?9.581?Å, β?=?102.66(2)°, V?=?836.9(4)?ų, Z?=?2, R1?=?0.0311, wR2?=?0.0830.     

The synthesis and photophysicochemical properties of low-symmetry zinc phthalocyanine analogues

The synthesis of a low-symmetry derivative, zinc mono-carboxy substituted phthalocyanine, ZnPc-COOH (4) has been reported. The photochemical and photophysical properties of ZnPc-COOH (4), ZnTMPyPc (5), ZnttbPc (6) and a previously synthesized low-symmetry derivative, ZnttbIPc (7), in various organic solvents are reported. The red-shifting of the spectra of 4 and 5 (relative to that of unsubstituted zinc phthalocyanine, ZnPc) is a function of the electron-donating sulfur-containing substituents attached to the periphery of the molecule. High triplet quantum yields (Ф_T) generally occur in response to substitution on the zinc phthalocyanine ring periphery. The highest Ф_T values and triplet lifetimes (τ_T) occur in DMSO for all derivatives as a result of the solvent's high viscosity. The strongly electron-withdrawing imido fused ring of ZnttbIPc (7) stabilizes it against photo-oxidative degradation relative to the other derivatives.     

Design of a zinc(II) ion specific fluorescence sensor

We report the synthesis of {[3-(biscarboxymethylamino)-2-methoxy-5-methylphenyl]carboxymethylamino}acetic acid, which functions as a Zn²⁺ selective fluorescence probe (sensor).     

Design and synthesis of novel propellanes by using claisen rearrangement and ring-closing metathesis as the key steps

Novel hexacyclic caged compounds are prepared by a combination of Claisen rearrangement and ring-closing metathesis (RCM). Additionally, a Grignard reaction in conjugation with RCM produced intricate hexacyclic caged molecules.     

The synthesis and characterization of zinc ferrite aerogels prepared by epoxide addition

Over the past decade sol–gel methods have become increasingly popular alternatives to the solid state synthesis of metal oxides. In many cases sol–gel synthesis is preferred due to desirable physical properties such as high surface area, high porosity, and small crystallite size. Monolithic zinc ferrite aerogels were produced by the epoxide addition sol–gel method. It was observed that addition of propylene oxide to 2-propanol solution of either the hydrated metal nitrate salts or the hydrated metal chloride salts resulted in the formation of stable red–brown gels. Aerogels were characterized using powder X-ray diffraction, high resolution scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption/desorption analysis. The metal salt used in the synthesis was found to significantly influence the properties of the aerogel. All aerogels synthesized exhibited low densities and high surface areas (>340 m²/g). Annealing of the aerogel at relatively low temperatures (below 450 °C) yielded a highly crystalline porous material which is composed of nanometer sized particles.     

The synthesis of luminescent lanthanide-based chemosensors for the detection of zinc ions

Herein, we report the synthesis of two lanthanide-based chemosensors, Tb-5 and Eu-6, designed to sense free zinc ions (Zn²⁺) in aqueous solutions. The Tb-5 complex features a bis(2-pyridinylmethyl)amine moiety as a zinc(II)-responsive lanthanide-sensitising ‘antenna’, while Eu-6 incorporates a quinoline-based moiety for this purpose. Luminescence enhancements of 210% and 340% are observed upon addition of Zn²⁺ ions to Tb-5 and Eu-6, respectively. Both sensors are selective for Zn²⁺ ions over several other cations of environmental significance.     

Thermogravimetry of heteroleptic zinc tri-tert-butoxysilanethiolates: synthesis and crystal structure of bis(tri-tert-butoxysilanethiolato)(pyridine) zinc(II)

Thermal behaviour of three silanethiolate zinc complexes i.e., bis(tri-tert-butoxysilanethiolato)bis(pyridine) zinc(II), bis(tri-tert-butoxysilanethiolato)bis(N-methylimidazole) zinc(II) and bis(tri-tert-butoxysilanethiolato) (2-methylpyridine) zinc(II) was studied. In order to determine the steps involved in thermal decay, decomposition intermediates were identified by means of IR spectroscopy and solid residues were analysed. Enthalpies of undergoing processes were estimated on the basis of DTA curves. The results of the study were applied to the synthesis of a new complex - bis(tri-tert-butoxysilanethiolato)(pyridine) zinc(II). NMR and IR spectra of this complex were measured and crystal and molecular structures were determined.     

Design and synthesis of pyrazolo[3,4-d]pyridazine 5,6-dioxides as novel NO-donors

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水溶液中锌粉促进邻二醇合成的研究

邻二醇是有机合成中重要的合成子,是合成烯烃、酮类化合物的重要中间体,广泛用于农药、医药等精细化工品的合成.合成邻二醇最有效的方法是羰基化合物的还原偶联,通常由羰基化合物与相应的金属试剂或金属络合物作用而实现,往往反应时间长,要求的条件苛刻,有的收率比较低.     

