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1.
Poly(vinylimidazole-co-methyl methacrylate)-silica hybrids, bonded through hydrogen bond (PVM-SiO2) or chemical bond (PVM(5)-SiO2) between organic and inorganic units, were prepared and characterized. The characterization of PVM-SiO2 and PVM(5)-SiO2 hybrids were confirmed by IR, 13C and 29Si NMR spectra. The intermolecular interaction between copolymer chains was studied by the spin-lattice relaxation time in the rotating frame (TH1ρ), and that between copolymer and silica was evaluated by the time constant for energy change between 1H and 29Si spin system (TSiH). TH1ρ and TSiH values in PVM-SiO2 hybrids were consistent with those in PVM(5)-SiO2 hybrids, and those were independent of the silica content. Moreover, the TH1ρ values are in order of poly(methyl methacrylate)-silica hybrids (PMMA-SiO2) ≧ PVM-SiO2 ≒ PVM(5)-SiO2 > polyvinylimidazole-silica hybrids (PVI-SiO2), while those of TSiH are in reverse order PMMA-SiO2 ≦ PVM(5)-SiO2 < PVI-SiO2.  相似文献   

2.
Poly(methyl methacrylate-co-glycidyl methacrylate-tris(hydroxymethyl)aminomethane) (PMGT) copolymers were obtained by copolymerization of methyl methacrylate (MMA) and a chelating monomer, glycidyl methacrylate-tris(hydroxymethyl)aminomethane (GMA-Tris), with potassium persulfate as an initiator. The glass transition temperature (Tg) and the proton spin-lattice relaxation time in the rotating frame () substantiated the formation of random copolymers. Borate-loaded PMGT (BPMGT) complexes were prepared by mixing PMGT and boric acid solution. The formation of coordination bond between PMGT and borate was studied using differential scanning calorimetry, infrared and 13C solid-state nuclear magnetic resonance spectroscopy. A single composition dependent Tg was obtained for the PMGT copolymers. The Tg value of BPMGT complex was much higher than that of PMGT copolymer with the same composition. The of the main chains in the PMGT copolymers and BPMGT complexes had one value, and that in the complexes was higher than that in the copolymers. The apparent activation energy (Ea) of the thermo-oxidative degradation of Tris units in complexes was larger than that in copolymers, whereas the Ea value of the MMA-GMA matrix was reversed.  相似文献   

3.
The free‐radical copolymerization of N‐phenylmaleimide (N‐PhMI) with acrylic acid was studied in the range of 25–75 mol % in the feed. The interactions of these copolymers with Cu(II) and Co(II) ions were investigated as a function of the pH and copolymer composition by the use of the ultrafiltration technique. The maximum retention capacity of the copolymers for Co(II) and Cu(II) ions varied from 200 to 250 mg/g and from 210 to 300 mg/g, respectively. The copolymers and polymer–metal complexes of divalent transition‐metal ions were characterized by elemental analysis, Fourier transform infrared, 1H NMR spectroscopy, and cyclic voltammetry. The thermal behavior was investigated with differential scanning calorimetry (DSC) and thermogravimetry (TG). The TG and DSC measurements showed an increase in the glass‐transition temperature (Tg) and the thermal stability with an increase in the N‐PhMI concentration in the copolymers. Tg of poly(N‐PhMI‐co‐AA) with copolymer composition 46.5:53.5 mol % was found at 251 °C, and it decreased when the complexes of Co(II) and Cu(II) at pHs 3–7 were formed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4933–4941, 2005  相似文献   

4.
A new mechanism Of H2 dissociation in electrical discharges (1011 ? ne ? 1012 cm?3, 2.10?16 ? E/N ? 3.10?16 V cm2, 300 ? Tg ? 1000 K, 3 ? p ? 30 torr) is presented and discussed. In this mechanism, called joint vibro-electronic mechanism (JVE), the electrons of the discharge create a strong vibrational disequilibrium with respect to the gas temperature (Tg) and promote electronic transitions from all vibrational levels of 1Σg H2 state to the repulsive 3Σu one. Moreover the V-V (vibration-vibration) and V-T (vibration-translation) energy exchanges are considered for building up the vibrational distribution of 1Σg state. A complete set of e - D cross sections (e + H2(1Σg,ν) → e + H2 (3Σu) → + 2H, ν = 0,14) is calculated by using an extension of the semiclassical Gryzinski theory in combination with the Franck-Condon principle. Dissociation rates calculated according to JVE are larger either than those obtained by the pure vibrational mechanism (PVM) discussed in our previous work or than those from the direct electronic impact mechanism (DEM) from the ground vibrational level. The behaviour of JVE rates as a function of gas temperature (Tg), of E/N, of electron density (ne) and of pressure is then reported. The results show strong differences as compared, with the corresponding values obtained, with PVM. Finally the influence of the atoms as well as their recombination on the dissociation rates is discussed. The results have been obtained by solving a system of vibrational master equations.  相似文献   

