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Base Complex (base + complex)

Distribution by Scientific Domains

Chemistry	58%
Polymers and Materials Science	33%

Kinds of Base Complex

schiff base complex

Selected Abstracts

Alternating Copolymerization of Carbon Dioxide and Propylene Oxide Catalyzed by Cobalt Schiff Base Complex

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2009
Yongsheng Niu
Abstract Cobalt 2,4-dinitrophenolate (complex 1) based upon a N,N,O,O -tetradentate Schiff base ligand framework was prepared. X-ray diffraction analysis confirmed that complex 1 was triclinic species with a six-coordinated central cobalt octahedron in the solid. Asymmetric alternating copolymerization of carbon dioxide (CO2) with racemic propylene oxide (rac -PO) proceeded effectively by complex 1 in conjunction with (4-dimethylamino)pyridine (DMAP), yielding a perfectly alternating and bimodal molecular weight distribution PO/CO2 poly(propylene carbonate) (PPC) with a small amount of cyclic carbonate byproducts. [source]

ChemInform Abstract: Efficient Oxidation of Hantzsch 1,4-Dihydropyridines with Tetrabutylammonium Peroxomonosulfate Catalyzed by Manganese(III) Schiff Base Complexes: The Effect of Schiff Base Complex on the Product Selectivity.

CHEMINFORM, Issue 15 2010
Masoud Nasr-Esfahani
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Direct Catalytic Asymmetric Aldol Reaction of ,-Keto Esters with Formaldehyde Promoted by a Dinuclear Ni2 -Schiff Base Complex.

CHEMINFORM, Issue 1 2010
Shinsuke Mouri
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Efficient Biomimetic Oxidative Decarboxylation of Some Carboxylic Acids Catalyzed by a Manganese(III) Schiff Base Complex.

CHEMINFORM, Issue 51 2009
Masoud Nasr-Esfahani
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Catalytic Oxidative Decarboxylation of Some Benzylcarboxylic Acid Derivatives by a New Iron(III) Schiff Base Complex.

CHEMINFORM, Issue 39 2009
Morteza Montazerozohori
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Direct Catalytic Asymmetric Mannich-Type Reaction of ,-Keto Phosphonate Using a Dinuclear Ni2,Schiff Base Complex.

CHEMINFORM, Issue 47 2008
Zhihua Chen
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: A Bench-Stable Homodinuclear Ni2,Schiff Base Complex for Catalytic Asymmetric Synthesis of ,-Tetrasubstituted anti-,,,-Diamino Acid Surrogates.

CHEMINFORM, Issue 26 2008
Zhihua Chen
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Ionic Liquid Grafted Mn(III),Schiff Base Complex: A Highly Efficient and Recyclable Catalyst for the Epoxidation of Chalcones.

CHEMINFORM, Issue 3 2006
Yanqing Peng
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

ChemInform Abstract: Oxo-Diels,Alder Reaction of Danishefsky,s Diene with Aldehydes, Catalyzed by Chiral Tridentate Chromium(III),Schiff Base Complexes.

CHEMINFORM, Issue 42 2010
Slawomir Miesowicz
Abstract The reaction is highly effective in the presence of CSB. [source]

ChemInform Abstract: Efficient Oxidation of Hantzsch 1,4-Dihydropyridines with Tetrabutylammonium Peroxomonosulfate Catalyzed by Manganese(III) Schiff Base Complexes: The Effect of Schiff Base Complex on the Product Selectivity.

Efficient Method for the Deprotection of tert-Butyldimethylsilyl Ethers with TiCl4,Lewis Base Complexes: Application to the Synthesis of 1,-Methylcarbapenems.

CHEMINFORM, Issue 49 2006
Akira Iida
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Corrigendum: Borane,Lewis Base Complexes as Homolytic Hydrogen Atom Donors

CHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2010
Johnny Hioe
No abstract is available for this article. [source]

Stabilization of G-Quadruplex DNA with Platinum(II) Schiff Base Complexes: Luminescent Probe and Down-Regulation of c- myc Oncogene Expression

