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1

Mechanisms of Phosphine Toxicity  

PubMed Central

Fumigation with phosphine gas is by far the most widely used treatment for the protection of stored grain against insect pests. The development of high-level resistance in insects now threatens its continued use. As there is no suitable chemical to replace phosphine, it is essential to understand the mechanisms of phosphine toxicity to increase the effectiveness of resistance management. Because phosphine is such a simple molecule (PH3), the chemistry of phosphorus is central to its toxicity. The elements above and below phosphorus in the periodic table are nitrogen (N) and arsenic (As), which also produce toxic hydrides, namely, NH3 and AsH3. The three hydrides cause related symptoms and similar changes to cellular and organismal physiology, including disruption of the sympathetic nervous system, suppressed energy metabolism and toxic changes to the redox state of the cell. We propose that these three effects are interdependent contributors to phosphine toxicity. PMID:21776261

Nath, Nisa S.; Bhattacharya, Ishita; Tuck, Andrew G.; Schlipalius, David I.; Ebert, Paul R.

2011-01-01

2

Confirmation of Circumstellar Phosphine  

NASA Astrophysics Data System (ADS)

Phosphine (PH3) was tentatively identified a few years ago in the carbon star envelopes IRC +10216 and CRL 2688 from observations of an emission line at 266.9 GHz attributable to the J = 1-0 rotational transition. We report the detection of the J = 2-1 rotational transition of PH3 in IRC +10216 using the HIFI instrument on board Herschel, which definitively confirms the identification of PH3. Radiative transfer calculations indicate that infrared pumping in excited vibrational states plays an important role in the excitation of PH3 in the envelope of IRC +10216, and that the observed lines are consistent with phosphine being formed anywhere between the star and 100 R * from the star, with an abundance of 10-8 relative to H2. The detection of PH3 challenges chemical models, none of which offer a satisfactory formation scenario. Although PH3 holds just 2% of the total available phosphorus in IRC +10216, it is, together with HCP, one of the major gas phase carriers of phosphorus in the inner circumstellar layers, suggesting that it could also be an important phosphorus species in other astronomical environments. This is the first unambiguous detection of PH3 outside the solar system, and is a further step toward a better understanding of the chemistry of phosphorus in space.

Agúndez, M.; Cernicharo, J.; Decin, L.; Encrenaz, P.; Teyssier, D.

2014-08-01

3

Multicomponent reactions involving phosphines, arynes and aldehydes.  

PubMed

Although nucleophilic phosphine-catalysis is a powerful tool for the construction of various carbocycles and heterocycles, the reactions in which phosphines are incorporated into the final product are rare, and the reports on phosphine addition to highly electrophilic arynes are scarce. Herein, we report the phosphine triggered multicomponent reaction of arynes and aldehydes, which takes place via the formal [3+2] cycloaddition of an initially generated 1,3-phosphonium zwitterion from phosphines and arynes with aldehydes. The reaction resulted in the formation of a diverse range of stable pentacovalent phosphoranes in good yields based on the benzooxaphosphole system. PMID:25123046

Bhunia, Anup; Kaicharla, Trinadh; Porwal, Digvijay; Gonnade, Rajesh G; Biju, Akkattu T

2014-10-01

4

Chiral phosphines in nucleophilic organocatalysis  

PubMed Central

Summary This review discusses the tertiary phosphines possessing various chiral skeletons that have been used in asymmetric nucleophilic organocatalytic reactions, including annulations of allenes, alkynes, and Morita–Baylis–Hillman (MBH) acetates, carbonates, and ketenes with activated alkenes and imines, allylic substitutions of MBH acetates and carbonates, Michael additions, ?-umpolung additions, and acylations of alcohols. PMID:25246969

Xiao, Yumei; Sun, Zhanhu

2014-01-01

5

?-Cationic phosphines: synthesis and applications.  

PubMed

In coordination chemistry, typical ancillary ligands are anionic or neutral species. Cationic ones are exceptions and, when used, the positively charged groups are normally attached to the periphery and not close to the donating atom. However, this concept article highlights a series of recent experimental, as well as theoretical results, suggesting that the utility in catalysis of cationic phosphines with no spacer between the phosphorus atom and the positively charged group(s) has been largely overlooked. In fact, a growing number of studies indicate that, because of their specific architecture, these cationic ligands depict excellent ?-acceptor character that can exceed that of phosphites or polyfluorinated phosphines. This property has been used to increase the Lewis acidity of the metals they coordinate. Specifically, new extreme ?-acid catalysts, mainly based on Pt(II) and Au(I) , have been recently prepared and their superior performance demonstrated along several mechanistically distinct transformations. In this concept article the current state of the art is critically assessed and possible future directions of the topic discussed. PMID:24890133

Alcarazo, Manuel

2014-06-23

6

New class of phosphine oxide donor-based supramolecular coordination complexes from an in situ phosphine oxidation reaction or phosphine oxide ligands.  

PubMed

A one-pot, multicomponent, coordination-driven self-assembly approach was used to synthesize the first examples of neutral bridging phosphine oxide donor-based supramolecular coordination complexes. The complexes were self-assembled from a fac-Re(CO)3 acceptor, an anionic bridging O donor, and a neutral soft phosphine or hard phosphine oxide donor. PMID:23984852

Shankar, Bhaskaran; Elumalai, Palani; Shanmugam, Ramasamy; Singh, Virender; Masram, Dhanraj T; Sathiyendiran, Malaichamy

2013-09-16

7

Cs2CO3-promoted one-pot synthesis of alkynylphosphonates, -phosphinates, and -phosphine oxides.  

PubMed

A novel and efficient Cs2CO3-promoted phosphorylation or phosphinylation of various 1,1-dibromo-1-alkenes with readily available trialkyl phosphites, ethyl diphenylphosphinite, or diethyl phenylphosphonite has been developed under metal-free conditions, providing a practical and powerful tool for one-pot synthesis of valuable alkynylphosphonates, -phosphinates, and -phosphine oxides in good to excellent yields. PMID:24661190

Wang, Yulei; Gan, Jiepeng; Liu, Liu; Yuan, Hang; Gao, Yuxing; Liu, Yan; Zhao, Yufen

2014-04-18

8

CYTOGENETIC EFFECTS OF PHOSPHINE INHALATION BY RODENTS  

EPA Science Inventory

Phosphine (PH3) is a highly toxic grain fumigant that can be produced from the reaction of metal phosphides with water. o determine the in vivo cytogenetic effects of inhalation of PH3, male CD-1 mice were exposed to either 0, 5, 10, or 15 ppm target concentrations of PH3 for 6 h...

9

Phosphine from rocks: mechanically driven phosphate reduction?  

PubMed

Natural rock and mineral samples released trace amounts of phosphine during dissolution in mineral acid. An order of magnitude more phosphine (average 1982 ng PH3 kg rock and maximum 6673 ng PH3/kg rock) is released from pulverized rock samples (basalt, gneiss, granite, clay, quartzitic pebbles, or marble). Phosphine was correlated to hardness and mechanical pulverization energy of the rocks. The yield of PH3 ranged from 0 to 0.01% of the total P content of the dissolved rock. Strong circumstantial evidence was gathered for reduction of phosphate in the rock via mechanochemical or "tribochemical" weathering at quartz and calcite/marble inclusions. Artificial reproduction of this mechanism by rubbing quartz rods coated with apatite-phosphate to the point of visible triboluminescence, led to detection of more than 70 000 ng/kg PH3 in the apatite. This reaction pathway may be considered a mechano-chemical analogue of phosphate reduction from lightning or electrical discharges and may contribute to phosphine production via tectonic forces and processing of rocks. PMID:16294866

Glindemann, Dietmar; Edwards, Marc; Morgenstern, Peter

2005-11-01

10

Synthesis of phosphaguanidines by hydrophosphination of carbodiimides with phosphine boranes.  

PubMed

The direct addition of anionic secondary phosphine boranes to carbodiimides yields both chiral and achiral phosphaguanidine boranes under ambient temperature conditions. An analogous preparation of menthol-derived phosphinite boranes is also described. These products can be deborinated to give the corresponding phosphines, and subsequently oxidized to give phosphine oxides. The robustness of this method was further demonstrated in the synthesis of structurally novel cyclic phosphaguanidines. PMID:25271367

Busacca, Carl A; Milligan, John A; Rattanangkool, Eakkaphon; Ramavarapu, Cyrus; Chen, Anji; Saha, Anjan K; Li, Zhibin; Lee, Heewon; Geib, Steven J; Wang, Guijun; Senanayake, Chris H; Wipf, Peter

2014-10-17

11

Synthesis and Characterization of a New Chiral Pentacyclic Phosphine  

Microsoft Academic Search

A new helically chiral pentacyclic phosphine, containing one thiophene ring, was prepared in good yield and purity via a five-step sequence involving a Wittig reaction, a palladium-catalysed Mizoroki-Heck coupling and classical oxidative photocyclization reactions. The investigation using UV-visible spectroscopy shows that the helicene precursor of the target helical phosphine as well as its phosphine oxide show an interesting behavior.

Souad Moussa; Faouzi Aloui; Béchir Ben Hassine

2012-01-01

12

7 CFR 305.7 - Phosphine treatment schedules.  

Code of Federal Regulations, 2010 CFR

... Regulations of the Department of Agriculture (Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS Chemical Treatments § 305.7 Phosphine treatment schedules....

2010-01-01

13

P-arylation: arynes to aryl-phosphonates, -phosphinates, and -phosphine oxides.  

PubMed

Synthesis of organo-phosphorus compounds and their application in organic synthesis and life sciences has been a topic of contemporary interest. Michaelis-Arbuzov reaction is the most extensively utilized method for their preparation, which works well only with aliphatic halides. Hence, relatively harsh reaction conditions using transition-metal-catalyzed P-arylation (Arbuzov/Hirao reaction) are used for the preparation of aryl-phosphorus compounds. Presented herein is a competent process for the synthesis of aryl-phosphonates, -phosphinates, and -phosphine oxides by making an efficient use of arynes for C-P bond construction. PMID:23590457

Dhokale, Ranjeet A; Mhaske, Santosh B

2013-05-01

14

Preparation of phosphines through C–P bond formation  

PubMed Central

Summary Phosphines are an important class of ligands in the field of metal-catalysis. This has spurred the development of new routes toward functionalized phosphines. Some of the most important C–P bond formation strategies were reviewed and organized according to the hybridization of carbon in the newly formed C–P bond. PMID:24991257

Wauters, Iris; Debrouwer, Wouter

2014-01-01

15

A NEW GENERATION OF FLAME RETARDED POLYAMIDES BASED ON PHOSPHINATES  

Microsoft Academic Search

Polyamide 6 and 66, especially glass fibre reinforced grades, can be effectively fire retarded with a new halogen free product based on an organic phosphinic acid salt. Organic phosphinates are a newly developed class of flame retardants for engineering thermoplastics, and are especially effective for polyamides and polyesters. The chemical registration process in Europe (ELINCS) and US (TSCA) has already

S. Hörold; O. Schacker; W. Wanzke

16

Nucleophilic conjugate 1,3-addition of phosphines to oligoynoates.  

PubMed

Herein we have elucidated unusual and unique nucleophilic conjugate 1,3-addition reactions of surveyed oligoynoates toward phosphines through spectroscopic and single crystal X-ray diffraction analyses of three-component reaction products of oligoynoates, phosphines and aldehydes. PMID:24950135

Deng, Jie-Cheng; Kuo, Chih-Wei; Chuang, Shih-Ching

2014-09-21

17

Prototypical phosphine complexes of antimony(III).  

PubMed

Complexes of the generic formula [Cln(PR3)mSb]((3-n)+) (n = 1, 2, 3, or 4 and m = 1 or 2) have been prepared featuring [ClSb](2+), [Cl2Sb](1+), Cl3Sb, or [Cl4Sb](1-) as acceptors with one or two phosphine ligands {PMe3, PPh3, PCy3 (Cy = C6H11)}. The solid-state structures of the complexes reveal foundational features that define the coordination chemistry of a lone pair bearing stibine acceptor site. The experimental observations are interpreted with dispersion-corrected density functional theory calculations to develop an understanding of the bonding and structural diversity. PMID:24773563

Chitnis, Saurabh S; Burford, Neil; McDonald, Robert; Ferguson, Michael J

2014-05-19

18

Diiodidobis(triphenyl-phosphine oxide)cadmium  

PubMed Central

In the title compound, [CdI2{(C6H5)3PO}2], the CdII atom is ligated by two I atoms and two O atoms from two triphenyl­phosphine oxide ligands in a disorted tetra­hedral arrangement. While the O—Cd—I angles vary from 106.67?(7) to 111.23?(7)°, the O—Cd—O angle is 88.60?(10)° and the I—Cd—I angle angle is 125.47?(2)°. The crystal structure is stabilized by van der Waals forces only. PMID:21522527

Shanthakumari, R.; Hema, R.; Ramamurthy, K.; Stoeckli-Evans, Helen

2011-01-01

19

Unsymmetrical Tertiary Phosphine Oxides from Diphenyl Phenylphosphonate: A Convenient Synthesis.  

National Technical Information Service (NTIS)

In view of recent developments concerning the cleavage of triphenylphosphine oxide by lithium reagents to give lithium intermediates which are useful in the synthesis of organophosphorus compounds, the availability of unsymmetrical tertiary phosphine oxid...

K. D. Berlin, M. Nagabhushanam

1964-01-01

20

Diphosphine Dioxide Cages and Hydrogen Peroxide Adducts of Phosphine Oxides: Syntheses and Applications in Surface Science  

E-print Network

Understanding the adsorption of phosphine oxides on silica surfaces has a threefold incentive. (a) Efficiently removing phosphine oxides from reaction mixtures is crucial after many synthetic procedures, for example the Wittig reaction. (b) Using...

Hilliard, Casie Renee

2013-12-09

21

The synthesis and applications of a biaryl-based asymmetric phosphine ligand  

E-print Network

The asymmetric biaryl backbone of a dialkylbiphenyl phosphine ligand was developed, synthesized, and resolved. The application of the chiral phosphine ligand to the asymmetric Suzuki-Miyaura cross-coupling reaction was ...

Hirai, Satoko

2005-01-01

22

Comparative Toxicity of Fumigants and a Phosphine Synergist Using a Novel Containment Chamber for the Safe Generation of Concentrated Phosphine Gas  

PubMed Central

Background With the phasing out of ozone-depleting substances in accordance with the United Nations Montreal Protocol, phosphine remains as the only economically viable fumigant for widespread use. However the development of high-level resistance in several pest insects threatens the future usage of phosphine; yet research into phosphine resistance mechanisms has been limited due to the potential for human poisoning in enclosed laboratory environments. Principal Findings Here we describe a custom-designed chamber for safely containing phosphine gas generated from aluminium phosphide tablets. In an improvement on previous generation systems, this chamber can be completely sealed to control the escape of phosphine. The device has been utilised in a screening program with C. elegans that has identified a phosphine synergist, and quantified the efficacy of a new fumigant against that of phosphine. The phosphine-induced mortality at 20°C has been determined with an LC50 of 732 ppm. This result was contrasted with the efficacy of a potential new botanical pesticide dimethyl disulphide, which for a 24 hour exposure at 20°C is 600 times more potent than phosphine (LC50 1.24 ppm). We also found that co-administration of the glutathione depletor diethyl maleate (DEM) with a sublethal dose of phosphine (70 ppm, phosphine in a laboratory environment has now been substantially reduced by the implementation of our novel gas generation chamber. We have also identified a novel phosphine synergist, the glutathione depletor DEM, suggesting an effective pathway to be targeted in future synergist research; as well as quantifying the efficacy of a potential alternative to phosphine, dimethyl disulphide. PMID:17205134

Valmas, Nicholas; Ebert, Paul R.

2006-01-01

23

Synthesis and structural characterization of isolable phosphine coinage metal ?-complexes  

PubMed Central

The chemical community has recently witnessed a dramatic increase in the application of cationic gold(I)-phosphine complexes as homogeneous catalysts for organic synthesis. The majority of gold(I)-catalyzed reactions rely on nucleophilic additions to carbon–carbon multiple bonds, which have been activated by coordination to a cationic gold(I) catalyst. However, structural evidence for coordination of cationic gold(I) complexes to alkynes has been limited. Here, we report the crystal structure of a gold(I)-phosphine ?2-coordinated alkyne. Related Ag(I) and Cu(I) complexes have been synthesized for comparison. The crystallization of these complexes was enabled by tethering a labile alkyne ligand to a strongly coordinating triarylphosphine. This approach also proved applicable to crystallization of the first gold(I)-phosphine ?2-coordinated alkene.

Shapiro, Nathan D.; Toste, F. Dean

2008-01-01

24

Enantioselective aldol reactions catalyzed by chiral phosphine oxides.  

PubMed

The development of enantioselective aldol reactions catalyzed by chiral phosphine oxides is described. The aldol reactions presented herein do not require the prior preparation of the masked enol ethers from carbonyl compounds as aldol donors. The reactions proceed through a trichlorosilyl enol ether intermediate, formed in situ from carbonyl compounds, which then acts as the aldol donor. Phosphine oxides activate the trichlorosilyl enol ethers to afford the aldol adducts with high stereoselectivities. This procedure was used to realize a directed cross-aldol reaction between ketones and two types of double aldol reactions (a reaction at one/two ? position(s) of a carbonyl group) with high diastereo- and enantioselectivities. PMID:23828817

Kotani, Shunsuke; Sugiura, Masaharu; Nakajima, Makoto

2013-08-01

25

Dipole moments and conformational analysis of tris(2-pyridyl)phosphine and tris(2-pyridyl)phosphine chalcogenides. Experimental and theoretical study  

NASA Astrophysics Data System (ADS)

Conformational analysis of tris(2-pyridyl)phosphine and tris(2-pyridyl)phosphine chalcogenides was carried out by the method of dipole moments and density functional theory calculations. The conformations of the examined compounds fit into the overall conformational picture for the PIII and PIV compounds: namely, these phosphines have non-eclipsed gauche- and trans-forms with propeller arrangement of the pyridyl radicals about the P = Y bond (Y = lone pair, O, S, Se).

Vereshchagina, Yana A.; Chachkov, Denis V.; Alimova, Alsu Z.; Malysheva, Svetlana F.; Gusarova, Nina K.; Ishmaeva, Eleonora A.; Trofimov, Boris A.

2014-11-01

26

Dialkylbiaryl Phosphines in Pd-Catalyzed Amination: A User's Guide  

PubMed Central

Dialkylbiaryl phosphines are a valuable class of ligand for Pd-catalyzed amination reactions and have been applied in a range of contexts. This review attempts to aid the reader in the selection of the best choice of reaction conditions and ligand of this class for the most commonly encountered and practically important substrate combinations. PMID:22432049

Surry, David S.

2012-01-01

27

Synthesis of 3-hydroxy-1-alkenylboronates via phosphine stabilized borylzirconacyclopropenes.  

PubMed

Zirconacyclopropenylboronates can be stabilized to dimerization by complexation with tributylphosphine; the phosphine stabilized zirconacycle boronates react with aliphatic and aromatic ketones and aldehydes at C2 of the triple bond to give the previously unknown 3-hydroxyvinylboronates in 61-80% isolated yields. PMID:18997961

Al Quntar, Abed Al Aziz; Botvinik, Alina; Rubinstein, Abraham; Srebnik, Morris

2008-11-21

28

40 CFR 180.225 - Phosphine; tolerances for residues.  

Code of Federal Regulations, 2010 CFR

...gas or phosphide compounds that produce phosphine gas. Commodity Parts per million Almond 0.1 Avocado 0.01 Banana 0.01 Barley, grain 0.1 Cabbage, Chinese, bok choy 0.01 Cabbage, Chinese, napa 0.01 Cacao...

2010-07-01

29

40 CFR 180.225 - Phosphine; tolerances for residues.  

Code of Federal Regulations, 2013 CFR

...gas or phosphide compounds that produce phosphine gas. Commodity Parts per million Almond 0.1 Avocado 0.01 Banana 0.01 Barley, grain 0.1 Cabbage, Chinese, bok choy 0.01 Cabbage, Chinese, napa 0.01 Cacao...

2013-07-01

30

40 CFR 180.225 - Phosphine; tolerances for residues.  

Code of Federal Regulations, 2012 CFR

...gas or phosphide compounds that produce phosphine gas. Commodity Parts per million Almond 0.1 Avocado 0.01 Banana 0.01 Barley, grain 0.1 Cabbage, Chinese, bok choy 0.01 Cabbage, Chinese, napa 0.01 Cacao...

2012-07-01

31

40 CFR 180.225 - Phosphine; tolerances for residues.  

Code of Federal Regulations, 2011 CFR

...gas or phosphide compounds that produce phosphine gas. Commodity Parts per million Almond 0.1 Avocado 0.01 Banana 0.01 Barley, grain 0.1 Cabbage, Chinese, bok choy 0.01 Cabbage, Chinese, napa 0.01 Cacao...

2011-07-01

32

[DIALKYLCARBAMOYLMETHYL] PHOSPHINE OXIDES ON THEIR EXTRACTION CAPACITY AND SELECTIVITY  

Microsoft Academic Search

Extraction of Am ( III), Pu( IV), U( VI) from nitric acid solutions by dialkyl ( aryl) [ dialkylcarbamoylmethyl] phosphine oxides of different structures has been studied.The nature of substituents at phosphorus and nitrogen atoms and in methylene bridge affects extraction capacity, solubility and selectivity of reagents.The increase in extraction capacity of reagents with respect to Am, U, Pu and

B. F. Myasoedov; M. K. Chmutova; N. E. Kochetkova; O. E. Koiro; G. A. Pribylova; N. P. Neeterova; T. Ya. Medved; M. I. Kabachnik

1986-01-01

33

Submicromolar phosphinic inhibitors of Escherichia coli aspartate transcarbamoylase.  

PubMed

The design, syntheses, and enzymatic activity of two submicromolar competitive inhibitors of aspartate transcarbamoylase (ATCase) are described. The phosphinate inhibitors are analogs of N-phosphonacetyl-l-aspartate (PALA) but have a reduced charge at the phosphorus moiety. The mechanistic implications are discussed in terms of a possible cyclic transition-state during enzymatic catalysis. PMID:19097895

Coudray, Laëtitia; Kantrowitz, Evan R; Montchamp, Jean-Luc

2009-02-01

34

Synthesis of binaphthyl based phosphine and phosphite ligands.  

PubMed

The development of large scale synthesis of enantiopure and thermally stable (R)- and (S)-BINOL molecules constitutes a key milestone in the field of asymmetric catalysis. Particularly, a great variety of chiral binaphthyl-based phosphorus compounds, herein represented by phosphite and phosphine classes, have earned considerable relevance due to their versatility as ligands in enantioselective metal-catalysed reactions, allowing the preparation of optically active products with the desired enantiopurity. This review highlights the most relevant concepts and accounts regarding general synthetic procedures for binaphthyl-based mono- and bidentate phosphites and phosphines. Furthermore, the search for environmentally benign chemical catalytic processes compelled us to also give special attention to the functionalisation of binaphthyl-based phosphorus ligands for use in alternative reaction media. When available, a critical selection of their applications in catalysis is briefly assessed. PMID:23783506

Pereira, Mariette M; Calvete, Mário J F; Carrilho, Rui M B; Abreu, Artur R

2013-08-21

35

Oxygen plasma resistant phosphine oxide containing imide/arylene copolymers  

NASA Technical Reports Server (NTRS)

A series of oxygen plasma resistant imide/arylene ether copolymers were prepared by reacting anhydride-terminated poly(amide acids) and amine-terminated polyarylene ethers containing phosphine oxide units. Inherent viscosities for these copolymers ranged from 0.42 to 0.80 dL/g. After curing, the resulting copolymers had glass transition temperatures ranging from 224 C to 228 C. Solution cast films of the block copolymers were tough and flexible with tensile strength, tensile moduli, and elongation at break up to 16.1 ksi, 439 ksi, and 23 percent, respectively at 25 C and 9.1 ksi, 308 ksi and 97 percent, respectively at 150 C. The copolymers show a significant improvement in resistance to oxygen plasma when compared to the commercial polyimide Kapton. The imide/arylene ether copolymers containing phosphine oxide units are suitable as coatings, films, adhesives, and composite matrices.

Jensen, Brian J.

1993-01-01

36

Retrievals of Jovian Tropospheric Phosphine from Cassini/CIRS  

NASA Technical Reports Server (NTRS)

On December 30th 2000, the Cassini-Huygens spacecraft reached the perijove milestone on its continuing journey to the Saturnian system. During an extended six-month encounter, the Composite Infrared Spectrometer (CIRS) returned spectra of the Jovian atmosphere, rings and satellites from 10-1400 cm(exp -1) (1000-7 microns) at a programmable spectral resolution of 0.5 to 15 cm(exp -1). The improved spectral resolution of CIRS over previous IR instrument-missions to Jupiter, the extended spectral range, and higher signal-to-noise performance provide significant advantages over previous data sets. CIRS global observations of the mid-infrared spectrum of Jupiter at medium resolution (2.5 cm(exp -1)) have been analysed both with a radiance differencing scheme and an optimal estimation retrieval model to retrieve the spatial variation of phosphine and ammonia fractional scale height in the troposphere between 60 deg S and 60 deg N at a spatial resolution of 6 deg. The ammonia fractional scale height appears to be high over the Equatorial Zone (EZ) but low over the North Equatorial Belt (NEB) and South Equatorial Belt (SEB) indicating rapid uplift or strong vertical mixing in the EZ. The abundance of phosphine shows a similar strong latitudinal variation which generally matches that of the ammonia fractional scale height. However while the ammonia fractional scale height distribution is to a first order symmetric in latitude, the phosphine distribution shows a North/South asymmetry at mid latitudes with higher amounts detected at 40 deg N than 40 deg S. In addition the data show that while the ammonia fractional scale height at this spatial resolution appears to be low over the Great Red Spot (GRS), indicating reduced vertical mixing above the approx. 500 mb level, the abundance of phosphine at deeper levels may be enhanced at the northern edge of the GRS indicating upwelling.

Irwin, P. G. J.; Parrish, P.; Fouchet, T.; Calcutt, S. B.; Taylor, F. W.; Simon-Miller, A. A.; Nixon, C. A.

2004-01-01

37

Biaryl Phosphine Ligands in Palladium-Catalyzed Amination  

PubMed Central

Palladium-catalyzed amination of aryl halides has undergone rapid development in the last 12 years. This has been largely driven by implementation of new classes of ligands. Biaryl phosphines have proven to provide especially active catalysts in this context. This review discusses the applications that these catalysts have found in C-N cross-coupling in heterocycle synthesis, pharmaceuticals, materials science and natural product synthesis. PMID:18663711

Surry, David S.

2012-01-01

38

Experiments in Thermodynamics and Kinetics of Phosphine Substitution in (p-Cymene)RuCl[subscript 2](PR[subscript 3])  

ERIC Educational Resources Information Center

This manuscript describes a set of three experiments that investigates the thermodynamic and kinetic aspects of phosphine substitution at a Ru center. In the first experiment, the students synthesize a Ru organometallic complex containing a phosphine ligand. In the second, equilibria for phosphine substitution involving several different…

Ozerov, Oleg V.; Fafard, Claudia M.; Hoffman, Norris W.

2007-01-01

39

Immobilization and chelation of metal complexes with bifunctional phosphine ligands: a solid-state NMR study  

E-print Network

, suspension NMR spectroscopy3can be applied routinely. Since most transition metals form stable phosphine com to bonding via one, two, or three siloxane bridges and there is also the possibility of cross- linking.' Therefore, we used the monoethoxy phosphine PPh2(C6H4)SiMe20Et1 that forms just one siloxane bridge when

Bluemel, Janet

40

PHOSPHINE-MEDIATED HEINZ BODY FORMATION AND HEMOGLOBIN OXIDATION IN HUMAN ERYTHROCYTES  

EPA Science Inventory

Exposure of hen erythrocytes in vitro to phosphine (PH 3) induces the development of Heinz body lesions. he lower limit for phosphine mediated Heinz body formation is 1.25 ppm for a four hour exposure. t exposure levels of 3.0 ppm or higher all erythrocytes are observed to contai...

41

DNA Alkylation by Leinamycin Can Be Triggered by Cyanide and Phosphines  

E-print Network

DNA Alkylation by Leinamycin Can Be Triggered by Cyanide and Phosphines Hong Zang, Leonid Breydo of the antibiotic with thiols. Here, it is shown that other soft nucleophiles such as cyanide and phosphines can also trigger DNA alkylation by leinamycin. Overall, the results suggest that reactions of cyanide

Gates, Kent. S.

42

[Distribution of matrix-bound phosphine in surface sediments of Jinpu Bay].  

PubMed

This work investigated the distribution of matrix-bound phosphine in surface sediments of Jinpu Bay and associated environmental factors in summer, using the gas chromatography combined with a pulsed flame detector (GC-PFPD). It showed that phosphine ubiquitously presented in the sediments of Jinpu Bay. Contents of matrix-bound phosphine varied between 62. 58 and 190. 81 ng.kg-1, with the average value of 114.42 ng.kg-1. In addition, the spatial distribution of matrix-bound phosphine indicated that matrix-bound phosphine in inshore sediments had relatively higher contents than those in offshore sediments. Statistical analysis showed that matrix-bound phosphine significantly related to organic phosphorus and alkaline phosphatase activity ( R = 0. 882, P = 0. 01; R = 0. 819, P =0. 023). However, there were no correlations between matrix-bound phosphine and organic nitrogen, inorganic phosphorus and sediment grain sizes. These results implied that accumulation and distribution of matrix-bound phosphined were mainly affected by the decomposition of organic phosphorus by microorganisms. PMID:24364296

You, Li-Li; Zong, Hai-Bo; Zhang, Shu-Fang; Yin, Guo-Yu; Li, Tao; Hou, Li-Jun

2013-10-01

43

Phosphinate-containing heterocycles: A mini-review  

PubMed Central

Summary This review provides an overview of recent efforts towards the synthesis of phosphinate heterocycles R1R2P(O)(OR). Our laboratory and others’ have been involved in this field and as a result new P–C, P–N, and P–O containing heterocyclic motifs are now available through a variety of methods. While developing rapidly, this area is still in its infancy so that biological testing of the compounds has not yet been conducted and applications are rare. The growing availability of synthetic methods will undoubtedly change this situation in the near future. PMID:24778726

Berger, Olivier

2014-01-01

44

Polyimides Containing Pendent Phosphine Oxide Groups for Space Applications  

NASA Technical Reports Server (NTRS)

As part of an ongoing materials development activity to produce high performance polymers that are durable to the space environment, phosphine oxide containing polyimides have been under investigation. A novel dianhydride was prepared from 2,5-dihydroxyphenyldiphenylphosphine oxide in good yield. The dianhydride was reacted with commercially available diamines, and a previously reported diamine was reacted with commercially available dianhydrides to prepare isomeric polyimides. The physical and mechanical properties, particularly thermal and optical properties, of the polymers were determined. One material exhibited a high glass transition temperature, high tensile properties, and low solar absorptivity. The chemistry, physical, and mechanical properties of these resins will be discussed.

