Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Phosphonates

  • nucleoside phosphonate

  • Terms modified by Phosphonates

  • phosphonate derivative
  • phosphonate ester
  • phosphonate group
  • phosphonate groups
  • phosphonate oxygen atom

  • Selected Abstracts

    A Tripodal Peptidic Titanium Phosphonate as a Homochiral Porous Solid Medium for the Heterogeneous Enantioselective Hydration of Epoxides

    Anat Milo
    Abstract A porous, homochiral titanium-phosphonate material based on a tripodal peptide scaffold was used as a heterogeneous reaction medium for the enantioselective hydration (>99%) of styrene oxide. This titanium-phosphonate material, which was shown to contain confined chiral spaces, was prepared by polymerization of L -leucine onto a tris(2-aminoethyl)amine initiator, followed by capping with phosphonate groups and completed by non-aqueous condensation with titanium isopropoxide. Circular dichroism confirmed that the peptide tethers yielded a secondary structure. X-ray powder diffraction and transmission electron microscopy supported by a semi-empirical model showed the likely formation of a porous, lamellar material that was quantified by nitrogen adsorption. [source]

    ChemInform Abstract: A Highly Conjunctive ,-Keto Phosphonate: Application to the Synthesis of Pyridine Alkaloids Xestamines C, E, and H.

    CHEMINFORM, Issue 26 2008
    Matthieu Corbet
    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: Preparation and Deprotection of 1,1-Diacetates (Acylals) Using Zirconium Sulfophenyl Phosphonate as Catalyst.

    CHEMINFORM, Issue 30 2002
    Massimo Curini
    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]

    Study of Intramolecular Competition between Carboxylate and Phosphonate for PtII with the Aid of a Novel Tridentate Carboxylato-Thioether-Phosphonato Ligand

    Matthieu Hamel Dr.
    Abstract The tridentate dianionic ligand 2-[2,-(hydroxyisopropoxyphosphoryl)phenylsulfanyl]benzoate (L2,) reacts with cis -[Pt(NH3)2(H2O)2]2+ to form an S,O-chelate in which the O-coordinated group is either carboxylate or phosphonate, depending on the degree of protonation of the complex. Carboxylate appears to be the stronger ligand, and the stoichiometric reaction between cis -[Pt(NH3)2(H2O)2]2+ and L2, yields the neutral species [Pt(L)(NH3)2], with L bound by sulfanyl and carboxylate groups, both in solution and in the solid state. Upon protonation of [Pt(L)(NH3)2], the stronger basicity of the carboxylate causes the Pt coordination to switch from carboxylate to phosphonate, and the uncoordinated carboxylate group becomes protonated. In methanolic solution, the first-order kinetics of this rearrangement could be observed by 31P,NMR spectroscopy. Both complexes,the carboxylate-bound neutral complex [Pt(L)(NH3)2],H2O (triclinic, P (no.,2), a=9.529(6), b=9.766(6), c=12.299(7),, ,=106.91(2), ,=101.71(2), ,=102.05(2), Z=2) and the perchlorate salt of the phosphonate-bound complex [Pt(LH)(NH3)2]ClO4,H2O (monoclinic, P21/c (no.,14), a=12.095(2), b=14.046(2), c=14.448(2),, ,=95.55(2), Z=4),were characterized by X-ray crystallography. [source]

    Synthesis and Characterization of 1-, 2-, and 3-Dimensional Bimetallic UO22+/Zn2+ Phosphonoacetates

    Karah E. Knope
    Abstract Four bimetallic UO22+/Zn2+ phosphonoacetates have been prepared from hydrothermal reactions of uranyl nitrate, zinc nitrate, and triethyl phosphonoacetate. These compounds, (UO2)2(PPA)2(H2O)2Zn(H2O)64H2O (1), (UO2)4(PPA)2(HPPA)2Zn(H2O)65H2O(2), (UO2)2(H2O)2(PPA)2Zn(H2O)4 (3), and (UO2)2(PPA)2(HPPA)Zn2(H2O)23(H2O) (4), adopt 1-, 2-, and 3-dimensional architectures wherein the UO22+ cation exhibits coordination preference for the phosphonate over the carboxylate oxygen atoms. The Zn2+ metal centers show an increased degree of ligand coordination with increasing reaction temperature. At 120 C, compounds 1 and 2 are formed. These structures are 1- and 2-dimensional, respectively, and contain fully hydrated [Zn(H2O)6]2+ cations. At 150 C and 180 C, the HPPA ligand displaces H2O molecules from the inner Zn2+ hydration sphere and binds to the metal centers via a ,CO2H oxygen atom in 3 and both carboxylate and phosphonate oxygen atoms in 4. The overall Zn2+ reaction can be expressed by the equation Zn(H2O)62+ + HPPA [rlarr2] Zn(H2O)5(HPPA) + H2O. Presented here are the syntheses, structures, and characterization of these materials. [source]