Pyrazine control of the solid-state supramolecular chemistry of zinc phthalocyanine

Crystals of monoaxially coordinated T-shaped and H-shaped supramolecular zinc(II) phthalocyaninato complexes with pyrazine are obtained. In both types of molecules the central Zn atom of ZnPc complexes with pyrazine exhibits 4 + 1 coordination. The Zn atom is equatorially coordinated by four isoindole N atoms of Pc macrocycle and axially by N atom of pyrazine molecule. The interaction of the central Zn atom of ZnPc with the axial N atom of pyrazine leads to a deviation of Zn from the centre of cavity by 0.371(2) Å in the T-shaped complex and by 0.296(2) Å in the H-shaped complex. Thermogravimetric analysis of the crystals exhibits three slopes down, corresponding to the loss in succession of solvated pyrazine molecules, than the loss of ligated pyrazine molecules from the T-shaped complex and the finally the loss of the bridged pyrazine molecule from the H-shaped complex. Finally the thermal processing leads to the β-ZnPc as residue. The UV–Vis spectrum taken in solution shows the batochromic shift in the polar solvent like α-chloronaphthalene in relation to the spectrum in non-polar solvent like benzene.     

Design,synthesis,characterization,cytotoxic and structure activity relationships of novel Ru(Ⅱ) complexes

Platinum containing compounds have shown antineoplastic potential, but their clinical applications have been limited by high toxicity. Ruthenium containing complexes have long been known to be well suited for biological applications, and have long been utilized as replacements to popular platinum based-drugs. Here, we report a novel series of ruthenium(II) arene compounds bearing thiosemicarbazone and isonicotinylhydrazone ligands with potent anticancer activity their structure activity relationships and apoptosis was studied. The cytotoxic activity of the new ruthenium(II) arene compounds has been evaluated in several cell lines (Molt 4/C8, L1210, CEM, HL60 and BEL7402). Among them, ten complexes were found to be excellent in vitro growth inhibitory activity against various cell lines with IC50 in the sub-micromolar range.     

Design,synthesis and evaluation of novel cis-p-menthane type Schiff base compounds as effective herbicides

p-Menthane type monoterpene derivatives were identified as bio-based compounds with high herbicidal activities. In order to search novel p-menthane type monoterpene derivatives in good performance, a series of novel cis-p-menthane type Schiff base derivatives were designed and synthesized. All target products were easily available novel compounds and characterized by FT-IR, ¹H NMR, ¹³C NMR and ESI⁺- MS. Their pre-emergence herbicidal activities against annual ryegrass were evaluated. The bioassays indicated that most of the target compounds displayed excellent herbicidal activities in pre-emergence treatment.     

Design,synthesis and computational approach to study novel pyrrole scaffolds as active inhibitors of enoyl ACP reductase (InhA) and Mycobacterium tuberculosis antagonists

Novel 54 pyrrolyl acetohydrazide analogues were designed, synthesized and screened for antitubercular activity against InhA. Enoyl-ACP reductase/InhA one of the significant enzymes implicated in type II FAS (fatty acid synthase) biosynthetic pathway of bacterial outer cell membrane, in addition Mycobacterium tuberculosis H37Rv inhibition potency has proven to be one of the most promising drug target used for designing and testing against TB. In silico molecular modeling was achieved using Surflex-docking method to recognize important binding sites of the enoyl-ACP reductase. 3D-QSAR studies like CoMFA and CoMSIA approaches were studied to create 3D-QSAR depictions for InhA inhibitors. Based on docking results the synthesized molecules are oriented towards the core of the active site. The pyrolyl acetohydrazides exhibited one or two H-bonding connections with InhA enzyme. Molecule 8l (MIC 0.4 μg/mL, InhA- 70% at 50 μM) showed H-bonding connections with Tyr158 and NAD⁺ in a similar mode to that of ligand pyrrolidine carboxamide. The tested molecules also showed good antibacterial (Escherichia coli, Staphylococcus aureus) activity (MIC 0.4–25 μg/mL), while the study against A549 lung adenocarcinoma cell line confirms nontoxic nature of the reported molecules. The QSAR model from CoMFA and CoMSIA through the database configuration showed the most excellent data. The prognostic ability of CoMFA and CoMSIA representations was developed by a test set of 15 molecules that produced cross validated correlation coefficients (q²) of 0.642 and 0.701, respectively. This study gives insight into structural requirement needed for the development of more active InhA inhibitors through in silico approach.