Thompson, C. M.; Smith, J. G., Jr.; Watson, K. A.; Connell, J. W.

2002-01-01

45

Isocyanide and Phosphine Oxide Coordination in Binuclear Chromium Pacman Complexes  

PubMed Central

The new binuclear chromium Pacman complex [Cr2(L)] of the Schiff base pyrrole macrocycle H4L has been synthesized and structurally characterized. Addition of isocyanide, C?NR (R = xylyl, tBu), or triphenylphosphine oxide donors to [Cr2(L)] gives contrasting chemistry with the formation of the new coordination compounds [Cr2(?-CNR)(L)], in which the isocyanides bridge the two Cr(II) centers, and [Cr2(OPPh3)2(L)], a Cr(II) phosphine oxide adduct with the ligands exogenous to the cleft. PMID:24489428

2013-01-01

46

Effect of the Phosphine Steric and Electronic Profile on the Rh-Promoted Dehydrocoupling of Phosphine-Boranes  

PubMed Central

The electronic and steric effects in the stoichiometric dehydrocoupling of secondary and primary phosphine–boranes H3B·PR2H [R = 3,5-(CF3)2C6H3; p-(CF3)C6H4; p-(OMe)C6H4; adamantyl, Ad] and H3B·PCyH2 to form the metal-bound linear diboraphosphines H3B·PR2BH2·PR2H and H3B·PRHBH2·PRH2, respectively, are reported. Reaction of [Rh(L)(?6-FC6H5)][BArF4] [L = Ph2P(CH2)3PPh2, ArF = 3,5-(CF3)2C6H3] with 2 equiv of H3B·PR2H affords [Rh(L)(H)(?,?-PR2BH3)(?1-H3B·PR2H)][BArF4]. These complexes undergo dehydrocoupling to give the diboraphosphine complexes [Rh(L)(H)(?,?2-PR2·BH2PR2·BH3)][BArF4]. With electron-withdrawing groups on the phosphine–borane there is the parallel formation of the products of B–P cleavage, [Rh(L)(PR2H)2][BArF4], while with electron-donating groups no parallel product is formed. For the bulky, electron rich, H3B·P(Ad)2H no dehydrocoupling is observed, but an intermediate Rh(I) ? phosphine–borane complex is formed, [Rh(L){?2-H3B·P(Ad)2H}][BArF4], that undergoes B–P bond cleavage to give [Rh(L){?1-H3B·P(Ad)2H}{P(Ad)2H}][BArF4]. The relative rates of dehydrocoupling of H3B·PR2H (R = aryl) show that increasingly electron-withdrawing substituents result in faster dehydrocoupling, but also suffer from the formation of the parallel product resulting from P–B bond cleavage. H3B·PCyH2 undergoes a similar dehydrocoupling process, and gives a mixture of stereoisomers of the resulting metal-bound diboraphosphine that arise from activation of the prochiral P–H bonds, with one stereoisomer favored. This diastereomeric mixture may also be biased by use of a chiral phosphine ligand. The selectivity and efficiencies of resulting catalytic dehydrocoupling processes are also briefly discussed. PMID:24617924

2014-01-01

47

Toxicity of phosphine to Carposina niponensis (Lepidoptera: Carposinadae) at low temperature.  

PubMed

Carposina niponensis Matsumura (Lepidoptera: Carposinadae), is widely distributed in pome fruit production areas in China and presents a problem in some export markets because it is considered a quarantine pest by some countries. Methyl bromide is the only fumigant used for fumigation of apples (Malus spp.) for export. However, phosphine is a candidate replacement that can be applied directly at low temperature. Here, laboratory tests showed that tolerance of different stages of C. niponensis to phosphine fumigation at 0 degrees C differed greatly; first-second-instar larvae were the least tolerant stage and the mature fifth instars were the most tolerant stage. In the mature larvae, fumigation tests, with a range of phosphine concentrations from 0.42 to 1.95 mg/liters and exposure periods of 24 h to 14 d at 0 degrees C indicated narcosis when phosphine concentration was > or = 1.67 mg/liter and that a 15.52-8.14-d fumigation period was required to achieve 99% mortality with different phosphine concentrations. The expression of C(0.7)T = k was obtained, which indicated that exposure time was much more important than concentration of phosphine in mortality of mature larvae of C. niponensis. All results suggested that phosphine fumigation at low temperature offers promising control of C. niponensis infestation in pome fruit. PMID:21309217

Bo, Liu; Fanhua, Zhang; Yuejin, Wang

2010-12-01

48

Oxygenated phosphine fumigation for control of Epiphyas postvittana (Lepidoptera: Tortricidae) eggs on lettuce.  

PubMed

Light brown apple moth, Epiphyas postvittana (Walker), is a quarantined pest in most countries. Its establishment in California and potential spread to other parts of the state and beyond make it urgent to develop effective postharvest treatments to control the pest on fresh commodities. Fumigation with cylindered phosphine at low temperature has emerged to be a practical methyl bromide alternative treatment for postharvest pest control on fresh commodities. However, its use to control E. postvittana eggs on sensitive commodities such as lettuce is problematic. E. postvittana eggs are tolerant of phosphine and long phosphine treatment also injures lettuce. In the current study, E. postvittana eggs were subjected to oxygenated phosphine fumigations to develop an effective treatment at a low storage temperature of 2 degrees C. In addition, soda lime as a CO2 absorbent was tested to determine its effects in reducing and preventing injuries to lettuce associated with phosphine fumigations. Three-day fumigation with 1,000 ppm phosphine under 60% O2 achieved 100% mortality of E. postvittana eggs in small-scale laboratory tests. In the presence of the CO2 absorbent, a 3-d large-scale fumigation of lettuce with 1,700 ppm phosphine under 60% O2 resulted in a relative egg mortality of 99.96% without any negative effect on lettuce quality. The 3-d fumigation treatment without the CO2 absorbent, however, resulted in significant injuries to lettuce and consequential quality reductions. The study demonstrated that oxygenated phosphine fumigation has the potential to control E. postvittana eggs and the CO2 absorbent has the potential to prevent injuries and quality reductions of lettuce associated with long-term oxygenated phosphine fumigation. PMID:25195424

Liu, Samuel S; Liu, Yong-Biao; Simmons, Gregory S

2014-08-01

49

Synthesis of P,N-Heterocycles from ?-Amino-H-Phosphinates: Conformationally Restricted ?-Amino Acid Analogs  

PubMed Central

P,N-Heterocycles (3-hydroxy-1,3-azaphospholane and 3-hydroxy-1,3-azaphosphorinane-3-oxide) are synthesized in moderate yield from readily available ?-amino-H-phosphinates and aldehydes or ketones via an intramolecular Kabachnik-Fields reaction. The products are conformationally restricted phosphinic analogs of ?-amino acids. The multi-gram scale syntheses of the H2N(CH2)nPO2H2 phosphinic precursors (n = 1, 2, 3) and some derivatives are also described. PMID:18855477

Queffelec, Clemence; Ribiere, Patrice; Montchamp, Jean-Luc

2009-01-01

50

The preparation of 2,6-disubstituted pyridinyl phosphine oxides as novel anti-cancer agents.  

PubMed

A series of 2,6-dimethoxylpyridinyl phosphine oxides have been synthesized and examined for their antitumor activity. 2,6-Dimethoxy-3-phenyl-4-diphenylphosphinoylpyridine 2 has been employed as the lead compound for this study. We found out that the presence of phosphine oxide on the 2,6-dimethoxylpyridine ring is important for the antitumor activity; the presence of bromine on this core leads to a further enhancement of its antitumor activity. This is the first reported work on the antitumor activity of the 2,6-dimethoxy-3,5-dibromopyridinyl phosphine oxide 5b towards MDAMB-231 breast cancer and SKHep-1 hepatoma cell lines. PMID:19321340

Lam, Kim Hung; Gambari, Roberto; Yuen, Marcus Chun Wah; Kan, Chi Wai; Chan, Penni; Xu, Lijin; Tang, Weijun; Chui, Chung Hin; Cheng, Gregory Yin Ming; Wong, Raymond Siu Ming; Lau, Fung Yi; Tong, Cindy Sze Wai; Chan, Andrew Kit Wah; Lai, Paul Bo San; Kok, Stanton Hon Lung; Cheng, Chor Hing; Chan, Albert Sun Chi; Tang, Johnny Cheuk On

2009-04-15

51

Hydroxymethyl phosphine compounds for use as diagnostic and therapeutic pharmaceuticals and method of making same  

DOEpatents

A compound and method of making a compound for use as a diagnostic or therapeutic pharmaceutical comprises at least one functionalized hydroxyalkyl phosphine donor group and one or more sulfur or nitrogen donor and a metal combined with the ligand.

Katti, Kattesh V. (Columbia, MO); Karra, Srinivasa Rao (Columbia, MO); Berning, Douglas E. (Columbia, MO); Smith, C. Jeffrey (Columbia, MO); Volkert, Wynn A. (Columbia, MO); Ketring, Alan R. (Columbia, MO)

1999-01-01

52

Hydroxymethyl phosphine compounds for use as diagnostic and therapeutic pharmaceuticals and method of making same  

DOEpatents

A compound and method of making a compound for use as a diagnostic or therapeutic pharmaceutical comprises at least one functionalized hydroxyalkyl phosphine donor group and one or more sulfur or nitrogen donor and a metal combined with the ligand.

Katti, Kattesh V. (Columbia, MO); Karra, Srinivasa Rao (Columbia, MO); Berning, Douglas E. (Columbia, MO); Smith, C. Jeffrey (Columbia, MO); Volkert, Wynn A. (Columbia, MO); Ketring, Alan R. (Columbia, MO)

2000-01-01

53

Tetraphenylethylene-based phosphine: tuneable emission and carbon dioxide fixation.  

PubMed

A tetraphenylethylene-based phosphine, 1,1,2,2-tetrakis((4-diphenylphosphino)phenyl)ethylene (TPE-P4), was synthesized and showed novel aggregation-induced and mechano-responsive emission. A mixture of TPE-P4 and Ag(+) could fix atmospheric CO2in situ as carbonate ions in neutral solution to yield a rare 3D metal-organic framework with zeolite-like SOD topology, [Ag2(TPE-P4)CO3]x?nH2O (Ag-TPE-P4). Ag-TPE-P4 showed turn-on luminescence of TPE-P4, emitting bright bluish green light in the solid state. PMID:25216390

Zhang, Jianyong; Yang, Qiuli; Zhu, Yixuan; Liu, Haoliang; Chi, Zhenguo; Su, Cheng-Yong

2014-10-01

54

Phosphine-Catalyzed ??-Umpolung Addition of Nucleophiles to Activated ?-Alkyl Allenes  

PubMed Central

Highly functionalized alkenes can be prepared through phosphine-catalyzed ??-umpolung additions of nucleophiles (carbon-, oxygen-, nitrogen-, and sulfur-centered) to activated ?-disubstituted allenes, providing many potentially useful synthetic intermediates in good to excellent yields, often with high levels of stereoselectivity for the product olefin geometry. Various substitution patterns around the allene are compatible with the process, showcasing the synthetic utility of allenes under the conditions of nucleophilic phosphine catalysis. PMID:21491870

Martin, Tioga J.; Vakhshori, Venus G.; Tran, Yang S.; Kwon, Ohyun

2011-01-01

55

Phosphine oxide-catalyzed enantioselective intramolecular aldol reaction via regioselective enolization of unsymmetrical diketones with tetrachlorosilane.  

PubMed

The phosphine oxide-catalyzed asymmetric intramolecular aldol reactions of diketones were investigated. The combination of tetrachlorosilane and a chiral phosphine oxide catalyst promoted the acetyl-selective enolization of diketones, and the subsequent intramolecular aldol reaction occurred in an enantioselective manner. The introduction of two trimethylsilyl groups at the 4- and 4'-positions in BINAP dioxide catalyst improved the enantioselectivity. This reaction provides an effective synthetic method to access ?-tertiary-hydroxy cyclohexanones in high yields and with high enantioselectivity. PMID:25192225

Kotani, Shunsuke; Aoki, Shohei; Sugiura, Masaharu; Ogasawara, Masamichi; Nakajima, Makoto

2014-09-19

56

The mechanism of the phosphine-modified nickel-catalyzed acetic acid process  

Microsoft Academic Search

The nickel-catalyzed methanol (MeOH) carbonylation reaction was studied with an in situ infrared technique using a high pressure cylindrical internal reflectance reactor (CIR-reactor). The role of phosphine ligands was investigated in order to determine the relationship between the structural and electronic properties of the ligand and catalytic properties. It was found that the highest carbonylation rates occurred for the phosphine

William R Moser; Barbara J Marshik-Guerts; Stanley J Okrasinski

1999-01-01

57

Applications of chiral phosphine-based organocatalysts in catalytic asymmetric reactions.  

PubMed

Chiral phosphines are versatile Lewis basic catalysts that are capable of promoting a wide range of asymmetric reactions. In particular, recently designed chiral phosphines based on the concept of bi-/multifunctionality have been demonstrated to be effective catalysts for many types of asymmetric reactions, such as (aza)-MBH reactions, cycloaddition reactions, and nucleophilic addition reactions. This short overview summarizes the recent advances in this field and highlights the most-significant achievements. PMID:24819715

Wei, Yin; Shi, Min

2014-10-01

58

Room temperature, palladium-mediated P-arylation of secondary phosphine oxides.  

PubMed

We show that a broad range of aryl iodides are efficiently coupled with secondary phosphine oxides using 1 mol % of a catalyst formed in situ from tris(dibenzylideneacetone)dipalladium and Xantphos (1). Scalemic (S)-methylphenylphosphine oxide [(S)-2e] is shown to undergo arylation without detectable stereoerosion. The application of this method to the synthesis of novel P-chiral phosphines and PCP ligands is demonstrated. PMID:22905711

Bloomfield, Aaron J; Herzon, Seth B

2012-09-01

59

Synergistic Extraction and Separation of Heavy Lanthanide by Mixtures of Bis(2,4,4?trimethylpentyl)phosphinic Acid and 2?Ethylhexyl Phosphinic Acid Mono?2?Ethylhexyl Ester  

Microsoft Academic Search

The extraction of Yb from chloride solution has been studied using mixtures of bis(2,4,4?trimethylpentyl)phosphinic acid (Cyanex272) and 2?ethylhexyl phosphinic acid mono?2?ethylhexl ester (P507). The results show that Yb is extracted into heptane as YbA3(HA)3 with Cyanex272, YbL3(HL)3 with P507, and YbA2L4H3 with synergistic mixture. The equilibrium constants, formation constants, and thermodynamic functions have been determined. Extraction mechanism and extraction process

Ying Xiong; Xianglan Wang; Deqian Li

2005-01-01

60

A novel tridentate bis(phosphinic acid)phosphine oxide based europium(III)-selective Nafion membrane luminescent sensor.  

PubMed

A new europium(III) membrane luminescent sensor based on a new tridentate bis(phosphinic acid)phosphine oxide (3) system has been developed. The synthesis of this new ligand is described and its full characterization by NMR, IR and elemental analyses is provided. The luminescent complex formed between europium(III) chloride and ligand 3 was evaluated in solution, observing that its spectroscopic and chemical characteristics are excellent for measuring in polymer inclusion membranes. Included in a Nafion membrane, all the parameters (ligand and ionic additives) that can affect the sensitivity and selectivity of the sensing membrane as well as the instrumental conditions were carefully optimized. The best luminescence signal (?exc = 229.06 nm and ?em = 616.02 nm) was exhibited by the sensing film having a Nafion?:?ligand composition of 262.3?:?0.6 mg mL(-1). The membrane sensor showed a short response time (t95 = 5.0 ± 0.2 min) and an optimum working pH of 5.0 (25 mM acetate buffer solution). The membrane sensor manifested a good selectivity toward europium(III) ions with respect to other trivalent metals (iron, chromium and aluminium) and lanthanide(III) ions (lanthanum, samarium, terbium and ytterbium), although a small positive interference of terbium(III) ions was observed. It provided a linear range from 1.9 × 10(-8) to 5.0 × 10(-6) M with a very low detection limit (5.8 × 10(-9) M) and sensitivity (8.57 × 10(-7) a.u. per M). The applicability of this sensing film has been demonstrated by analyzing different kinds of spiked water samples obtaining recovery percentages of 95-97%. PMID:23967443

Sainz-Gonzalo, F J; Popovici, C; Casimiro, M; Raya-Barón, A; López-Ortiz, F; Fernández, I; Fernández-Sánchez, J F; Fernández-Gutiérrez, A

2013-10-21

61

A novel family of (1-aminoalkyl)(trifluoromethyl)- and -(difluoromethyl)phosphinic acids - analogues of ?-amino acids  

PubMed Central

Summary A series of novel (1-aminoalkyl)(trifluoromethyl)- and -(difluoromethyl)phosphinic acids – analogues of proteinogenic and nonproteinogenic ?-amino acids were prepared. The synthetic methodology was based on nucleophilic addition of (trifluoromethyl)phosphinic acid or (difluoromethyl)phosphinic acid or its ethyl ester to substrates with C=N or activated C=C double bonds. Analogues of glycine, phenylglycine, alanine, valine, proline, aminomalonic and aspartic acids were thus prepared. Three-component one-pot reactions of (trifluoromethyl)phosphinic acid and dibenzylamine with aldehydes were also tested to prepare the title compounds. PMID:24778725

Pavlenko, Natalia V; Oos, Tatiana I; Gerus, Igor I; Doeller, Uwe; Willms, Lothar

2014-01-01

62

Synthesis and Coordination Chemistry of Phosphine Oxide Decorated Dibenzofuran Platforms  

SciTech Connect

A four-step synthesis for 4,6-bis(diphenylphosphinoylmethyl)dibenzofuran (4) from dibenzofuran and a two-step synthesis for 4,6-bis(diphenylphosphinoyl)dibenzofuran (5) are reported along with coordination chemistry of 4 with In(III), La(III), Pr(III), Nd(III), Er(III), and Pu(IV) and of 5 with Er(III). Crystal structure determinations for the ligands, 4 {center_dot} CH{sub 3}OH and 5, the 1:1 complexes [In(4)(NO{sub 3}){sub 3}], [Pr(4)(NO{sub 3}){sub 3}(CH{sub 3}CN)] {center_dot} 0.5CH{sub 3}CN, [Er(4)(NO{sub 3}){sub 3}(CH{sub 3}CN)] {center_dot} CH{sub 3}CN, [Pu(4)Cl4] {center_dot} THF and the 2:1 complex [Nd(4){sub 2}(NO{sub 3}){sub 2}]{sub 2}(NO{sub 3}){sub 2} {center_dot} (H{sub 2}O) {center_dot} 4(CH{sub 3}OH) are described. In these complexes, ligand 4 coordinates in a bidentate POP{prime}O{prime} mode via the two phosphine oxide O-atoms. The dibenzofuran ring O-atom points toward the central metal cations, but in every case it is more than 4 {angstrom} from the metal. A similar bidentate POP{prime}O{prime} chelate structure is formed between 5 and Er(III) in the complex, {l_brace}[Er(5){sub 2}(NO{sub 3}){sub 2}](NO{sub 3}) {center_dot} 4(CH{sub 3}OH){r_brace}0.5, although the nonbonded Er{hor_ellipsis} O{sub furan} distance is reduced to 3.6 {angstrom}. The observed bidentate chelation modes for 4 and 5 are consistent with results from molecular mechanics computations. The solvent extraction performance of 4 and 5 in 1,2-dichloroethane for Eu(III) and Am(III) in nitric acid solutions is described and compared against the extraction behavior of n-octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (O{Phi}DiBCMPO) measured under identical conditions.

Rosario-Amorin, Daniel [University of New Mexico, Albuquerque; Duesler, Eileen N. [University of New Mexico, Albuquerque; Paine, Robert T. [University of New Mexico, Albuquerque; Hay, Benjamin [ORNL; Delmau, Laetitia Helene [ORNL; Reilly, Sean D. [Los Alamos National Laboratory (LANL); Gaunt, Andrew J. [Los Alamos National Laboratory (LANL); Scott, Brian L. [Los Alamos National Laboratory (LANL)

2012-01-01

63

Phosphine-promoted cross-coupling reactions of propargylcopper reagents and alkenyl iodides and the total synthesis of (-)-gloeosporone via nickel-catalyzed epoxide-alkyne reductive macrocyclization  

E-print Network

I. Phosphine-Promoted Cross-Coupling Reactions of Propargylcopper Alkenyl Iodides Reagents and Alkenyl Iodides. An electron-rich phosphine additive is critical and sufficient for propargyl-selective couplings of propargylcopper ...

Trenkle, James D. (James Douglas)

2007-01-01

64

Synthesis of p-aminophenyl aryl H-phosphinic acids and esters via cross-coupling reactions: elaboration to phosphinic acid pseudopeptide analogues of pteroyl glutamic acid and related antifolates.  

PubMed

The synthesis of suitably protected p-aminophenyl H-phosphinic acids and esters from the corresponding para-substituted aryl halides has been accomplished via the Pd-catalyzed cross-coupling reaction of anilinium hypophosphite, either in the absence or presence of a tetraalkyl orthosilicate, to provide the free H-phosphinic acid or the corresponding ester, respectively. Subsequent conjugate addition of either a PIII species or phosphorus anion, generated in situ from either the free H-phosphinic acid or ester, to a 2-methylene glutaric acid ester provided the aryl phosphinic acid analogue of p-aminobenzoyl glutamic acid. Alkylation of these suitably protected p-aminophenyl phosphinic acid esters with a 6-(bromomethyl)pteridine or the corresponding (bromomethyl)pyridopyrmidine, followed by hydrolytic removal of protecting groups, provided the target aryl phosphinic acid analogues of folic acid and related antifolates. Alternatively, for the synthesis of the folate or 5-deazafolate analogues on a slightly larger scale, reductive amination with either N2-acetyl or N2-pivaloyl-6-formylpterin or the corresponding formylpyridopyrmidine and the same suitably protected p-aminophenyl phosphinic acid esters, followed by removal of protecting groups, is preferred. In the course of this research, it was observed that the nucleophilicity of both the aniline nitrogen and various PIII species derived from p-aminophenyl phosphinic acid derivatives is significantly reduced compared to that of the unsubstituted counterpart. PMID:17602593

Yang, Yonghong; Coward, James K

2007-07-20

65

Phosphine-gold(I) compounds as anticancer agents: general description and mechanisms of action.  

PubMed

Gold complexes have been explored as metallodrugs with great potential applications as antitumoral agents. In particular, gold-phosphine derivatives seemed quite promising since the use of the antiarthritic auranofin drug (thiolate-Au-PEt3 complex) presented also biological activity against different cancer cells. So, different auranofin analogues have been explored within this context and for this reason, the main number of phosphine-gold complexes developed with this goal contain thiolate ligands. Other complexes have been also studied such as tetrahedral bis(phosphine)gold(I) and phosphine-gold-halides. Very recently, phosphine-gold-alkynyl complexes have also shown very interesting biological activities although few reports are published related to them. Their mechanism of action seems to be clearly different that the used by platinum drugs (DNA intercalating processes) and recent studies point to be related to the inhibition of Trx reductase. Cellular uptake and biodistribution studies are well reported in the original works but the use of luminescence techniques is relatively less explored. For this, the use of these techniques is also specifically reported in this review. PMID:21864238

Lima, João Carlos; Rodriguez, Laura

2011-12-01

66

A Bis(phosphine)-Modified Peptide Ligand for Stable and Luminescent Quantum Dots in Aqueous Media  

PubMed Central

We describe a new class of ligands for semiconductor nanoparticles (quantum dots = QDs), which bind well and allow for their facile dissolution in aqueous solution. As a proof of principle, we have designed and synthesized a novel bis(phosphine)-modified peptide (BPMP) and shown that it has the ability to solubilize quantum dots in aqueous media. We further showed that the corresponding phosphine oxide derivatives of these new ligands are less good at solubilizing the quantum dots. These new bis(phosphine)-modified peptide ligands are easy to prepare and may well replace thiol-containing binding sequences in functionalized peptides for quantum dot coating, potentially resulting in quantum dots with higher quantum yields. PMID:24729639

Jung, Michael E.; Trzoss, Michael; Tsay, James M.; Weiss, Shimon

2014-01-01

67

Phosphine on Jupiter and Saturn from Cassini/CIRS  

NASA Astrophysics Data System (ADS)

The global distribution of phosphine (PH 3) on Jupiter and Saturn is derived using 2.5 cm -1 spectral resolution Cassini/CIRS observations. We extend the preliminary PH 3 analyses on the gas giants [Irwin, P.G.J., and 6 colleagues, 2004. Icarus 172, 37-49; Fletcher, L.N., and 9 colleagues, 2007a. Icarus 188, 72-88] by (a) incorporating a wider range of Cassini/CIRS datasets and by considering a broader spectral range; (b) direct incorporation of thermal infrared opacities due to tropospheric aerosols and (c) using a common retrieval algorithm and spectroscopic line database to allow direct comparison between these two gas giants. The results suggest striking similarities between the tropospheric dynamics in the 100-1000 mbar regions of the giant planets: both demonstrate enhanced PH 3 at the equator, depletion over neighbouring equatorial belts and mid-latitude belt/zone structures. Saturn's polar PH 3 shows depletion within the hot cyclonic polar vortices. Jovian aerosol distributions are consistent with previous independent studies, and on Saturn we demonstrate that CIRS spectra are most consistent with a haze in the 100-400 mbar range with a mean optical depth of 0.1 at 10 ?m. Unlike Jupiter, Saturn's tropospheric haze shows a hemispherical asymmetry, being more opaque in the southern summer hemisphere than in the north. Thermal-IR haze opacity is not enhanced at Saturn's equator as it is on Jupiter. Small-scale perturbations to the mean PH 3 abundance are discussed both in terms of a model of meridional overturning and parameterisation as eddy mixing. The large-scale structure of the PH 3 distributions is likely to be related to changes in the photochemical lifetimes and the shielding due to aerosol opacities. On Saturn, the enhanced summer opacity results in shielding and extended photochemical lifetimes for PH 3, permitting elevated PH 3 levels over Saturn's summer hemisphere.

Fletcher, L. N.; Orton, G. S.; Teanby, N. A.; Irwin, P. G. J.

2009-08-01

68

Selective catalytic behavior of a phosphine-tagged metal-organic framework organocatalyst.  

PubMed

Steric hindrance by a metal-organic framework (MOF) is shown to influence the outcome of a catalytic reaction by controlling the orientation of its intermediates. This is demonstrated using an organocatalyst, phosphine MOF LSK-3, which is evaluated with the aid of molecular modeling and NMR spectroscopy techniques. This report is the first application of phosphine MOFs in organocatalysis and explores the potential of a framework steric hindrance to impose selectivity on a catalytic reaction. These findings expand the opportunities for control and design of the active site in the pocket of heterogeneous catalysts. PMID:25283694

Xu, Xiaoying; Rummelt, Stephan M; Morel, Flavien L; Ranocchiari, Marco; van Bokhoven, Jeroen A

2014-11-17

69

Phosphinic acid analogues of GABA are antagonists at the GABAB receptor in the rat anococcygeus.  

PubMed Central

CGP 35348 (3-aminopropyl(diethoxymethyl)phosphinic acid) and 3-aminopropyl(n-hexyl)phosphinic acid (3-APHPA) were tested in the rat anococcygeus muscle against CGP 27492 (3-aminopropylphosphinic acid), a selective GABAB agonist, for their antagonist activity. Their antagonist potency was compared with that of 2-hydroxysaclofen. The pA2 values for CGP 35348, 3-APHPA and 2-hydroxysaclofen were 5.38, 4.86, 4.45 respectively in the rat anococcygeus muscle. These results confirm the previous reports of GABAB antagonist activity for these compounds and show a marginal improvement in potency over 2-hydroxysaclofen. PMID:1646062

Hills, J. M.; Sellers, A. J.; Mistry, J.; Broekman, M.; Howson, W.

1991-01-01

70

A synthetic study of chiral ?-hydroxy-H-phosphinates based on proline catalysis.  

PubMed

A highly enantioselective synthesis of ?-hydroxyphosphinates was achieved based on the L-proline-catalyzed aldol reaction of ?-acylphosphinates and acetone. Due to the preexisting chirality at the phosphorus center, mixtures of two diastereomers of the ?-hydroxyphosphinates were obtained in moderate to good yields, with simultaneously high enantioselectivity for both diastereomers. The products could be converted into ?-hydroxy-H-phosphinates with satisfactory yields. Furthermore, an unprecedented oxidation-reduction reaction of the ?-hydroxyphosphinates or ?-hydroxy-H-phosphinates to form phosphonates was observed, and the mechanism involved in such a chemical transformation is discussed. PMID:23471759

Yao, Qiuli; Yuan, Chengye

2013-05-01

71

Penguins significantly increased phosphine formation and phosphorus contribution in maritime Antarctic soils.  

PubMed

Most studies on phosphorus cycle in the natural environment focused on phosphates, with limited data available for the reduced phosphine (PH3). In this paper, matrix-bound phosphine (MBP), gaseous phosphine fluxes and phosphorus fractions in the soils were investigated from a penguin colony, a seal colony and the adjacent animal-lacking tundra and background sites. The MBP levels (mean 200.3?ng kg(-1)) in penguin colony soils were much higher than those in seal colony soils, animal-lacking tundra soils and the background soils. Field PH3 flux observation and laboratory incubation experiments confirmed that penguin colony soils produced much higher PH3 emissions than seal colony soils and animal-lacking tundra soils. Overall high MBP levels and PH3 emissions were modulated by soil biogeochemical processes associated with penguin activities: sufficient supply of the nutrients phosphorus, nitrogen, and organic carbon from penguin guano, high soil bacterial abundance and phosphatase activity. It was proposed that organic or inorganic phosphorus compounds from penguin guano or seal excreta could be reduced to PH3 in the Antarctic soils through the bacterial activity. Our results indicated that penguin activity significantly increased soil phosphine formation and phosphorus contribution, thus played an important role in phosphorus cycle in terrestrial ecosystems of maritime Antarctica. PMID:25394572

Zhu, Renbin; Wang, Qing; Ding, Wei; Wang, Can; Hou, Lijun; Ma, Dawei

2014-01-01

72

Highly enantioselective phosphination and hydrophosphonylation of azomethine imines: using chiral squaramide as a hydrogen bonding organocatalyst.  

PubMed

Enantioselective phosphination and hydrophosphonylation reactions between azomethine imines and diarylphosphine oxides or dialkyl phosphites were respectively developed by the use of a chiral squaramide as the hydrogen bonding organocatalyst, which afforded two types of phosphorus containing product in high yields with good to excellent enantioselectivities. PMID:25252601

Kong, Ling-Pei; Li, Nai-Kai; Zhang, Shao-Yun; Chen, Xiang; Zhao, Min; Zhang, Ya-Fei; Wang, Xing-Wang

2014-10-15

73

Three-coordinate, luminescent, water-soluble gold(I) phosphine complexes: structural characterization and photoluminescence  

E-print Network

Three-coordinate, luminescent, water-soluble gold(I) phosphine complexes: structural some beautiful work involving gold Abstract The trigonal planar Au(I) complex Cs8[Au(TPPTS)3]Ã?/5.25H2O The photoluminescent properties of several types of three-coordinate gold(I) complexes in organic solvents

Abdou, Hanan E.