CHEMISTRY - A EUROPEAN JOURNAL, Issue 47 2009
Peng Wu Dr.
Abstract The interactions of a series of platinum(II) Schiff base complexes with c- myc G-quadruplex DNA were studied. Complex [PtL1a] (1,a; H2L1a=N,N,-bis(salicylidene)-4,5-methoxy-1,2-phenylenediamine) can moderately inhibit c- myc gene promoter activity in a cell-free system through stabilizing the G-quadruplex structure and can inhibit c- myc oncogene expression in cultured cells. The interaction between 1,a and G-quadruplex DNA has been examined by 1H NMR spectroscopy. By using computer-aided structure-based drug design for hit-to-lead optimization, an in silico G-quadruplex DNA model has been constructed for docking-based virtual screening to develop new platinum(II) Schiff base complexes with improved inhibitory activities. Complex [PtL3] (3; H2L3=N,N,-bis{4-[1-(2-propylpiperidine)oxy]salicylidene}-4,5-methoxy-1,2-phenylenediamine) has been identified with a top score in the virtual screening. This complex was subsequently prepared and experimentally tested in vitro for its ability to stabilize or induce the formation of the c -myc G-quadruplex. The inhibitory activity of 3 (IC50=4.4,,M) is tenfold more than that of 1,a. The interaction between 1,a or 3 with c- myc G-quadruplex DNA has been examined by absorption titration, emission titration, molecular modeling, and NMR titration experiments, thus revealing that both 1,a and 3 bind c- myc G-quadruplex DNA through an external end-stacking mode at the 3' terminal face of the G-quadruplex. Such binding of G-quadruplex DNA with 3 is accompanied by up to an eightfold increase in the intensity of photoluminescence at ,max=652,nm. Complex 3 also effectively down-regulated the expression of c- myc in human hepatocarcinoma cells. [source]

Alternating copolymerization of carbon dioxide and epoxide catalyzed by an aluminum Schiff base,ammonium salt system

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2005
Hiroshi Sugimoto
Abstract The alternating copolymerization of carbon dioxide (CO2) and cyclohexene oxide (CHO) with an aluminum Schiff base complex in conjunction with an appropriate additive as a novel initiator is demonstrated. A typical example is the copolymerization of CO2 and CHO with the (Salophen)AlMe (1a),tetraethylammonium acetate (Et4NOAc) system. When a mixture of the 1a,Et4NOAc system and CHO was pressurized by CO2 (50 atm) at 80 °C in CH2Cl2, the copolymerization of CO2 and CHO took place smoothly and produced a high polymer yield in 24 h. From the IR and NMR spectra, the product was characterized to be a copolymer of CO2 and CHO with an almost perfect alternating structure. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis indicated that an unfavorable reaction between Et4NOAc and CH2Cl2 and a possible chain-transfer reaction with concomitant water occurred, and this resulted in the bimodal distribution of the obtained copolymer. With carefully predried reagents and apparatus, the alternating copolymerization in toluene gave a copolymer with a unimodal and narrower molecular weight distribution. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4172,4186, 2005 [source]

Stereoselective polymerization of rac -lactide with a bulky aluminum/Schiff base complex

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2004
Zhaohui Tang
Abstract An aluminum/Schiff base complex {[2,2-dimethyl-1,3-propylenebis(3,5-di- tert -butylsalicylideneiminato)](isopropanolato)aluminum(III) (2)} based on a bulky ligand and aluminum isopropoxide was prepared and employed for the stereoselective ring-opening polymerization (ROP) of rac -lactide (rac -LA). The initiator was characterized with nuclear magnetic resonance (NMR), crystal structure measurements, and elemental analysis. It contained a five-coordinate aluminum atom that was trigonal bipyramidal in the solid state according to the crystal structure measurements. The two conformational stereoisomers of 2 exchanged quickly on the NMR scale. Compound 2 polymerized rac -LA into a crystalline polymer that was characterized with 1H NMR, wide-angle X-ray diffraction, electrospray ionization mass spectrometry, and gel permeation chromatography. The kinetics of the polymerization were first-order in both the monomer and initiator, and there was a linear relationship between the rac -LA conversion and the number-average molecular weight of poly(rac -LA) with a narrow molecular distribution (1.04,1.08). These features showed that the polymerization was well controlled. The high melting temperature (196,201 °C) and isotacticity of poly(rac -LA) indicated that complex 2 was a highly stereoselective initiator for the ROP of rac -LA. The stereoselectivity was as high as 90%, and the stereoblocks of poly(rac -LA) by complex 2 contained an average of 20 units (average block length = 20) of enantiomerically pure lactic acid. The activation energy (23.6 kJ mol,1) was obtained according to an Arrhenius equation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5974,5982, 2004 [source]

Bis(salicyladiminato)Ni(II) Schiff base complexes, grafted on H-terminated Si(100) surfaces, observed by Scanning Near-field Optical/Atomic Force Microscopy (SNOM/AFM)

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2005
A. Ustione
Abstract This paper reports the synthesis and structure of a dipolar nonlinear optical bis(salicyladiminato)Ni(II) derived Schiff base complex, chemisorbed on H-terminated Si(100) surfaces. The existence of a monolayer of the derived complex, chemisorbed on the Si(100) surface is unambiguously confirmed by high resolution core-level XPS and AFM/SNOM analyses. The comparison between the optical SNOM images highlights the contribution of the monolayer to the local reflectivity of the sample. Angle-resolved XPS data indicate the presence of chlorine head-atoms on the monolayer surface. Altogether, XPS and AFM/SNOM data suggest the formation of a homogeneous, complete, and ordered monolayer self-assembled on the Si(100) surface. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Biodegradable poly(ester-ether)s: ring-opening polymerization of D,L-3-methyl-1,4-dioxan-2-one using various initiator systems