    Synthesis and Structural Characterisation of Palladium and Group-12 Metal Complexes with a Hybrid Phosphanylphosphonate Ferrocene Ligand


    Abstract Diethyl [1,-(diphenylphosphanyl)ferrocenyl]phosphonate (1) was synthesised by stepwise metallation/functionalisation of 1,1,-dibromoferrocene and studied as a ligand for palladium(II) and group-12 metals. Treatment of [PdCl2(cod)] (cod = ,2:,2 -cycloocta-1,5-diene) with 1 in 1:1 or 1:2 molar ratios gave, respectively, the dinuclear, chloride-bridged complex [{Pd(,-Cl)Cl(1 -,P2)}2] (2) and the mononuclear complex trans -[PdCl2(1 -,P2)2] (3), where 1 coordinates exclusively through the phosphane function. The reactions between 1 and group-12 metal bromides MBr2 in a 1:1 molar ratio gave the adducts [MBr2(1)] [M = Zn (4), Cd (5), and Hg (6)], whose crystal structures change considerably with the metal ion. Thus, whereas 4 is a molecular complex with 1 coordinating as an O1,P2 -chelate, its cadmium(II) analogue is a polymer built up from symmetric {CdBr(,-Br)}2 units interconnected by pairs of O1,P2 -bridging phosphanylphosphonate ligands. Finally, the mercury(II) complex 6 is a halide-bridged dimer, [{Hg(,-Br)Br(1 -,P2)}2]. However, this compound is structurally fluxional in solution (NMR spectra) and, in the crystal, it attains a structure similar to 5 owing to weak interactions between mercury and phosphonate-O1 atoms from adjacent molecules. An isomer to 6, [{HgBr2(1 -,2O1,P2)}2] (7), was isolated from attempted alkylation of 6 and structurally characterised as a dimer, where ligands 1 bridge two {HgBr2} units. All compounds were studied by spectroscopic methods (IR, NMR, mass) and the solid-state structures of 1, 2,H2O, 34,CHCl3, 4, 5, 65,C6H6, and 7 have been determined by single-crystal X-ray diffraction. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    Propyne Iminium Salts and Phosphorus(III) Nucleophiles: Synthesis of (3-Morpholinoallenyl)phosphanes and -phosphane Oxides or 1-(Morpholinopropargyl)phosphanes and -phosphonates

    Martin Reisser
    Abstract Treatment of 4-(1,3-diphenyl-l-propynylidene)morpholinium triflate (1a) with the neutral phosphorus nucleophiles Me3Si,PPh2, Me3Si,P(Ph)C5H11, and Me3SiO,PPh2 affords (3-morpholinoallenyl)phosphanes 4 and 5 and (3-morpholinoallenyl)phosphane oxide 11, respectively. In contrast to these conjugate addition reactions at the ambident propyne iminium moiety of 1a, nucleophilic attack by Me3Si,PEt2 and Me3SiO,P(OEt)2 takes place at the iminium function and gives (1-morpholinopropargyl)phosphane 6 and (1-morpholinopropargyl)phosphonate 12, respectively. Propyne iminium salt 1b reacts with Me3Si,PPh2 to form (3-morpholino-1,3-butadienyl)phosphane oxide 8. The bis(donor)-substituted allene 4 is transformed by oxidation of the phosphorus substituent into the push-pull substituted allenylphosphane oxide 11. Treatment of allene 4 with elemental sulfur results in the formation of betaine 16, which undergoes [3+2] cycloaddition reactions with acetylenic esters to afford 5-benzylidene-4,5-dihydrothiophenes 17 and 18. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

    Acylation of lysophosphatidylcholine plays a key role in the response of monocytes to lipopolysaccharide