74

Phosphaannulation by palladium-catalyzed carbonylation of C-H bonds of phosphonic and phosphinic acids.  

PubMed

An efficient phosphaannulation by Pd-catalyzed carbonylation of C-H bonds of phosphonic and phosphinic acids for the synthesis of oxaphosphorinanone oxides is reported. These compounds are novel phosphorus heterocyclic scaffolds, thus opening a new avenue to sequential C-C/C-O bond formation in one pot. PMID:24856076

Shin, Seohyun; Jeong, Yeonseok; Jeon, Woo Hyung; Lee, Phil Ho

2014-06-01

75

The Bis(pentafluoroethyl)phosphinous acid (C2F5)2POH.  

PubMed

The industrial product (C(2)F(5))(3)PF(2) is transformed into the phosphinic acid chloride (C(2)F(5))(2)P(O)Cl, which reacts with an excess of Bu(3)SnH in a clean, multistep reaction to give the stannyl derivative (C(2)F(5))(2)POSnBu(3). Subsequent treatment with gaseous HBr leads to the formation of (C(2)F(5))(2)POH, which is isolated in 70 % yield. Besides (CF(3))(2)POH, bis(pentafluoroethyl)phosphinous acid, (C(2)F(5))(2)POH, represents the second known example of a phosphinous acid that is predicted by using density functional theory calculations at the B3PW91/6-311G(3d,p) level to be more stable than the phosphane oxide tautomer, the energy difference being 11.7 kJ mol(-1). Only the phosphinous acid isomer is detectable in the gas phase and in solution. However, investigations of the neat liquid reveal a temperature-dependent tautomeric equilibrium with the phosphane oxide isomer (C(2)F(5))(2)P(O)H, which is characterized by vibrational and multinuclear NMR spectroscopic methods in combination with quantum-chemical calculations. PMID:19219874

Hoge, Berthold; Bader, Julia; Beckers, Helmut; Kim, Yong Seol; Eujen, Reint; Willner, Helge; Ignatiev, Nikolai

2009-01-01

76

Phosphine-initiated domino reaction: a convenient method for the preparation of spirocyclopentanones.  

PubMed

An efficient synthetic approach has been developed for the construction of the spirocyclopentanone skeleton via a phosphine-catalyzed [3+2] annulation reaction. With this novel and economical protocol, various quaternary carbon-centered spirocyclopentanones could be readily obtained. PMID:24678009

Liang, Ling; Li, Erqing; Xie, Peizhong; Huang, You

2014-05-01

77

Preparation of Cadmium Selenide-Polyolefin Composites from Functional Phosphine Oxides and Ruthenium-Based  

E-print Network

Preparation of Cadmium Selenide-Polyolefin Composites from Functional Phosphine OxidesVersity of Massachusetts, Amherst, Massachusetts 01003 Received November 21, 2001 Abstract: Cadmium selenide nanoparticles by employing more easily handled cadmium sources, such as CdO. Both methods give well-defined nanoparticles

78

Penguins significantly increased phosphine formation and phosphorus contribution in maritime Antarctic soils  

PubMed Central

Most studies on phosphorus cycle in the natural environment focused on phosphates, with limited data available for the reduced phosphine (PH3). In this paper, matrix-bound phosphine (MBP), gaseous phosphine fluxes and phosphorus fractions in the soils were investigated from a penguin colony, a seal colony and the adjacent animal-lacking tundra and background sites. The MBP levels (mean 200.3?ng kg?1) in penguin colony soils were much higher than those in seal colony soils, animal-lacking tundra soils and the background soils. Field PH3 flux observation and laboratory incubation experiments confirmed that penguin colony soils produced much higher PH3 emissions than seal colony soils and animal-lacking tundra soils. Overall high MBP levels and PH3 emissions were modulated by soil biogeochemical processes associated with penguin activities: sufficient supply of the nutrients phosphorus, nitrogen, and organic carbon from penguin guano, high soil bacterial abundance and phosphatase activity. It was proposed that organic or inorganic phosphorus compounds from penguin guano or seal excreta could be reduced to PH3 in the Antarctic soils through the bacterial activity. Our results indicated that penguin activity significantly increased soil phosphine formation and phosphorus contribution, thus played an important role in phosphorus cycle in terrestrial ecosystems of maritime Antarctica. PMID:25394572

Zhu, Renbin; Wang, Qing; Ding, Wei; Wang, Can; Hou, Lijun; Ma, Dawei

2014-01-01

79

National grain storage extension—phosphine awareness, use, changed practices and challenges  

Microsoft Academic Search

Phosphine is used to fumigate 80% of Australia's cereal crop. It was under threat from several areas and deemed by growers and the Grains Research and Development Corporation (GRDC) worthy of proactive protection. In January 2000, the GRDC commissioned a three-year national stewardship campaign to foster its more sustainable and safe use. The campaign brought together a group of extension

Peter Botta; John Cameron; Peter J. Hughes; Philip R. Burrill; Julianne Farrell; Peter G. Fulwood; Chris R. Newman

80

Phosphinate stabilised ZnO and Cu colloidal nanocatalysts for CO2 hydrogenation to methanol.  

PubMed

Colloidal solutions of ZnO-Cu nanoparticles can be used as catalysts for the reduction of carbon dioxide with hydrogen. The use of phosphinate ligands for the synthesis of the nanoparticles from organometallic precursors improves the reductive stability and catalytic activity of the system. PMID:24141490

Brown, N J; Weiner, J; Hellgardt, K; Shaffer, M S P; Williams, C K

2013-12-01

81

Acute Oral Toxicity (LD50) of 4-Nitrophenyl Monochloromethyl (Phenyl) Phosphinate (TA009) in Female Rats.  

National Technical Information Service (NTIS)

The acute oral toxicity of 4-nitrophenyl monochloromethyl (phenyl) phosphinate was determined in female, albino, Sprague-Dawley rats by using the single dose oral gavage method. LD1, LD50, and LD95 with the 95% confidence limits were calculated by probit ...

C. W. White, J. Rodriguez, T. P. Kellner

1984-01-01

82

Asymmetric Catalytic Synthesis of P-Stereogenic Phosphines via a Nucleophilic Ruthenium Phosphido Complex  

E-print Network

reaction. On the basis of the strong basicity and nucleophilicity of previously reported iron and rutheniumAsymmetric Catalytic Synthesis of P-Stereogenic Phosphines via a Nucleophilic Ruthenium Phosphido@berkeley.edu; fdtoste@berkeley.edu Many reactions rely upon the activation of an electrophile via coordination

Toste, Dean

83

Synthesis of P,N-heterocycles from omega-amino-H-phosphinates: conformationally restricted alpha-amino acid analogs.  

PubMed

P,N-heterocycles (3-hydroxy-1,3-azaphospholane and 3-hydroxy-1,3-azaphosphorinane-3-oxide) are synthesized in moderate yield from readily available omega-amino-H-phosphinates and aldehydes or ketones via an intramolecular Kabachnik-Fields reaction. The products are conformationally restricted phosphinic analogs of alpha-amino acids. The multigram-scale syntheses of the H2N(CH2)(n)PO2H2 phosphinic precursors (n = 1, 2, 3) and some derivatives are also described. PMID:18855477

Queffelec, Clémence; Ribière, Patrice; Montchamp, Jean-Luc

2008-11-21

84

Asymmetric Carbon-Carbon Bond Formation gamma to a Carbonyl Group: Phosphine-Catalyzed Addition of Nitromethane to Allenes  

E-print Network

A chiral phosphine catalyzes the addition of a carbon nucleophile to the ? position of an electron-poor allene (amide-, ester-, or phosphonate-substituted), in preference to isomerization to a 1,3-diene, in good ee and ...

Smith, Sean W.

85

Can a functionalized phosphine ligand promote room temperature luminescence of the [Ru(bpy)(tpy)]2+ core?  

PubMed

Unexpected room temperature luminescence is observed and rationalized by highly challenging excited state calculations for a functionalized phosphine ligand coordinated on the [Ru(bpy)(tpy)](2+) core. PMID:22121501

Lebon, Emilie; Bastin, Stéphanie; Sutra, Pierre; Vendier, Laure; Piau, Rémi E; Dixon, Isabelle M; Boggio-Pasqua, Martial; Alary, Fabienne; Heully, Jean-Louis; Igau, Alain; Juris, Alberto

2012-01-18

86

Pd(quinoline-8-carboxylate)(2) as a low-priced, phosphine-free catalyst for Heck and Suzuki reactions.  

PubMed

N,O-Bidentate compounds were systematically evaluated as phosphine-free ligands for Pd-catalyzed C-C bond-formation reactions through kinetic measurements. Pd(quinoline-8-carboxylate)2 was identified as one of the most efficient, yet still low-priced, phosphine-free catalysts for Heck as well as Suzuki reactions of unactivated aryl bromides with high turnover numbers up to ca. 10,000. PMID:17973432

Cui, Xin; Li, Juan; Zhang, Zhi-Ping; Fu, Yao; Liu, Lei; Guo, Qing-Xiang

2007-11-23

87

Phosphine-catalyzed alpha-P-addition on activated alkynes: A new route to P-C-P backbones.  

PubMed

n-Tributylphosphine was found to efficiently catalyze the alpha-P addition of H-phosphonates, H-phosphinates, and H-phosphine oxide pronucleophiles on alkynes bearing phosphane oxide activating moieties. The reaction leads to 2-aryl-1-vinyl-1,1-diphosphane dioxide derivatives in good yields affording a new route to P-C-P backbones. The products of this reaction are easily converted to biologically important 1,1-bis-phosphonates analogues. PMID:16956207

Lecerclé, Delphine; Sawicki, Marcin; Taran, Frédéric

2006-09-14

88

Mechanisms of cytotoxicity and antitumor activity of gold(I) phosphine complexes: the possible role of mitochondria  

Microsoft Academic Search

Well known for their clinical anti-arthritic properties, gold-based drugs have also attracted interest as potential antitumor agents with gold(I) phosphine derivatives being among the most active in vivo. Auranofin, a linear tetraacetylthioglucose gold(I) phosphine complex, increased the life span of mice inoculated with P388 leukaemia, inhibited DNA polymerases and was preferentially cytotoxic to cells with altered mitochondria. Triethylphosphine gold(I) chloride

Mark J McKeage; Lenushka Maharaj; Susan J Berners-Price

2002-01-01

89

2Hydroxy1, 1Biphenyl and -Binaphthyl-2?-Phosphines - Synthesis, Structure and Use in Rh-Catalyzed Carbonylation  

Microsoft Academic Search

Dibenzofuran and dinaphthofuran are cleaved by lithium in presence of electron transfer catalysts to yield C,O-dilithium reagents. These are reacted with chloro- or alkoxyphosphines providing 2-hydroxy-1,l ‘-biphenyl-2’-phosphines and 2-hydroxy-1,‘-binaphthyl-2’-phosphines which form solvent complexes with O…H?O or P…H?O bridging bonds. The planes of the benzene rings of the biphenyl units are nearly perpen-dicular in the unit cell. Line form analysis of

J. Heinicke; R. Kadyrov; M. K. Kindermann; D. Heller; R. Selke; A. K. Fischer; P. G. Jones

1999-01-01

90

Phosphines are ribonucleotide reductase reductants that act via C-terminal cysteines similar to thioredoxins and glutaredoxins  

PubMed Central

Ribonucleotide reductases (RNRs) catalyze the formation of 2?-deoxyribonucleotides. Each polypeptide of the large subunit of eukaryotic RNRs contains two redox-active cysteine pairs, one in the active site and the other at the C-terminus. In each catalytic cycle, the active-site disulfide is reduced by the C-terminal cysteine pair, which in turn is reduced by thioredoxins or glutaredoxins. Dithiols such as DTT are used in RNR studies instead of the thioredoxin or glutaredoxin systems. DTT can directly reduce the disulfide in the active site and does not require the C-terminal cysteines for RNR activity. Here we demonstrate that the phosphines tris(2-carboxyethyl)phosphine (TCEP) and tris(3-hydroxypropyl)phosphine (THP) are efficient non-thiol RNR reductants, but in contrast to the dithiols DTT, bis(2-mercaptoethyl)sulfone (BMS), and (S)-(1,4-dithiobutyl)-2-amine (DTBA) they act specifically via the C-terminal disulfide in a manner similar to thioredoxin and glutaredoxin. The simultaneous use of phosphines and dithiols results in ~3-fold higher activity compared to what is achieved when either type of reductant is used alone. This surprising effect can be explained by the concerted action of dithiols on the active-site cysteines and phosphines on the C-terminal cysteines. As non-thiol and non-protein reductants, phosphines can be used to differentiate between the redox-active cysteine pairs in RNRs. PMID:24986213

Domkin, Vladimir; Chabes, Andrei

2014-01-01

91

The distribution of phosphine in Jupiter and Saturn from the Cassini CIRS experiment  

NASA Astrophysics Data System (ADS)

We present a reanalysis of the global distribution of phosphine derived by the Cassini Composite Infrared Radiometer (CIRS) in both Jupiter and Saturn. Many thousands of CIRS spectra from both the 2000 Jupiter encounter and the 2004-08 Cassini prime mission, at a variety of spectral resolutions, were used to update the earlier work of Irwin et al. (2004, Icarus 172, 37) and Fletcher et al. (2007, Icarus 188, 72). We include a thorough analysis of aerosol and ammonia properties, multiple datasets with improved calibration, and extended latitudinal coverage on both planets. The use of the same retrieval algorithm for analysis of both planets provides a vital tool for direct comparisons. In particular, we seek to understand the relation between phosphine and belt/zone contrasts, the hemispherical asymmetry of its distribution in Jupiter, its equatorial enhancement on Saturn, and its depletions within Saturn's polar vortices.

Orton, Glenn; Fletcher, Leigh; Teanby, Nicholas; Irwin, Patrick

92

Synthesis and Lanthanide Coordination Chemistry of Phosphine Oxide Decorated Dibenzothiophene and Dibenzothiophene Sulfone Platforms  

SciTech Connect

Syntheses for new ligands based upon dibenzothiophene and dibenzothiophene sulfone platforms, decorated with phosphine oxide and methylphosphine oxide donor groups, are described. Coordination chem. of 4, 6- bis(diphenylphosphinoylmethyl) dibenzothiophene (8) , 4, 6- bis(diphenylphosphinoylmethyl) dibenzothiophene- 5, 5- dioxide (9) and 4, 6- bis(diphenylphosphinoyl) dibenzothiophene- 5, 5- dioxide (10) with lanthanide nitrates, Ln(NO3) 3 (H2O) n is outlined, and crystal structure detns. reveal a range of chelation interactions on Ln(III) ions. The HNO3 dependence of the solvent extn. performance of 9 and 10 in 1, 2- dichloroethane for Eu(III) and Am(III) is described and compared against the extn. behavior of related dibenzofuran ligands (2, 3; R = Ph) and n- octyl(phenyl) - N, N- diisobutylcarbamoylmethyl phosphine oxide (4) measured under identical conditions.

Rosario-Amorin, Daniel [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque; Ouizem, Sabrina [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque; Dickie, D. A. [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque; Paine, Robert T. [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque; Cramer, Roger E. [University of Hawaii] [University of Hawaii; Hay, Benjamin [ORNL] [ORNL; Podair, Julien [ORNL] [ORNL; Delmau, Laetitia Helene [ORNL] [ORNL

2014-01-01

93

Extraction and separation of rare earth metals using microcapsules containing bis(2-ethylhexyl)phosphinic acid  

Microsoft Academic Search

The separation of rare earth metals using microcapsules (MC) consisting styrene (St)–divinylbenzene (DVB) copolymer and containing bis(2-ethylhexyl)phosphinic acid (PIA-226) has been investigated. Microcapsules containing PIA-226 can be prepared by adding PIA-226 to the dispersed phase during the preparation process. The extraction of rare earth metals with the microcapsules progresses via the same scheme, as proposed in the conventional liquid–liquid extraction

Syouhei Nishihama; Nobuya Sakaguchi; Takayuki Hirai; Isao Komasawa

2002-01-01

94

Matrix-bound phosphine: A new form of phosphorus found in sediment of Jiaozhou Bay  

Microsoft Academic Search

Matrix-bound phosphine (PH3), a new form of phosphorus, was found in sediment of Jiaozhou Bay in December 2001. Concentration and distribution of PH3 in different layers of sediment with different stations were analyzed. The results show that PH3 concentrations are various with different layers and different stations. PH3 concentrations in the bottom layer of sediment (20–30 cm) are usually higher

Zhiming Yu; Xiuxian Song

2003-01-01

95

Synthesis and Oxidative Addition Reactions of a Phosphine Carbonyl Complex of Osmium(0).  

National Technical Information Service (NTIS)

The first phosphine complex of osmium(0), Os(CO)3(P(C6H5)3)2, has been prepared from a new class of osmium(II) complexes, OsX2(CO)2(P(C6H5)3)2, by zinc reduction in the presence of carbon monoxide. The osmium(II) complexes were prepared from OsCl3.xH2O an...

J. P. Collman, W. R. Roper

1966-01-01

96

Designing Organic Phosphine Oxide Host Materials Using Heteroaromatic Building Blocks: Inductive Effects on Electroluminescence  

SciTech Connect

Phosphine oxide substitution of small molecules with high triplet exciton energies allows development of vacuum sublimable, electron transporting host materials for blue OLEDs. Heteroaromatic building blocks (carbazole, dibenzofuran and dibenzothiophene) with ET ~ 3 eV were incorporated into phosphine oxide (PO) structures. External quantum efficiencies (EQEs) at lighting brightness (i.e., 800 cd/m2) reached as high as 9.8% at 5.2V for OLEDs using the heteroaromatic PO hosts doped with the sky blue phosphor, iridium(III)bis(4,6-(di-fluorophenyl)-pyridinato-N,C2’) picolinate (FIrpic). Comparing device properties at a similar current density (i.e., J = 13 mA/cm2) showed the dibenzothiophene-bridged PO compound exhibits the highest EQEs and lowest operating voltages at all phosphor dopant levels. These results are explained with respect to the effects of the inductive phosphine oxide substituents on electrochemical, photophysical and electroluminescence properties of the substituted heteroaromatic building blocks.

Sapochak, Linda S.; Padmaperuma, Asanga B.; Vecchi, Paul A.; Cai, Xiuyu; Burrows, Paul E.

2007-11-19

97

Multicomponent Reactions of Phosphines, Diynedioates, and Aryl Aldehydes Generated Furans Appending Reactive Phosphorus Ylides through Cumulated Trienoates as Key Intermediates: A Phosphine ?-Addition-?-Evolvement of an Anion Pathway.  

PubMed

Multicomponent reactions of phosphines, diynedioates, and aryl aldehydes have been demonstrated, providing trisubstituted furans appending reactive phosphorus ylides, through cumulated trienoates as key intermediates. The proposed trienoate intermediates, 1,5-dipolar species formed via nucleophilic ?-attack of phosphines toward diynedioates (?-addition-?-evolvement of an anion, abbreviated ?A?E), undergo addition to aryl aldehydes followed by 5-endo-dig cyclization, proton transfer, and resonance to give trisubstituted furans. Furthermore, the phosphorus ylides are oxidized to ?-keto ester furans and utilized as Wittig reagents. PMID:25338301

Deng, Jie-Cheng; Chuang, Shih-Ching

2014-11-01

98

Photophysical properties of endohedral amine-functionalized bis(phosphine) Pt(II) complexes as models for emissive metallacycles.  

PubMed

The photophysical properties of bis(phosphine) Pt(II) complexes constructed from 2,6-bis(pyrid-3-ylethynyl) aniline and 2,6-bis(pyrid-4-ylethynyl) aniline vary significantly, even though the complexes differ only in the position of the coordinating nitrogen. By capping the ligands with an aryl bis(phosphine) Pt(II) metal acceptor, the photophysical properties of the two isomeric systems were directly compared, revealing that the low-energy absorption and emission bands of the two systems were separated by 30 nm (1804 cm(-1)) and 39 nm (1692 cm(-1)), respectively. From the analysis of time-dependent density functional (TD-DFT) calculations and excited-state lifetime measurements, it was determined that the nature of the Pt-N bond in the HOMO and the sums of the radiative (k(rad)) and nonradiative (k(nr)) rate constants were significantly different in the two systems. As the dominant nonradiative decay pathway in aniline systems is relaxation from the triplet state through intersystem crossing (ISC), the difference in k(nr) can be ascribed to changes in ISC between isomers of the bis(phosphine) Pt(II)-capped 2,6-bis(pyrid-3-ylethynyl) aniline system. It was also determined that the photophysical properties of these capped systems can be altered by functionalizing the aryl capping ligand on the bis(phosphine) Pt(II) metal center, which perturbs the molecular orbitals involved in the observed optical transitions. In addition, an isoelectronic bis(phosphine) Pd(II)-capped system was prepared for comparison with the bis(phosphine) Pt(II) suite of complexes. The Pd(II) system showed significant changes in its low-energy absorption band, but preserved the characteristic emissive properties of its Pt(II) analogue with an even higher quantum yield. PMID:23909761

Pollock, J Bryant; Cook, Timothy R; Schneider, Gregory L; Lutterman, Daniel A; Davies, Andrew S; Stang, Peter J

2013-08-19

99

The relation between phosphine sorption and terminal gas concentrations in successful fumigation of food commodities.  

PubMed

Owing to increased tolerance and the development of resistance in stored product insects to the fumigant phosphine, in recent years there has been a shift in the target terminal concentration from 100 ppm (100 mL m(-3)) to a higher level of 1000 ppm to achieve 100% insect mortality in 7 day commodity treatments. Therefore, there is a need to investigate whether the revised target concentration could be achieved for food commodities fumigated with phosphine at the standard dose of 2 g m(-3) for 7 days under airtight conditions at > or = 25 degrees C. When different types of food commodity (total 74) were fumigated (300 g per replicate) with phosphine at 2 g m(-3) for 7 days, the terminal gas concentrations in the free space of the commodities varied from 0 to > 2000 ppm. In chambers containing no substrate, a 1417 ppm concentration was recorded. Paddy rice, most of the oilseeds, shelled tree nuts, butter beans, cardamom, green gram splits, coriander powder, rice bran and cocoa powder were more sorptive (> or =60%), such that the target concentration of 1000 ppm was not achieved at the end of 7 days. For these commodities, increased doses of 3-6 g m(-3) were required to attain 1000 ppm. In-shell almonds, green cardamom, in-shell peanuts, leaf tea, tamarind pulp and sunflower seeds were exceptionally sorptive (>90%), so that 0, 41, 112, 168, 203 and 217 ppm respectively were noted at the end of 7 days; the dose must exceed 6 g m(-3) for effective fumigation of these commodities. PMID:17051623

Reddy, Palvai Vanitha; Rajashekar, Yellappa; Begum, Khamrunissa; Leelaja, Bhadravathi Chandrappa; Rajendran, Somiahnadar

2007-01-01

100

Solvent extraction of rare-earth metals with bis(2-ethylhexyl)phosphinic acid  

Microsoft Academic Search

The extraction behavior of tervalent rare-earth metals (Ln) using a heptane solution containing bis(2-ethylhexyl)phosphinic\\u000a acid (PIA-8, HR) from 0.1?mol\\/dm3 sodium perchlorate media was studied. The pH0.5 values and separation factors obtained were compared among the metals. The stoichiometry of the extracted species and the\\u000a extraction constants for the present aqueous\\/heptane system were determined by slope analysis. It is demonstrated that

Yukio Nagaosa; Yao Binghua

1997-01-01

101

Phosphine-imidazolyl ligands for the efficient ruthenium-catalyzed hydrogenation of carboxylic esters.  

PubMed

The synthesis of phosphine-imidazolyl ligands 1 and 2 in good yields is presented. In combination with [{Ru(benzene)Cl(2)}(2)], ligands 1?c and 1?e formed efficient catalyst systems for the selective hydrogenation of various carboxylic esters into their corresponding primary alcohols. Furthermore, the structures of four ruthenium complexes with ligands 1?b, 1?c, 1?d, and 1?e were determined by X-ray crystallography, which showed the formation of different coordination modes depending on the ligand structure. PMID:22733711

Junge, Kathrin; Wendt, Bianca; Westerhaus, Felix Alexander; Spannenberg, Anke; Jiao, Haijun; Beller, Matthias

2012-07-16

102

Tricarbonyl-bis(tricyclo-hexyl-phosphine-?P)ruthenium(0) toluene solvate  

PubMed Central

The title compound, [Ru(C18H33P)2(CO)3]·C7H8, shows a distorted trigonal-bipyramdial coordination around the central Ru atom, with the two phosphine ligands occupying the axial positions. Two toluene mol­ecules per asymmetric unit with site-occupation factors of 0.5 are observed. One of them forces two of the CO ligands to enclose a wider C—Ru—C bond angle [127.5?(3)°] than in the solvent-free crystal structure of [Ru(PCy3)2(CO)3] (Cy is cyclo­hexyl). PMID:21580893

Nader, Andreas; Gorls, Helmar; Imhof, Wolfgang

2008-01-01

103

Addition of optically pure H-phosphinate to ketones: selectivity, stereochemistry and mechanism.  

PubMed

Aromatic methyl ketones and cyclic asymmetric ketones underwent hydrophosphorylation with P-stereogenic H-P species in the presence of potassium carbonate to produce P,C-stereogenic tertiary ?-hydroxyl phosphinates in excellent yields with up to 99?:?1 dr. The diastereoselectivity was induced by a reversible conversion of less stable stereomer of product to that of a more stable one via an equilibrium, which was confirmed by aldehyde/ketone exchanging reaction. Toward the exchange, aliphatic or aldehyde carbonyl were more active than aromatic or ketone carbonyls, respectively. The stability difference between the two diastereomers was controlled by the sizes of substituents linking to phosphorus or ?-carbon. PMID:25327336

Sun, Yong-Ming; Xin, Nana; Xu, Zhong-Yuan; Liu, Li-Juan; Meng, Fan-Jie; Zhang, He; Fu, Bao-Ci; Liang, Qiu-Ju; Zheng, Hong-Xing; Sun, Li-Jun; Zhao, Chang-Qiu; Han, Li-Biao

2014-12-14

104

A gold(I) phosphine complex selectively induces apoptosis in breast cancer cells: Implications for anticancer therapeutics targeted to mitochondria  

Microsoft Academic Search

Bis-chelated gold(I) phosphine complexes have shown great potential as anticancer agents, however, their efficacy has been limited by their high toxicity and lack of selectivity for cancer cells. Here, we have investigated the anticancer activity of a new bis-chelated Au(I) bidentate phosphine complex of the novel water soluble ligand 1,3-bis(di-2-pyridylphosphino)propane (d2pypp). We show that this gold complex [Au(d2pypp)2]Cl, at submicromolar

Oliver Rackham; Scott J. Nichols; Peter J. Leedman; Susan J. Berners-Price; Aleksandra Filipovska

2007-01-01

105

Phosphinic acid functionalized carbon nanotubes for sensitive and selective sensing of chromium(VI).  

PubMed

Single-walled carbon nanotubes (SWCNTs) have been functionalized with a phosphinic acid derivative 'bis(2,4,4-trimethylpentyl) phosphinic acid' (PA/d). It has been achieved by treating the chlorinated SWCNTs with PA/d at 80°C. Successful functionalization and different nanomaterial properties have been investigated by UV-vis-NIR, FTIR, Raman spectroscopy, AFM and FE-SEM. PA/d conjugated SWCNTs (CNT-PA) are dispersible in some common organic solvents, e.g. CH2Cl2, DMF, CHCl3, and THF. The 'CNT-PA' complex was spin-casted on boron doped silicon wafer. Thus fabricated sensing electrode is demonstrated for sensitive and selective electrochemical sensing of chromium(VI) ions. A linear response is obtained over a wide range of Cr(VI) concentration (0.01-10 ppb). The sensor's sensitivity and the limit of detection are observed to be 35 ± 4 nA/ppb and 0.01 ppb, respectively. The practical utility of the proposed sensor is demonstrated by determining the Cr(VI) concentration in an industrial effluent sample and an underground water sample. PMID:25016454

Deep, Akash; Sharma, Amit L; Tuteja, Satish K; Paul, A K

2014-08-15

106

Influence of phosphine on Ge/Si(001) island growth by chemical vapor deposition  

NASA Astrophysics Data System (ADS)

When Ge is deposited epitaxially on Si, the strain energy from the lattice mismatch causes the Ge to form distinctive, three-dimensional islands. The shape of the islands is determined by the energies of the surface facets, facet edges, and interfaces. When phosphorus is added during chemical vapor deposition of Ge, the surface energies change, modifying the island shapes and sizes. Three different island shapes are found for doped layers, as for undoped layers; however, each doped island type is smaller than the corresponding undoped island type. The intermediate-size doped islands are of the same family as the undoped multifaceted "dome" structures, but are considerably smaller; they also have a narrow size distribution. The largest doped islands are related to the defective "superdomes" found for undoped islands, but are bounded by a smaller number of facets, creating pyramidal-shaped structures with their edges aligned along <110> directions. The distribution of Ge among the different island types depends on the phosphine partial pressure. Phosphorus appears to act as a mild surfactant, suppressing small islands at high PH3 partial pressures. Within the assumptions made, the segregation enthalpy is estimated to be -0.4 eV. Phosphine decreases the Ge deposition rate because of competitive adsorption; however, the steady-state surface coverage (as indicated by the Ge deposition rate) is not reached for thin layers.

Kamins, T. I.; Medeiros-Ribeiro, G.; Ohlberg, D. A. A.; Williams, R. Stanley

2003-09-01

107

Synthesis and fuel cell characterization of blend membranes from phenyl phosphine oxide containing flourinated novel polymers  

NASA Astrophysics Data System (ADS)

Novel fluorinated poly(arylene ether)'s are synthesized from polycondensation of bis (p-hydroxy-tetrafluoro) phenyl) phenyl phosphine oxide (PFPPO-OH) with 4,4?-dichlorodiphenyl sulfone (DCDPS) and 2,2-bis(4-hydroxyphenyl)propane (Bisfenol A) (Copolymer 1a) or 2,2-bis(4-hydroxyphenyl) hexafluoropropane (Bisphenol AF) (Copolymer 1b). The fluorinated copolymers have been blended with sulphonated poly(ether ether ketone)-SPEEK by solvent casting method. The water uptake and proton conductivity of the blend membranes decreases with the increase of copolymer content as expected, but proton conductivity values are still comparable to that of Nafion117® membrane. Addition of hydrophobic copolymer 1b to the SPEEK caused increase in water vapor transmission. Methanol permeability of the membranes is decreased to 8.2 × 10-8 cm2 s-1 and 1.3 × 10-9 cm2 s-1 by addition of Copolymer 1a and 1b, respectively and they are much lower than that of Nafion® 117 (1.21E-06 (cm2 s-1). The blend membranes endure up to 6.5 h before it starts to dissolve. Hydrogen and oxygen permeability of the blend membranes is one-hundredth of the Nafion®. Fluorinated polymer improved chemical, mechanical, and hydrolytic stability and also phenyl phosphine oxide structure in the ionomer increased the thermal stability, gas and methanol permeability and overcomed the drawbacks of the Nafion® type membranes.

