共查询到20条相似文献,搜索用时 15 毫秒
1.
Plants that contain elevated foliar metal concentrations can be categorized as accumulators or, if the accumulation is extreme, hyperaccumulators. The defense hypothesis suggests that these plants may be defended against folivore attack, and recent research has indicated that metal concentrations at or below the accumulator range may be defensively effective. This experiment explored the toxicity of four metals hyperaccumulated by plants (Cd, Ni, Pb, and Zn) and asked if combinations of metals, or metals and organic chemicals, might broaden the defensive effectiveness of metals. Metals were used alone and in certain metal + metal (Zn plus Ni, Pb, or Cd) and metal + organic defensive chemical (Ni plus tannic acid, atropine, or nicotine) combinations. Artificial diet amended with these treatments was fed to larvae of the crucifer specialist herbivore Plutella xylostella. Combinations of metals and metals + organic chemicals significantly decreased survival and pupation rates, compared to single treatments, for at least some concentrations in every experiment. Effects of combinations were additive rather than synergistic or antagonistic. Because Zn enhanced the toxicity of other metals and Ni enhanced the toxicity of organic defensive chemicals, our findings suggest that the defensive effects of metals are more widespread among plants than previously believed. They also support the hypothesis that herbivore defense may have led to the evolution of metal hyperaccumulation by increasing the preexisting defensive effects of metals at accumulator levels in plants. 相似文献
2.
Methods for the synthesis of cyclic monomers that have both metal–metal bonds and carbon–carbon double bonds are reported. Ring opening metathesis polymerization (ROMP) of these monomers would yield polymers that are photochemically degradable. The first method investigated involved substitution of Cp2Fe2(CO)4 by the bidentate phosphine ligand DPPEN (Ph2P
CH=CH–PPh2). Cp2Fe2(CO)2(
-DPPEN) was synthesized and the X-ray crystal structure is reported but the molecule could not be polymerized by a ROMP method using Grubbs’s catalyst. The inability of this monomer to polymerize (or copolymerize with cyclooctatetraene) was attributed to the bulky phenyl rings being in close proximity to the C=C in the DPPEN ligand, which prevents coordination of the monomer to the catalyst. To decrease the steric interactions, the DPPBN ligand was synthesized (DPPBN=Ph
CH
CH=CH
CH
PPh2). However, the reaction of DPPBN with Cp2Fe2(CO)4 yielded the product Cp2Fe2(CO)2(
-1,2,4-triphos), where the 1,2,4-triphos ligand is a tridentate ligand formed by the formal additional of Ph2PH to DPPBN (1,2,4-triphos=Ph
CH
CH(PPh2)
CH
CH
PPh2). An X-ray structure of the Cp2Fe2(CO)2(
-1,2,4-triphos) complex revealed that the 1,2,4-triphos ligand chelates exclusively through the two phosphorus atoms that are bridged by two carbon atoms. It is suggested that this structural feature may simply reflect the increased stability of the 6-membered ring over the 7- and 8-membered rings. The reactions of the Cp2Mo2(CO)6 and Cp2Mo2(CO)4 dimers with DPPBN were investigated next. Reactions of Cp2Mo2(CO)6 and Cp2Mo2(CO)4 with the DPPEN and DPPBN ligands resulted in the disproportionation of the dimers. The X-ray crystal structure of [CpMo(CO)2(DPPEN)][CpMo(CO)3] was determined and is reported. The CpMo(CO)(DPPEN)Cl complex was formed when these same reactions were carried out in the presence of CH2Cl2. The X-ray crystal structure of this molecule is also reported. 相似文献
3.
Anish Khan Aftab Aslam Parwaz Khan Abdullah M. Asiri Samia A. Kosa 《Polymer-Plastics Technology and Engineering》2015,54(15):1615-1624
A new class of PANI/Sn(II)SiO3/FCNTs nanocomposite was synthesized by mixing polyaniline into the gel of Sn(II)SiO3 followed by FCNTs (Polyaniline/Sn(II)SiO3/Functionalized Carbon nanotubes). The physico-chemical characterization was carried out by scanning electron microscope, XRD (X-ray Diffraction), FTIR (Fourier Transform Infrared Spectroscopy), ultraviolet–visible spectroscopy, and simultaneous thermogravimetric analysis studies. The ion-exchange capacity (1.2 meq/g) and distribution studies were also determined to understand the ion-exchange capabilities. The DC electrical conductivity studies revile it in the range of 3–5 × 10?3 S/cm. On the basis of distribution studies, ion-selective membrane electrode was designed for Hg(II). The analytical utility of this membrane was established by using it as an indicator electrode in electrometric titrations. 相似文献
4.