5.
KHALIL M. M. H.  MASHALY M. M.   《中国化学》2008,26(9):1669-1677
A new series of binary mononuclear complexes were prepared from the reaction of the hydrazone ligand, 2-carboxyphenylhydrazo-benzoylacetone (H2L), with the metal ions, Cd(II), Cu(II), Ni(II), Co(II), Th(IV) and UO2(VI). The binary Cu(II) complex of H2L was reacted with the ligands 1,10-phenanthroline or 2-aminopyridine to form mixed-ligand complexes. The binary complexes of Cu(II) and Ni(II) are suggested to have octahedral configurations. The Cd(II) and Co(II) complexes are suggested to have tetrahedral and/or square-planar geometries, respectively. The Th(IV) and UO2(VI) complexes are suggested to have octahedral and dodecahedral geometries, respectively. The mixed-ligand complexes have octahedral configurations. The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, 1H NMR and TG-DSC measurements as well as by mass spectroscopy. The ligand and some of the metal complexes were found to activate the enzyme pectinlyase.  相似文献   

6.
Heteronuclear complexes containing oxorhenium(V), with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) ions were prepared by the reaction of the complex ligands [ReO(HL1)(PPh3)(OH2)Cl]Cl (a) and/or [ReO(H2L2)(PPh3)(OH2)Cl]Cl (b), where H2L1?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(5,6-diphenyl-1,2,4-triazine-3-ylhydrazone) and H3L2?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(1H-benzimidazol-2-ylhydrazone), with transition and actinide salts. Heterodinuclear complexes of ReO(V) with Fe(III), Co(II), Ni(II), Cu(II) and Cd(II) were obtained using a 1?:?1 mole ratio of the complex ligand and the metal salt. Heterotrinuclear complexes were obtained containing ReO(V) with UO2(VI) and Cu(II) using 2?:?1 mole ratios of the complex ligand and the metal salts. The complex ligands a and b coordinate with the heterometal ion via a nitrogen of the heterocyclic ring and the nitrogen atom of the C=N7 group. All transition metal cations in the heteronuclear complexes have octahedral configurations, while UO2(VI)?complexes have distorted dodecahedral geometry. The structures of the complexes were elucidated by IR, ESR, electronic and 1H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the complex ligands and their heteronuclear complexes towards Alternaria alternata and Aspergillus niger showed comparable behavior with some well-known antibiotics.  相似文献   

7.
The effects of composition on the glass transition of dry and hydroplasticised copolymers of methyl methacrylate (MMA), butyl methacrylate (BMA) and 2-hydroxypropyl methacrylate (HPMA) were studied by differential scanning calorimetry. Results from the hydroplasticisation studies showed that a high PHPMA content (>75 wt.%) was required for high water absorption and that the amount of water uptake was not linear with HPMA content but increased in an accelerating manner with increasing HPMA content. This behaviour was attributed to the increase in the hydrophilic character of the copolymer due to the strong hydroxyl-hydroxyl interactions at high PHPMA content. The Tgs of the dry copolymers were successfully predicted by all three equations used (rule of mixtures, Fox and Gordon-Taylor) but were poorly predicted for the hydroplasticised copolymers. This failure was attributed to the inadequacy of the equations in accounting for the specific interactions between the different segments of the copolymer chains. HPMA depressed the Tg of the water-saturated copolymers but enhanced the Tg of the dry system and this behaviour has particular relevance to its use in water-based latex paints.  相似文献   

8.
A series of binuclear Co(II), Ni(II) and Cu(II) complexes were synthesized by the template condensation of glyoxal, biacetyl or benzil bis-hydrazide, 2,6-diformyl-4-methylphenol and Co(II), Ni(II) or Cu(II) chloride in a 2:2:2 M ratio in ethanol. These 22-membered macrocyclic complexes were characterized by elemental analyses, magnetic, molar conductance, spectral, thermal and fluorescence studies. Elemental analyses suggest the complexes have a 2:1 stoichiometry of the type [M2LX2nH2O and [Ni2LX22H2O]·nH2O (where M = Co(II) and Cu(II); L = H2L1, H2L2 and H2L3; X = Cl; n = 2). From the spectroscopic and magnetic studies, it has been concluded that the Co(II) and Cu(II) complexes display a five coordinated square pyramidal geometry and the Ni(II) complexes have a six coordinated octahedral geometry. The Schiff bases and their metal complexes have also been screened for their antibacterial and antifungal activities by the MIC method.  相似文献   