Gürtekin Seden, Merve; Ba?türk, Emre; Inan, Tülay Y.; Kayaman Apohan, Nilhan; Güngör, Atilla

2014-12-01

108

Pillar[5]arenes bearing phosphine oxide pendents as Hg(2+) selective receptors.  

PubMed

Pillar[5]arenes bearing ten phosphine oxide groups (1a-e), as analogs of their corresponding calix[4]arene-based phosphine oxide, have demonstrated intriguing recognition performance for some representative heavy metal cations including Co(2+), Cu(2+), Ni(2+), Zn(2+), Cd(2+), Pb(2+), Ag(2+) and Hg(2+) compared to their acyclic species (2a-e). Their extraction abilities toward these cations were evaluated by the solvent extraction method. The extraction results revealed that 1a-e were efficient and selective cation receptors for Hg(2+) over other selected cations. In addition, the complexation behavior of 1a-e for Hg(2+) was also investigated by using NMR and UV-vis techniques. The pillarareen receptors have been first used in the determination of inorganic mercury in natural water by inductively coupled plasma atomic emission spectrometry (ICP-AES), after back-extracting into aqueous phase with 3 mol L(-1) HCl and 1% CS(NH2)2 solution. PMID:24840451

Jia, Yiming; Fang, Yuyu; Li, Yan; He, Lutao; Fan, Wenhua; Feng, Wen; Yang, Yuanyou; Liao, Jiali; Liu, Ning; Yuan, Lihua

2014-07-01

109

Tri(pyridylmethyl)phosphine: the elusive congener of TPA shows surprisingly different coordination behavior.  

PubMed

Tri(pyridylmethyl)phosphine (TPPh), the remarkably elusive congener of tri(pyridylmethyl)amine (TPA), has been prepared, as well as the relative tri(N-methyl-pyridylamino)phosphine (TPAMP). The coordination properties of these new ligands have been evaluated for chromium(III), iron(II), and ruthenium(II) complexes and compared with the related TPA complexes. In all cases, a different coordination behavior has been observed whereby TPPh and TPAMP always act as tridentate ligands. A chromium(III) complex [Cr(TPPh)Cl3] has been prepared, which has shown low ethylene oligomerization activity. Octahedral low spin iron(II) complexes [Fe(TPPh)2](2+) and [Fe(TPAMP)2](2+) were obtained with two ligands bound to the metal center. Ruthenium(II) chloro complexes of TPA and TPPh undergo ligand exchange reactions in acetonitrile, and the ruthenium(II) complex [Ru(MeCN)2(TPA)](2+) can be oxidized by m-CPBA in acetonitrile to give a transient ruthenium(IV) oxo complex [Ru(O)(MeCN)(TPA)](2+). Attempts to generate high valent ruthenium(IV) oxo TPPh or TPAMP complexes could not be achieved, probably due to insufficient stabilization by these strong field ligands. PMID:23701515

Whiteoak, Christopher J; Nobbs, James D; Kiryushchenkov, Evgeny; Pagano, Sandro; White, Andrew J P; Britovsek, George J P

2013-06-17

110

/sup 31/P and /sup 119/Sn NMR of adducts of tin tetrahalides with tertiary phosphines  

SciTech Connect

The donor-acceptor interaction of SnX/sub 4/ (X = Cl, Br) with tertiary phosphines (nBu/sub 3/P, Me/sub 2/PhP, Ph/sub 3/P) has been studied by /sup 31/P and /sup 119/Sn spectroscopy over a broad range of temperatures and with varous donor-acceptor ratios (D/A) in solutions in methylene chloride. An analysis of the direct spin-spin coupling constants /sup 1/J(/sup 119/Sn-/sup 31/P) and the multiplicity in the /sup 119/Sn NMR spectra made it possible to propose a complexation mechanism, which includes the formation of intermediate ionic structures along with the molecular complexes AD and AD/sub 2/. It has been shown that an excess of the acceptor is not a sufficient condition for the formation of the complex AD. The coexistence of cis and trans isomers of the AD/sub 2/ complexes in solution has been established, and the dependence of /sup 1/J(/sup 119/Sn-/sup 31/P) on the geometry of the P-Sn-P fragment in the octahedral complexes has been demonstrated. The use of low-temperature NMR made it possible, in most cases, to suppress the occurrence of the redox reaction between the compounds of Sn(IV) and the tertiary phosphines.

Yashina, N.S.; Gefel, E.I.; Kosina, A.N.; Petrosyan, V.S.; Reutov, O.A.

1986-10-01

111

Cyclopalladation of the prochiral (di-tert-butyl)(diphenylmethyl)phosphine: kinetic lability of the corresponding (+)-phosphapalladacyclic Pd-C bond and the reluctance of the phosphine to bind in a monodentate fashion.  

PubMed

The ortho palladation of prochiral (di-tert-butyl)(diphenylmethyl)phosphine proceeded readily to give rise to the dimeric complex, di-mu-chlorobis{[(phenyl)(di-tert-butylphosphino)methyl]phenyl-C2, P}dipalladium(II). The (S,S)-(+)-dimer was subsequently obtained by optical resolution with sodium (S)-prolinate. The absolute configuration of the optically resolved (+)-dimer was concluded from the X-ray diffraction studies of the derivatized O,O-acetylacetonate complex. The availability of the (+)-dimer is crucial to the study of the properties of the Pd-C bond. The phosphapalladacycle Pd-C bond exhibited a remarkable thermodynamic stability. It could not be permanently ruptured to give rise to the eta1-P monodentate even in a refluxing acetone solution containing concentrated hydrochloric acid. Instead, the phosphine was noted to fluctuate between the ring closed and opened states via the reversible Pd-C bond cleavage/formation under this condition. Inevitably, this resulted in the racemization of the five-membered organopalladium ring structure. In contrast, such bond cleavage was not observed at room temperature in the absence of HCl. In fact, the phosphine was observed to readily ortho palladate even under conditions not favorable to cyclopalladation. Indeed, the difficulty of isolating the phosphine as a simple eta1-P monodentate coordination complex was further noted by its lack of reactivity toward the N,N-dimethyl-1-(1'naphthyl)ethylaminate palladacycle mu-chloro dimer. Only by enhancing the Lewis acidity of the palladacycle in the form of the positively charged bis(acetonitrile) complex could the phosphine be encouraged to participate in monodentate eta1-P bonding. Even then, this form of coordination was weak and was only observed by NMR spectroscopy. PMID:17489588

Ng, Joseph Kok-Peng; Chen, Shuli; Li, Yongxin; Tan, Geok-Kheng; Koh, Lip-Lin; Leung, Pak-Hing

2007-06-11

112

Efficacies of spinosad and a combination of chlorpyrifos-methyl and deltamethrin against phosphine-resistant Rhyzopertha dominica (Coleoptera: Bostrichidae) and Tribolium castaneum (Coleoptera: Tenebrionidae) on wheat.  

PubMed

Highly phosphine-resistant populations of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) have recently been found in Oklahoma grain storage facilities. These findings necessitate development of a phosphine resistance management strategy to ensure continued effective use of phosphine. Therefore, we investigated the efficacies of two grain insecticides, namely, spinosad applied at label rate of 1 ppm and a mixture of chlorpyrifos-methyl and deltamethrin applied at label rates of 3 and 0.5 ppm, respectively, against highly phosphine-resistant R. dominica and T. castaneum. Adult mortality and progeny production suppression of spinosad- or chlorpyrifos-methyl + deltamethrin mixture-treated wheat that had been stored for 2, 84, 168, 252, and 336 d posttreatment were assessed. We found that both spinosad and chlorpyrifos-methyl + deltamethrin were effective against phosphine-resistant R. dominica and caused 83-100% mortality and also caused total progeny production suppression for all storage periods. Spinosad was not effective against phosphine-resistant T. castaneum; the highest mortality observed was only 3% for all the storage periods. Chlorpyrifos-methyl + deltamethrin was effective against phosphine-resistant T. castaneum only in treated wheat stored for 2 and 84 d, where it caused 93-99% mortality. However, chlorpyrifos-methyl + deltamethrin was effective and achieved total suppression of progeny production in T. castaneum for all the storage periods. Spinosad was not as effective as chlorpyrifos-methyl + deltamethrin mixture at suppressing progeny production of phosphine-resistant T. castaneum. These two insecticides can be used in a phosphine resistance management strategy for R. dominica and T. castaneum in the United States. PMID:24224266

Bajracharya, N S; Opit, George P; Talley, J; Jones, C L

2013-10-01

113

Room temperature alkynylation of H-phosphi(na)tes and secondary phosphine oxides with ethynylbenziodoxolone (EBX) reagents.  

PubMed

Highly efficient protocols for the alkynylation of H-phosphi(na)tes and secondary phosphine oxides with silyl, aryl and alkyl ethynyl-benziodoxolone (EBX) reagents are reported. Alkynyl phosphorus compounds were obtained in 69-93% yield without the need for a transition metal catalyst at room temperature under open flask conditions. PMID:25216020

Chen, C Chun; Waser, Jerome

2014-11-01

114

Copper- and phosphine-ligand-free palladium-catalyzed direct allylation of electron-deficient polyfluoroarenes with allylic chlorides.  

PubMed

Simply id(all)ylic: a copper- and phosphine-ligand-free Pd-catalyzed direct allylation of electron-deficient polyfluoroarenes with allylic chlorides and the reaction mechanism are described. The simple catalytic system, broad substrate scope, and excellent functional-group compatibility of this protocol provides a useful and facile access to allylated polyfluoroarenes. PMID:23055245

Yu, Yan-Bo; Fan, Shilu; Zhang, Xingang

2012-11-12

115

Trichlorosilyl triflate-mediated enantioselective directed cross-aldol reaction between ketones using a chiral phosphine oxide as an organocatalyst.  

PubMed

Trichlorosilyl triflate-promoted directed cross-aldol reaction between ketones in the presence of a chiral phosphine oxide as an organocatalyst is described. This is the first enantioselective cross-aldol reaction between simple ketones with good enantioselectivity. PMID:22543407

Aoki, Shohei; Kotani, Shunsuke; Sugiura, Masaharu; Nakajima, Makoto

2012-06-01

116

Kinetics and mechanism of the racemization of aryl allenes catalyzed by cationic gold(I) phosphine complexes.  

PubMed

The kinetics of the racemization of aromatic 1,3-disubstituted allenes catalyzed by gold phosphine complexes has been investigated. The rate of gold-catalyzed allene racemization displayed first-order dependence on allene, and catalyst concentration and kinetic analysis of gold-catalyzed allene racemization as a function of allene and phosphine electron-donor ability established the accumulation of electron density on the phosphine atom and the depletion of electron density on the terminal allenyl carbon atoms in the rate-limiting transition state for racemization. These and other observations were in accord with a mechanism for allene racemization involving rapid and reversible inter- and intramolecular allene exchange followed by turnover-limiting, unimolecular conversion of a chiral gold ?(2)-allene complex to an achiral ?(1)-allylic cation intermediate through a bent and twisted ?(1)-allene transition state. With respect to proper ligand selection, these studies reveal that both electron-poor phosphine ligands and polar solvents facilitate racemization. PMID:25111202

Harris, Robert J; Nakafuku, Kohki; Widenhoefer, Ross A

2014-09-15

117

Phosphine Adsorption on the In-Rich InP(001) Surface: Evidence of Surface Dative Bonds at Room Temperature  

E-print Network

bonded complex on the InP surface at room temperature. 1. Introduction Chemisorption of molecules adsorbed species on semiconductor surfaces observed at room temperature are limited, especially whenPhosphine Adsorption on the In-Rich InP(001) Surface: Evidence of Surface Dative Bonds at Room

Hicks, Robert F.

118

Evidence for a SN2-type pathway for phosphine exchange in phosphine-phosphenium cations, [R2P--PR'3]+.  

PubMed

Abstraction of a Cl(-) ion from the P-chlorophospholes, R4C4PCl (R=Me, Et), produced the P--P bonded cations [R4C4P--P(Cl)C4R4]+, which reacted with PPh3 to afford X-ray crystallographically characterised phosphine-phosphenium cations [R4C4P(PPh3)]+ (R=Me, Et). Examination of the 31P-{1H} NMR spectrum of a solution (CH2Cl(2)) of [Et4C4P-(PPh3)]+ and PPh3 revealed broadening of the resonances due to both free and coordinated PPh3, and importantly it proved possible to measure the rate of exchange between PPh3 and [Et4C4P-(PPh3)]+ by line shape analysis (gNMR programmes). The results established second-order kinetics with DeltaS( not equal)=(-106.3+/-6.7) J mol(-1) K(-1), DeltaH( not equal)=(14.9+/-1.6) kJ mol(-1) and DeltaG( not equal) (298.15 K)=(46.6+/-2.6) kJ mol(-1), values consistent with a SN2-type pathway for the exchange process. This result contrasts with the dominant dissociative (S(N)1-type) pathway reported for the analogous exchange reactions of the [ArNCH2CH2N(Ar)P(PMe3)]+ ion, and to understand in more detail the factors controlling these two different reaction pathways, we have analysed the potential energy surfaces using density functional theory (DFT). The calculations reveal that, whilst phosphine exchange in [Et4C4P(PPh3)]+ and [ArNCH2CH2N(Ar)P(PMe3)](+) is superficially similar, the two cations differ significantly in both their electronic and steric requirements. The high electrophilicity of the phosphorus center in [Et4C4P]+, combined with strong pi-pi interactions between the ring and the incoming and outgoing phenyl groups of PPh3, favours the SN2-type over the SN1-type pathway in [Et4C4P(PPh3)]+. Effective pi-donation from the amide groups reduces the intrinsic electrophilicity of [ArNCH2CH2N(Ar)P]+, which, when combined with the steric bulk of the aryl groups, shifts the mechanism in favour of a dissociative SN1-type pathway. PMID:17541996

Slattery, John M; Fish, Cheryl; Green, Michael; Hooper, Thomas N; Jeffery, John C; Kilby, Richard J; Lynam, Jason M; McGrady, John E; Pantazis, Dimitrios A; Russell, Christopher A; Willans, Charlotte E

2007-01-01

119

Development of polymeric sensing films based on a tridentate bis(phosphinic amide)-phosphine oxide for detecting europium(III) in water.  

PubMed

A novel europium(III) membrane luminescence sensor based on a tridentate bis(phosphinic amide)-phosphine oxide, PhPO(C(6)H(4)POPhN(CH(CH(3))(2))(2))(2) (1), is described. The new luminescent complex, [Eu(1)(2)]Cl(3)2, which is formed between europium(III) and ligand 1 and has a 1 : 2 stoichiometry, has been evaluated in solution. It has the excellent spectroscopic and chemical characteristics that make it appropriate for sensing film applications. All the parameters (polymer, plasticizer, ligand and ionic additive) that can affect the sensitivity and selectivity of the membrane sensor and instrumental conditions have been carefully optimized. The best sensing response (?(exc) = 229.04 nm, ?(em) = 616.02 nm) was observed for 33.4 : 65.1 : 1.5 (%, w/w) PVC : DOS : 1. The sensing film shows a good response time (10 min) and a very good selectivity toward europium(III) with respect to other lanthanides(III) ions, such as La, Sm, Tb and Yb. The newly-developed sensing film has a linear range from 1.6 × 10(-7) to 5.0 × 10(-6) mol L(-1) for Eu ions with a very low detection limit (4.8 × 10(-8) mol L(-1)) and good sensitivity (9.41 × 10(-7) a.u. mol(-1) L(-1)) to europium. Complexes of [Eu(1)(2)]Cl(3) (2) and [Eu(1)]Cl(3) (4) were isolated by mixing ligand 1 with Eu(Cl(3))·6H(2)O in acetonitrile at room temperature in ligand : metal molar ratios of 1 : 2 and 1 : 1, respectively. The 1 : 1 derivative is the product of thermodynamic control when a molar ratio of ligand to europium salt of 1 : 1 is used. The new compounds have been characterized in both the solid form (IR, MS-TOF, elemental analysis, TGA and X-ray diffraction) and in solution (multinuclear magnetic resonance). In both europium complexes, the ligand acts as a tridentate chelate. Thermogravimetric (TG) studies demonstrated that neither complex 2 or 4 possess any water molecules directly bound to the lanthanide metal, which corroborates the X-ray structure. The investigation of the solution behaviour of the Y(III) complexes with pulsed gradient spin-echo (PGSE) NMR diffusion measurements showed that average structures with 1 : 1 and 1 : 2 stoichiometries are retained in acetonitrile solutions. PMID:22535314

Sainz-Gonzalo, F J; Casimiro, M; Popovici, C; Rodríguez-Diéguez, A; Fernández-Sánchez, J F; Fernández, I; López-Ortiz, F; Fernández-Gutiérrez, A

2012-06-14

120

Effect of phosphine ligands on the activity and selectivity of Pd(II) complexes in the catalysis of the hydrocarboxylation of olefins  

SciTech Connect

A study was carried out on the effect of the phosphine ligand structure on the rate and regioselectivity of the hydrocarboxylation of 1-heptene in dioxane in the presence of the PdCl/sub 2/(PR/sub 3/)/sub 2/-PR/sub 3/ catalytic system (R = aryl, alkyl). An increase in the basicity of phosphines with similar conic angle values leads to a decrease in the reaction rate and increase in selectivity. An increase in the conic angle in phosphines with similar pK/sub a/ values leads to a decrease in the selectivity relative to formation of the linear isomer.

Protchenko, A.V.; Kron, T.E.; Karpyuk, A.D.; Petrov, E.S.; Tsvetkov, E.N.; Beletskaya, I.P.

1986-06-20

121

Microstructure degradation of YSZ in Ni/YSZ anodes of SOFC operated in phosphine-containing fuels  

SciTech Connect

The interaction of trace (ppm) phosphine with the nickel/yttria stabilized zirconia (YSZ) anode of commercial solid oxide fuel cells has been investigated and evaluated for both synthesis gas and hydrogen fuels in an effort to examine P–Y reactions. The Ni poisoning effects reported in literature were confirmed and degradation was examined by electrochemical methods and post-test microstructural and chemical analyses. The results indicate that P-induced degradation rates and mechanisms are fuel dependent and that degradation of cells operated in synthesis gas (syngas) with phosphine is more severe than that of cells operated in hydrogen with phosphine. As reported in published literature, a cell operated in syngas containing 10 ppm phosphine demonstrated significant microstructural degradation within the Ni phase, including formation of Ni–P phases concentrated on the outer layer of the anode and significant pitting corrosion in the Ni grains. In this research, a previously undetected YPO{sub 4} phase is observed at the YSZ/YSZ/Ni triple grain junctions located at the interface with the YSZ electrolyte. Tetragonal YSZ (t-YSZ) and cubic-YSZ (c-YSZ) domains with sizes of several tens of nanometers are also newly observed along the Ni/YSZ interface. These observations contrast with data obtained for a cell operated in dry hydrogen with phosphine, where no YPO{sub 4} phase is observed and the alternating t-YSZ and c-YSZ domains at the Ni/YSZ interface are smaller with typical sizes of 5–10 nm. The data imply that electrolyte attack by P is a potentially debilitating mode of degradation in SOFC anodes, and that the associated reaction mechanisms and rates are worthy of further examination.

Chen, Yun; Chen, Song; Hackett, Gregory; Finklea, Harry; Zondlod, John; Celik, Ismail; Song, Xueyan; Gerdes, Kirk

2013-03-07

122

Efficient bulky phosphines for the selective telomerization of 1,3-butadiene with methanol.  

PubMed

A series of bulky phosphines containing substituted biphenyl, 2-methylnaphthyl, or 2,7-di-tert-butyl-9,9-dimethylxanthene moiety were prepared. They were used in the preparation of new monophosphine-palladium(0)-dvds complexes, which were employed as catalysts for the selective telomerization of 1,3-butadiene with methanol to obtain 1-methoxyocta-2,7-diene (1-MOD), the key intermediate in the Dow 1-octene process. Several ligands showed improved selectivity and yield compared to that of the benchmark ligand PPh(3). Especially 2,7-di-tert-butyl-9,9-dimethylxanthen-4-yl-diphenylphosphine (4, "mono-xantphos") stands out as an excellent ligand in terms of yield, selectivity, and stability. PMID:20405840

Tschan, Mathieu J-L; García-Suárez, Eduardo J; Freixa, Zoraida; Launay, Hélène; Hagen, Henk; Benet-Buchholz, Jordi; van Leeuwen, Piet W N M

2010-05-12

123

Phosphine-catalyzed asymmetric synthesis of ?-lactones from disubstituted ketenes and aldehydes.  

PubMed

In this article we describe a general catalytic procedure for the formation of ?-lactones bearing two stereogenic centers, from disubstituted ketenes and achiral aldehydes. BINAPHANE was found to display excellent enantioselectivity (?90% ee for eight examples) and good diastereoselectivity (?90:10 for 13 examples) in catalyzing the formation of ?-lactones bearing two stereogenic centers from achiral aldehydes (both aromatic and aliphatic) and alkylarylketenes or dialkylketenes. A preference for formation of the trans diastereomer was observed in these reactions. For those reactions where BINAPHANE failed as a catalyst, tri-n-butylphosphine was found to be an effective achiral nucleophilic catalyst, effecting good yield and diastereoselectivity in racemic ?-lactone formation. Evidence for the involvement of phosphonium enolate intermediates in the reaction mechanism was obtained through reaction monitoring by (31)P NMR spectroscopy and by comparison with previously characterized intermediates observed in the phosphine-catalyzed ketene homodimerization reaction. PMID:24810117

Chen, Shi; Mondal, Mukulesh; Ibrahim, Ahmad A; Wheeler, Kraig A; Kerrigan, Nessan J

2014-06-01

124

Novel Cyclic Phosphinic Acids as GABAC ? Receptor Antagonists: Design, Synthesis, and Pharmacology.  

PubMed

Understanding the role of GABAC receptors in the central nervous system is limited due to a lack of specific ligands. Novel ?-aminobutyric acid (GABA) analogues based on 3-(aminomethyl)-1-oxo-1-hydroxy-phospholane 17 and 3-(guanido)-1-oxo-1-hydroxy-phospholane 19 were investigated to obtain selective GABAC receptor antagonists. A compound of high potency (19, K B = 10 ?M) and selectivity (greater than 100 times at ?1 GABAC receptors as compared to ?1?2?2L GABAA and GABAB(1b,2) receptors) was obtained. The cyclic phosphinic acids (17 and 19) are novel lead agents for developing into more potent and selective GABAC receptor antagonists with increased lipophilicity for future in vivo studies. PMID:24900248

Gavande, Navnath; Yamamoto, Izumi; Salam, Noeris K; Ai, Tu-Hoa; Burden, Peter M; Johnston, Graham A R; Hanrahan, Jane R; Chebib, Mary

2011-01-13

125

Phosphinic acid functionalized polyazacycloalkane chelators for radiodiagnostics and radiotherapeutics: unique characteristics and applications.  

PubMed

Given the wide application of positron emission tomography (PET), positron-emitting metal radionuclides have received much attention recently. Of these, gallium-68 has become particularly popular, as it is the only PET nuclide commercially available from radionuclide generators, therefore allowing local production of PET radiotracers independent of an on-site cyclotron. Hence, interest in optimized bifunctional chelators for the elaboration of (68) Ga-labeled bioconjugates has been rekindled as well, resulting in the development of improved triazacyclononane-triphosphinate (TRAP) ligand structures. The most remarkable features of these ligands are unparalleled selectivity for Ga(III) , rapid Ga(III) complexation kinetics, extraordinarily high thermodynamic stability, and kinetic inertness of the respective Ga(III) chelates. As a result, TRAP chelators exhibit very favorable (68) Ga-labeling properties. Based on the scaffolds NOPO (1,4,7-triazacyclononane-1,4-bis[methylene(hydroxymethyl)phosphinic acid]-7-[methylene(2-carboxyethyl)phosphinic acid]) and TRAP-Pr, tailored for convenient preparation of (68) Ga-labeled monomeric and multimeric bioconjugates, a variety of novel (68) Ga radiopharmaceuticals have been synthesized. These include bisphosphonates, somatostatin receptor ligands, prostate-specific membrane antigen (PSMA)-targeting peptides, and cyclic RGD pentapeptides, for in vivo PET imaging of bone, neuroendocrine tumors, prostate cancer, and integrin expression, respectively. Furthermore, TRAP-based (68) Ga-labeled gadolinium(III) complexes have been proposed as bimodal probes for PET/MRI, and a cyclen-based analogue of TRAP-Pr has been suggested for the elaboration of targeted radiotherapeutics comprising radiolanthanide ions. Thus, polyazacycloalkane-based polyphosphinic acid chelators are a powerful toolbox for pharmaceutical research, particularly for the development of (68) Ga radiopharmaceuticals. PMID:24700633

Notni, Johannes; Šime?ek, Jakub; Wester, Hans-Jürgen

2014-06-01

126

Phosphine and methylphosphine production by simulated lightning—a study for the volatile phosphorus cycle and cloud formation in the earth atmosphere  

Microsoft Academic Search

Phosphine (PH3), was recently found worldwide even in the remote atmosphere (Naturwissenschaften83(1996a)131; Atmos. Environ. 37(2003)2429). It is of interest to find natural mechanisms which could produce phosphine gas and drive a volatile link of the atmospheric phosphorus cycle and the formation of phosphoric acid as possible condensation nuclei for clouds.Here, we report on simulated lightning exposing sodium phosphate in a

Dietmar Glindemann; Marc Edwards; Otto Schrems

2004-01-01

127

Remote plasma enhanced chemical vapor deposition of GaP with in situ generation of phosphine precursors  

NASA Technical Reports Server (NTRS)

Thin homoepitaxial films of gallium phosphide (GaP) were grown by remote plasma enhanced chemical vapor deposition utilizing in situ generated phosphine precursors. The GaP forming reaction is kinetically controlled with an activation energy of 0.65 eV. The increase of the growth rate with increasing radio frequency (rf) power between 20 and 100 W is due to the combined effects of increasingly complete excitation and the spatial extension of the glow discharge toward the substrate, however, the saturation of the growth rate at even higher rf power indicates the saturation of the generation rate of phosphine precursors at this condition. Slight interdiffusion of P into Si and Si into GaP is indicated from GaP/Si heterostructures grown under similar conditions as the GaP homojunctions.

Choi, S. W.; Lucovsky, G.; Bachmann, Klaus J.

1993-01-01

128

Remote plasma enhanced chemical vapor deposition of GaP with in situ generation of phosphine precursors  

NASA Technical Reports Server (NTRS)

Thin homoepitaxial films of gallium phosphide (GaP) have been grown by remote plasma enhanced chemical vapor deposition utilizing in situ-generated phosphine precursors. The GaP forming reaction is kinetically controlled with an activation energy of 0.65 eV. The increase of the growth rate with increasing radio frequency (RF) power between 20 and 100 W is due to the combined effects of increasingly complete excitation and the spatial extension of the glow discharge toward the substrate; however, the saturation of the growth rate at even higher RF power indicates the saturation of the generation rate of phosphine precursors at this condition. Slight interdiffusion of P into Si and Si into GaP is indicated from GaP/Si heterostructures grown under similar conditions as the GaP homojunctions.

Choi, S. W.; Lucovsky, G.; Bachmann, K. J.

1992-01-01

129

Investigation of the surface chemistry of phosphine-stabilized ruthenium nanoparticles--an advanced solid-state NMR study.  

PubMed

(31)P-(13)C REDOR NMR measurements allowed a reasonable approximation of distances between stabilizing ligands and carbon monoxide (CO) molecules on the surface of phosphine-stabilized ruthenium nanoparticles (RuNPs). The studied systems are RuNPs in the size range of 1-2 nm stabilized with 1,3,5-triaza-7-phosphaadamantane (PTA) or triphenylphosphine (PPh3) and exposed to a CO atmosphere. This study sheds some light on the interactions between CO and phosphine molecules as well as on their binding geometries on the surface of the RuNPs. As information on the ligand location and mobility is precious for the understanding of the chemical and catalytic properties of nanoparticles, these results support the interest of using sophisticated NMR tools to investigate their surface chemistry. PMID:24022656

Gutmann, Torsten; Bonnefille, Eric; Breitzke, Hergen; Debouttière, Pierre-Jean; Philippot, Karine; Poteau, Romuald; Buntkowsky, Gerd; Chaudret, Bruno

2013-10-28

130

A Bulky Biaryl Phosphine Ligand Allows for Palladium-Catalyzed Amidation of Five-Membered Heterocycles as Electrophiles**  

PubMed Central

Palladium-catalyzed amidation of five-membered heterocyclic bromides that contain multiple heteroatoms was achieved for the first time using the Pd/1 catalyst system. This system allows for efficient access to N-arylated imidazoles, pyrazoles, thiazoles, pyrroles, and thiophenes in moderate to excellent yield. Experimental results and DFT calculations point to the need for electron-rich and especially sterically demanding biaryl phosphine ligand to promote these difficult cross-coupling reactions. PMID:22473747

Su, Mingjuan; Buchwald, Stephen L.

2012-01-01

131

The gilded edge in acetylenic scaffolding: pd-catalyzed cross-coupling reactions of phosphine-gold(I) oligoynyl complexes.  

PubMed

Stable bis(gold(I) alkynyl) complexes of tetraethynylethene (TEE) derivatives were readily prepared and employed in Sonogashira-like palladium-catalyzed phosphine-gold(I) halide elimination reactions with aryl iodides and redox-active tetrathiafulvalene (TTF) mono- and bisiodides. This presents a particularly convenient method for the preparation of symmetrical and asymmetrical tetrathiafulvalene (TTF)-fused radiaannulenes in good yields. PMID:25007357

Mazzanti, Virginia; Jiang, Huixin; Gotfredsen, Henrik; Morsing, Thorbjørn J; Parker, Christian R; Nielsen, Mogens Brøndsted

2014-07-18

132

Phosphine-catalyzed [3 + 2] cycloaddition of sulfamate-derived cyclic imines with allenoate: synthesis of sulfamate-fused dihydropyrroles.  