POLYMER INTERNATIONAL, Issue 9 2010
Yemanlall Lochee
Abstract The synthesis and detailed characterization of racemic 3-methyl-1,4-dioxan-2-one (3-MeDX) are reported. The bulk ring-opening polymerization of 3-MeDX, to yield a poly(ester-ether) meant for biomedical applications, in the presence of various initiators such as tin(II) octanoate, tin(II) octanoate/n -butyl alcohol, aluminium tris -isopropoxide and an aluminium Schiff base complex (HAPENAlOiPr) under varying experimental conditions is here detailed for the first time. Polymerization kinetics were investigated and compared with those of 1,4-dioxan-2-one. The studies reveal that the rate of polymerization of 3-MeDX is less than that of 1,4-dioxan-2-one. Experimental conditions to achieve relatively high molar masses have been established. Thermodynamic parameters such as enthalpy and entropy of 3-MeDX polymerization as well as ceiling temperature have been determined. Poly(D,L -3-MeDX) is found to possess a much lower ceiling temperature than poly(1,4-dioxan-2-one). Poly(D,L -3-MeDX) was characterized using NMR spectroscopy, matrix-assisted laser desorption ionization mass spectrometry, size exclusion chromatography and differential scanning calorimetry. This polymer is an amorphous material with a glass transition temperature of about ,20 °C. Copyright © 2010 Society of Chemical Industry [source]

Modification of Nafion membrane using poly(4-vinyl pyridine) for direct methanol fuel cell

POLYMER INTERNATIONAL, Issue 5 2006
Jeon Chan Woong
Abstract Perfluorinated membrane such as Nafion (from Du-Pont) has been used as a polymer electrolyte membrane. Nafion 117 membrane, which was usually used as the electrolyte membrane for the polymer electrolyte membrane fuel cell (PEMFC), was modified by using poly(4-vinyl pyridine) (P4VP) to reduce the methanol crossover, which cause fuel losses and lower power efficiency, by the formation of an ionic crosslink structure (sulfonic acid-pyridine complex) on the Nafion 117 surface. Nafion film was immersed in P4VP/N -methyl pyrrolidone (NMP) solution. P4VP weight percent of modified membrane was controlled by changing the concentration of P4VP/NMP solution and the dipping time. P4VP weight percent increased with increasing concentration of dipping solution and dipping time. The thickness of the P4VP layer increased with increasing concentration of dipping solution and dipping time when the concentration of the dipping solution was low. At high P4VP concentration, the thickness of the P4VP layer was almost constant owing to the formation of acid,base complex which interrupted the penetration of P4VP. FTIR results showed that P4VP could penetrate up to 30 µm of Nafion 117 membrane. Proton conductivity and methanol permeability of modified membrane were lower than those of Nafion 117. Both decreased with increasing concentration of dipping solution and dipping time. Methanol permeability was observed to be more dependent on the penetration depth of P4VP. Water uptake of the modified membrane, the important factor in a fuel cell, was lower than that of Nafion 117. Water uptake also decreased with increasing of P4VP weight. On the basis of this study, the thinner the P4VP layer on the Nafion 117 membrane, the higher was the proton conductivity. Methanol permeability decreased exponentially as a function of P4VP weight percent. Copyright © 2006 Society of Chemical Industry [source]

Synthesis of polymer-supported metal-ion complexes and evaluation of their catalytic activities