    FEBS JOURNAL, Issue 13 2003
    Bernhard Schmid
    Mononuclear phagocytes play a pivotal role in the progression of septic shock by producing tumor necrosis factor-, (TNF-,) and other inflammatory mediators in response to lipopolysaccharide (LPS) from Gram-negative bacteria. Our previous studies have shown monocyte and macrophage activation correlate with changes in membrane phospholipid composition, mediated by acyltransferases. Interferon-, (IFN-,), which activates and primes these cells for enhanced inflammatory responses to LPS, was found to selectively activate lysophosphatidylcholine acyltransferase (LPCAT) (P < 0.05) but not lysophosphatidic acid acyltransferase (LPAAT) activity. When used to prime the human monocytic cell line MonoMac 6, the production of TNF-, and interleukin-6 (IL-6) was approximately five times greater in cells primed with IFN-, than unprimed cells. Two LPCAT inhibitors SK&F 98625 (diethyl 7-(3,4,5-triphenyl-2-oxo2,3-dihydro-imidazole-1-yl)heptane phosphonate) and YM 50201 (3-hydroxyethyl 5,3,-thiophenyl pyridine) strongly inhibited (up to 90%) TNF-, and IL-6 production in response to LPS in both unprimed MonoMac-6 cells and in cells primed with IFN-,. In similar experiments, these inhibitors also substantially decreased the response of both primed and unprimed peripheral blood mononuclear cells to LPS. Sequence-based amplification methods showed that SK&F 98625 inhibited TNF-, production by decreasing TNF-, mRNA levels in MonoMac-6 cells. Taken together, the data from these studies suggest that LPCAT is a key enzyme in both the pathways of activation (priming) and the inflammatory response to LPS in monocytes. [source]

    First Total Synthesis of Mappain with a Prenylated and Geranylated Stilbene

    Lakkoju Chakrapani
    Abstract The first total synthesis of naturally occurring mappain has been achieved by a convergent sequence. The key strategy involved in the synthesis of mappain was a (E)-stilbene formation by Horner,Wadsworth,Emmons reaction of the corresponding prenylated benzaldehyde with a geranylated benzyl phosphonate. [source]

    Novel routes to aminophosphonic acids: Interaction of dimethyl H-phosphonate with hydroxyalkyl carbamates

    K. Troev
    It was found that the reaction of dimethyl H-phosphonate (1) with 2-hydroxyalkyl- N -2,-hydroxyalkyl carbamates at 135C includes several chemical reaction steps: (i) chemical transformations of 1-methyl-2-hydroxyethyl- N -2,-hydroxyethyl carbamate (2) and 2-methyl-2-hydroxyethyl- N -2,-hydroxyethyl carbamate (3); (ii) transesterification of dimethyl H -phosphonate with 2 and 3, and with secondary hydroxyl-containing compounds that are formed during the course of the chemical transformation of 2-hydroxyalkyl- N -2,-hydroxyalkyl carbamates; (iii) hydrolysis of 1 and dialkyl H-phosphonates, formed via transesterification of 1 with secondary hydroxyl-containing compounds. The interaction was studied by means of 1H, 13C, 31P NMR, and FAB mass spectroscopy. 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:119,124, 2008; Published online in Wiley InterScience ( DOI 10.1002/hc.20404 [source]

    Rapid Microfluidic Generation of Patterned Aldehydes from Hydroxy-Terminated Self-Assembled Monolayers for Ligand and Cell Immobilization on Optically Transparent Indium Tin Oxide Surfaces

    ADVANCED MATERIALS, Issue 30 2009
    Abigail Pulsipher
    Selective immobilization of a wide range of ligands on an indium tin oxide (ITO) surface is demonstrated. A chemoselective immobilization strategy to tailor ITO surfaces is developed by selectively oxidizing hydroxyl-terminated phosphonate self-assembled monolayers (SAMs) to aldehyde-presenting SAMs using microfluidic channels and then reacting with oxyamine-containing ligands , all on a chip. [source]