PubMed

Ph3P-catalyzed [3 + 2] cycloaddition reaction of sulfamate-derived cyclic imines with allenoate has been developed, affording sulfamate-fused dihydropyrroles under very mild conditions in high yields. Using amino acid-based bifunctional phosphine as chiral catalyst, its asymmetric variant provided the corresponding products in good yields with moderate to excellent enantiomeric excesses (up to 91% yield and up to 98% ee). Subsequent transformations of the heterocyclic products gave various pharmaceutically attractive compounds. PMID:23895382

Yu, Hao; Zhang, Lei; Yang, Zhilin; Li, Zhen; Zhao, Yan; Xiao, Yumei; Guo, Hongchao

2013-09-01

133

Tris(2-carboxyethyl)phosphine stabilization of RNA: comparison with dithiothreitol for use with nucleic acid and thiophosphoryl chemistryq  

Microsoft Academic Search

We assessed the utility of the sulfhydryl reductant Tris(2-carboxyethyl)phosphine (TCEP) for both nucleic acid and thiophos- phate chemistry, including its effects on organomercurial gel electrophoresis, RNA catalysis, RNA backbone stability, and the intrinsic stability of TCEP. The sulfhydryls of dithiothreitol (DTT) compete with thiophosphates for binding to the mercury within ((N-acryloylamino)phenyl) mercuric chloride (APM) polyacrylamide gels, whereas millimolar concentrations of

Steven S. Rhee; Donald H. Burke

134

High efficiency of cavity-based triaryl-phosphines in nickel-catalysed Kumada-Tamao-Corriu cross-coupling.  

PubMed

Combining diaryl-calixarenyl phosphines with [Ni(cod)(2)] resulted in highly active Kumada-Tamao-Corriu cross-coupling catalysts. With one of the ligands, TOFs up to 439,000 mol(ArBr) mol(Ni)(-1) h(-1) were observed in the reaction of 1-bromonaphthalene with PhMgBr. The systems were also found to be active at room temperature with aryl chlorides. PMID:21544285

Monnereau, Laure; Sémeril, David; Matt, Dominique

2011-06-21

135

Determination of phosphine in plant materials: method optimization and validation in interlaboratory comparison tests.  

PubMed

The optimization and validation of a method for the determination of phosphine in plant materials are described. The method is based on headspace sampling over the sample heated in 5% sulfuric acid. Critical factors such as sample amount, equilibration conditions, method of quantitation, and matrix effects are discussed, and validation data are presented. Grinding of coarse samples does not lead to lower results and is a prerequisite for standard addition experiments, which present the most reliable approach for quantitation because of notable matrix effects. Two interlaboratory comparisons showed that results varied considerably and that an uncertainty of measurement of about 50% has to be assessed. Flame photometric and mass spectrometric detection gave similar results. The proposed method is well reproducible within one laboratory, and results from the authors' laboratories using different injection and detection techniques are very close to each other. The considerable variation in the interlaboratory comparison shows that this analysis is still challenging in practice and further proficiency testing is needed. PMID:24564743

Amrein, Thomas M; Ringier, Lara; Amstein, Nathalie; Clerc, Laurence; Bernauer, Sabine; Baumgartner, Thomas; Roux, Bernard; Stebler, Thomas; Niederer, Markus

2014-03-01

136

Copper loaded on sol-gel-derived alumina adsorbents for phosphine removal.  

PubMed

The hydride gas of phosphine (PH3) is commonly used for semiconductor and optoelectronic industries. The local scrubbers must immediately abate it because of its high toxicity. In this study, copper (Cu) loaded on the sol-gel-derived gamma-alumina (Al2O3) adsorbents are prepared and tested to investigate the possibility of PH3 removal and sorbent regeneration. Test results showed that during the breakthrough time of over 99% PH3 removal efficiency, the maximum adsorption capacity of Cu loaded on the sol-gel-derived gamma-Al2O3 adsorbent is 18 mg-PH3/g-adsorbent. This is much higher than that of Cu loaded on the commercial gamma-Al2O3 adsorbent--8.6 mg-PH3/g-adsorbent. The high specific surface area, narrow pore size distribution, and well dispersion of Cu loaded on the sol-gel-derived gamma-Al2O3 could be the reasons for its high PH3 adsorption capacity. The regeneration test shows that Cu loaded on the sol-gel-derived gamma-Al2O3 adsorbent can be regenerated after a simple air purging procedure. The cumulative adsorption capacity for five regeneration cycles is 65 mg-PH3/g-adsorbent, which is approximately double that of the Cu/zeolite adsorbent demonstrated in the literature. PMID:20480862

Hsu, Jung-Nan; Bai, Hsunling; Li, Shou-Nan; Tsai, Chuen-Jinn

2010-05-01

137

Homogeneous, single-phase hydroformylation of olefins using ionic phosphines and novel catalyst/product separation  

SciTech Connect

A high efficiency low pressure hydroformylation process for higher molecular weight olefins has been developed using rhodium/ionic phosphine catalyst. Catalyst solubilization in the non-polar reactants and products is achieved using specialized solubilizing agents, such as N-methyl pyrrolidone (NMP), yielding single-phase systems. Separation of catalyst from product is induced by the addition of small amounts of water outside the hydroformylation reactor. Under the two-phase conditions, most of the catalyst components are found in the polar NMP/water phase, and the products (aldehydes, olefins, reaction byproducts) in a separate, non-polar, phase. The catalyst phase is recycled to the reactors after thorough drying to ensure a single homogeneous phase at reaction conditions. Traces of catalyst and solubilizing agent are effectively recovered from the product and recycled. A major advantage of this process, over water-based two-phase systems, is the high catalytic reactivities and concomitant high olefin efficiencies (>90%) which are achieved with olefins of low, water solubility.

Abatjoglou, A.G.; Peterson, R.R.; Bryant, D.R. [Union Carbide Technical Center, South Charleston, WV (United States)

1995-12-01

138

Sky-blue luminescent Au(I)-Ag(I) alkynyl-phosphine clusters.  

PubMed

Treatment of the (AuC2R)n acetylides with phosphine ligand 1,4-bis(diphenylphosphino)butane (PbuP) and Ag(+) ions results in self-assembly of the heterobimetallic clusters of three structural types depending on the nature of the alkynyl group. The hexadecanuclear complex [Au12Ag4(C2R)12(PbuP)6](4+) (1) is formed for R = Ph, and the octanuclear species [Au6Ag2(C2R)6(PbuP)3](2+) adopting two structural arrangements in the solid state were found for the aliphatic alkynes (R = Bu(t) (2), 2-propanolyl (3), 1-cyclohexanolyl (4), diphenylmethanolyl (5), 2-borneolyl (6)). The structures of the compounds 1-4 and 6 were determined by single crystal X-ray diffraction analysis. The NMR spectroscopic studies revealed complicated dynamic behavior of 1-3 in solution. In particular, complexes 2 and 3 undergo reversible transformation, which involves slow interconversion of two isomeric forms. The luminescence behavior of the titled clusters has been studied. All the compounds exhibit efficient sky-blue room-temperature phosphorescence both in solution and in the solid state with maximum quantum yield of 76%. The theoretical DFT calculations of the electronic structures demonstrated the difference in photophysical properties of the compounds depending on their structural topology. PMID:23517461

Koshevoy, Igor O; Karttunen, Antti J; Kritchenkou, Ilya S; Krupenya, Dmitrii V; Selivanov, Stanislav I; Melnikov, Alexei S; Tunik, Sergey P; Haukka, Matti; Pakkanen, Tapani A

2013-04-01

139

Phosphine Oxide Based Electron Transporting and Hole Blocking Materials for Blue Electrophosphorescent Organic Light Emitting Devices  

SciTech Connect

We report the design, synthesis, thermal, and photophysical properties of two phosphine oxide based electron transport/hole blocking materials, 2,6-bis(4-(diphenylphosphoryl)phenyl)pyridine (BM-A11) and 2,4-bis(4-(diphenyl-phosphoryl)phenyl)pyridine (BM-A10) for blue electrophosphorescent organic light emitting devices (OLEDs). The use of these materials in blue OLED with iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C2’]picolinate (Firpic) as the phosphor was demonstrated. Using the dual host device architecture with BM-A10 as the ETM yields a maximum EQE of 8.9% with a power efficiency of 21.5 lm/W (4.0V and 35 cd/m2). When BM-A11 is used as the ETM, the maximum EQE and power efficiency improves to 14.9% and 48.4 lm/W, respectively (3.0V and 40 cd/m2).

Von Ruden, Amber L.; Cosimbescu, Lelia; Polikarpov, Evgueni; Koech, Phillip K.; Swensen, James S.; Wang, Liang; Darsell, Jens T.; Padmaperuma, Asanga B.

2010-10-26

140

C6, C7, and C8 perfluoroalkyl-substituted phosphinic acids.  

PubMed

Reaction of red phosphorus with RfI in a 1:2 molar ratio at 230 degrees C led to the formation of a mixture of (Rf)2PI and (Rf)PI2 (Rf = C6F13, C7F15, C8F17) in about a 70:30 ratio, respectively. These mixtures were separated by vacuum distillation. (Rf)2PI (Rf = C6F13, C7F15) are yellow liquids whereas (C8F17)2PI is a yellow solid. Oxidation of (Rf)2PI with excess NO2 led to (Rf)2P(O)OH (Rf = C6F13, C7F15, C8F17) in > 90% isolated yields after aqueous hydrolysis of the anhydride intermediates. These highly fluorinated phosphinic acids are white solids with sharp melting points and are highly soluble in methyl sulfoxide (DMSO) and 1,1,2-trichlorotrifluoroethane. However, solubility in chloroform and methylene dichloride is low. These perfluoroalkylphosphinic acids were characterized by IR, NMR (1H, 19F, and 31P), and mass spectra and elemental analysis. PMID:12526569

Singh, R P; Shreeve, J M

2000-04-17

141

Synthesis of unsymmetrically substituted phosphane oxides (R(1)R(2)P(O)H) and phosphinous acids (R(1)R(2)POH).  

PubMed

This paper describes the synthesis of unsymmetrically substituted phosphinous acids and phosphane oxides featuring at least one electron-withdrawing pentafluoroethyl group. The presence of a diethylamino function as a protecting group allows a selective reaction of RClPNEt2 (R=CF3 , C6 F5 , C6 H5 ) with LiC2 F5 . On treatment with para-toluenesulfonic acid the isolated aminophosphanes R(C2 F5 )PNEt2 are readily converted into the corresponding phosphinous acids or phosphane oxides, respectively. Investigation of the tautomeric equilibrium between oxide and acid tautomer revealed (CF3 )(C2 F5 )POH as a stable phosphinous acid, whereas the pentafluorophenyl and phenyl derivatives constitute a solvent dependent equilibrium between the acid and the oxide tautomer. PMID:24842615

Allefeld, Nadine; Grasse, Michael; Ignat'ev, Nikolai; Hoge, Berthold

2014-07-01

142

Phosphine and methylphosphine production by simulated lightning—a study for the volatile phosphorus cycle and cloud formation in the earth atmosphere  

NASA Astrophysics Data System (ADS)

Phosphine (PH 3), was recently found worldwide even in the remote atmosphere (Naturwissenschaften83(1996a)131; Atmos. Environ. 37(2003)24 29). It is of interest to find natural mechanisms which could produce phosphine gas and drive a volatile link of the atmospheric phosphorus cycle and the formation of phosphoric acid as possible condensation nuclei for clouds. Here, we report on simulated lightning exposing sodium phosphate in a reducing medium (methane model atmosphere or organic matter) for 5 s to a spark induced by microwave. The gas product analyzed by gas chromatography contained phosphine (yield up to 0.6 g kg -1 phosphate P) and methylphosphine (CH 3)PH 2 (yield up to 0.02 g kg -1 phosphate P). We suggest a plasma-chemical formation mechanism where organic compounds or methane or secondary hydrogen thereof reduce phosphate to phosphine of which a small fraction can subsequently react with methyl radicals to form methylphosphine. A small yield of 6 mg phosphine per kg phosphate P was even obtained in methane free medium, by simple plasmatic recombination of inorganic phosphorus. We believe that methane and hydrogen are useful model substances of pyrolytic gases with high reducing power which may form if lightning strikes biomass, soil and aerosol. These results suggest evidence that phosphine and methylphosphine (detectable in the field by intense garlic odor) are produced when atmospheric lightning strikes the ground or aerosol which is containing oxidized forms of phosphorus and chemical reductants. Additional reviewed data show that laboratory lightning was able to reduce a much more significant portion of phosphate to phosphite (up to 25% yield), methylphosphonic acid (up to 8.5% yield) and traces of hypophosphite in a matter of seconds.

Glindemann, Dietmar; Edwards, Marc; Schrems, Otto

143

Experimental and Computational Studies of the Isomerization Reactions of Bidentate Phosphine Ligands in Triosmium Clusters  

SciTech Connect

The diphosphine ligand 1,2-bis(diphenylphosphino)benzene (dppbz) reacts with the activated cluster 1,2-Os{sub 3}(CO){sub 10}(MeCN){sub 2} (1) at room temperature to furnish a mixture of the triosmium clusters 1,2-Os{sub 3}(CO){sub 10}(dppbz) (2) and 1,1-Os{sub 3}(CO){sub 10}(dppbz) (3), along with a trace amount of the hydride cluster HOs{sub 3}(CO){sub 9}[{mu}-1,2-PhP(C{sub 6}H{sub 4}-{eta}{sup 1})C{sub 6}H{sub 4}PPh{sub 2}] (4). The dppbz-bridged cluster 2 forms as the kinetically controlled product and irreversibly transforms to the corresponding chelated isomer 3 at ambient temperature. The disposition of the dppbz ligand in 2 and 3 has been established by X-ray crystallography and {sup 31}P NMR spectroscopy, and the kinetics for the conversion 2 {yields} 3 have been followed by UV-vis spectroscopy in toluene over the temperature range 318-343 K. The calculated activation parameters ({Delta}H{sub {+-}} = 21.6(3) kcal/mol; {Delta}S{sub {+-}} = -11(1) eu) and lack of CO inhibition support an intramolecular isomerization mechanism that involves the simultaneous migration of phosphine and CO groups about the cluster polyhedron. The reaction between 1 and the fluorinated diphosphine ligand 1,2-bis(diphenylphosphino)tetrafluorobenzene (dppbzF{sub 4}) was examined under similar reaction conditions and was found to afford the chelated cluster 1,1-Os{sub 3}(CO){sub 10}(dppbzF{sub 4}) (6) as the sole observable product. The absence of the expected bridged isomer 1,2-Os{sub 3}(CO){sub 10}(dppbzF{sub 4}) (5) suggests that the dppbzF{sub 4} ligand destabilizes 5, thus accounting for the rapid isomerization of 5 to 6. Near-UV irradiation of clusters 3 and 6 leads to CO loss and ortho metalation of an ancillary aryl group. The resulting hydride clusters 4 and HOs{sub 3}(CO){sub 9}[{mu}-1,2-PhP(C{sub 6}H{sub 4}-{eta}{sup 1})C{sub 6}F{sub 4}PPh{sub 2}] (7) have been isolated and fully characterized by spectroscopic and X-ray diffraction analyses. Both 4 and 7 react with added CO under mild conditions to regenerate 3 and 6, respectively, in quantitative yield. The rearrangements of bridged to chelated diphosphine complexes in this genre of decacarbonyl clusters have been investigated by DFT calculations. The computational results support a concerted process, involving the scrambling of equatorial CO and phosphine groups via a classical merry-go-round exchange scheme. The barriers computed for this mechanism agree well with those that have been measured, and steric compression within the bridged diphosphine groups of the reactants has been calculated to reduce the barrier heights for the rearrangement.

Xue, Zhang [University of North Texas; Kandala, Srikanth [University of North Texas; Yang, Li [University of North Texas; Watson, William H. [Texas Christian University; Wang, Xiaoping [ORNL; Hrovat, David A. [University of North Texas

2011-01-01

144

Synthesis of carbocyclic hydantocidins via regioselective and diastereoselective phosphine-catalyzed [3 + 2]-cycloadditions to 5-methylenehydantoins.  

PubMed

The phosphine-catalyzed [3 + 2]-cycloaddition of 5-methylenehydantoins 4 with the ylides 5, derived from addition of tributylphosphine to the 2-butynoic acid derivatives, 6a-d, gives spiro-heterocyclic products. The camphor sultam derivative 6b gives optically active products. Noteable was that the ylides derived from ethyl 2-butynoate and the 3-(2-butynoyl)-1,3-oxazolidin-2-one derivatives 6c and 6d gave spiro-heterocyclic products with reverse regioselectivities. The N,N-dibenzylprotected cycloadduct has been converted to carbocyclic hydantocidin and 6,7-diepi-carbocyclic hydantocidin. PMID:16050699

Pham, Tien Q; Pyne, Stephen G; Skelton, Brian W; White, Allan H

2005-08-01

145

Anaerobic utilization of phosphite/phosphine as a sole source of phosphorus - Implication to growth in the Jovian environment  

NASA Technical Reports Server (NTRS)

The ability of anaerobic soil isolate microorganisms to metabolize hypophosphite as the sole phosphorus source was studied. Isolates were inoculated into defined medium; growth was determined by turbidity readings, and concentrations of P-32-hypophosphite and its metabolites were determined. Evidence for growth was obtained. Experiments will be performed to see if anaerobes can use phosphine as a sole phosphorous source; the ability of earth organisms to utilize reduced forms of phosphorus would suggest that contaminating organisms from earth would not be eliminated by the absence of phosphate in the Jovian atmosphere.

Foster, T. L.; Winans, L., Jr.

1977-01-01

146

Synthesis of Carbocyclic Hydantocidins via Regioselective and Diastereoselective Phosphine-Catalyzed [3 + 2]-Cycloadditions to 5-Methylenehydantoins  

SciTech Connect

The phosphine-catalyzed [3 + 2]-cycloaddition of 5-methylenehydantoins 4 with the ylides 5, derived from addition of tributylphosphine to the 2-butynoic acid derivatives, 6a-d, gives spiro-heterocyclic products. The camphor sultam derivative 6b gives optically active products. Noteable was that the ylides derived from ethyl 2-butynoate and the 3-(2-butynoyl)-1,3-oxazolidin-2-one derivatives 6c and 6d gave spiro-heterocyclic products with reverse regioselectivities. The N,N-dibenzylprotected cycloadduct has been converted to carbocyclic hydantocidin and 6,7-diepi-carbocyclic hydantocidin.

Pham, Tien Q.; Pyne, Stephen G.; Skelton, Brian W.; White, Allan H. (UWA); (Wollongong)

2010-07-20

147

Evidence for erbium-erbium energy migration in erbium(III) bis(perfluoro-p-tolyl)phosphinate  

NASA Astrophysics Data System (ADS)

Photoluminescence lifetime measurements of the erbium decay in samples of erbium(III) bis(perfluoro-p-tolyl)phosphinate, Er[(p-CF3C6F4)2PO2]3, as a function of erbium concentration have been made. It has been found that for concentrations greater than 50%, the lifetime could be fitted with a stretched exponential function, which is indicative of erbium-erbium energy migration to quenching sites, most likely at the surface of the finely divided powder. At concentrations below 50%, the decay was single exponential with a maximum lifetime of ˜700?s.

Tan, R. H. C.; Pearson, J. M.; Zheng, Y.; Wyatt, P. B.; Gillin, W. P.

2008-03-01

148

In vitro antitumor activity of the water soluble copper(I) complexes bearing the tris(hydroxymethyl)phosphine ligand.  

PubMed

Monocationic hydrophilic complexes [Cu(thp)4](+) 3 and [Cu(bhpe)2](+) 4 were synthesized by ligand exchange reactions starting from the labile [Cu(CH3CN)4][PF6] precursor in the presence of an excess of the relevant hydrophilic phosphine. Complexes 3 and 4 were tested against a panel of several human tumor cell lines. Complex 3 has been shown to be about 1 order of magnitude more cytotoxic than cisplatin. Chemosensitivity tests performed on cisplatin and multidrug resistance phenotypes suggested that complex 3 acts via a different mechanism of action than the reference drug. Different short-term proliferation assays suggested that lysosomal damage is an early cellular event associated with complex 3 cytotoxicity, probably mediated by an increased production of reactive oxygen species. Cytological stains and flow cytometric analyses indicated that the phosphine copper(I) complex is able to inhibit the growth of tumor cells via G2/M cell cycle arrest and paraptosis accompanied with the loss of mitochondrial transmembrane potential. PMID:18251492

Marzano, Cristina; Gandin, Valentina; Pellei, Maura; Colavito, Davide; Papini, Grazia; Lobbia, Giancarlo Gioia; Del Giudice, Elda; Porchia, Marina; Tisato, Francesco; Santini, Carlo

2008-02-28

149

Phosphine-catalyzed asymmetric [4+1] annulation of activated ?,?-unsaturated ketones with Morita-Baylis-Hillman carbonates: enantioselective synthesis of spirooxindoles containing two adjacent quaternary stereocenters.  

PubMed

The asymmetric [4+1] annulation of activated ?,?-unsaturated ketones with MBH carbonates catalyzed by bifunctional thiourea-phosphine catalysts derived from an axially chiral binaphthyl scaffold has been developed, giving spirooxindoles with two adjacent quaternary stereocenters in good yields with high enantioselectivities and moderate diastereoselectivities under mild conditions. PMID:24976341

Hu, Fang-Le; Wei, Yin; Shi, Min

2014-08-18

150

Three-hindered quadrant phosphine ligands with an aromatic ring backbone for the rhodium-catalyzed asymmetric hydrogenation of functionalized alkenes.  

PubMed

The three-hindered quadrant phosphine ligands (R)-1-tert-butylmethylphosphino-2-(di-tert-butylphosphino)benzene ((R)-3H-BenzP*) and (R)-2-tert-butylmethylphosphino-3-(di-tert-butylphosphino)quinoxaline ((R)-3H-QuinoxP*) exhibited good to excellent enantioselectivities in the rhodium-catalyzed asymmetric hydrogenation of selected dehydroamino acid derivatives, enamides, and ethenephosphonates. PMID:22443232

Zhang, Zhenfeng; Tamura, Ken; Mayama, Daisuke; Sugiya, Masashi; Imamoto, Tsuneo

2012-04-20

151

Phosphine-mediated [3+2] cycloaddition reactions of ethyl 5,5-diarylpenta-2,3,4-trienoates with arylmethylidenemalononitriles and N-tosylimines.  

PubMed

Ethyl 5,5-diarylpenta-2,3,4-trienoates were synthesized and utilized in the phosphine-mediated [3+2] cycloaddition reactions with arylmethylidenemalononitriles and N-tosylimines in the presence of tributylphosphine. These reactions provide an easy access to a variety of novel polysubstituted cyclopentenes or pyrrolidines in good to excellent yields under mild conditions. PMID:19173598

Guan, Xiao-Yang; Shi, Min

2009-03-01

152

Phosphine gold(I) bis-(trifluoromethanesulfonyl)imidate complexes as new highly efficient and air-stable catalysts for the cycloisomerization of enynes.  

PubMed

[reaction: see text] A study concerning the synthesis of new phosphine gold(I) complexes using the bis(trifluoromethanesulfonyl)imidate moiety as a weakly coordinating counter-anion is described. These new air-stable complexes are more convenient to prepare, store, and handle and are exceedingly active for the catalysis of a wide range of enynes cycloisomerizations. PMID:16146370

Mézailles, Nicolas; Ricard, Louis; Gagosz, Fabien

2005-09-15

153

The rph1 Gene Is a Common Contributor to the Evolution of Phosphine Resistance in Independent Field Isolates of Rhyzopertha Dominica  

PubMed Central

Phosphine is the only economically viable fumigant for routine control of insect pests of stored food products, but its continued use is now threatened by the world-wide emergence of high-level resistance in key pest species. Phosphine has a unique mode of action relative to well-characterised contact pesticides. Similarly, the selective pressures that lead to resistance against field sprays differ dramatically from those encountered during fumigation. The consequences of these differences have not been investigated adequately. We determine the genetic basis of phosphine resistance in Rhyzopertha dominica strains collected from New South Wales and South Australia and compare this with resistance in a previously characterised strain from Queensland. The resistance levels range from 225 and 100 times the baseline response of a sensitive reference strain. Moreover, molecular and phenotypic data indicate that high-level resistance was derived independently in each of the three widely separated geographical regions. Despite the independent origins, resistance was due to two interacting genes in each instance. Furthermore, complementation analysis reveals that all three strains contain an incompletely recessive resistance allele of the autosomal rph1 resistance gene. This is particularly noteworthy as a resistance allele at rph1 was previously proposed to be a necessary first step in the evolution of high-level resistance. Despite the capacity of phosphine to disrupt a wide range of enzymes and biological processes, it is remarkable that the initial step in the selection of resistance is so similar in isolated outbreaks. PMID:22363668

Mau, Yosep S.; Collins, Patrick J.; Daglish, Gregory J.; Nayak, Manoj K.; Pavic, Hervoika; Ebert, Paul R.

2012-01-01

154

Synthesis of Monomeric Fe(II) and Ru(II) Complexes of Tetradentate Phosphines  

SciTech Connect

rac-Bis[{l_brace}(diphenylphosphino)ethyl{r_brace}-phenylphosphino]methane (DPPEPM) reacts with iron(II) and ruthenium(II) halides to generate complexes with folded DPPEPM coordination. The paramagnetic, five-coordinate Fe(DPPEPM)Cl{sub 2} (1) in CD{sub 2}Cl{sub 2} features a tridentate binding mode as established by {sup 31}P{l_brace}{sup 1}H{r_brace} NMR spectroscopy. Crystal structure analysis of the analogous bromo complex, Fe(DPPEPM)Br{sub 2} (2) revealed a pseudo-octahedral, cis-{alpha} geometry at iron with DPPEPM coordinated in a tetradentate fashion. However, in CD{sub 2}Cl{sub 2} solution, the coordination of DPPEPM in 2 is similar to that of 1 in that one of the external phosphorus atoms is dissociated resulting in a mixture of three tridentate complexes. The chloro ruthenium complex cis-Ru({kappa}{sup 4}-DPPEPM)Cl{sub 2} (3) is obtained from rac-DPPEPM and either [RuCl{sub 2}(COD)]{sub 2} [COD = 1,5-cyclooctadiene] or RuCl{sub 2}(PPh{sub 3}){sub 4}. The structure of 3 in both the solid state and in CD{sub 2}Cl{sub 2} solution features a folded {kappa}{sup 4}-DPPEPM. This binding mode was also observed in cis-[Fe({kappa}{sup 4}-DPPEPM)(CH{sub 3}CN){sub 2}](CF{sub 3}SO{sub 3}){sub 2} (4). Addition of an excess of CO to a methanolic solution of 1 results in the replacement of one of the chloride ions by CO to yield cis-[Fe({kappa}{sup 4}-DPPEPM)Cl(CO)](Cl) (5). The same reaction in CH{sub 2}Cl{sub 2} produces a mixture of 5 and [Fe({kappa}{sup 3}-DPPEPM)Cl{sub 2}(CO)] (6) in which one of the internal phosphines has been substituted by CO. Complexes 2, 3, 4, and 5 appear to be the first structurally characterized monometallic complexes of {kappa}{sup 4}-DPPEPM.

Jana, Barun; Ellern, Arkady; Pestovsky, Oleg; Sadow, Aaron; Bakac, Andreja

2011-03-07

155

REACTIONS OF {eta}{sup 5}-CYCLOPENTADIENYLCOBALT(III) ALKYLS WITH COBALT(I) PHOSPHINES AND IRON CARBONYLS. EVIDENCE FOR DIRECT {eta}{sup 5} -CYCLOPENTADIENYL AND TRIMETHYLPHOSPHINE GROUP TRANSFER BETWEEN METAL CENTERS  

SciTech Connect

We have found that {eta}{sup 5}-methylcyclopentadienyl- (triphenylphosphine)dimethylcobalt(III) (1) undergoes intermolecular cyclopentadienyl ligand exchange with {eta}{sup 5}-cyclopentadienylbistriphenylphosphinecobalt(I). The unsubstituted cyclopentadienyl(triphenylphosphine)dimethylco-balt(III) undergoes exchange of phosphine for carbon monoxide with both Fe(CO){sub 4} and Fe(CO){sub 5} by two different mechanisms. The first involves electrophilic displacement of coordinated phosphine by unsaturated Fe(CO){sub 4} and the second takes place by electrophilic displacement of CO from Fe(CO){sub 5} by the unsaturated CpCoMe{sub 2} fragment (generated by phosphine dissociation from the saturated starting material).

Bryndza, H.E.; Bergman, R.G.

1980-08-01

156

Catalytic reduction of hydrazine to ammonia by a mononuclear iron(II) complex on a tris(thiolato)phosphine platform.  

PubMed

To provide the mechanistic information of nitrogenase at a molecular level, much effort has been made to develop synthetic metal complexes that have enzyme-like reactivity. Herein we obtain an iron(II) complex binding with a tris(thiolato)phosphine ligand, [P(Ph)4][Fe(PS3?)(CH3CN)] [1; PS3? = P(C6H3-3-Me3Si-2-S)3(3-)] that catalyzes the reduction of hydrazine, an intermediate and a substrate of nitrogenase. The substrate- and product-bound adducts, [N(Bu)4][Fe(PS3?)(N2H4)] (2) and [N(Et)4][Fe(PS3?)(NH3)] (3), respectively, are also synthesized. This work provides the feasibility that the late stage of biological nitrogen fixation can be conducted at a single iron site with a sulfur-rich ligation environment. PMID:24377381

Chang, Ya-Ho; Chan, Pooi-Mun; Tsai, Yi-Fang; Lee, Gene-Hsiang; Hsu, Hua-Fen

2014-01-21

157

Polystyrene-Anchored Palladium(II) Schiff Base Complex: A Reusable Catalyst for Phosphine-Free and Copper-Free Sonogashira Cross-Coupling Reaction in Aqueous Medium  

Microsoft Academic Search

A novel polystyrene-supported palladium(II) complex, an excellent and recyclable catalyst, was synthesized for Sonogashira reactions. The present complex shows high catalytic activity for Sonogashira cross-coupling reaction of aryl halides with phenylacetylene under phosphine-free and copper-free reaction conditions in aqueous (DMF–H2O) medium. The catalyst could be reused for at least six reaction cycles with almost unchanged catalytic properties.

Manirul Islam; P. Mondal; A. Singha Roy; K. Tuhina; S. Mondal; D. Hossain

2011-01-01

158

EXTRACTION OF Am(III), Eu(III) AND U(VI) FROM PERCHLORIC ACID AND MIXTURES OF ACIDS BY DIALKYL(DIARYL) [DIETHYLCARBAMOYLMETHYL] PHOSPHINE OXIDES  

Microsoft Academic Search

Extraction of Am(III), Eu(III) and U(VI) from perchloric acid solutions by dialkyl(diaryl) [diethyl-carbamoy line thy 1 ] phosphine oxides (CMPO) has been investigated.It has been shown that elements are extracted more effectively from perchloric acid solutions than from nitric acid. An “anomalous aryl effect” increases sufficiently in perchloric media as compared with nitric media.Solvate numbers of elements also increase in

M. K. Chmutova; M. N. Litvina; N. P. Nesterova; B. F. Myasoedov; M. I. Kabachnik

1992-01-01

159

Phosphine-catalyzed [4+1] annulation of 1,3-(aza)dienes with maleimides: highly efficient construction of azaspiro[4.4]nonenes.  