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008
K. C. Gupta
Abstract Polymer-supported transition-metal-ion complexes of the N,N,-bis(o -hydroxy acetophenone) propylenediamine (HPPn) Schiff base were prepared by the complexation of iron(III), cobalt(II), and nickel(II) ions on a polymer-anchored N,N,-bis(5-amino- o -hydroxy acetophenone) propylenediamine Schiff base. The complexation of iron(III), cobalt(II), and nickel(II) ions on the polymer-anchored HPPn Schiff base was 83.44, 82.92, and 89.58 wt%, respectively, whereas the unsupported HPPn Schiff base showed 82.29, 81.18, and 87.29 wt % complexation of these metal ions. The iron(III) ion complexes of the HPPn Schiff base showed octahedral geometry, whereas the cobalt(II) and nickel(II) ion complexes were square planar in shape, as suggested by spectral and magnetic measurements. The thermal stability of the HPPn Schiff base increased with the complexation of metal ions, as evidenced by thermogravimetric analysis. The HPPn Schiff base showed a weight loss of 51.0 wt % at 500°C, but its iron(III), cobalt(II), and nickel(II) ion complexes showed weight losses of 27.0, 35.0, and 44.7 wt % at the same temperature. The catalytic activity of the unsupported and supported metal-ion complexes was analyzed by the study of the oxidation of phenol and epoxidation of cyclohexene in the presence of hydrogen peroxide. The supported HPPn Schiff base complexes of iron(III) ions showed a 73.0 wt % maximum conversion of phenol and 90.6 wt % epoxidation of cyclohexene, but unsupported complexes of iron(III) ions showed 63.8 wt % conversion of phenol and 83.2 wt % epoxidation of cyclohexene. The product selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was 93.1 wt % and 98.1 wt % with the supported HPPn Schiff base complexes of iron(III) ions, but it was low with the supported Schiff base complexes of cobalt(II) and nickel(II) ions. The selectivity for CTL and ECH varied with the molar ratio of the metal ions but remained unaffected by the molar ratio of hydrogen peroxide to the substrate. The energy of activation for the epoxidation of cyclohexene and oxidation of phenol with the polymer-supported Schiff base complexes of iron(III) ions was 10.0 and 12.7 kJ/mol, respectively, but it was found to be higher with the supported HPPn Schiff base complexes of cobalt(II) and nickel(II) ions and with the unsupported HPPn Schiff base complexes of iron(III), cobalt(II), and nickel(II) ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source]

Bis(salicyladiminato)Ni(II) Schiff base complexes, grafted on H-terminated Si(100) surfaces, observed by Scanning Near-field Optical/Atomic Force Microscopy (SNOM/AFM)

Catalytic activities of polymer-supported metal complexes in oxidation of phenol and epoxidation of cyclohexene

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2008
K. C. Gupta
Abstract The metal complexes of N, N,-bis (o -hydroxy acetophenone) propylene diamine (HPPn) Schiff base were supported on cross-linked polystyrene beads. The complexation of iron(III), copper(II), and zinc(II) ions on polymer-anchored HPPn Schiff base was 83.4, 85.7, and 84.5,wt%, respectively, whereas the complexation of these metal ions on unsupported HPPn Schiff base was 82.3, 84.5, and 83.9,wt%. The iron(III) complexes of HPPn Schiff base were octahedral in geometry, whereas copper(II) and zinc(II) ions complexes were square planar and tetrahedral. Complexation of metal ions increased the thermal stability of HPPn Schiff base. Catalytic activity of metal complexes was tested by studying the oxidation of phenol and epoxidation of cyclohexene in the presence of hydrogen peroxide. The polymer-supported HPPn Schiff base complexes of iron(III) ions showed 73.0,wt% conversion of phenol and 90.6,wt% conversion of cyclohexene at a molar ratio of 1:1:1 of substrate to catalyst and hydrogen peroxide, but unsupported complexes of iron(III) ions showed 63.8,wt% conversion for phenol and 83.2,wt% conversion for cyclohexene. The product selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was 93.1 and 98.3,wt%, respectively with supported HPPn Schiff base complexes of iron(III) ions but was lower with HPPn Schiff base complexes of copper(II) and zinc(II) ions. Activation energy for the epoxidation of cyclohexene and phenol conversion with unsupported HPPn Schiff base complexes of iron(III) ions was 16.6,kJ,mol,1 and 21.2,kJ,mol,1, respectively, but was lower with supported complexes of iron(III) ions. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Supramolecular association in proton-transfer adducts containing benzamidinium cations.

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010

Four organic salts, namely benzamidinidium orotate (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylate) hemihydrate, C7H9N2+·C5H3N2O4,·0.5H2O (BenzamH+·Or,), (I), benzamidinium isoorotate (2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate) trihydrate, C7H9N2+·C5H3N2O4,·3H2O (BenzamH+·Isor,), (II), benzamidinium diliturate (5-nitro-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-olate) dihydrate, C7H9N2+·C4H2N3O5,·2H2O (BenzamH+·Dil,), (III), and benzamidinium 5-nitrouracilate (5-nitro-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide), C7H9N2+·C4H2N3O4, (BenzamH+·Nit,), (IV), have been synthesized by a reaction between benzamidine (benzenecarboximidamide or Benzam) and the appropriate carboxylic acid. Proton transfer occurs to the benzamidine imino N atom. In all four acid,base adducts, the asymmetric unit consists of one tautomeric aminooxo anion (Or,, Isor,, Dil, and Nit,) and one monoprotonated benzamidinium cation (BenzamH+), plus one-half (which lies across a twofold axis), three and two solvent water molecules in (I), (II) and (III), respectively. Due to the presence of protonated benzamidine, these acid,base complexes form supramolecular synthons characterized by N+,H...O, and N+,H...N, (±)-charge-assisted hydrogen bonds (CAHB). [source]