    Iron-Catalyzed Oxidative Mono- and Bis-Phosphonation of N,N -Dialkylanilines

    Wei Han
    Abstract The dehydrogenative ,-phosphonation of substituted N,N -dialkylanilines by dialkyl H -phosphonates was achieved under mild conditions by using environmentally benign iron(II) chloride as catalyst and tert -butyl hydroperoxide as oxidant. The reaction proceeded in the presence of electron-donating (methoxy, methyl, benzyl) and electron-withdrawing ring-substitutents (bromo, carbonyl, carboxyl, m -nitro) in moderate to good yields. The X-ray crystal structure of N -(5,5-dimethyl-2-oxo-2,5 -[1,3,2]dioxaphosphinan-2-yl-methyl)- N -methyl- p -toluidine was determined. Bis-(4-(dimethylamino)phenyl)methane and bis-4,4,-(dimethylamino)benzophenone underwent bisphosphonation selectively by respective monophosphonation at the remote dimethylamino groups. Furthermore, the use of excess dialkyl H -phosphonate and oxidant allowed us to functionalize both methyl groups of N(CH3)2 in N,N -dimethyl- p -toluidine and N,N -dimethylaminomesidine, respectively, to obtain ,,,,-bisphosphonatoamines in high yield. [source]

    Synthesis of acyclic nucleoside phosphonates as antiviral compounds

    Frank Wormstdt
    Reaction of 6-chloropyrimidines with diethyl [(2-aminoethoxy)methyl]phosphonate allows for a ready access to acyclic nucleoside phosphonates. A series of 5-substituted pyrimidines bearing a phosphonate side chain at position 6 were synthesized and tested against herpes simplex viruses (HSV-1 and HSV-2) and human immunodeficiency virus (HIV-1). Some compounds showed weak antiviral activity against HSV-1. [source]

    A pyrazolylamine-phosphonate monoester chelator for the fac -[M(CO)3]+ core (M = Re, 99mTc): synthesis, coordination properties and biological assessment

    Elisa Palma
    Abstract Aiming to develop new strategies for the labeling of hydroxyl-containing biomolecules with the organometallic core fac -[99mTc(CO)3]+, we have prepared a new model bifunctional chelator, L4 (ethyl hydrogen (2-{[2-(3,5-dimethyl-1H -pyrazol-1-yl)ethyl]amino}ethyl)phosphonate), combining a pyrazolyl-amine chelating group and a monophosphonate ethyl ester function (,P(O)OHOEt). The phosphonate group allows metal stabilization, and, simultaneously, can be considered as a potential attachment site for a biomolecule. Reaction of L4 with the precursor [99mTc(H2O)3(CO)3]+ gave the model radiocomplex [99mTc(CO)3(k3 -L4)] (6a). This radiocomplex was identified by comparing its chromatographic profile with that of the corresponding Re analog (6) under the same conditions, also prepared and fully characterized by the usual analytical techniques. Radiocomplex 6a is moderately lipophilic (log Po/w = 1.07), presenting high stability in vitro without any measurable decomposition or ligand exchange, even in the presence of strong competing chelators such as histidine and cysteine (37C, 24 h). Biodistribution studies of the complex in CD-1 mice indicated a rapid blood clearance, and a rapid clearance from main organs, occurring primarily through the hepatobiliary pathway. Complex 6a presents also a high robustness in vivo, demonstrated by its resistance to metabolic degradation in blood, and intact excretion into the urine, after RP-HPLC analysis of blood and urine samples. Copyright 2007 John Wiley & Sons, Ltd. [source]

    DNA aptamers developed against a soman derivative cross-react with the methylphosphonic acid core but not with flanking hydrophobic groups

    John G. Bruno
    Abstract Twelve rounds of systematic evolution of ligands by exponential enrichment (SELEX) were conducted against a magnetic bead conjugate of the para -aminophenylpinacolylmethylphosphonate (PAPMP) derivative of the organophosphorus (OP) nerve agent soman (GD). The goal was to develop DNA aptamers that could scavenge GD in vivo, thereby reducing or eliminating the toxic effects of this dangerous compound. Aptamers were sequenced and screened in peroxidase-based colorimetric plate assays after rounds 8 and 12 of SELEX. The aptamer candidate sequences exhibiting the highest affinity for the GD derivative from round 8 also reappeared in several clones from round 12. Each of the highest affinity PAPMP-binding aptamers also bound methylphosphonic acid (MPA). In addition, the aptamer with the highest overall affinity for PAPMP carried a sequence motif (TTTAGT) thought to bind MPA based on previously published data (J. Fluoresc 18: 867,876, 2008). This sequence motif was found in several other relatively high affinity PAPMP aptamer candidates as well. In studies with the nerve agent GD, pre-incubation of a large molar excess of aptamer candidates failed to protect human butyrylcholinesterase (BuChE) from inhibition. With the aid of three-dimensional molecular modeling of the GD derivative it appears that a hydrophilic cleft sandwiched between the pinacolyl group and the p -aminophenyl ring might channel nucleotide interactions to the phosphonate portion of the immobilized GD derivative. However, bona fide GD free in solution may be repulsed by the negative phosphate backbone of aptamers and rotate its phosphonate and fluorine moieties away from the aptamer to avoid being bound. Future attempts to develop aptamers to GD might benefit from immobilizing the pinacolyl group of bona fide GD to enhance exposure of the phosphonate and fluorine to the random DNA library. Copyright 2008 John Wiley & Sons, Ltd. [source]