PubMed

Phosphine-catalyzed [4+1] annulation of electron-deficient 1,3-dienes or 1,3-azadienes with maleimides has been successfully developed under very mild conditions, providing a convenient and highly efficient method for constructing 2-azaspiro[4.4]nonenes and 1,7-diazaspiro[4.4]nonenes. This reaction represents the first example of [4+1] cyclization between electron-deficient 4?-conjugated systems and non-allylic phosphorus ylides. PMID:25233907

Yang, Mei; Wang, Tianyi; Cao, Shixuan; He, Zhengjie

2014-10-01

160

Chemistry and stereochemistry of the interaction of the water-soluble phosphine [HO(CH2)3]3P with cinnamaldehyde in aqueous media.  

PubMed

To learn more about the bleaching action of pulps by (hydroxymethyl)phosphines, cinnamaldehyde was reacted with tris(3-hydroxypropyl)phosphine, [HO(CH2)3]3P (THPP), in aqueous solution at room temperature under argon. Self-condensation of the aldehyde into two isomeric products, 2-benzyl-5-phenyl-pent-2,4-dienal and 5-phenyl-2-(phenylmethylene)-4-pentenal, is observed; this implies initial nucleophilic attack of the phosphine at the beta-carbon of the alpha,beta-unsaturated aldehyde. Reaction in D2O gives the same products in which all but the phenyl and CHO protons are replaced by deuterons. NMR studies are consistent with carbanion formation and subsequent condensation of two phosphonium-containing aldehyde moieties to generate the products with concomitant elimination of phosphine oxide. In D2O in the presence of HCl, THPP reversibly attacks the aldehyde-C atom to form the (alpha-hydroxy)phosphonium derivative [PhCH=C(H)CH(OD)PR3]Cl (where R=(CH2)3OD), which slowly converts into the deuterated bisphosphonium salt [R3PCH(Ph)CD(H)CH(OD)PR3]Cl2 via the deuterated monophosphonium salt [R3PCH(Ph)CD(H)CHO]Cl. The phosphonium intermediates and phosphonium products in this chemistry, although having up to three chiral carbon centers, are formed with high stereoselectivity just in enantiomeric forms. In acetone-H2O (1:1 v/v), a cross-condensation of cinnamaldehyde with acetone to give 6-phenyl-3,5-hexadien-2-one is promoted by THPP via generation of OH-. PMID:17432851

Moiseev, Dmitry V; James, Brian R; Hu, Thomas Q

2007-05-28

161

Bis[2-(4-carboxyphenoxy)carbonylethyl]phosphinic Acid (BCCEP): A Novel Affinity Reagent for the ?-Cleft Modification of Human Hemoglobin  

Microsoft Academic Search

The design, synthesis, and hemoglobin cross-linking studies of a novel organic reagent, bis[2-(4 carboxyphenoxy)carbonylethyl]phosphinic acid (BCCEP, 1) have been reported. The reagent was designed with the aid of molecular modeling, employing crystal coordinates of human hemoglobin A0. It was synthesized in three steps commencing from 4-t-butoxycarbonylphenol. The tri-sodium salt of 1 was employed to cross-link human oxyHb. While SDS–PAGE analyses

Ramachandra S. Hosmane; S. Prasad Peri; Vishweshwar S. Bhadti; Victor W. Macdonald

1998-01-01

162

Partitioning of Actinides from High Level Waste of PUREX Origin Using Octylphenyl-N,N'-diisobutylcarbamoylmethyl Phosphine Oxide (CMPO)Based Supported Liquid Membrane  

Microsoft Academic Search

The present studies deal with the application of the supported liquid membrane (SLM) technique for partitioning of actinides from high level waste of PUREX origin. The process uses a solution of octylphenyl-N,N'-diisobutylcarbamoylmethyl phosphine oxide (CMPO) in n-dodecane as a carrier with a polytetrafluoroethylene support and a mixture of citric acid, formic acid, and hydrazine hydrate as the receiving phase. The

A. Ramanujam; P. S. Dhami; V. Gopalakrishnan; N. L. Dudwadkar; R. R. Chitnis; J. N. Mathur

1999-01-01

163

Electrochemistry of transition metal complex catalysts. Part 9. One and two-electron oxidation of iridium complexes with cyclohexane-derived tripod phosphine ligands  

Microsoft Academic Search

The redox chemistry of Ir tripod-type tri-phosphine complexes in dichloromethane is investigated by cyclic voltammetry, hold-ramp experiments, and preparative electrolysis at Pt electrodes. Products are identified by spectroscopic data, as well as EDX and EXAFS results. Complexes with the Ir central atom in the oxidation states +I, +II and +III are detected and several follow-up reactions are possible from those.

Silke Buchmann; Hermann A Mayer; Bernd Speiser; Michael Seiler; Martin P Feth; Helmut Bertagnolli; Stefan Steinbrecher; Erich Plies

2003-01-01

164

Palladium-phosphinous acid-catalyzed cross-coupling of aryl and acyl halides with aryl-, alkyl-, and vinylzinc reagents.  

PubMed

Several palladium-phosphinous acids have been prepared and employed in cross-coupling reactions of aryl or acyl halides with aliphatic and aromatic organozinc reagents. The POPd7-catalyzed reaction of aryl halides, including electron-rich aryl chlorides, and arylzinc reagents was found to afford biaryls exhibiting alkoxy, alkylthio, amino, ketone, cyano, nitro, ester, and heteroaryl groups in 75-93% yield. Excellent results were obtained with sterically hindered substrates which gave di- and tri -ortho-substituted biaryls in up to 92% yield. Aryl halides also undergo POPd7-catalyzed aryl-vinyl and aryl-alkyl bond formation under mild conditions. Styrenes and alkylarenes were prepared in 79-93% yield from aryl halides and vinyl or alkylzinc reagents. The replacement of aryl halides by acyl halides provides access to ketones which were produced in up to 98% yield when POPd was used as catalyst. This approach overcomes the limited substrate scope, reduced regiocontrol, and low functional group tolerance of traditional Friedel-Crafts acylation methods. PMID:18767805

Xu, Hanhui; Ekoue-Kovi, Kekeli; Wolf, Christian

2008-10-01

165

Method for the synthesis of phosphinic acids from hypophosphites. V. The synthesis of pseudo-alpha,alpha-dipeptides.  

PubMed

The method for the synthesis of 2-substituted 2-hydroxycarbonylethyl-1-aminoalkylphosphinic acids (I) (pseudo-alpha,alpha-dipeptides) from ammonium and potassium hypophosphites (II) is described. The proposed route to the synthesis of pseudo-alpha,alpha-dipeptides consists in addition hypophosphite to acrylic compounds and formation of the first phosphorus-carbon bond with following addition of aminoacid fragment and formation of the second phosphorus-carbon bond. The key intermediates of the synthesis - phosphonous acids (III) and their silylic esters (IV) were obtained at the first stage of the process as the result of the addition of the bis(trimethylsilyl)hypophosphite in situ to suitably substituted acrylates. The modificated procedure for the Kabachnik-Fields reaction of 2-substituted 2-alkoxycarbonylethyl phosphonous acids (III), acetamide, benzaldehyde in acetic anhydride with following hydrolysis results in 2-substituted 2-hydroxycarbonylethyl-alpha-aminobenzyl phosphinic acids (Ia-c) (pseudo-phenylglycylpeptides). Bis(trimethylsilyl) 2-substituted 2-alkoxycarbonylethylphosphonites (IV) in situ were added to N-tritylmethanimine and following alcoholysis and acid hydrolysis of addition products gave 2-substituted 2-hydroxycarbonylethyl-aminomethylphosphinic acids (Id-f) (pseudo-glycylpeptides). PMID:15880266

Rozhko, L F; Ragulin, V V

2005-08-01

166

ExoMol line lists VII: The rotation-vibration spectrum of phosphine up to 1500 K  

E-print Network

A comprehensive hot line list is calculated for $^{31}$PH$_3$ in its ground electronic state. This line list, called SAlTY, contains almost 16.8 billion transitions between 7.5 million energy levels and it is suitable for simulating spectra up to temperatures of 1500~K. It covers wavelengths longer than 1~$\\mu$m and includes all transitions to upper states with energies below $hc \\cdot 18\\,000$~cm$^{-1}$ and rotational excitation up to $J=46$. The line list is computed by variational solution of the Schr\\"odinger equation for the rotation-vibration motion employing the nuclear-motion program TROVE. A previously reported {\\it ab initio} dipole moment surface is used as well as an updated `spectroscopic' potential energy surface (PES), obtained by refining an existing \\textit{ab initio} surface through least-squares fitting to the experimentally derived energies. Detailed comparisons with other available sources of phosphine transitions confirms SAlTY's accuracy and illustrates the incompleteness of previous ex...

Sousa-Silva, Clara; Tennyson, Jonathan; Yurchenko, Sergei N

2014-01-01

167

Recent Progress on the Photonic Properties of Conjugated Organometallic Polymers Built Upon the trans-Bis(para-ethynylbenzene)bis(phosphine)platinum(II) Chromophore and Related Derivatives.  

PubMed

This review article surveys the electronic and photophysical properties of conjugated organometallic polymers built upon the title compound and its related derivatives focussing primarily on systems investigated in our laboratories. The general structure of the polymers is (trans-bis(para-ethynylbenzene)bis(phosphine)platinum(II)-G)(n) where G is a conjugated group such as thiophene, fluorene, carbazole, substituted silole, quinone derivative, and metalloporphyrin residue, or a non-conjugated main-group moiety. Systems based on substituted phenylene units and other related fused rings are also discussed. The phosphine ligands are generally triethyl- or tri-n-butylphosphine groups. These trans-platinum(II) polymers and the corresponding model compounds are compared to the corresponding ortho-derivatives in the quinone series, and the newly prepared paracyclophane-containing polymers. For the porphyrin series, a comparison of fully conjugated oligomers exhibiting the general structure (trans-bis(para-ethynyl(zinc(porphyrin)))bis(phosphine)platinum(II))(n) (i.e., the C(6) H(4) group is absent from the main chain) will be made. This contribution also includes a description of the properties of the mononuclear chromophore itself, properties that define those of the polymers. Potential applications with regard to electronic and optical devices will be highlighted. These soluble and stable materials feature both the processing advantages of polymers and the functionality provided by the presence of metal centers. These multifunctional organometallic polyyne polymers exhibit convenient structural variability as well as optical and electronic properties, which renders them important for use in different research domains as chemical sensors and sensor protectors, as converters for light/electricity signals, and as patternable precursors to magnetic metal alloy nanoparticles. PMID:21590959

Wong, Wai-Yeung; Harvey, Pierre D

2010-04-20

168

Selective extraction of U(VI) and some other metals from nitric acid media by poly-phosphine poly-oxides  

SciTech Connect

For the selective extraction of radionuclides from nitrate media, the extractabilities of organo-poly-phosphine poly-oxides were examined in the form of impregnated resins. It was found that the extractability of 1,1,3,5,5-pentaphenyl-1,3,5-tri-phospha-pentane trioxide (PPTPT) for U(VI) is quite unusual with very high values at both low and high concentrations of nitric acid, which is not observed for other types of extractants. Thus, this extractant might be promising for the selective extraction of U(VI) in very high concentrations of HNO{sub 3}. (authors)

Nogami, M.; Sugiyama, Y.; Ikeda, Y. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-34 O-okayama, Meguro-ku, Tokyo 152-8550 (Japan); Maruyama, K. [Mitsubishi Chemical, Corp., 1000 Kamoshida-cho, Aoba-ku, Yokohama 227-8502 (Japan)

2008-07-01

169

High-efficiency turquoise-blue electrophosphorescence from a Pt(II)-pyridyltriazolate complex in phosphine oxide host  

SciTech Connect

We have demonstrated high-efficiency turquoise-blue electrophosphorescence from the complex Pt(ptp)2 = bis[3,5–bis(2–pyridyl)–1,2,4–triazolato]platinum(II) doped in the wide band-gap, ambipolar phosphine oxide host HM-A1 = 4-(diphenylphosphoryl)-N,N-diphenylaniline. For devices with 5% Pt(ptp)2 doping in HM-A1, we have achieved a peak external quantum efficiency and power efficiency of (11.8 ± 0.6) % and (61.2 ± 5.9) lm/W with high-pixel values of 13.1 % and 70.6 lm/W, respectively. These parameters maintained (10.6 ± 0.2) % and (40.3 ± 1.2) lm/W at a brightness of 1000 cd/m2 with high-pixel values of 10.8 % and 41.6 lm/W. Examination of several device structures suggests that the high performance is due to improved charge transport and exciton confinement in the emissive region. Devices with 1-10% doping concentration exhibit turquoise-blue emissions (?max ~ 480 nm) with a monotonic decrease in monomer/excimer intensity ratio upon increasing the doping concentration. Devices with 5% doping exhibit sufficient blue contribution to attain white light upon combination with highly-doped or neat emissive layers of the same phosphor; the work herein represents a significant backdrop toward optimizing such white OLEDs given the performance metrics above, which to our knowledge represent the highest performance for OLEDs that exhibit blue emission maxima.

Bhansali, Unnat S.; Polikarpov, Evgueni; Swensen, James S.; Chen, Wei; Jia, Huiping; Gaspar, Daniel J.; Gnade, Bruce E.; Padmaperuma, Asanga B.; Omary, Mohammad A.

2009-12-10

170

Melatonin reduces phosphine-induced lipid and DNA oxidation in vitro and in vivo in rat brain.  

PubMed

Phosphine (PH(3)), a widely used pesticide, was found in our recent study to induce oxidative damage in the brain, liver and lung of rats. We also observed that melatonin significantly blocked this action. The present study focused on brain and the magnitude and mechanism of protection of PH(3)-induced oxidative damage by melatonin in vitro and in vivo. PH(3) in whole brain homogenate (3 mg protein/mL Tris-HCl pH 7.4 buffer) induced increasing lipid peroxidation [as malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA)] dependent on concentration (0.25-2 mM) and time (30-150 min), reaching a maximum level of 2.9-fold at 90 min after PH(3) at 1 mM. Elevation of MDA + 4-HDA levels by PH(3) at 1 mM was also observed in homogenates of cerebral cortex, cerebellum, hippocampus and hypothalamus examined individually. Melatonin at 0.1-2 mM progressively inhibited PH(3)-induced lipid peroxidation in brain and regions thereof. Additionally, PH(3) induced brain DNA oxidation in vitro and in vivo determined as 8-hydroxyguanosine (8-OH-dG). Melatonin at 1 mM significantly suppressed PH(3)-induced brain DNA oxidation in vitro. PH(3) at 4 mg/kg i.p. significantly elevated 8-OH-dG in frontal cortex and melatonin prevented it. PH(3) in vivo marginally lowered brain glutathione peroxidase activity and melatonin restored it completely. In contrast, PH(3) and melatonin both stimulated superoxide dismutase production. Brain glutathione (GSH) levels in PH(3)-treated rats were significantly reduced at 30 min and recovered gradually. It is concluded that melatonin, probably because of its free radical scavenging ability, confers marked protection against PH(3)-induced oxidative toxicity in brain. PMID:11841601

Hsu, Ching-Hung; Chi, Bei-Ching; Casida, John E

2002-01-01

171

Reactions of (eta/sup 5/-cyclopentadienyl)cobalt(III) alkyls with cobalt(I) phosphines and iron carbonyls. Evidence for direct eta/sup 5/-cyclopentadienyl and trimethylphosphine group transfer between metal centers  

SciTech Connect

We have found that (eta/sup 5/-methylcyclopentadienyl)(triphenylphosphine)dimethylcobalt(III) undergoes intermolecular cyclopentadienyl ligand exchange with (eta/sup 5/-cyclopentadienyl)bis(triphenylphosphine)cobalt. The unsubstituted cyclopentadienyl(triphenylphosphine)dimethylcobalt(III) reacts in two different types of processes, with both Fe/sub 2/(CO)/sub 9/ and Fe(CO)/sub 5/. The first involves electrophilic displacement of coordinated phosphine by unsaturated Fe(CO)/sub 4/, and the second takes place by abstraction of CO from Fe(CO)/sub 5/ by the unsaturated CpCoMe/sub 2/ fragment (generated by phosphine dissociation from the saturated starting material).

Bryndza, H.E.; Bergman, R.G.

1981-09-01

172

Determination of polyfluoroalkyl phosphoric acid diesters, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, perfluoroalkyl carboxylic acids, and perfluoroalkane sulfonic acids in lake trout from the Great Lakes region.  

PubMed

A comprehensive method to extract perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphoric acid diesters simultaneously from fish samples has been developed. The recoveries of target compounds ranged from 78 % to 121 %. The new method was used to analyze lake trout (Salvelinus namaycush) from the Great Lakes region. The results showed that the total perfluoroalkane sulfonate concentrations ranged from 0.1 to 145 ng/g (wet weight) with perfluorooctane sulfonate (PFOS) as the dominant contaminant. Concentrations in fish between lakes were in the order of Lakes Ontario ? Erie > Huron > Superior ? Nipigon. The total perfluoroalkyl carboxylic acid concentrations ranged from 0.2 to 18.2 ng/g wet weight. The aggregate mean perfluorooctanoic acid (PFOA) concentration in fish across all lakes was 0.045 ± 0.023 ng/g. Mean concentrations of PFOA were not significantly different (p > 0.1) among the five lakes. Perfluoroalkyl phosphinic acids were detected in lake trout from Lake Ontario, Lake Erie, and Lake Huron with concentration ranging from non-detect (ND) to 0.032 ng/g. Polyfluoroalkyl phosphoric acid diesters were detected only in lake trout from Lake Huron, at levels similar to perfluorooctanoic acid. PMID:22722738

Guo, Rui; Reiner, Eric J; Bhavsar, Satyendra P; Helm, Paul A; Mabury, Scott A; Braekevelt, Eric; Tittlemier, Sheryl A

2012-11-01

173

Metabolism of aspirin and procaine in mice pretreated with O-4-nitrophenyl methyl(phenyl)phosphinate or O-4-nitrophenyl diphenylphosphinate  

SciTech Connect

Concentrations of (carboxyl-/sup 14/C)procaine in blood of mice were increased threefold for 27 min by exposure to O-4-nitrophenyl diphenylphosphinate 2 hr prior to (carboxyl-/sup 14/C)procaine injection ip, while there was no effect of O-4-nitrophenyl methyl(phenyl)phosphinate pretreatment. There was no effect of either organophosphinate on the primary hydrolysis of (acetyl-l-/sup 14/C)aspirin when assessed by the expiration of (/sup 14/C)carbon dioxide; however, O-4-nitrophenyl diphenylphosphinate pretreatment produced transient increases in blood concentrations of both (carboxyl-/sup 14/C)aspirin and (carboxyl-/sup 14/C)salicylic acid following administration of (carboxyl-/sup 14/C)aspirin. Liver carboxylesterase activity in O-4-nitrophenyl diphenylphosphinate pretreated mice was 11% of control activity. These results indicate the potential for drug interaction with O-4-nitrophenyl diphenylphosphinate but not with O-4-nitrophenyl methyl(phenyl)phosphinate. It appears that liver carboxylesterase activity has a minor role in hydrolysis of aspirin in vivo, but may be more important in procaine metabolism.

Joly, J.M.; Brown, T.M.

1986-07-01

174

Structure-guided, single-point modifications in the phosphinic dipeptide structure yield highly potent and selective inhibitors of neutral aminopeptidases.  

PubMed

Seven crystal structures of alanyl aminopeptidase from Neisseria meningitides (the etiological agent of meningitis, NmAPN) complexed with organophosphorus compounds were resolved to determine the optimal inhibitor-enzyme interactions. The enantiomeric phosphonic acid analogs of Leu and hPhe, which correspond to the P1 amino acid residues of well-processed substrates, were used to assess the impact of the absolute configuration and the stereospecific hydrogen bond network formed between the aminophosphonate polar head and the active site residues on the binding affinity. For the hPhe analog, an imperfect stereochemical complementarity could be overcome by incorporating an appropriate P1 side chain. The constitution of P1'-extended structures was rationally designed and the lead, phosphinic dipeptide hPheP?[CH2]Phe, was modified in a single position. Introducing a heteroatom/heteroatom-based fragment to either the P1 or P1' residue required new synthetic pathways. The compounds in the refined structure were low nanomolar and subnanomolar inhibitors of N. meningitides, porcine and human APNs, and the reference leucine aminopeptidase (LAP). The unnatural phosphinic dipeptide analogs exhibited a high affinity for monozinc APNs associated with a reasonable selectivity versus dizinc LAP. Another set of crystal structures containing the NmAPN dipeptide ligand were used to verify and to confirm the predicted binding modes; furthermore, novel contacts, which were promising for inhibitor development, were identified, including a ?-? stacking interaction between a pyridine ring and Tyr372. PMID:25192493

Vassiliou, Stamatia; W?glarz-Tomczak, Ewelina; Berlicki, Lukasz; Pawe?czak, Ma?gorzata; Nocek, Bogus?aw; Mulligan, Rory; Joachimiak, Andrzej; Mucha, Artur

2014-10-01

175

Synthesis of bis(3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoyl)(phenyl)phosphine oxide - a tailor-made photoinitiator for dental adhesives  

PubMed Central

Summary Because of the poor solubility of the commercially available bisacylphosphine oxides in dental acidic aqueous primer formulations, bis(3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoyl)(phenyl)phosphine oxide (WBAPO) was synthesized starting from 3-(chloromethyl)-2,4,6-trimethylbenzoic acid by the dichlorophosphine route. The substituent was introduced by etherification with 2-(allyloxy)ethanol. In the second step, 3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoic acid was chlorinated. The formed acid chloride showed an unexpected low thermal stability. Its thermal rearrangement at 180 °C resulted in a fast formation of 3-(chloromethyl)-2,4,6-trimethylbenzoic acid 2-(allyloxy)ethyl ester. In the third step, the acid chloride was reacted with phenylphosphine dilithium with the formation of bis(3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoyl)(phenyl)phosphine, which was oxidized to WBAPO. The structure of WBAPO was confirmed by 1H NMR, 13C NMR, 31P NMR, and IR spectroscopy, as well as elemental analysis. WBAPO, a yellow liquid, possesses improved solubility in polar solvents and shows UV–vis absorption, and a high photoreactivity comparable with the commercially available bisacylphosphine oxides. A sufficient storage stability was found in dental acidic aqueous primer formulations. PMID:20502649

Lamparth, Iris; Angermann, Jorg; Fischer, Urs Karl; Zeuner, Frank; Bock, Thorsten; Liska, Robert; Rheinberger, Volker

2010-01-01

176

Air-stable gold nanoparticles ligated by secondary phosphine oxides for the chemoselective hydrogenation of aldehydes: crucial role of the ligand.  

PubMed

The synthesis of air-stable and homogeneous gold nanoparticles (AuNPs) employing tert-butyl(naphthalen-1-yl)phosphine oxide as supporting ligand is described via NaBH4 reduction of a Au(I) precursor, [(tert-butyl(naphthalen-1-yl)phosphine oxide)AuCl]2. This highly reproducible and simple procedure furnishes small (1.24 ± 0.16 nm), highly soluble nanoparticles that are found to be highly active catalysts for the hydrogenation of substituted aldehydes, giving high conversions and chemoselectivities for a wide variety of substrates. In addition to catalytic studies the role of the novel stabilizer in the remarkable activity and selectivity exhibited by this system was interrogated thoroughly using a wide range of techniques, including ATR FT-IR, HRMAS NMR, XPS, and EDX spectroscopy. In particular, isotopic labeling experiments enabled us to probe the coordination mode adopted by the SPO ligand bound to the nanoparticle surface by ATR FT-IR spectroscopy. In combination with a series of control experiments we speculate that the SPO ligand demonstrates ligand-metal cooperative effects and plays a seminal role in the heterolytic hydrogenation mechanism. PMID:24444462

Cano, Israel; Chapman, Andrew M; Urakawa, Atsushi; van Leeuwen, Piet W N M

2014-02-12

177

Structure, magnetism and colour in simple bis(phosphine)nickel(II) dihalide complexes: an experimental and theoretical investigation.  

PubMed

The complex [1,2-bis(di-tert-butylphosphanyl)ethane-?(2)P,P']diiodidonickel(II), [NiI2(C18H40P2] or (dtbpe-?(2)P)NiI2, [dtbpe is 1,2-bis(di-tert-butylphosphanyl)ethane], is bright blue-green in the solid state and in solution, but, contrary to the structure predicted for a blue or green nickel(II) bis(phosphine) complex, it is found to be close to square planar in the solid state. The solution structure is deduced to be similar, because the optical spectra measured in solution and in the solid state contain similar absorptions. In solution at room temperature, no (31)P{(1)H} NMR resonance is observed, but the very small solid-state magnetic moment at temperatures down to 4?K indicates that the weak paramagnetism of this nickel(II) complex can be ascribed to temperature independent paramagnetism, and that the complex has no unpaired electrons. The red [1,2-bis(di-tert-butylphosphanyl)ethane-?(2)P,P']dichloridonickel(II), [NiCl2(C18H40P2] or (dtbpe-?(2)P)NiCl2, is very close to square planar and very weakly paramagnetic in the solid state and in solution, while the maroon [1,2-bis(di-tert-butylphosphanyl)ethane-?(2)P,P']dibromidonickel(II), [NiBr2(C18H40P2] or (dtbpe-?(2)P)NiBr2, is isostructural with the diiodide in the solid state, and displays paramagnetism intermediate between that of the dichloride and the diiodide in the solid state and in solution. Density functional calculations demonstrate that distortion from an ideal square plane for these complexes occurs on a flat potential energy surface. The calculations reproduce the observed structures and colours, and explain the trends observed for these and similar complexes. Although theoretical investigation identified magnetic-dipole-allowed excitations that are characteristic for temperature-independent paramagnetism (TIP), theory predicts the molecules to be diamagnetic. PMID:24311488

Schultz, Madeleine; Plessow, Philipp-Nikolaus; Rominger, Frank; Weigel, Laura

2013-12-15

178

The coordination of perrhenate and pertechnetate to thorium(IV) in the presence of phosphine oxide or phosphate ligands.  

PubMed

A series of thorium(IV) perrhenato- and pertechnetato-complexes with P[double bond, length as m-dash]O donor ligands have been prepared and characterised both in the solid state and in solution. Isostructural complexes of general formula [Th(MO(4))(4)(L)(4)], where M = Re or Tc and L = triethylphosphate (TEP) (2 and 7), tri-iso-butylphosphate (TiBP) (3 and 8) and tri-n-butylphosphine oxide (TBPO) (4 and 9) have been prepared from the novel starting materials [Th(ReO(4))(4)] x 4H(2)O (1) and [Th(TcO(4))(4)] x 4H(2)O (6). The reaction of or with triphenylphosphine oxide (TPPO) in MeOH has also led to the synthesis of [Th(MO(4))(3)(TPPO)(3)(OCH(3))(HOCH(3))] (M = Re (5) or Tc (10)). While the structural characterisation of 4 and 9 has been previously described, we report for the first time the structural characterisation of 2 and 5, with a partial structural refinement of 3. Vibrational spectroscopic analysis confirms that the Tc complexes not characterised by single crystal X-ray diffraction are indeed isostructural with the perrhenate complexes with the same P[double bond, length as m-dash]O donor ligand. In all cases, monodentate coordination of the Group 7 tetraoxo anion is observed. (31)P NMR spectroscopy indicates that in all the phosphine oxide-based complexes there is one dominant solution species. For the phosphate based systems, the presence of pertechnetate appears to inhibit P[double bond, length as m-dash]O donor ligand complexation in solution, whereas a significant proportion of each phosphate remains coordinated to Th(IV) when perrhenate is present as the counter ligand. These results give some indication as to the mechanism of pertechnetate co-extraction with tetravalent cations in the presence of tri-n-butyl phosphate in the Plutonium and Uranium Recovery by Extraction (PUREX) process. PMID:17146538

Sutton, Andrew D; May, Iain; Sharrad, Clint A; Sarsfield, Mark J; Helliwell, Madeleine

2006-12-28

179

Molecular control of the nanoscale: effect of phosphine-chalcogenide reactivity on CdS-CdSe nanocrystal composition and morphology.  

PubMed

We demonstrate molecular control of nanoscale composition, alloying, and morphology (aspect ratio) in CdS-CdSe nanocrystal dots and rods by modulating the chemical reactivity of phosphine-chalcogenide precursors. Specific molecular precursors studied were sulfides and selenides of triphenylphosphite (TPP), diphenylpropylphosphine (DPP), tributylphosphine (TBP), trioctylphosphine (TOP), and hexaethylphosphorustriamide (HPT). Computational (DFT), NMR ((31)P and (77)Se), and high-temperature crossover studies unambiguously confirm a chemical bonding interaction between phosphorus and chalcogen atoms in all precursors. Phosphine?chalcogenide precursor reactivity increases in the order: HPTE < TOPE < TBPE < DPPE phosphine, the selenide is always more reactive than the sulfide. CdS(1-x)Se(x) quantum dots were synthesized via single injection of a R(3)PS-R(3)PSe mixture to cadmium oleate at 250 °C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis and PL optical spectroscopy reveal that relative R(3)PS and R(3)PSe reactivity dictates CdS(1-x)Se(x) dot chalcogen content and the extent of radial alloying (alloys vs core/shells). CdS, CdSe, and CdS(1-x)Se(x) quantum rods were synthesized by injection of a single R(3)PE (E = S or Se) precursor or a R(3)PS-R(3)PSe mixture to cadmium-phosphonate at 320 or 250 °C. XRD and TEM reveal that the length-to-diameter aspect ratio of CdS and CdSe nanorods is inversely proportional to R(3)PE precursor reactivity. Purposely matching or mismatching R(3)PS-R(3)PSe precursor reactivity leads to CdS(1-x)Se(x) nanorods without or with axial composition gradients, respectively. We expect these observations will lead to scalable and highly predictable "bottom-up" programmed syntheses of finely heterostructured nanomaterials with well-defined architectures and properties that are tailored for precise applications [corrected]. PMID:22519805

Ruberu, T Purnima A; Albright, Haley R; Callis, Brandon; Ward, Brittney; Cisneros, Joana; Fan, Hua-Jun; Vela, Javier

2012-06-26

180

Extraction of Am(III), Eu(III) and U(VI) from perchloric acid and mixtures of acids by dialkyl-(diaryl) [diethylcarbamoylmethyl] phosphine oxides  

SciTech Connect

Extraction of Am(III), and Eu(III) and U(VI) from perchloric acid solutions by dialkyl(diaryl) [diethyl-carbamoylmethyl] phosphine oxides (CMPO) has been investigated. It has been shown that elements are extracted more effectively from perchloric acid solutions than from nitric acid. An `anomalous aryl effect` increases sufficiently in perchloric media as compared with nitric media. Solvate numbers of elements also increase in perchloric acid, they being extremely high for aryl-substituted reagents and not so high for alkyl-substituted compounds. It has been shown that in HNO{sub 3} and HClO{sub 4} solutions the value of `anomalous aryl effect` directly depends on the difference in values of element solvate numbers in complexes with aryl- and alkyl-substituted CMPO. Am(III), Eu(III) and U(VI) are not practically extracted from phosphoric and sulphuric acids by CMPO solutions. 16 refs., 7 figs., 3 tabs.