9.
Glycidyl methacrylate (GM) random copolymers with styrene and methylstyrene (in a 1:1 and 1:3 mole ratio) were synthesized by solution free radical polymerizations at 70 ± 1 °C using α,α′-azoisobutyronitrile as an initiator. The copolymer compositions were obtained using related 1H NMR spectra and the polydispersity indices of the copolymers determined using gel permeation chromatography (GPC). Both types of polymer could be modified by incorporation of the highly sterically demanding tris(trimethylsilyl)methyl substituent (Me3Si)3C-(Tsi = trisyl) through the ring opening reaction of the epoxy groups in copolymers. Chemical modification was determined by 1H NMR and infrared spectroscopies. The glass transition temperature Tg of all copolymers was determined by differential scanning calorimetry (DSC). The Tg value of the copolymers containing bulky trisyl groups was found to increase with incorporation of trisyl groups in polymer structures. The presence of trisyl groups in the polymer side chain created new macromolecules with novel modified properties and potential use as membranes for fluid separation.  相似文献   

10.
Copolymers containing styrene and alkyl methacrylate (n-butyl-, n-hexyl-, or stearyl methacrylate) at different compositions have been prepared by radical copolymerization. The monomer reactivity ratios were estimated using the Finemann-Ross, the inverted FR and the Kelen-Tüdos graphical methods. Structural parameters of the copolymers were obtained calculating the dyad monomer sequence fractions. The effect of the size of the alkyl methacrylate on the copolymer structure is discussed. The glass transition temperature, Tg of the copolymers with butyl and hexyl methacrylate was examined in the frame of several theoretical equations allowing the prediction of these Tg values. The best fit was obtained using methods that take into account the monomer sequence distribution of the copolymers. The copolymers of styrene with stearyl methacrylate exhibited the characteristic melting endotherm, due to the crystallinity of the methacrylate sequences and the polystyrene glass transition temperature.  相似文献   

11.
The phase behavior and motional mobility in binary blends of poly(4‐methylstyrene) (P4MS) and poly(cyclohexyl methacrylate) (PCHMA) have been examined by 13C solid state NMR techniques. The blend miscibility was studied by measuring the 1H spin‐relaxation times in the laboratory frame (T1H) and in the rotating frame (TH), respectively. Although intermolecular spin diffusion contributes to the proton relaxations in accordance with homogeneity, TH data shows signs of in complete averaging. The TH relaxation behavior indicates the existence of heterogeneous do mains with shortest dimensions in the nanometer range, which is also sup ported by the intermolecular cross polarization experiments with variable contact times. In addition, according to the resuits of carbon T relaxation time measurements, it is concluded that mixing is intimate some what enough to cause a reduction in local chain mobility for P4MS and vice versa for PCHMA.  相似文献   

12.

A tridentate ONN donor ligand, 5-methyl-3-(2-hydroxyphenyl)pyrazole; H2L, was synthesized by reaction of 2-(3-ketobutanoyl)phenol with hydrazine hydrate. The ligand was characterized by IR, 1H NMR and mass spectra. 1H NMR spectra indicated the presence of the phenolic OH group and the imine NH group of the heterocyclic moiety. Different types of mononuclear metal complexes of the following formulae [(HL)2M][sdot]xH2O (M=VO, Co, Ni, Cu, Zn and Cd), [(HL)2M(H2O)2] (M=Mn and UO2) and [(HL)LFe(H2O)2] were obtained. The Fe(III) complex, [(HL)LFe(H2O)2] undergoes solvatochromism. Elemental analyses, IR, electronic and ESR spectra as well as thermal, conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared metal complexes. A square-pyramidal geometry is suggested for the VO(IV) complex, square-planar for the Cu(II), Co(II) and Ni(II) complexes, octahedral for the Fe(III) and Mn(II) complexes and tetrahedral for the Zn(II) and Cd(II) complexes, while the UO2(VI) complex is eight-coordinate. Transmetallation of the UO2(VI) ion in its mononuclear complex by Fe(III), Ni(II) or Cu(II) ions occurred and mononuclear Fe(III), Ni(II) and Cu(II) complexes were obtained. IR spectra of the products did not have the characteristic UO2 absorption band and the electronic spectra showed absorption bands similar to those obtained for the corresponding mononuclear complexes. Also, transmetallation of the Ni(II) ion in its mononuclear complex by Fe(III) has occurred. The antifungal activity of the ligand and the mononuclear complexes were investigated.  相似文献   

13.