    Synthesis of lipophilic 2-oxoamides based on ,-aminobutyric and ,-aminovaleric analogues and their activity against phospholipase A2

    Panagiota Moutevelis-Minakakis
    Abstract A variety of lipophilic 2-oxoamides based on ,-aminobutyric and ,-aminovaleric analogues were synthesized. 2-oxoamides containing a tetrazole, a thioethyl or a thioacetyl group are weak inhibitors of GIVA cPLA2, while derivatives containing a methyl tetrazole, a diethyl phosphonate or a thioethyl group are weak inhibitors of GV sPLA2. Copyright 2007 European Peptide Society and John Wiley & Sons, Ltd. [source]

    An efficient process for synthesizing and hydrolyzing a phosphonated methacrylate: Investigation of the adhesive and anticorrosive properties

    Zhor El Asri
    Abstract A new phosphonated methacrylate, namely dimethyl(methacryloyloxy)methyl phosphonate (MAPC1), has been synthesized using paraformaldehyde and potassium carbonate according to the Pudovik reaction. The quantitative synthesis of MAPC1 was followed by selective hydrolysis of the ester group with sodium bromide to replace NaI (imparting non-negligible ecological impact). Pure MAPC1(OH) was obtained in high yield and efficiently copolymerized with MMA. The r1 for MAPC1(OH)) and r2 (for MMA) values are 0.99 and 1.02, respectively, which indicates that the monophosphonic groups are statistically linked to the methacrylate backbone. When blended with PVDF, MMA/MAPC1(OH) copolymers show very good adhesion promoters in both dry and wet conditions and subsequently provide good anticorrosive properties. 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4794,4803, 2008 [source]

    Phosphorylated copolymers containing pendant, crosslinkable spiro orthoester moieties

    J. Canadell
    Abstract The synthesis of a novel spiro orthoester containing monomer, 1,4,6-trioxaspiro[4.4]-2-nonylmethyl acrylate, is presented. This monomer was polymerized via a free-radical system to yield the homopolymer and a series of copolymers with phosphorus-containing comonomers. Diethyl vinyl phosphonate, allyldiphenylphosphine oxide, and diethyl(methacryoyoxymethyl)phosphonate were used in various feed ratios to produce copolymers with different phosphorous concentrations containing crosslinkable spiro orthoester side-chain units. The crosslinking of the polymers was performed cationically with ytterbium triflate, and in all cases, the expansion of the polymer was observed. Moreover, the incorporation of phosphorus into the copolymers increased the limiting oxygen indices, regardless of the percentage of phosphorus used. 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6728,6737, 2006 [source]

    Advanced flame-retardant epoxy resins from phosphorus-containing diol

    M. Jos Alcn
    Abstract Phosphorus-containing epoxy systems were prepared from isobutylbis(hydroxypropyl)phosphine oxide (IHPO) and diglycidyl ether of bisphenol A (DGEBA). Diethyl- N,N -bis(2-hydroxyethyl) aminomethyl phosphonate (Fyrol 6) could not be incorporated into the epoxy backbone by a reaction with either epichlorohydrin or DGEBA because intramolecular cyclization took place. The curing behavior of the IHPO,DGEBA prepolymer with two primary amines was studied, and materials with moderate glass-transition temperatures were obtained. V-0 materials were obtained when the resins were tested for ignition resistance with the UL-94 test. 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3510,3515, 2005 [source]

    Effect of an aliphatic spacer group on the adsorption mechanism on the colloidal silver surface of L -proline phosphonodipeptides