Chmutova, M.K.; Litvina, M.N.; Nesterova, N.P.; Myasoedov, B.F.; Kabachnik, M.I. [Vernadsky Inst. of Geochemistry and Analytical Chemistry, Moscow (Russian Federation)

1992-07-01

181

Third phase formation in the extraction of Nd(III) by octyl(phenyl)-N,N-diisobutyl carbamoyl methyl phosphine oxide (O{Phi}CMPO)  

SciTech Connect

Third phase formation in the extraction of Nd(III) by 0.2 M Octyl(Phenyl)-N,N-Diisobutyl Carbamoyl methyl phosphine oxide (O{Phi}CMPO) in n-dodecane has been studied with tri-n-butyl phosphate (TBP) and tri-n-amyl phosphate (TAP) as modifiers to provide a comparison between these two modifier systems. The effect of concentration of TAP as modifier for the extraction of Nd(III) by 0.2 M O{Phi}CMPO has been studied. The extraction of Nd(III) by TAP/n-dodecane in the absence of O{Phi}CMPO has also been studied and the results are reported here.

Suresh, A.; Brahmmananda Rao, C.V.S.; Sabharwal, K.N.; Srinivasan, T.G.; Vasudeva Rao, P.R. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.

1999-01-01

182

Aspects of the cleavage of phosphines with potassium: Synthesis and reactivity of lithium and potassium bis(p-(dimethylamino)phenyl)phosphide  

SciTech Connect

The cleavage of the triarylphosphines P(p-C{sub 6}H{sub 4}NMe{sub 2}){sub 3} and PhP(p-C{sub 6}H{sub 4}NMe{sub 2}){sub 2} with potassium in ether solvents was found to occur at room temperature. Cleavage of the mixed phosphine PhP(p-C{sub 6}H{sub 4}NMe{sub 2}){sub 2} was found to give a mixture of products that reflects the relative stability of the phosphides KP(Ph)(p-C{sub 6}H{sub 4}NMe{sub 2}) and KP(p-C{sub 6}H{sub 4}NMe{sub 2}){sub 2}. Cleavage with lithium resulted in the scrambling of the aryl groups so that the products LiPPh{sub 2} and P(Ph){sub 2}(p-C{sub 6}H{sub 4}NMe{sub 2}) also were obtained.

Toth, I.; Hanson, B.E.; Davis, M.E. (Virginia Polytechnic Institute and State Univ., Blacksburg (USA))

1990-03-01

183

Bis(azido) compounds of Pd and Pt with bulky phosphine ligands (dppn=1,8-bis(diphenylphosphino)naphthalene, dppf=1,1?-bis(diphenylphosphino)ferrocene, 1dpn=1-diphenylphosphino-naphthalene): Preparation, structures, and reactivity toward isocyanides  

Microsoft Academic Search

Pd-bis(azido) compounds [Pd(dppn)(N3)2] and [Pd(dppf)(N3)2], which contain bulky chelating bis(phosphine) ligands (dppn=1,8-bis(diphenylphosphino)naphthalene, dppf=1,1?-bis(diphenylphosphino)ferrocene), were prepared from the corresponding chlorides and NaN3. We also prepared the Pt-bis(azido) compound [Pt(1-dpn)(SMe2)(N3)2] containing a bulky monodentate phosphine (1-dpn=1-diphenylphosphino-naphthalene). All these compounds underwent [2+3] cycloaddition with isocyanides (R–NC, R=cyclohexyl, tert-butyl, 2,6-dimethylphenyl) to convert azido ligands to five-membered, C-coordinated tetrazolate rings. In addition, we observed the

Hyun Sue Huh; Yeon Kyoung Lee; Soon W. Lee

2006-01-01

184

Bis(azido) compounds of Pd and Pt with bulky phosphine ligands (dppn=1,8-bis(diphenylphosphino)naphthalene, dppf=1,1'-bis(diphenylphosphino)ferrocene, 1dpn=1-diphenylphosphino-naphthalene): Preparation, structures, and reactivity toward isocyanides  

Microsoft Academic Search

Pd-bis(azido) compounds [Pd(dppn)(N3)2] and [Pd(dppf)(N3)2], which contain bulky chelating bis(phosphine) ligands (dppn=1,8-bis(diphenylphosphino)naphthalene, dppf=1,1'-bis(diphenylphosphino)ferrocene), were prepared from the corresponding chlorides and NaN3. We also prepared the Pt-bis(azido) compound [Pt(1-dpn)(SMe2)(N3)2] containing a bulky monodentate phosphine (1-dpn=1-diphenylphosphino-naphthalene). All these compounds underwent [2+3] cycloaddition with isocyanides (R NC, R=cyclohexyl, tert-butyl, 2,6-dimethylphenyl) to convert azido ligands to five-membered, C-coordinated tetrazolate rings. In addition, we observed

Hyun Sue Huh; Yeon Kyoung Lee; Soon W. Lee

2006-01-01

185

Phosphoryl group as a strong ?-donor anionic phosphine-type ligand: a combined experimental and theoretical study on long-lived room temperature luminescence of the [Ru(tpy)(bpy)(Ph2PO)]+ complex.  

PubMed

A phosphoryl Ru(II) polypyridyl complex was prepared in a one-pot process. Theoretical analysis suggests that the phosphoryl ligand may be viewed as a strong ?-donor anionic phosphine L-type ligand. State-of-the-art free-energy profile calculations on the excited states demonstrate that both favorable thermodynamic and kinetic factors are responsible for the remarkable room temperature luminescence properties of the phosphoryl complex. PMID:24471922

Lebon, Emilie; Sylvain, Rémy; Piau, Rémi E; Lanthony, Cloé; Pilmé, Julien; Sutra, Pierre; Boggio-Pasqua, Martial; Heully, Jean-Louis; Alary, Fabienne; Juris, Alberto; Igau, Alain

2014-02-17

186

Evaluation of microwave irradiation for analysis of carbonyl sulfide, carbon disulfide, cyanogen, ethyl formate, methyl bromide, sulfuryl fluoride, propylene oxide, and phosphine in hay.  

PubMed

Fumigant residues in hay were "extracted" by microwave irradiation. Hay, in gastight glass flasks, was placed in a domestic microwave oven, and fumigants were released into the headspace by microwave irradiation. Power settings for maximum release of fumigants were determined for carbonyl sulfide (COS), carbon disulfide (CS(2)), cyanogen (C(2)N(2)), ethyl formate (EF), methyl bromide (CH(3)Br), sulfuryl fluoride (SF), propylene oxide (PPO), and phosphine (PH(3)). Recoveries of fortified samples were >91% for COS, CS(2), CH(3)Br, SF, PPO, and PH(3) and >76% for C(2)N(2) and EF. Completeness of extraction was assessed from the amount of fumigant retained by the microwaved hay. This amount was determined from further microwave irradiation and was always small (<5% of the amount obtained from the initial procedure). Limits of quantification were <0.1 mg/kg for COS, CS(2), C(2)N(2), EF, and PH(3) and <0.5 mg/kg for CH(3)Br, SF, and PPO. These low limits were essentially due to the absence of interference from solvents and no necessity to inject large-volume gas samples. The microwave method is rapid and solvent-free. However, care is required in selecting the appropriate power setting. The safety implications of heating sealed flasks in microwave ovens should be noted. PMID:17199310

Ren, Yonglin; Mahon, Daphne

2007-01-10

187

Octahedral metal carbonyls. 62. The mechanism of piperidine (pip) displacement by phosphines and phosphites (L') from cis-(pip)(L)W(CO)/sub 4/ complexes in chlorobenzene  

SciTech Connect

Parallel thermal and pulsed laser flash photolysis studies of cis-(pip)(L)W(CO)/sub 4/ complexes (pip = piperidine; L = phosphines and phosphites) in their reactions with L' in chlorobenzene (CB) solvent and in CB/CH mixtures (CH = cyclohexane) indicate these reactions to proceed via reversible fission of the W-pip bond to produce square-pyramidal ((L)W(CO)/sub 4/) intermediates in which L occupies a position in the equatorial plane. These species undergo very rapid competitive reaction with pip, with L', and with CB to afford, ultimately, the thermally stable cis-(L')(L)W(CO)/sub 4/ products, which may undergo subsequent isomerization. The competition ratios for reactions of chlorobenzene, pip, and L' with ((L)W(CO)/sub 5/) have been measured photochemically and/or thermally, and these ratios have assisted in the identification of cis-((CB)(L)W(CO)/sub 4/), in which CB functions as a coordinating ligand, as the predominant species formed after photolysis. Rate constants and activation parameters for most steps in the ligand-substitution process are reported and are discussed in terms of the steric and electronic properties of both coordinated L, incoming L', and solvent.

Asali, K.J.; Basson, S.S.; Tucker, J.S.; Hester, B.C.; Cortes, J.E.; Awad, H.H.; Dobson, G.R.

1987-09-02

188

In vitro and in vivo anticancer activity of copper(I) complexes with homoscorpionate tridentate tris(pyrazolyl)borate and auxiliary monodentate phosphine ligands.  

PubMed

Tetrahedral copper(I) TpCuP complexes 1-15, where Tp is a N,N,N-tris(azolyl)borate and P is a tertiary phosphine, have been synthesized and characterized by means of NMR, ESI-MS, and XAS-EXAFS, and X-ray diffraction analyses on the representative complexes 1 and 10, respectively. All copper(I) complexes were evaluated for their antiproliferative activity against a panel of human cancer cell lines (including cisplatin and multidrug-resistant sublines). The two most effective complexes [HB(pz)3]Cu(PCN), 1, and [HB(pz)3]Cu(PTA), 2, showed selectivity toward tumor vs normal cells, inhibition of 26S proteasome activity associated with endoplasmic reticulum (ER) stress, and unfolded protein response (UPR) activation. No biochemical hallmarks of apoptosis were detected, and morphology studies revealed an extensive cytoplasmic vacuolization coherently with a paraptosis-like cell death mechanism. Finally, the antitumor efficacy of complex 1 was validated in the murine Lewis Lung Carcinoma (LLC) model. PMID:24793739

Gandin, Valentina; Tisato, Francesco; Dolmella, Alessandro; Pellei, Maura; Santini, Carlo; Giorgetti, Marco; Marzano, Cristina; Porchia, Marina

2014-06-12

189

Halloysite-nanotubes supported FeNi alloy nanoparticles for catalytic decomposition of toxic phosphine gas into yellow phosphorus and hydrogen.  

PubMed

The FeNi alloy nanoparticles (FeNi and BFeNi) supported on natural halloysite nanotubes (HNTs) were prepared for catalytic decomposition of toxic phosphine (PH?) to yellow phosphorus and hydrogen. The Fourier transform infrared spectroscopy, X-ray diffraction, inductively coupled plasma, scanning electron microscope, and hydrogen temperature-programmed reduction tests were carried out to characterize the physicochemical properties of HNTs and the prepared nano-catalysts. Nearly 100% PH? was decomposed into yellow phosphorus and hydrogen at 420 °C with prepared FeNi/HNTs catalysts. Metallic Ni and Fe?O? could be the catalytic active sites in FeNi/HNTs for PH? decomposition under the low temperature. The boron (B) additives decrease the catalytic activity of FeNi/HNTs for PH? decomposition due to the formation of the spinal NiFe?O? and Fe?B which replace the active Fe?O? and metallic Ni in catalysts. The developed FeNi/HNTs are low-cost and effective catalysts for air-pollution control and recycle of the hazardous waste PH? gas in industry. PMID:23490180

Tang, Xuejiao; Li, Lili; Shen, Boxiong; Wang, Chengjun

2013-05-01

190

Broad HOMO-LUMO gap tuning through the coordination of a single phosphine, aminophosphine or phosphite onto a Ru(tpy)(bpy)2+ core.  

PubMed

The synthesis of new ruthenium(II) terpyridine bipyridine complexes bearing a phosphorus(III) ligand is presented. The steric and electronic properties of the phosphorus ligand were varied using aminophosphines, alkyl and aryl phosphites and the bulky tri(isopropyl)phosphine. All complexes were characterized by multi-nuclear NMR spectroscopy, mass spectrometry and X-ray diffraction analysis. The electronic properties of the complexes were probed by cyclic voltammetry, absorption and luminescence spectroscopy. The complexes do not show luminescence at room temperature, whereas at 77 K in an alcoholic matrix, emission is observed in the range 600-650 nm with lifetimes of 3.5-5.5 micros, originating from 3MLCT states. The MLCT transition spans over 65 nm, which corresponds to a variation of 0.4 eV in the HOMO-LUMO gap. The oxidation potential of the ruthenium varies over a broad range of 290 mV, from +1.32 V vs. SCE with L = PiPr3 to +1.61 V vs. SCE with L = P(OPh)3. This range is unprecedented upon the variation of a single monodentate ligand coordinated by the same heteroatom in the same oxidation and charge states. This work underlines the specific capacity of phosphorus in bringing up a large variety of electronic properties by changing its substituents. PMID:18854901

Dixon, Isabelle M; Lebon, Emilie; Loustau, Gilles; Sutra, Pierre; Vendier, Laure; Igau, Alain; Juris, Alberto

2008-11-01

191

Reversible formation of [P{sub 2}PtH]{sub 2} platinum(I) complexes from cis-P{sub 2}PtH{sub 2} complexes, where P{sub 2} is a chelating phosphine  

SciTech Connect

Several platinum cis-dihydride phosphine complexes, (diphos)PtH{sub 2} [4, diphos = iPr{sub 2}P(CH{sub 2}){sub 2}PiPr{sub 2} (dippe); 5, diphos = Cy{sub 2}P(CH{sub 2}){sub 2}PCy{sub 2} (dcype); and 6, diphos = tBu{sub 2}P(CH{sub 2}){sub 2}PtBu{sub 2} (dtbpe)], have been found to be unstable in solution, reversibly losing H{sub 2} and forming binuclear complexes of the general formula [(P-P)Pth]{sub 2}. The extent of dimerization in solution is directly related to the steric size of the phosphine ligand, larger phosphines imparting kinetic stability to the cis-dihydride monomers. The dimeric complexes possess terminal hydride ligands on the basis of their IR spectra; however, the room-temperature {sup 1}H, {sup 31}P({sup 1}H), and {sup 195}Pt({sup 1}H) NMR spectra show equivalence within the sets of H, Pt, and P nuclei, indicating that the dimers are fluxional in solution. This fluxional process can be stopped at low temperature for the (dippe) and (dcype) derivatives, 1 and 2, but not for the (dtbpe) derivative, 3. The complex 1 crystallizes in the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1} in a cell of dimensions a = 9.245(2) A, b = 16.966(2) A, c = 22.690(6) A, and Z = 4. 22 refs., 10 figs., 8 tabs.

Schwartz, D.J.; Andersen, R.A. [Lawrence Berkeley Lab., CA (United States)]|[Univ. of California, Berkeley, CA (United States)

1995-04-12

192

Zwitterionic and cationic bis(phosphine) platinum(II) complexes: structural, electronic, and mechanistic comparisons relevant to ligand exchange and benzene C-H activation processes.  

PubMed

Structurally similar but charge-differentiated platinum complexes have been prepared using the bidentate phosphine ligands [Ph(2)B(CH(2)PPh(2))(2)], ([Ph(2)BP(2)], [1]), Ph(2)Si(CH(2)PPh(2))(2), (Ph(2)SiP(2), 2), and H(2)C(CH(2)PPh(2))(2), (dppp, 3). The relative electronic impact of each ligand with respect to a coordinated metal center's electron-richness has been examined using comparative molybdenum and platinum model carbonyl and alkyl complexes. Complexes supported by anionic [1] are shown to be more electron-rich than those supported by 2 and 3. A study of the temperature and THF dependence of the rate of THF self-exchange between neutral, formally zwitterionic [Ph(2)BP(2)]Pt(Me)(THF) (13) and its cationic relative [(Ph(2)SiP(2))Pt(Me)(THF)][B(C(6)F(5))(4)] (14) demonstrates that different exchange mechanisms are operative for the two systems. Whereas cationic 14 displays THF-dependent, associative THF exchange in benzene, the mechanism of THF exchange for neutral 13 appears to be a THF independent, ligand-assisted process involving an anchimeric, eta(3)-binding mode of the [Ph(2)BP(2)] ligand. The methyl solvento species 13, 14, and [(dppp)Pt(Me)(THF)][B(C(6)F(5))(4)] (15), each undergo a C-H bond activation reaction with benzene that generates their corresponding phenyl solvento complexes [Ph(2)BP(2)]Pt(Ph)(THF) (16), [(Ph(2)SiP(2))Pt(Ph)(THF)][B(C(6)F(5))(4)] (17), and [(dppp)Pt(Ph)(THF)][B(C(6)F(5))(4)] (18). Examination of the kinetics of each C-H bond activation process shows that neutral 13 reacts faster than both of the cations 14 and 15. The magnitude of the primary kinetic isotope effect measured for the neutral versus the cationic systems also differs markedly (k(C(6)H(6))/k(C(6)D(6)): 13 = 1.26; 14 = 6.52; 15 approximately 6). THF inhibits the rate of the thermolysis reaction in all three cases. Extended thermolysis of 17 and 18 results in an aryl coupling process that produces the dicationic, biphenyl-bridged platinum dimers [[(Ph(2)SiP(2))Pt](2)(mu-eta(3):eta(3)-biphenyl)][B(C(6)F(5))(4)](2) (19) and [[(dppp)Pt](2)(mu-eta(3):eta(3)-biphenyl)][B(C(6)F(5))(4)](2) (20). Extended thermolysis of neutral [Ph(2)BP(2)]Pt(Ph)(THF) (16) results primarily in a disproportionation into the complex molecular salt [[Ph(2)BP(2)]PtPh(2)](-)[[Ph(2)BP(2)]Pt(THF)(2)](+). The bulky phosphine adducts [Ph(2)BP(2)]Pt(Me)[P(C(6)F(5))(3)] (25) and [(Ph(2)SiP(2))Pt(Me)[P(C(6)F(5))(3)

Thomas, J Christopher; Peters, Jonas C

2003-07-23

193

A photochemical study of the kinetics of the reactions of NH2 with phosphine, ethylene, and acetylene using flash photolysis-laser induced fluorescence. Ph.D. Thesis Catholic Univ. of America; [ammonia in the atmosphere of Jupiter  

NASA Technical Reports Server (NTRS)

The photochemistry of the reactions of NH2 was investigated in an attempt to explain the existence of an abundance of ammonia in the Jovian atmosphere. The production of ammonia reservoirs from the coupling of ammonia with other atmospheric constituents was considered. The rate constants for the reactions of NH2 radicals with phosphine, acetylene, and ethylene were measured. Flash photolysis was used for the production of NH2 radicals and laser induced fluorescence was employed for radical detection. It was determined that the rates of the reactions were too slow to be significant as a source of ammonia reservoirs in the Jovian atmosphere.

Bosco, S. R.

1982-01-01

194

Acceleration of reductive elimination of [Ar-Pd-C(sp3)] by a phosphine/electron-deficient olefin ligand: a kinetic investigation.  

PubMed

The kinetics of the reductive elimination step of a C(sp(3))-C(sp(2)) Negishi cross-coupling catalyzed by a 1:1 complex 2 of palladium and the phosphine/electron-deficient olefin ligand (E)-3-(2-diphenylphosphanylphenyl)-1-phenyl-propenone (1) was studied. Complex 2 is an exceptionally efficient and highly selective catalyst for Negishi cross-coupling reactions involving primary and secondary alkylzinc reagents bearing beta-hydrogen atoms. Turnover numbers (TONs) as high as 10(5) and turnover frequencies (TOFs) as high as 1000 s(-1) were observed. The reactions occurred rapidly and selectively even at 0 degrees C. The fact that the reaction was first order in [Pd] is consistent with homogeneous catalysis by Pd complexes rather than by Pd nanoparticles (NPs). Through systematic kinetic investigations of the Negishi coupling of ethyl 2-iodobenzoate with alkylzinc chlorides, the rate constants for reductive elimination of [Ar-Pd-C(sp(3))] were determined to be >0.3 s(-1), which is about 4 or 5 orders of magnitude greater than the values previously reported for [Pd(dppbz)] and [Pd(PPh(3))(2)] systems (dppbz = 1,2-bis(diphenylphosphino)benzene). The use of a 2:1 ratio of 1:Pd resulted in reduced catalytic activity and selectivity, presumably because the olefin moiety could no longer assist in the reductive elimination step. Importantly, hydrogenation of the C=C double bond in ligand 1 generated a saturated ligand (1H(2)), which was not only less effective than 1, but also gave rise to substantial amount of ethylbenzoate formed by competing beta-hydride elimination. Thus, the pi-accepting olefin moiety in 1 must enhance reductive elimination rates, and, consequently, inhibit formation of byproducts resulting from beta-hydride elimination. PMID:19229935

Zhang, Heng; Luo, Xiancai; Wongkhan, Kittiya; Duan, Hui; Li, Qiang; Zhu, Lizheng; Wang, Jian; Batsanov, Andrei S; Howard, Judith A K; Marder, Todd B; Lei, Aiwen

2009-01-01

195

Solution-processible brilliantly luminescent Eu(III) complexes with host-featured phosphine oxide ligands for monochromic red-light-emitting diodes.  

PubMed

A series of solution-processible electroluminescent (EL) Eu(3+) complexes were constructed with a self-host strategy, in which neutral ligands were employed as functionalized bidentate phosphine oxide (PO) ligands named DPEPOArn (DPEPO = bis(2-(diphenylphosphino)phenyl) ether oxide). The solubility of these complexes was dramatically improved owing to the increased ratios of organic components. This further enhanced the antenna effect of these ligands in both singlet and triplet energy-transfer processes to support high photoluminescent quantum yields (PLQYs) up to 86?% for their Eu(3+) complexes, which is outstanding among conjugated Eu(3+) complexes. Density function theory (DFT) simulations and electrochemical analysis further verified the contributions of DPEPOArn to the carrier injecting/transporting ability of the complexes. In this sense, these functionalized PO ligands served as hosts in optoelectronic processes, which rendered the self-host feature of their Eu(3+) complexes. With the enhanced electrical properties, the spin-coated single-layer organic light-emitting diodes (OLEDs) of these complexes achieved improved low driving voltages, such as onset voltages about 6?V, compared to their Eu(3+)-contained red-emitting polymeric analogues. [Eu(DBM)3DPEPODPNA2] (DBM = 1,3-diphenylpropane-1,3-dione, DPNA = diphenylnaphthylamine) with the most enhanced electrical properties and suitable frontier molecular orbital (FMO) and triplet state locations endowed its devices with the biggest maximum luminance of >90?cd?m(-2) and the highest EL efficiencies. This work verified the potential of small molecular EL Eu(3+) complexes for solution-processed OLEDs through rational function integrations. PMID:25065610

Wang, Jianzhe; Han, Chunmiao; Xie, Guohua; Wei, Ying; Xue, Qin; Yan, Pengfei; Xu, Hui

2014-08-25

196

Potent Suppression of Kv1.3 Potassium Channel and IL-2 Secretion by Diphenyl Phosphine Oxide-1 in Human T Cells  

PubMed Central

Diphenyl phosphine oxide-1 (DPO-1) is a potent Kv1.5 channel inhibitor that has therapeutic potential for the treatment of atrial fibrillation. Many other Kv1.5 channel blockers also potently inhibit the Kv1.3 channel, but whether DPO-1 blocks Kv1.3 channels has not been investigated. The Kv1.3 channel is highly expressed in activated T cells, which is considered a favorable target for immunomodulation. Accordingly, we hypothesized that DPO-1 may exert immunosuppressive and anti-inflammatory effects by inhibiting Kv1.3 channel activity. In this study, DPO-1 blocked Kv1.3 current in a voltage-dependent and concentration-dependent manner, with IC50 values of 2.58 µM in Jurkat cells and 3.11 µM in human peripheral blood T cells. DPO-1 also accelerated the inactivation rate and negatively shifted steady-state inactivation. Moreover, DPO-1 at 3 µM had no apparent effect on the Ca2+ activated potassium channel (KCa) current in both Jurkat cells and human peripheral blood T cells. In Jurkat cells, pre-treatment with DPO-1 for 24 h decreased Kv1.3 current density, and protein expression by 48±6% and 60±9%, at 3 and 10 µM, respectively (both p<0.05). In addition, Ca2+ influx to Ca2+-depleted cells was blunted and IL-2 production was also reduced in activated Jurkat cells. IL-2 secretion was also inhibited by the Kv1.3 inhibitors margatoxin and charybdotoxin. Our results demonstrate for the first time that that DPO-1, at clinically relevant concentrations, blocks Kv1.3 channels, decreases Kv1.3 channel expression and suppresses IL-2 secretion. Therefore, DPO-1 may be a useful treatment strategy for immunologic disorders. PMID:23717641

Zhao, Ning; Dong, Qian; Du, Li-Li; Fu, Xiao-Xing; Du, Yi-Mei; Liao, Yu-Hua

2013-01-01

197

Highly regio- and stereoselective acylboration, acylsilation, and acylstannation of allenes catalyzed by phosphine-free palladium complexes: an efficient route to a new class of 2-acylallylmetal reagents.  

PubMed

A new method for the synthesis of substituted 2-acylallylmetal reagents in a highly regio- and stereoselective fashion involving a three-component assembly of allenes, acyl chlorides, and bimetallic reagents (B-B, Si-Si, and Sn-Sn) catalyzed by phosphine-free palladium complexes is described. Treatment of various allenes (CR(2)R(3)=C=CH(2)) with acyl chlorides (R(1)COCl) and bispinacolatodiboron in the presence of PdCl(2)(CH(3)CN)(2) in toluene at 80 degrees C gave 2-acylallylboronates in moderate to good yields. The acylsilation of allenes with acid chlorides and hexamethyldisilane (5) proceeded successfully in the presence of Pd(dba)(2) in CH(3)CN affording the corresponding allylsilanes (CR(2)R(3)=C(COR(1))CH(2)SiMe(3)) in good to moderate yields. Several chloroformates (R(4)OCOCl) also react with 1,1-dimethylallene (2a) and 5 to afford allylsilanes (CR(2)R(3)=C(COOR(4))CH(2)SiMe(3)) in 66-70% yields. Acylstannation of allenes could also be achieved by slow addition of hexabutylditin (10) to the reaction mixture of acyl chloride (or chloroformate) and allene 2a in CH(3)CN in the presence of Pd(dba)(2) at 60 degrees C; the corresponding 2-substituted allylstannanes were isolated in moderate to good yields. The above catalytic reactions are completely regioselective and highly stereoselective. A mechanism is proposed to account for the catalytic reactions and the stereochemistry. PMID:14531703

Yang, Feng-Yu; Shanmugasundaram, Muthian; Chuang, Shih-Yih; Ku, Po-Jen; Wu, Ming-Yuan; Cheng, Chien-Hong

2003-10-15

198

Reactions of Ph4Se4Br4 with tertiary phosphines. Structural isomerism within a series of R3PSe(Ph)Br compounds.  

PubMed

The synthesis and characterisation of Ph(4)Se(4)Br(4) (1) directly from the reaction of Ph(2)Se(2) with dibromine is reported. The solid-state structure of 1 consists of four PhSeBr units linked by weak selenium-selenium bonds [3.004(2)-3.051(2) A] into a Se(4) square, and is structurally analogous to the previously reported Ph(4)Te(4)I(4). The reactions of Ph(4)Se(4)Br(4) with a variety of tertiary phosphines have been undertaken, resulting in the formation of compounds of formula R(3)PSe(Ph)Br. X-Ray crystallographic analysis of three of the compounds reveals different structural isomers. Ph(3)PSe(Ph)Br (2) is a charge-transfer (CT) compound [Se-Br 3.0020(8) A], with an essentially linear P-Se-Br bond angle, 172.15(4) degrees and T-shaped geometry at selenium. Me(3)PSe(Ph)Br (5) also contains the selenium atom in a T-shaped geometry, consistent with a CT formulation, although the Se-Br distance of 3.327(3) A is considerably longer than observed for 2. In contrast, Cy(3)PSe(Ph)Br (6) is an ionic phosphonium salt, [Cy(3)PSePh]Br with no short Se-Br interactions. Geometry at selenium is bent, as expected for an ionic compound. These results are discussed with reference to the previously reported iodo-compounds Ph(3)PSe(Ph)I and [(Me(2)N)(3)PSe(Ph)]I. PMID:16538270

Barnes, Nicholas A; Godfrey, Stephen M; Halton, Ruth T A; Mushtaq, Imrana; Pritchard, Robin G; Sarwar, Shamsa

2006-03-28

199

Bis(azido) compounds of Pd and Pt with bulky phosphine ligands (dppn=1,8-bis(diphenylphosphino)naphthalene, dppf=1,1?-bis(diphenylphosphino)ferrocene, 1-dpn=1-diphenylphosphino-naphthalene): Preparation, structures, and reactivity toward isocyanides  

NASA Astrophysics Data System (ADS)

Pd-bis(azido) compounds [Pd(dppn)(N 3) 2] and [Pd(dppf)(N 3) 2], which contain bulky chelating bis(phosphine) ligands (dppn=1,8-bis(diphenylphosphino)naphthalene, dppf=1,1'-bis(diphenylphosphino)ferrocene), were prepared from the corresponding chlorides and NaN 3. We also prepared the Pt-bis(azido) compound [Pt(1-dpn)(SMe 2)(N 3) 2] containing a bulky monodentate phosphine (1-dpn=1-diphenylphosphino-naphthalene). All these compounds underwent [2+3] cycloaddition with isocyanides (R-NC, R=cyclohexyl, tert-butyl, 2,6-dimethylphenyl) to convert azido ligands to five-membered, C-coordinated tetrazolate rings. In addition, we observed the [Pd(dppn)Cl 2]-mediated C-C coupling of PhC tbnd6 CH to generate the ? 2-PhC tbnd6 C-C tbnd6 CPh ligand. All compounds have been structurally characterized by X-ray diffraction.

Huh, Hyun Sue; Lee, Yeon Kyoung; Lee, Soon W.