Detonation properties of mixtures of condensed high explosives with metal additives are studied. A scheme of measurement of high electrical conductivity of detonation products ( > 10 –1 · cm–1) with a time resolution of 10 nsec is developed. It is shown that the properties of detonation products depend significantly on the content of the additive in the HE and on dispersion and density of the mixture. The electrical conductivity of detonation products of the compositions examined reaches 5 · 103 –1 · cm–1, which is more than three orders higher than the electrical conductivity of the HE without the additive. Significant variation of electrical conductivity of detonation products over the conducting region thickness has been found. The main conductivity corresponds to a sector 1 mm long near the detonation front. The overdriven state of the detonation wave has a strong effect on electrical conductivity and conducting region thickness. It is assumed that the behavior of electrical conductivity with time is caused by successive processes of shock compression of the HE, excitation of the chemical reaction (including the reaction of the additive with detonation products), and expansion of detonation products. The measurement technique used is highly informative due to the possibility of studying detonation in various regimes. 相似文献
5.
Ali El-Shekeil Hussein Al-Maydama Ashour Al-Karbooly 《Journal of Inorganic and Organometallic Polymers》1998,8(3):167-178
Poly(1,2-phenylenedithiocarbamate) (PPDTC) was prepared by the reaction of 2-aminothiophenol with carbon disulfide followed by condensation through the removal of H2S gas. PPDTC was used as a ligand to prepare four poly(1,2-phenylenedithiocarbamate)–metal complexes of iron(II), cobalt(II), copper(II), and lead(II), by refluxing with the metal salts. The polymer and its metal complexes were investigated by elemental analyses, UV–visible and IR spectroscopy, inherent viscosity, and magnetic susceptibility. The DC electrical conductivity variation with the temperature in the range 298–498 K of PPDTC and its polymeric copper complex was measured. Both polymer and polymer metal complexes showed an increase in electrical conductivity with an increase in temperature: typical semiconductor behavior. The proposed structure of the complexes is (MLX2·mH2O)
n
. 相似文献
6.
Selwyn F. Mapolie John R. Moss Gregory S. Smith 《Journal of Inorganic and Organometallic Polymers》1997,7(4):233-250
A series of metal-containing vinylic monomers of the type
and
was homopolymerized using 2,2-azobisisobutyronitrile (AIBN) as the free-radical initiator. These monomers were also copolymerized with styrene in the presence of AIBN. These compounds represent a class of organometallic polymers in which the metal is bonded to the polymer backbone via a metal–carbon bond. The new compounds were characterized by IR and 1H NMR spectroscopy as well as scanning electron microscopy, gel permeation chromatography, and thermoanalytical studies (DSC and TGA). The properties of the new organometallic polymers are discussed. 相似文献
7.
Sarah E. Brady Ginger V. Shultz David R. Tyler 《Journal of Inorganic and Organometallic Polymers and Materials》2010,20(3):511-518
The [(η5-C5H4(CH2)3OC(O)(CH2)2C≡CH)Mo(CO)3]2 complex (1) was synthesized and used to explore the feasibility of using the Huisgen cycloaddition reaction (a click reaction) to incorporate
molecules with metal–metal bonds into polymer backbones. In a model reaction, coupling of 1 with benzyl azide was observed in 24 h using Cp*Ru(PPh3)2Cl as a catalyst. In contrast, the reaction of 1 with benzyl azide using a CuBr/ligand catalyst (where the ligand is either PMDETA or bipyridine), resulted in disproportionation
of the Mo–Mo unit in 1. Complex 1 was also coupled with telechelic azide-terminated polystyrene oligomers. With either the CuBr/PMDETA or CuBr/bipyridine catalyst,
disproportionation of the Mo–Mo bonded unit occurred before complete coupling was observed. The reaction was also slow when
the Cp*Ru(PPh3)2Cl catalyst was used; however, no disproportionation products were observed and a high molecular weight polymer (M
n = 120,000 g/mol) was produced. The Cp*Ru(PPh3)2Cl catalyst was also used to couple 1 with azide-terminated poly(ethylene glycol). After 15 h, this reaction produced a polymer with M
n = 73,000 g mol−1. It is concluded that, although somewhat slow, click chemistry using the Cp*Ru(PPh3)2Cl catalyst is an excellent method for synthesizing high molecular weight polymers with metal–metal bonds along the backbone. 相似文献
8.