    Edyta Podstawka
    Abstract A comparative study of molecular structures of five L -proline (L -Pro) phosphonodipeptides: L -Pro-NH-C(Me,Me)-PO3H2 (P1), L -Pro-NH-C(Me,iPr)-PO3H2 (P2), L -Pro- L -NH-CH(iBu)-PO3H2 (P3), L -Pro- L -NH-CH(PA)-PO3H2 (P4) and L -Pro- L -NH-CH(BA)-PO3H2 (P5) has been carried out using Raman and absorption infrared techniques of molecular spectroscopy. The interpretation of the obtained spectra has been supported by density functional theory calculations (DFT) at the B3LYP; 6,31 + + G** level using Gaussian 2003 software. The surface-enhanced Raman scattering (SERS) on Ag-sol in aqueous solutions of these phosphonopeptides has also been investigated. The surface geometry of these molecules on a silver colloidal surface has been determined by observing the position and relative intensity changes of the Pro ring, amide, phosphonate and so-called spacer (,R) groups vibrations of the enhanced bands in their SERS spectra. Results show that P4 and P5 adsorb onto the silver as anionic molecules mainly via the amide bond (,1630, ,1533, ,1248, ,800 and ,565 cm,1), Pro ring (,956, ,907 and ,876 cm,1) and carboxylate group (,1395 and ,909 cm,1). Coadsorption of the imine nitrogen atom and PO group with the silver surface, possibly by formation of a weaker interaction with the metal, is also suggested by the enhancement of the bands at 1158 and 1248 cm,1. P1, P2 and P3 show two orientations of their main chain on the silver surface resulting from different interactions of the CCH3, NH and CONH fragments with this surface. Bonding to the Ag surface occurs mainly through the imino atom (1166 cm,1) for P2, while for P1 and P3 it occurs via the methyl group(s) (1194,1208 cm,1). The amide group functionality (CONH) is practically not involved in the adsorption process for P1 and P2, whereas the CsP bonds do assist in the adsorption. Copyright 2008 John Wiley & Sons, Ltd. [source]

    Novel Phosphorus-Containing Poly(ether sulfone)s and Their Blends with an Epoxy Resin: Thermal Decomposition and Fire Retardancy

    Ulrike Braun
    Abstract Summary: The decomposition of novel phosphorus-containing poly(oxyphenylene-sulfonyl-phenylene-oxy-diphenyl phenylene phosphine oxide) (PSU_I), 2,5-dihydroxy-1-biphenylene-phosphine oxide based polysulfone (PSU_II), poly(sulfonyl-diphenylphenylene phosphonate) (PSU_P) and bisphenol A-based polysulfone (PSU) is studied. The influence of the chemical structure, charring and phosphorus release is discussed based on the mass loss, kinetics and products. The pyrolysis and fire behaviour of blends with epoxy resin (EP) are studied. For EP-PSU_II, phosphorus initiates water elimination and changes the decomposition pathway of EP. The fire behaviour of EP-PSU shows some improvements, whereas the heat release rate is crucially reduced for EP-PSU_II due to simultaneous char formation and flame inhibition. Decomposition model of PSU_II. [source]

    Efficacy of phosphonic acid, metalaxyl-M and copper hydroxide against Phytophthora ramorum in vitro and in planta

    PLANT PATHOLOGY, Issue 1 2009
    M. Garbelotto
    The ability of metalaxyl-M, phosphonic acid in the form of phosphonate, and copper hydroxide to inhibit different stages in the life cycle of Phytophthora ramorum, the causal agent of sudden oak death (SOD), was tested in vitro using 12 isolates from the North American forest lineage. In addition, experiments were conducted in planta to study the ability of phosphonic acid injections and metalaxyl-M drenches to control pathogen growth on saplings of California coast live oak (Quercus agrifolia), and of copper hydroxide foliar sprays to control infection of California bay laurel (Umbellularia californica) leaves. Phytophthora ramorum was only moderately sensitive to phosphonic acid in vitro, but was highly sensitive to copper hydroxide. In planta experiments indicated the broad efficacy of phosphonic acid injections and of copper hydroxide sprays in preventing growth of P. ramorum in oaks and bay laurels, respectively. Finally, although metalaxyl-M was effective in vitro, drenches of potted oak trees using this active ingredient were largely ineffective in reducing the growth rate of the pathogen in planta. [source]