Abstract  

Acetone [N-(3-hydroxy-2-naphthoyl)] hydrazone (H2AHNH) has been prepared and its structure confirmed by elemental analysis and 1H NMR spectroscopy. It has been used to produce diverse complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and U(VI)O2 ions. The complexes obtained have been investigated by thermal analysis, spectral studies (1H NMR, IR, UV–visible, ESR), and magnetic measurements. IR spectra suggest that H2AHNH acts as a bidentate ligand. The electronic spectra of the complexes and their magnetic moments provide information about geometries. The ESR spectra give evidence for the proposed structure and the bonding for some Cu(II) complexes. Thermal decomposition of the Ni(II) and Cu(II) complexes afforded metal oxides as final products. Kinetic data were obtained for each stage of thermal degradation of some of the complexes using the Coats–Redfern method. The formation of complexes in solution was studied pH-metrically and the order of their stability constants (log K) was found to be U(VI)O2 > Cu(II) > Zn(II) > Ni(II) > Cd(II) > Co(II). Antimicrobial and eukaryotic DNA studies were carried out.  相似文献   

14.
High precision magnetoresistance (MR) Δρ/ρ(H,T) and magnetization M(H,T) measurements have been carried out for well known and typical strongly correlated electron system—cerium hexaboride. The detailed measurements have been fulfilled on single crystalline samples of CeB6 over a wide temperature range in magnetic fields up to 70 kOe. It was shown that the MR anomalies in the magnetic heavy fermion compound under investigation can be consistently interpreted in the frameworks of a simple relation between resistivity and magnetization—Δρ/ρM2 obtained by Yosida [Phys. Rev. 107(1957)396]. A local magnetic susceptibility χloc(T,H)=(1/H*(d(Δρ/ρ)/dH))1/2 was deduced directly from the MR Δρ(H,T) measurements and compared with the experimental data of magnetization M(H,T). The magnetic susceptibility dependences χloc(T,H) and χ(T,H) obtained in this study for CeB6 allow us to analyze the complicated H-T magnetic phase diagram of this so-called dense Kondo-system.  相似文献   

15.
The structural relaxation of poly(methyl‐methacrylate) (PMMA)‐based copolymers with different chain flexibility has been studied by DSC with the classical procedure of the isothermal and dynamical approach. Modified PMMA with different chain flexibility have been prepared by free radical polymerization in solution using a mixture of monomers containing 10 mol % of alkyl methacrylate (i.e., ethyl, buthyl, and hexyl methacrylate). The molecular characteristics of all the prepared copolymers have been performed by a multiangle laser light scattering (MALS) photometer on‐line to a size exclusion chromatography (SEC) system (SEC‐MALS) after and before the thermal treatments, NMR (1H and 13C) and MALDI‐TOF mass spectrometry. A comparison of the apparent relaxation rate (RH) was appraised from the enthalpy loss by annealing the different samples at the same level of undercooling (Ta = Tg ? 18 °C). It was found an increase of RH increasing the chain flexibility in the copolymers. Dynamical tests, performed at different cooling rates, have been used to estimate the apparent activation energy of the relaxation process. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 596–607, 2009  相似文献   

16.
Complexes of Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Hg(II) and U(VI)O2 with 2-acetylpyridine-[N-(3-hydroxy-2-naphthoyl)] hydrazone (H2APHNH) have been prepared and characterized by elemental analysis, molar conductance, thermal (TG, DTG), spectral (1H NMR, IR, UV–Vis, ESR) and magnetic measurements. 1H NMR spectrum of the ligand suggests the presence of intramolecular hydrogen bonding. IR spectra show that H2APHNH is a bidentate, tridentate and/or tetradentate ligand. Thermal decomposition of some complexes ended with metal oxide as a final product. ESR spectra gave evidence for the proposed structure and the bonding for some Cu(II) complexes. Biological activity measurements were carried out.  相似文献   

17.
A new tridentate Schiff base, 5-bromosalicylaldehyde S-allylisothiosemicarbazone hydrobromide (H2L), and several new mononuclear complexes of copper(II) and molybdenum(VI) of this ligand with general formulas ([Cu(L)Im] (1)), ([Cu(L)NH3]·4H2O (2)), and ([MoO2(L)1-MeIm] (3), Imidazole: Im, 1-methylimidazole: 1-MeIm) were prepared and characterized by elemental analyses, IR, proton magnetic resonance Spectroscopy, and ultraviolet–visible techniques. The physico-chemical results suggested that the H2L coordinates in the dianionic tridentate form. Crystal structures of the Cu(II) complexes reveal a square planar configuration surrounded by the dianionic tridentate isothiosemicarbazone (ONN) and Im and NH3 for 1 and 2, respectively. The L2-, two oxo, and 1-methylimidazole are coordinated to molybdenum(VI) in a distorted octahedral geometry in 3. Formation of pure metal oxide residues was confirmed by thermal degradation of the complexes.  相似文献   