Safaa El-din H. Etaiw Mohamed M. El-bendary 《Journal of Inorganic and Organometallic Polymers and Materials》2013,23(3):510-518
The structure of the new metal–organic framework, [(CuCN)2·(3-Clpy)], 1, was characterized by IR, UV–visible, TGA and X-ray single crystal analysis. The structure of 1 consists of CuCN building blocks, which are connected by CN group to form two different chains; one puckered chain with TP-3 geometry around Cu(1) and a linear Cu(2)(CN)2 chain. The two kinds of chains are bonded by cuprophilic interactions creating a 3D-network. The network structure of 1 is further close-backed by π–π stacking and hydrogen bonds. The electronic absorption and emission spectra as well as the thermodynamic parameters from TGA of the MOF 1 are discussed. MOF 1 was used as an effective heterogeneous catalyst for the oxidative discoloration of methylene blue dye by dilute solution of hydrogen peroxide as the oxidant. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine the in vitro antitumor activity of MOF 1 on human breast cancer cell line, MCF7. 相似文献
9.
《国际聚合物材料杂志》2012,61(1):41-56
A monomeric Schiff base was prepared by the condensation reaction of salicylaldehyde and semicarbazide, which further react with formaldehyde and barbituric acid-formed polymeric Schiff base. Its metal polychelates were then formed with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II). All the synthesized compounds were characterized by elemental analysis, magnetic moment, FTIR, 1HNMR, and electronic spectroscopies. The elemental analysis data show the formation of 1:1 [M: L] metal polychelates. Thermogravimetric analysis was carried out to find the thermal behavior of all the synthesized polymeric compounds and thermal data revealed that all the metal polychelates are more thermally stable than their parent polymeric Schiff base. All the synthesized polymeric compounds were screened for antimicrobial activity against some clinically important microorganisms, such as Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Staphylococcus typhi, Candida albicans, Microsporum canis, and Aspergillus niger. In vitro antimicrobial activity was determined by the Agar Well Diffusion method and the result shows that all the metal polychelates exhibited better antimicrobial activity than their parent polymeric Schiff base. 相似文献
10.
Construction of Two New Metal–Organic Frameworks from Pamoic Acid and N-Containing Auxiliary Ligands
Chang-wei Lv Jing Li Zheng Hou Ming-kai Li 《Journal of Inorganic and Organometallic Polymers and Materials》2014,24(2):388-394
Two new metal–organic frameworks; namely, [Cd2(pam)2(bpe)1.5(DMF)2(H2O)] n ·2n(DMF) (1) and [Cd(pam)(bix)] n (2) (H2pam = pamoic acid, bpe = 1,2-di(4-pyridyl)ethylene, bix = 4,4′-bis(imidazol-1-ylmethyl)benzene, DMF = N,N′-dimethylformamide), were solvothermally synthesized via varying the auxiliary ligand. Single crystal X-ray diffraction analysis reveals that compound 1 shows a 2D→3D polythreaded motif based on (3,4)-connected 2D sheets, while compound 2 features a 4-connected sql tetragonal plane net, which further extended into a 3D supramolecular framework through intermolecular CH···π interactions. In addition, the luminescent and thermal stabilities properties of these two compounds were investigated. 相似文献
11.
Layer-by-layer (LbL) assembly of multilayers is an established method for the construction of layered nanostructures on surfaces, affording control of the thickness, composition, and organization in the vertical direction. Binding between layers is accomplished using various types of interactions, including electrostatic binding, hydrogen bonding, covalent bonding, metal–organic coordination, host–guest interactions, biospecific interactions, and others. Here we focus on LbL assembly using metal–organic coordination, and specifically on layered nanostructures based on bishydroxamate–M4+ binding. The coordination approach offers attractive features, such as a simple reaction, a defined geometry, and reversibility under certain conditions. The basic scheme includes self-assembly of a ligand (anchor) monolayer on the surface, followed by alternate binding of metal ions and multi-functional ligand layers, to form a coordination multilayer. This approach is demonstrated by the construction of a variety of coordinated nanostructures, including bilayers, multilayers, dendrimers, and nanoparticle assemblies, prepared on gold and oxide substrates. 相似文献
12.