    Fireproofing of polyurethane elastomers by reactive organophosphonates

    Wassef El Khatib
    Abstract Polyurethane elastomers were prepared with hydroxytelechelic polybutadiene (HTPB) as polyol, modified 4,4,-diphenylmethane diisocyanate (modified MDI) as liquid polyisocyanate, and phosphonate diols as chain extenders and flame retardant compounds. These phosphonate diols were synthesized by radical thiol,ene addition of allyl or vinyl dialkyl phosphonate to 3-mercapto-1,2-propanediol. For various percentages of phosphorus (0 to 3%, w/w), polyurethane elastomers remain stable up to 250,C. The percentage of residual char at 600,C increases with increasing phosphorus content. For the soft segments, no variation in the glass transition temperature (Tg) is observed as the percentage of P increases, whereas the Tg of hard segments increases. Above 0.5% phosphorus content, the limiting oxygen index (LOI) becomes higher than the percentage of oxygen in the air. 2003 Society of Chemical Industry [source]

    Dynamically cured natural rubber/EVA blends: influence of NR- g -poly(dimethyl (methacryloyloxymethyl)phosphonate) compatibilizer

    Punyanich Intharapat
    Abstract Graft copolymer of natural rubber and poly(dimethyl(methacryloyloxymethyl)phosphonate) (NR- g -PDMMMP) was prepared in latex medium via photopolymerization. It was then used to promote the blend compatibility of dynamically cured 40/60 natural rubber (NR)/ethylene vinylacetate copolymer (EVA) blends using various loading levels at 1, 3, 5, 7, 9, 12, and 15,wt%. It was found that the increasing loading levels of NR- g -PDMMMP in the blends caused the increasing elastic modulus and complex viscosity until reaching the maximum values at a loading level of 9,wt%. The properties thereafter decreased with the increasing loading levels of NR- g -PDMMMP higher than 9,wt%. The smallest vulcanized rubber particles dispersed in the EVA matrix with the lowest tan , value was also observed at a loading level of 9,wt%. Furthermore, the highest tensile strength and elongation at break (i.e., 17.06 MPa and 660%) as well as the lowest tension set value (i.e., 27%) were also observed in the blend using this loading level of the compatibilizer. Addition of NR- g -PDMMMP in the dynamically cured NR/EVA blends also improved the thermal stability of the blend. That is, the decomposition temperature increased with the addition of the graft copolymer. However, the addition of NR- g -PDMMMP in the blends caused the decreasing degree of crystallinity of the EVA phase in the blend. However, the strength properties of the blend are still high because of the compatibilizing effect. Copyright 2009 John Wiley & Sons, Ltd. [source]

    Stereochemical effects in fragmentation of diastereoisomers of protected diethyl 1,2-diamino-alkylphosphonates

    Ewelina Drabik
    Diastereoisomers of diethyl 5-substituted (2-thioxo-imidazolidin-4-yl)phosphonates, which can be regarded as protected diethyl 1,2-diaminoalkylphosphonates, have been analyzed by electron ionization mass spectrometry. Significant differences in the fragmentation of cis - and trans -diastereoisomers were found. The stereospecificity of the elimination of diethyl phosphonate and the loss of the diethoxyphosphoryl group were studied using specific labeled compounds and collision-induced dissociation. The relative abundances of ions formed via these fragmentation processes can be used for differentiation of both diastereoisomers. Copyright 2010 John Wiley & Sons, Ltd. [source]

    A tetrahedrally coordinated cobalt(II) phosphonate with a three-dimensional framework containing two-dimensional channels

    Shu-Juan Fu
    The structure of poly[caesium(I) [(,4 -ethylenediphosphonato)cobalt(II)]], {Cs[Co(C2H5O6P2)]}n, reveals a three-dimensional polymeric open framework consisting of tetrahedral CoII atoms coordinated by four different ethylenediphosphonate O atoms and intermolecular O,H...O hydrogen bonds. The largest open window is made of corner-sharing CoO4 and PO3C tetrahedra, giving 16-membered rings of dimensions 9.677,(5) 4.684,(4),2. There are two independent ethylenediphosphonate ligands, each lying about an inversion centre. [source]