18.
《Polyhedron》2001,20(22-23):2787-2798
1H-Pyrazole complexes, [Cu(HL)HPz Cl] nH2O and [Cu(L)HPz] nH2O were prepared and characterized, where HL and L, respectively, refer to the mononegative and dinegative N-salicylidenearoylhydrazine anions. The X-ray crystal and molecular structure of [monochloro(N-salicylidenebenzoylhydrazinato)ONO(−1)monopyrazole] copper(II) monohydrate, [Cu(HSBzh)HPz Cl] H2O, and [(N-salicylidenebenzoylhydrazinato)ONO(−2)monopyrazole] copper(II) hemihydrate, [Cu(SBzh)HPz] 1/2H2O, were determined. The Cu(II) in [Cu(HSBzh)HPz Cl] H2O is in a distorted square pyramidal environment and is bound in the equatorial plane with the mononegative tridentate aroylhydrazone anion and pyrazole nitrogen, the axial fifth coordination site is occupied by a chloride ion. On the other hand, the complex [Cu(SBzh)HPz] 1/2H2O consists of two monomeric crystallographically independent but chemically similar molecules. In each molecule, the Cu(II) is in a distorted square planar geometry and is coordinated to the dinegative tridentate aroylhydrazone via the phenoxy oxygen, azomethine nitrogen and enolimide oxygen, and the fourth coordination site is occupied by the pyrazole nitrogen. The mono(μ-pyrazolate) dicopper(II) complexes, K[Cu2(L)2Pz] nH2O, were also prepared and the X-ray molecular structure of K2[Cu4(SBzh)4(Pz)2] 2H2O 1/2CH3OH was determined. In this complex, two copper(II) atoms are bridged by only one pyrazolate anion forming a dicopper mono(μ-pyrazolate) unit. Each two units are connected together by a five coordinate K+ cation forming a tetranuclear assembly. These tetranuclear assemblies are connected together by another K+ cation forming a supramolecular structure. Variable temperature magnetic studies on these pyrazolate complexes indicated antiferromagnetic behaviour with −2J values varying from 25 to 36 cm−1.  相似文献   

19.
Poly(methyl methacrylate-ran-perfluoroalkyl ethyl methacrylate) copolymers having varying perfluoroalkyl ethyl methacrylate ester (Zonyl-TM) contents were synthesized in supercritical CO2. Complete amorphous structures of the copolymers were verified by XRD. Young's modulus (Ymod) of the copolymers was decreased linearly from 1.57 to 1.08 GPa and Tg values from 102 to 77 °C with the increase of Zonyl-TM content. A linear relationship between the Ymod and the Tg values of the copolymer was also found. The increase of the large branched pendant groups resulted in the increase of the free volume and a corresponding decrease in Ymod and Tg of the copolymers. A good fit was found when the Schneider equation was used. Negative deviation from the Gordon-Taylor equation was observed when Zonyl-TM content was lower than 14% due to rapid increase in free volume and then a positive deviation was found due to the dipole-dipole interactions between the methyl ester and fluoroalkyl ester groups.  相似文献   

20.
Abstract  Acetone [N-(3-hydroxy-2-naphthoyl)] hydrazone (H2AHNH) has been prepared and its structure confirmed by elemental analysis and 1H NMR spectroscopy. It has been used to produce diverse complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and U(VI)O2 ions. The complexes obtained have been investigated by thermal analysis, spectral studies (1H NMR, IR, UV–visible, ESR), and magnetic measurements. IR spectra suggest that H2AHNH acts as a bidentate ligand. The electronic spectra of the complexes and their magnetic moments provide information about geometries. The ESR spectra give evidence for the proposed structure and the bonding for some Cu(II) complexes. Thermal decomposition of the Ni(II) and Cu(II) complexes afforded metal oxides as final products. Kinetic data were obtained for each stage of thermal degradation of some of the complexes using the Coats–Redfern method. The formation of complexes in solution was studied pH-metrically and the order of their stability constants (log K) was found to be U(VI)O2 > Cu(II) > Zn(II) > Ni(II) > Cd(II) > Co(II). Antimicrobial and eukaryotic DNA studies were carried out. Graphical abstract     相似文献   

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