Feng Wang Kejian Deng Guiling Wu Hongyan Liao Honglin Liao Lulu Zhang Shemin Lan Jianmin Zhang Xuegang Song Lili Wen 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(4):680-685
The treatment of Ln(NO3)3·6H2O (Ln?=?La, Ce, Eu, Gd, Dy) with 1,3,5-benzenetricarboxylic acid (H3BTC) in a water–ethanol solution facilely yields crystal nanorods of rare earth metal–organic frameworks (MOFs) at room temperature. Electron micrographs show that the nanorods are 50–200?nm in width, 50–100?nm in thickness and 1–2?μm in length. All the crystal nanorods have the same Ln(BTC)(H2O)6 structure as identified by power X-ray diffraction, elemental analysis, thermogravimetric and Fourier transform infrared analysis. The optical properties of all the compounds are recorded; and, the nanoscale MOFs (NMOFs) with Eu3+ and Dy3+ show excellent photoluminescence. 相似文献
13.
Samira Sadat Abolmaali Ali Tamaddon Haniye Najafi Rasoul Dinarvand 《Journal of Inorganic and Organometallic Polymers and Materials》2014,24(6):977-987
The study was aimed to investigate the effect of chemical modification of branched poly ethyleneimine (PEI) on chelation of transition metal ions (Me2+) including Zn2+, Cu2+ or Ni2+ and sol–gel conversion thereof. To modulate chelation property of PEI, imidazole moieties were introduced into the polymer backbone by carbodiimide chemistry at different molar ratios of fmoc-protected l-histidine. The synthesis was characterized by 1H-NMR spectroscopy and size exclusion chromatography. Potentiometric titration of PEI/Me2+ aqueous dispersions showed formation of stable complexes at pH above 5 depending on the degree of l-histidine substitution. FT-IR spectroscopy showed the imidazole ring of l-histidine was involved in the coordination interactions between PEI and Me2+. Addition of Zn2+ to PEI solution induced sol–gel conversion at a critical molar ratio decreasing by a higher degree of l-histidine modification. The gelation process led to formation of stable globular nanostructures as confirmed by atomic force microscopy with projected mean diameters less than 200 nm. Cellular experiment showed that l-histidine substitution enhanced cyto-compatibility of PEI, moreover cytotoxicity decreased significantly upon coordination of Zn2+ with the polymers. Conclusively, the coordination complexes of Zn2+ and l-histidine substituted PEI could serve as a nano system for biomedical applications. 相似文献
14.
Zhaleh Moradi Kamran Akhbari Anukorn Phuruangrat Ferdinando Costantino 《Journal of Inorganic and Organometallic Polymers and Materials》2017,27(6):1712-1718
The reactions between 2-mercaptobenzothiazole (HMBT) and AgNO3 in ultrasonic bath with low and high concentrations of initial reagents provided yellow precipitates of [Ag6(MBT)6] (1), which can be considered as 1L and 1H, respectively. Powder XRD patterns of them showed that they have crystalline structure and SEM images of 1L and 1H approved that microblocks and nanosheets of 1 were formed, respectively. Similar studies after mechanical and thermo-mechanical treatment of 1L and 1H indicated that compound 1 with nanoparticle and agglomerated nanoparticle morphologies were obtained. As a result of heat and energy created from the friction process and also external heat source a roughening transition was occurred and the crystalline samples of 1L and 1H, loses their facets. This can be understood by considering compound 1 surface above the roughening temperature as a liquid surface. 相似文献
15.
A. Upadhyaya E. J. Acosta J. F. Scamehorn D. A. Sabatini 《Journal of surfactants and detergents》2007,10(4):269-277
This research evaluates the adsorption of anionic and cationic surfactant mixtures on charged metal oxide surfaces (i.e.,
alumina and silica). For an anionic-rich surfactant mixture below the CMC, the adsorption of anionic surfactant was found
to substantially increase with the addition of low mole fractions of cationic surfactant. Two anionic surfactants (sodium
dodecyl sulfate and sodium dihexyl sulfosuccinate) and two cationic surfactants (dodecyl pyridinium chloride and benzethonium
chloride) were studied to evaluate the effect of surfactant tail branching. While cationic surfactants were observed to co-adsorb
with anionic surfactants onto positively charged surfaces, the plateau level of anionic surfactant adsorption (i.e., at or
above the CMC) did not change significantly for anionic–cationic surfactant mixtures. At the same time, the adsorption of
anionic surfactants onto alumina was dramatically reduced when present in cationic-rich micelles and the adsorption of cationic
surfactants on silica was substantially reduced in the presence of anionic-rich micelles. This demonstrates that mixed micelle
formation can effectively reduce the activity of the highly adsorbing surfactant and thus inhibit the adsorption of the surfactant,
especially when the highly adsorbing surfactant is present at a low mole fraction in the mixed surfactant system. Thus surfactant
adsorption can be either enhanced or inhibited using mixed anionic–cationic surfactant systems by varying the concentration
and composition.