    Synthesis of Tyrosinase Inhibitory Kojic Acid Derivative

    ARCHIV DER PHARMAZIE, Issue 3 2006
    Yong Sup Lee
    Abstract Kojic acid derivative 2 was synthesized by joining two pyrone rings through an ethylene linkage by Horner-Emmons reaction of phosphonate 6 with aldehyde 7. The intermediates 6 and 7 were derived from kojic acid. The tyrosinase inhibitory activity of 2 was about 8 times more potent (IC50 = 3.63 ,M) than that of kojic acid (IC50 = 30.61 ,M). Compound 2 also exhibited potent melanin synthesis inhibitory activity (19.53% inhibition at 5 ,g) indicating that the connection of two pyrone rings of kojic acid through a suitable linker can be an useful strategy for identification of potent tyrosinase inhibitiors. [source]

    Conformational evaluation of labeled C3,-O-P- 13CH2 -O-C4, phosphonate internucleotide linkage, a phosphodiester isostere

    BIOPOLYMERS, Issue 7 2009

    Abstract Modified internucleotide linkage featuring the C3,-O-P-CH2 -O-C4, phosphonate grouping as an isosteric alternative to the phosphodiester C3,-O-P-O-CH2 -C4, bond was studied in order to learn more on its stereochemical arrangement, which we showed earlier to be of prime importance for the properties of the respective oligonucleotide analogues. Two approaches were pursued: First, the attempt to prepare the model dinucleoside phosphonate with 13C-labeled CH2 group present in the modified internucleotide linkage that would allow for a more detailed evaluation of the linkage conformation by NMR spectroscopy. Second, the use of ab initio calculations along with molecular dynamics (MD) simulations in order to observe the most populated conformations and specify main structural elements governing the conformational preferences. To deal with the former aim, a novel synthesis of key labeled reagent (CH3O)2P(O)13CH2OH for dimer preparation had to be elaborated using aqueous 13C-formaldehyde. The results from both approaches were compared and found consistent. 2009 Wiley Periodicals, Inc. Biopolymers 91: 514,529, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at [source]

    ChemInform Abstract: Ring Opening of Cyclic Vinylogous Acyl Triflates Using Stabilized Carbanion Nucleophiles: Claisen Condensation Linked to Carbon,Carbon Bond Cleavage.

    CHEMINFORM, Issue 37 2010
    David M. Jones
    Abstract Treatment of the cyclic triflates (I) and (VII) with carbanion nucleophiles provides acyclic alkynes bearing 1,3-diketone, ,-keto ester, ,-keto phosphonate, or ,-keto phosphine oxide moieties. [source]

    Lanthanide(III) Complexes of 4,10-Bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans -H6do2a2p) in Solution and in the Solid State: Structural Studies Along the Series

    M. Paula
    Abstract Complexes of 4,10-bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans -H6do2a2p, H6L) with transition metal and lanthanide(III) ions were investigated. The stability constant values of the divalent and trivalent metal-ion complexes are between the corresponding values of H4dota and H8dotp complexes, as a consequence of the ligand basicity. The solid-state structures of the ligand and of nine lanthanide(III) complexes were determined by X-ray diffraction. All the complexes are present as twisted-square-antiprismatic isomers and their structures can be divided into two series. The first one involves nona-coordinated complexes of the large lanthanide(III) ions (Ce, Nd, Sm) with a coordinated water molecule. In the series of Sm, Eu, Tb, Dy, Er, Yb, the complexes are octa-coordinated only by the ligand donor atoms and their coordination cages are more irregular. The formation kinetics and the acid-assisted dissociation of several LnIII,H6L complexes were investigated at different temperatures and compared with analogous data for complexes of other dota-like ligands. The [Ce(L)(H2O)]3, complex is the most kinetically inert among complexes of the investigated lanthanide(III) ions (Ce, Eu, Gd, Yb). Among mixed phosphonate,acetate dota analogues, kinetic inertness of the cerium(III) complexes is increased with a higher number of phosphonate arms in the ligand, whereas the opposite is true for europium(III) complexes. According to the 1H,NMR spectroscopic pseudo-contact shifts for the Ce,Eu and Tb,Yb series, the solution structures of the complexes reflect the structures of the [Ce(HL)(H2O)]2, and [Yb(HL)]2, anions, respectively, found in the solid state. However, these solution NMR spectroscopic studies showed that there is no unambiguous relation between 31P/1H lanthanide-induced shift (LIS) values and coordination of water in the complexes; the values rather express a relative position of the central ions between the N4 and O4 planes. [source]