相似文献
D. A. SabatiniEmail: |
16.
Christopher W. Jones 《Topics in Catalysis》2010,53(13-14):942-952
Research on heterogenized metal complex catalysts has been carried out for 40 years. Despite thousands of published catalysts, there are only two significant commercial processes that utilize supported metal complex catalysts. Most academic papers are simply “demonstration of concept” studies reporting myriad ways to support various metal complex catalysts. Too few papers focus on rigorous studies of reaction kinetics, catalyst recycle, catalyst stability and deactivation pathways. Here, preliminary stability and deactivation studies of supported enantioselective Co-salen epoxide ring-opening catalysts and enantioselective Ru-salen olefin cyclopropanation catalysts are summarized. Insights with regard to catalyst deactivation suggest methodologies for catalyst stabilization, allowing for more effective catalyst recycle and enhanced catalyst turnover. Further examples where supported metal complex catalysts are applied in commercial processes will require the field to shift focus from “demonstration of concept” studies to more detailed investigations of catalyst stability and recyclability. 相似文献
17.
Syed Ashfaq Nabi Sajad Ahmad Ganai Amjad Mumtaz Khan 《Journal of surfactants and detergents》2008,11(3):207-213
The adsorption behavior of a thermally and chemically stable hybrid ion-exchange material, acrylamide aluminum tungstate was
explored in cationic (CTAB) and anionic (SDS) surfactants and acidic solvents. Critical micellar concentration (CMC) appears
to be an important parameter in determining the adsorption behavior of metal ions. Equilibration time and temperature studies
on the distribution coefficient of metal ions were studied. On the basis of the distribution coefficient, this material was
successfully used for quantitative separations of some binary synthetic mixtures of metal ions by the column method. Hg(II)
ion was selectively determined quantitatively in synthetic mixture. The material appears to be promising for separating toxic
metal ions in a real matrix (industrial effluents and waste water) and can be utilized as a packing material in HPLC and GC
columns for faster and more efficient separation.
相似文献
Syed Ashfaq NabiEmail: |
18.
Abdelmoaty Alaa S. El-Wakeel Shaimaa T. Fathy Nady Hanna Adly A. 《Journal of Inorganic and Organometallic Polymers and Materials》2022,32(7):2557-2567
Journal of Inorganic and Organometallic Polymers and Materials - In this paper, UiO-66 metal–organic framework (MOF) was prepared by a hydrothermal method and modified consequently with... 相似文献
19.
Chunyan Kong 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(1):189-194
Three new coordination polymers, [Ni(2,4′-oba)(1,10-phen)]
n
(1), {[Ni (2,4′-Hoba)2(4,4′-bipy)(H2O)2]·2H2O}
n
(2) and [Zn(2,4′-oba) (4,4′-bipy)]
n
(3) (2,4′-H2oba = 2-(4-carboxyphenoxy)benzoic acid, 1,10- phen = 1,10-phenanthroline, and 4,4′-bipy = 4,4′-bipyridine) have been obtained
by hydrothermal synthesis. The framework structures of these polymeric complexes have been determined by single-crystal X-ray
diffraction studies. Complex 1 exhibits double-helical chains formed by π–π stacking interactions from the phenyl rings of the 1,10-phen ligands. Complex 2 forms a two-dimensional supramolecular architecture directed by hydrogen bonding. Complex 3 exhibits a three-dimensional structure; Schl?fli symbol of {44·610·8}. The luminescent property of compound 3 is discussed. 相似文献
20.
This paper describes a simple and low-cost fabrication method for multi-functional nanostructures with outstanding anti-reflective and super-hydrophobic properties. Our method employed phase separation of a metal salt–polymer nanocomposite film that leads to nanoisland formation after etching away the polymer matrix, and the metal salt island can then be utilized as a hard mask for dry etching the substrate or sublayer. Compared to many other methods for patterning metallic hard mask structures, such as the popular lift-off method, our approach involves only spin coating and thermal annealing, thus is more cost-efficient. Metal salts including aluminum nitrate nonahydrate (ANN) and chromium nitrate nonahydrate (CNN) can both be used, and high aspect ratio (1:30) and high-resolution (sub-50 nm) pillars etched into silicon can be achieved readily. With further control of the etching profile by adjusting the dry etching parameters, cone-like silicon structure with reflectivity in the visible region down to a remarkably low value of 2% was achieved. Lastly, by coating a hydrophobic surfactant layer, the pillar array demonstrated a super-hydrophobic property with an exceptionally high water contact angle of up to 165.7°. 相似文献