2006-05-01

200

Structural Properties, Cytotoxicity, and Anti-Inflammatory Activity of Silver(I) Complexes with tris(p-tolyl)Phosphine and 5-Chloro-2-Mercaptobenzothiazole  

PubMed Central

The synthesis and characterization of the silver(I) chloride complex of formula {[AgCI(CMBZT)(TPTP)2] · (MeOH)} (1) (CMBZT = 5-chloro-2-mercaptobenzothiazole, TPTP = tris(p-tolyl)phosphine) is described. Also the structure of the hydrate derivative {[AgCI(TPTP)3] · (0.5 · H2O)} (2) of the corresponding known anhydrous silver complex (Zartilas et al., 2009), and the polymorph 3 of the known [AgI(TPTP)3] complex (Zartilas et al., 2009) were determined and compared with the known ones. In addition, the structure of the known one silver(I) cluster {[AgI(TPTP)]4} (4) (Meijboom et al., 2009) was re-determined at 120(2) K and possible Ag-Ag interactions were analyzed. The compounds 1–4 were characterized by X-ray crystallography at r.t (1) and 120 K (2–4). All these complexes and {[(Et3NH)+]2 · [Ag6(?3-Hmna)4(?3-mna)2]2? · (DMSO)2 · (H2O)} (5) (Hmna = 2-mercaptonicotinic acid) were evaluated for cytotoxic and anti-inflammatory activity. The in vitro testing of cytotoxic activity of 1–5 against leiomyosarcoma cancer cells (LMS), were evaluated with Trypan Blue and Thiazolyl Blue Tetrazolium Bromide or 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) assays. The flow cytometry assay for complex 1 and showed that at 15??M of 1, 62.38% of LMS cells undergo apoptosis, while 7% of LMS cells undergo cell necrosis. The antitumor activity of 3 is comparable with that of its reported polymorph (Zartilas et al., 2009). The anti-inflammatory, activity of complexes 1–3 and 5 was also studied. The activity towards cell viability was 2 > 3 > 5 > 1 > 4, while the order of the inhibitory activity in cell growth proliferation follows the order, 2 > 3 > 1 > 4 > 5. The anti-inflammatory activity on the other hand is 1 > 2 > 5 > ? >3. PMID:20379345

Kyros, L.; Kourkoumelis, N.; Kubicki, M.; Male, L.; Hursthouse, M. B.; Verginadis, I. I.; Gouma, E.; Karkabounas, S.; Charalabopoulos, K.; Hadjikakou, S. K.

2010-01-01

201

Homogeneous catalysts supported on soluble polymers: biphasic Sonogashira coupling of aryl halides and acetylenes using MeOPEG-bound phosphine-palladium catalysts for efficient catalyst recycling.  

PubMed

The Sonogashira coupling of various aryl bromides and iodides with different acetylenes was studied under biphasic conditions with soluble, polymer-modified catalysts to allow the efficient recycling of the homogeneous catalyst. For this purpose, several sterically demanding and electron-rich phosphines of the type R(P)PR(2) were synthesised. They are covalently linked to a monomethyl polyethylene glycol ether with a mass of 2000 Dalton (R(P)=MeOPEG(2000)) R(P)PR(2): -PR(2)= -CH(2)C(6)H(4)CH(2)P(1-Ad)(2), -C(6)H(4)-P(1-Ad)(2), -C(6)H(4)-PPh(2). To couple aryl iodides and acetylenes, the catalyst [(MeCN)(2)PdCl(2)]/2 R(P)-C(6)H(4)-PPh(2) was used in CH(3)CN/Et(3)N/n-heptane (5/2/5). The combined yields of coupling product over five reaction cycles are between 80-95 percent. There is no apparent leaching of the catalyst into n-heptane, as evidenced by (1)H NMR spectroscopy. The new catalyst [(MeCN)(2)PdCl(2)]/2 (1-Ad)(2)PBn can be used for room-temperature coupling of various aryl bromides and acetylenes in THF with HNiPr(2) as a base. A closely related catalyst Na(2)[PdCl(4)]/2 R(P)-CH(2)C(6)H(4)CH(2)P(1-Ad)(2) linked to the polymer was used to couple aryl bromides and acetylenes in DMSO or DMSO/n-heptane at 60 degrees C with 0.5 mol percent Na(2)[PdCl(4)], 1 mol percent R(P)PR(2) and 0.33 mol percent CuI. The combined yield of coupling products over five cycles is always greater than 90 percent, except for sterically hindered aryl bromides. The determination of the turnover frequency (TOF) of the catalyst indicates only a small decrease in activity over five cycles. Leaching of the catalyst into the product containing n-heptane solution could not be detected by means of (1)H NMR and TXRF; this is indicative of >99.995 percent catalyst retention in the DMSO solvent. PMID:12645031

Köllhofer, Axel; Plenio, Herbert

2003-03-17

202

Catalytic dimerization of propene by nickel-phosphine complexes in 1-butyl-3-methylimidazolium chloride/AlEt{sub x}Cl{sub 3{minus}x} (x = 0, 1) ionic liquids  

SciTech Connect

The dimerization of propene was catalyzed by cationic nickel complexes in a two-phase solvent system using organochloroaluminate ionic liquids as the solvent for the catalyst. In ionic liquids containing an excess of strongly coordinating chloride ions, i.e., basic, no activity was observed. In contrast, melts containing an excess of alkylchloroaluminum species, i.e., acidic, stabilized the active cationic nickel species. The reaction products separate as an organic layer. Molecular organochloroaluminum species were extracted, and the composition of the salt was strongly modified. This was circumvented using a salt which contains an excess of aluminum chloride. The propene dimers obtained by this way can be transformed either into ethers or into alkanes to produce high octane number additives for gasoline. The effects of phosphine ligands coordinated on nickel and operating variables were investigated in order to maximize the octane number of the corresponding alkanes and ethers.

Chauvin, Y.; Einloft, S.; Olivier, H. [Inst. Francais du Petrole, Rueil-Malmaison (France)

1995-04-01

203

The preparation of phosphine tellurides  

E-print Network

these compounds to yield tellurium and a clear 10 solution. Acetone and cyclohexane gave a gray solution which resulted. from a dispersion of black tellurium, while n-butyl ether gave a gray gelatinous precipitate. From the solubility studies, it was found... these compounds to yield tellurium and a clear 10 solution. Acetone and cyclohexane gave a gray solution which resulted. from a dispersion of black tellurium, while n-butyl ether gave a gray gelatinous precipitate. From the solubility studies, it was found...

Steeves, Brian Howard

2012-06-07

204

A Cell-Permeable Phosphine-Borane Complex Delays Retinal Ganglion Cell Death After Axonal Injury Through Activation of The Pro-Survival extracellular signal-regulated kinases 1/2 Pathway  

PubMed Central

The reactive oxygen species superoxide has been recognized as a critical signal triggering retinal ganglion cell (RGC) death after axonal injury. Although the downstream targets of superoxide are unknown, chemical reduction of oxidized sulfhydryls has been shown to be neuroprotective for injured RGCs. Based on this, we developed novel phosphine-borane complex compounds that are cell permeable and highly stable. Here, we report that our lead compound, bis (3-propionic acid methyl ester) phenylphosphine borane complex 1 (PB1), promotes RGC survival in rat models of optic nerve axotomy and in experimental glaucoma. PB1-mediated RGC neuroprotection did not correlate with inhibition of stress-activated protein kinase signaling, including ASK1, JNK or p38. Instead, PB1 led to a striking increase in retinal BDNF levels and downstream activation of the ERK1/2 pathway. Pharmacological inhibition of ERK1/2 entirely blocked RGC neuroprotection induced by PB1. We conclude that PB1 protects damaged RGCs through activation of pro-survival signals. These data support a potential cross-talk between redox homeostasis and neurotrophin-related pathways leading to RGC survival after axonal injury. PMID:21749374

Almasieh, Mohammadali; Lieven, Christopher J.; Levin, Leonard A.; Di Polo, Adriana

2011-01-01

205

Application of 4,4,4-Trifluoro-1-(Biphenyl-4-yl)Butane-1,3-Dione as a Chelating Extractant in the Solvent Extraction and Separation of Light Lanthanoids in Combination with Phosphine Oxides.  

PubMed

The 4,4,4-trifluoro-1-(biphenyl-4-yl)butane-1,3-dione(HL) has been synthesized and its complexation properties in solution was examined. Mixed ligand chelate extraction of light trivalent lanthanoids (La÷Gd) from chloride medium at constant ionic strength µ = 0.1 into C6H6 with HL in combination with one of the three phosphine oxide compounds trioctylphosphine oxide(TOPO), tributylphosphine oxide(TBPO) or triphenyphosphine oxide(TPPO) was studied. The composition of the extracted species was established as LnL3 with HL alone and as LnL3 2S in the presence of TOPO and TBPO or LnL3 S with the mixture of HL-TPPO. The 28 values of the overall equilibrium constants were calculated. A synergic effect up to 103-104 was observed for the extraction of the above-mentioned lanthanoid ions with binary mixtures of extractants. The change of the synergistic agent causes a significant increase of the KL,S values in the order TBPO < TPPO < TOPO. The parameters of the extraction process were determined and the separation factors between two adjacent Ln(III) were calculated. PMID:24061883

Atanassova, Maria; Kaloyanova, Stefka; Deligeorgiev, Todor

2010-12-01

206

Efficient general procedure to access a diversity of gold(0) particles and gold(I) phosphine complexes from a simple HAuCl4 source. Localization of homogeneous/heterogeneous system's interface and field-emission scanning electron microscopy study.  

PubMed

Soluble gold precatalysts, aimed for homogeneous catalysis, under certain conditions may form nanoparticles, which dramatically change the mechanism and initiate different chemistry. The present study addresses the question of designing gold catalysts, taking into account possible interconversions and contamination at the homogeneous/heterogeneous system's interface. It was revealed that accurate localization of boundary experimental conditions for formation of molecular gold complexes in solution versus nucleation and growth of gold particles opens new opportunities for well-known gold chemistry. Within the developed concept, a series of practical procedures was created for efficient synthesis of soluble gold complexes with various phosphine ligands (R3P)AuCl (90-99% yield) and for preparation of different types of gold materials. The effect of the ligand on the particles growth in solution has been observed and characterized with high-resolution field-emission scanning electron microscopy (FE-SEM) study. Two unique types of nanostructured gold materials were prepared: hierarchical agglomerates and gold mirror composed of ultrafine smoothly shaped particles. PMID:23276227

Zalesskiy, Sergey S; Sedykh, Alexander E; Kashin, Alexey S; Ananikov, Valentine P

2013-03-01

207

Bioinspired Hydrogenase Models: The Mixed-Valence Triiron Complex [Fe3(CO)7(?-edt)2] and Phosphine Derivatives [Fe3(CO)7–x(PPh3)x(?-edt)2] (x = 1, 2) and [Fe3(CO)5(?2-diphosphine)(?-edt)2] as Proton Reduction Catalysts  

PubMed Central

The mixed-valence triiron complexes [Fe3(CO)7–x(PPh3)x(?-edt)2] (x = 0–2; edt = SCH2CH2S) and [Fe3(CO)5(?2-diphosphine)(?-edt)2] (diphosphine = dppv, dppe, dppb, dppn) have been prepared and structurally characterized. All adopt an anti arrangement of the dithiolate bridges, and PPh3 substitution occurs at the apical positions of the outer iron atoms, while the diphosphine complexes exist only in the dibasal form in both the solid state and solution. The carbonyl on the central iron atom is semibridging, and this leads to a rotated structure between the bridged diiron center. IR studies reveal that all complexes are inert to protonation by HBF4·Et2O, but addition of acid to the pentacarbonyl complexes results in one-electron oxidation to yield the moderately stable cations [Fe3(CO)5(PPh3)2(?-edt)2]+ and [Fe3(CO)5(?2-diphosphine)(?-edt)2]+, species which also result upon oxidation by [Cp2Fe][PF6]. The electrochemistry of the formally Fe(I)–Fe(II)–Fe(I) complexes has been investigated. Each undergoes a quasi-reversible oxidation, the potential of which is sensitive to phosphine substitution, generally occurring between 0.15 and 0.50 V, although [Fe3(CO)5(PPh3)2(?-edt)2] is oxidized at ?0.05 V. Reduction of all complexes is irreversible and is again sensitive to phosphine substitution, varying between ?1.47 V for [Fe3(CO)7(?-edt)2] and around ?1.7 V for phosphine-substituted complexes. In their one-electron-reduced states, all complexes are catalysts for the reduction of protons to hydrogen, the catalytic overpotential being increased upon successive phosphine substitution. In comparison to the diiron complex [Fe2(CO)6(?-edt)], [Fe3(CO)7(?-edt)2] catalyzes proton reduction at 0.36 V less negative potentials. Electronic structure calculations have been carried out in order to fully elucidate the nature of the oxidation and reduction processes. In all complexes, the HOMO comprises an iron–iron bonding orbital localized between the two iron atoms not ligated by the semibridging carbonyl, while the LUMO is highly delocalized in nature and is antibonding between both pairs of iron atoms but also contains an antibonding dithiolate interaction. PMID:24748710

2014-01-01

208

Penta-carbonyl-1?2 C,2?3 C-(ferrocenyl-diphenyl-phosphine-1?P)[?-2-(4-methyl-phen-yl)-2-aza-propane-1,3-dithiol-ato-1:2?4 S,S?:S,S?]diiron(I)(Fe--Fe)  

PubMed Central

The title compound, [Fe2(C9H11NS2){Fe(C5H5)(C17H14P)}(CO)5], was prepared as an aza­dithiol­ato–iron model for the iron-only hydrogenase active site. The Fe2S2 unit exhibits a butterfly conformation and the ferrocenyldiphenyl­phosphine ligand is trans to the Fe—Fe bond. The Fe—Fe distance of 2.5160?(8)?Å is longer than found in related model structures. Intra­molecular C—H?S and inter­molecular C—H?O hydrogen bonds are observed. PMID:21580868

Tang, Yan-Feng; Zhu, Jin-Li

2008-01-01

209

Isomer Dependence in the Assembly and Lability of Silver(I) Trifluoromethanesulfonate Complexes of the Heteroditopic Ligands, 2-, 3-, and 4-[Di(1H-pyrazolyl)methyl]phenyl(di-p-tolyl)phosphine.  

PubMed

Three isomers of a new heteroditopic ligand that contains a di(1H-pyrazolyl)methyl (-CHpz2) moiety connected to a di(p-tolyl)phosphine group via a para-, meta-, or ortho-phenylene spacer (pL, mL, and oL, respectively) have been synthesized by using a palladium(0)-catalyzed coupling reaction between HP(p-tolyl)2 and the appropriate isomer of (IC6H4)CHpz2. The 1:1 complexes of silver(I) trifluoromethanesulfonate, Ag(OTf), were prepared to examine the nature of ligand coordination and the type of supramolecular isomer (monomeric, cyclic oligomeric, or polymeric) that would be obtained. The single crystal X-ray diffraction studies showed that [Ag(pL)](OTf), 1, and [Ag(mL)](OTf), 2, possessed cyclic dimeric dications, whereas [Ag(oL)](OTf), 3, was a coordination polymer. The polymeric chain in 3 could be disrupted by reaction with triphenylphosphine, and the resulting complex, [Ag(oL)(PPh3)](OTf), 4, possessed a monometallic cation where the ligand was bound to silver in a chelating ?(2)P,N- coordination mode. The solution structures of 1-4 were probed via a combination of IR, variable-temperature multinuclear ((1)H, (13)C, (31)P) NMR spectroscopy, as well as by electron spray ionization (ESI)(+) mass spectrometry. A related complex [Ag(m-IC6H4CHpz2)2](OTf), 5, was also prepared, and its solid-state and solution spectroscopic properties were studied for comparison purposes. These studies suggest that the cyclic structures of 1 and 2 are likely preserved but are dynamic in solution at room temperature. Moreover, both 3 and 4 have dynamic solution structures where 3 is likely extensively dissociated in CH3CN or acetone rather than being polymeric as in the solid state. PMID:25375040

Gardinier, James R; Hewage, Jeewantha S; Lindeman, Sergey V

2014-11-17

210

Synthesis, characterization, and in vitro antitumor properties of tris(hydroxymethyl)phosphine copper(I) complexes containing the new bis(1,2,4-triazol-1-yl)acetate ligand.  

PubMed

The new sodium bis(1,2,4-triazol-1-yl)acetate ligand, Na[HC(CO(2))(tz)(2)], has been prepared in methanol solution by using 1,2,4-triazole, dibromoacetic acid, and NaOH. Treatment of the [Cu(CH(3)CN)(4)][PF(6)] acceptor with Na[HC(CO(2))(tz)(2)] or Na[HC(CO(2))[(pz(Me2))(2)] in the presence of the tris(hydroxymethyl)phosphine coligand in methanol/acetonitrile solutions produced unprecedented mononuclear copper(I) complexes of the [L(n)]Cu[P(CH(2)OH)(3)](2) (L(1), 2; L(2), 3) [(CH(3)CN)(2)Cu(P(CH(2)OH)(3))(2)]PF(6), 4. These compounds have been characterized by elemental analyses, FTIR, ESI-MS, and multinuclear (1H and 31P) NMR spectral data. The new copper(I) complexes were tested for their cytotoxic properties against a panel of several human tumor cell lines. The results reported here indicate that all the complexes showed in vitro antitumor activity similar or better than that of cisplatin, the most used metal-based antitumor drug. In particular, [HC(CO(2))(pz(Me2))(2)]Cu[P(CH(2)OH)(3)](2), 3 showed IC(50) values markedly lower than the reference compound against all tumor cell lines. Chemosensitivity tests performed on cisplatin sensitive and resistant cell lines have demonstrated that all these Cu(I) complexes were able to overcome cisplatin resistance, supporting the hypothesis of a different mechanism of action compared to that exhibited by the reference drug. Flow cytometric analysis on 2008 human ovarian carcinoma cells revealed that complex 3, chosen as the best candidate, induced a marked enlargement of both cell size and granularity, and a significant increase in the fraction of G2/M cells that, differently from cisplatin, was not accompanied by the appearance of a relevant sub-G1 fraction. Besides, no evidence of caspase-3 activation was detected in cells treated with complex 3. We hypothesize that the cytotoxic activity of the new copper(I) complex may be correlated to its ability to trigger paraptosis, a nonapoptotic mechanism of cell death. PMID:17149861

Marzano, Cristina; Pellei, Maura; Colavito, Davide; Alidori, Simone; Lobbia, Giancarlo Gioia; Gandin, Valentina; Tisato, Francesco; Santini, Carlo

2006-12-14

211

Application of organolithium compounds for the preparation of some aliphatic and alicyclic phosphines, phosphine oxides and phosphine sulfides  

E-print Network

~ thol- p tolplpheepheaaio, It? POC1 + p ho?Aid. P ~CSItPO OCt + f441 4 4 4t Mlhhallov aed Kaehereva, a?lag the phoapl& a aaphthpl, 9 1 pheaaathrpl y ~thrply 1 y 0 hooeaathr lid Fl sad Xy 5+hoasasi4hP+f Fl lithias derivatives prepared... ~~& RNR p o 2HRH 2 50 Oilsaag He aa4 Voraea, Ce Co ~ P ~ diorama ~Ch ai ~op t8, 1C63(1926) ~ ge Williaasi Rt Ho aad Haailtoay Le Le ~ ~be +by 5 $18(1952) ~ 7 ~ Libera~ L aa4 Scholar) '&e ~ ~H? Q6y 23(1913) ~ Si Johaanis, Ri Ai, gee@o r~a. , +, 557...

Screttas, Constantinos G

2012-06-07

212

Technetium(III) complexes with the tetradentate umbrella ligand tris (o-mercaptophenyl)phosphinate: X-ray structural characterization of Tc(P(o-C sub 6 H sub 4 S) sub 3 )(CNC sub 3 H sub 7 ) and Tc(P(o-C sub 6 H sub 4 S) sub 3 )(CNC sub 3 H sub 7 ) sub 2  

SciTech Connect

Tris(o-mercaptophenyl) phosphinate (PS3) binds to Tc(III) as a tetradentate ligand to form the formally 14-electron complex Tc(PS3)(CNMe). An x-ray single-crystal structure determination of the isopropyl isocyanide derivative Tc(PS3)(CN-i-Pr) shows sulfurs bound in the equatorial plane. The crystal data for MF = C{sub 22}H{sub 19}NPS{sub 3}Tc is presented. In the presence of a large excess of isonitrile, these electron-deficient complexes bind a sixth ligand. The six-coordinate complex Tc(PS3)(CN-i-Pr){sub 2}, was also structurally characterized and the crystal data is presented. 8 refs., 2 figs., 4 tabs.

de Vries, N.; Cook, J.; Davison, A. (Massachusetts Inst. of Tech., Cambridge (United States)); Jones, A.G. (Harvard Medical School, Boston, MA (United States))

1991-06-12

213

Cyanidotetra-kis-(trimethyl-phosphine)cobalt(I).  

PubMed

The title compound, [Co(CN)(C(3)H(9)P)(4)], was obtained as a product of the reaction of [Co(PMe(3))(4)] with a molar equivalent of 2,6-difluoro-benzonitrile in diethyl ether. This compound is stable in the air for several hours, but rapidly decomposes at room temperature in solution. The cobalt(I) atom has s trigonal-bipyramidal coordination enviroment in which the cyano group and one of the PMe(3) groups are in the axial positions. PMID:21754010

Xu, Xiaofeng; Feng, Lei; Li, Xiaoyan

2011-04-01

214

The synthesis and preparation of some phosphines and phosphine sulfides containing highly condensed aromatic groups  

E-print Network

mole) of butyllithium in 400 ml. of anhydrous ethyl othsx' at 0 , was added 41. )Z g. (0. 20 mole) 0 of 1 bromonaphthalene 1n 100 rQ. of anhydrous ethyl ether, with stirring, ovsz a period of 15 min. The rsact1on mixtuxs was refluxed for 30 min... mole) of butyllithium in 400 ml. of anhydrous ethyl othsx' at 0 , was added 41. )Z g. (0. 20 mole) 0 of 1 bromonaphthalene 1n 100 rQ. of anhydrous ethyl ether, with stirring, ovsz a period of 15 min. The rsact1on mixtuxs was refluxed for 30 min...

Tefteller, Joseph Wilburn

2012-06-07

215

Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/CdxZn1 - xS/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen  

NASA Astrophysics Data System (ADS)

Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/CdxZn1 - xS/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml - 1.

Shen, Huaibin; Yuan, Hang; Niu, Jin Zhong; Xu, Shasha; Zhou, Changhua; Ma, Lan; Li, Lin Song

2011-09-01

216

Development of an extractive spectrophotometric method for estimation of uranium in ore leach solutions using 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A) and tri-n-octyl phosphine oxide (TOPO) mixture as extractant and 2-(5-bromo-2-pyridylozo)-5-diethyl aminophenol (Br-PADAP) as chromophore  

NASA Astrophysics Data System (ADS)

An extractive spectrophotometric analytical method has been developed for the determination of uranium in ore leach solution. This technique is based on the selective extraction of uranium from multielement system using a synergistic mixture of 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A) and tri-n-octyl phosphine oxide (TOPO) in cyclohexane and color development from the organic phase aliquot using 2-(5-Bromo-2-pyridylazo)-5-diethyl aminophenol (Br-PADAP) as chromogenic reagent. The absorption maximum (?max) for UO22+-Br-PADAP complex in organic phase samples, in 64% (v/v) ethanol containing buffer solution (pH 7.8) and 1,2-cyclohexylenedinitrilotetraacetic acid (CyDTA) complexing agent, has been found to be at 576 nm (molar extinction coefficient, ?: 36,750 ± 240 L mol-1 cm-1). Effects of various parameters like stability of complex, ethanol volume, ore matrix, interfering ions etc. on the determination of uranium have also been evaluated. Absorbance measurements as a function of time showed that colored complex is stable up to >24 h. Presence of increased amount of ethanol in colored solution suppresses the absorption of a standard UO22+-Br-PADAP solution. Analyses of synthetic standard as well as ore leach a solution show that for 10 determination relative standard deviation (RSD) is <2%. The accuracy of the developed method has been checked by determining uranium using standard addition method and was found to be accurate with a 98-105% recovery rate. The developed method has been applied for the analysis of a number of uranium samples generated from uranium ore leach solutions and results were compared with standard methods like inductively coupled plasma emission spectrometry (ICPAES). The determined values of uranium concentrations by these methods are within ±2%. This method can be used to determine 2.5-250 ?g mL-1 uranium in ore leach solutions with high accuracy and precision.

Biswas, Sujoy; Pathak, P. N.; Roy, S. B.

2012-06-01

217

Phosphine-Free EWG-Activated Ruthenium Olefin Metathesis Catalysts  

NASA Astrophysics Data System (ADS)

Hoveyda-Grubbs catalyst has been successfully fine-tuned by us in order to increase its activity and applicability by the introduction of electron-withdrawing groups (EWGs) to diminish donor properties of the oxygen atom. As a result, the stable and easily accessible nitro-substituted Hoveyda-Grubbs catalyst has found a number of successful applications in various research and industrial laboratories. Some other EWG-activated Hoveyda-type catalysts are commercially available. The results described herewith demonstrate that the activity of ruthenium (Ru) metathesis catalysts can be enhanced by introduction of EWGs without detriment to catalysts stability. Equally noteworthy is the observation that different Ru catalysts turned out to be optimal for different applications. This shows that no single catalyst outperforms all others in all possible applications.

Grela, Karol; Szadkowska, Anna; Michrowska, Anna; Bieniek, Michal; Sashuk, Volodymyr

218

A structural and spectroscopic investigation of octahedral platinum bis(dithiolene)phosphine complexes: platinum dithiolene internal redox chemistry induced by phosphine association.  

PubMed

The complexes [Pt(mdt)2] (4; mdt = methyldithiolene, [Me2C2S2](n-)), [Pt(adt)2] (5; adt = p-anisyldithiolene, [(MeO-p-C6H4)2C2S2](n-)), and [Pd(adt)2] (10) have been prepared in yields of ?90% via transmetalation reactions with the corresponding [R2Sn(S2C2R'2)] complexes (R = (n)Bu, R' = Me; R = Me, R' = -C6H4-p-OMe, 3). Intraligand C-S and C-Cchelate bond lengths (~1.71 and ~1.40 Å, respectively) obtained by X-ray crystallography show these compounds to be comprised of radical monoanions mdt(•-) and adt(•-). The six-coordinate octahedral adducts [Pt(adt)2(dppe)] [6; dppe = 1,2-bis(diphenylphosphino)ethane], trans-[Pt(adt)2(PMe3)2] (8), and trans-[Pt(mdt)2(PMe3)2] (9) have also been prepared, and crystal structures reveal dithiolene ligands that are fully reduced ene-1,2-dithiolates (C-S and C-C(chelate) = ~1.77 and 1.35 Å, respectively). Reduction of the dithiolene ligand thus occurs to accommodate the +IV oxidation state typical of octahedral six-coordinate platinum. The cyclic voltammogram of 5 shows two fully reversible reductions at -0.11 and -0.84 V in CH2Cl2 (vs Ag/AgCl), attributed to successive (adt(•-) + e(-) ? adt(2-)) processes, and a reversible oxidation at +1.01 V. The cyclic voltammogram of 9 shows two reversible oxidations at +0.38 and +0.86 V, which are assigned as successive (adt(2-) ? adt(•-) + e(-)) oxidations. Consistent with their formulation as having fully reduced dithiolene ligands, the UV-vis spectra for 6, 8, and 9 show no low-energy absorptions below 700 nm, and the S K-edge XAS spectra of 6 and 8 show dithiolene sulfur that is reduced relative to that in 5. The introduction of PMe3 to 10 did not produce the palladium analogue of 8 but rather [Pd(adt)(PMe3)2] (11). The reaction of [PdCl2(PPh3)2] with Li2(mdt) produced a mixture of [Pd(mdt)(PPh3)2] (12, 20%) and [(Ph3P)Pd(?-1,2-mdt-S,S':S)2Pd(PPh3)] (13, 28%), with the latter having C2 symmetry with a Pd2S2 core structure folded along the S···S axis. PMID:25113575

Chandrasekaran, P; Greene, Angelique F; Lillich, Karen; Capone, Stephen; Mague, Joel T; DeBeer, Serena; Donahue, James P

2014-09-01

219

The characterization and reactivity of dinuclear gold complexes containing phosphonium or tertiary phosphine bridging ligands  

E-print Network

and were identified to be benzoic acid (melting point 120O C) ~ DISCUSSION Reaction with Alkyl Halides of the Type C4H402N-X While C H 0 N-X compounds are properly classified as N-halo 4 4 2 amides, both the chloro- and the bromo-succinimide analogues... and were identified to be benzoic acid (melting point 120O C) ~ DISCUSSION Reaction with Alkyl Halides of the Type C4H402N-X While C H 0 N-X compounds are properly classified as N-halo 4 4 2 amides, both the chloro- and the bromo-succinimide analogues...

Diebold, Julia Shain

2012-06-07

220

A porphyrin complex of Gold(I): (Phosphine)gold(I) azides as cation precursors  

PubMed Central

A silver- and Brönsted acid-free protocol for generating the (tricyclohexylphosphine)gold(I) cation from the corresponding azide complexes is disclosed. The gold(I) cations so liberated are trapped by complexation with octaethylporphyrin. The first structurally authenticated gold(I) porphyrin complex crystallizes with formula C72H112Au2F12N4P2Sb2, space group C2/c, a = 21.388 (4), b = 19.679 (4), c = 19.231 (3) ?; ? = 111.030 (3)°. Solution spectroscopic studies indicate that the di-gold complex fragments on dissolution in organic solvents. Approximate density-functional theory calculations find an electrostatic origin for the binding of two gold(I) centers to the unprotonated nitrogen atoms, despite greater orbital density on the porphyrin meso carbons. PMID:18780788

Partyka, David V.; Robilotto, Thomas J.; Zeller, Matthias; Hunter, Allen D.; Gray, Thomas G.

2008-01-01

221

Phosphine complexes of aluminium(iii) halides - preparation and structural and spectroscopic systematics.  

PubMed

Six-coordinate pseudo-octahedral complexes trans-[AlX2(L-L)2][AlX4] (X = Cl, Br or I; L-L = o-C6H4(PMe2)2, Me2P(CH2)2PMe2) are produced from reaction of AlX3 with the diphosphine in CH2Cl2 (X = Cl) or toluene (X = Br or I) solution. Four-coordinate dimers [Cl3Al(?-L'-L')AlCl3] (L'-L' = Me2P(CH2)2PMe2, Cy2P(CH2)2PCy2), and the tetrahedral cation [AlCl2{o-C6H4(PPh2)2}][AlCl4] were also obtained. Both four- and five-coordinate complexes [AlX3(PMe3)] and [AlX3(PMe3)2] could be isolated with PMe3 depending upon the ratio of reagents used. These extremely moisture sensitive complexes have been characterised by microanalysis, IR and multinuclear NMR ((1)H, (31)P{(1)H} and (27)Al) spectroscopy. X-ray crystal structures are reported for [AlCl2{o-C6H4(PMe2)2}2][AlCl4], [AlCl2{Me2P(CH2)2PMe2}2][AlCl4], [Cl3Al{?-Me2P(CH2)2PMe2}AlCl3], [Cl3Al{?-Cy2P(CH2)2PCy2}AlCl3], [AlCl3(PMe3)], [AlCl3(PMe3)2], and for the six-coordinate cation complex [AlCl2{o-C6H4(PPh2)2}2][AlCl4], although a bulk sample of the last could not be isolated. Tertiary arsines (AsPh3 or AsEt3) form only 1?:?1 complexes even with excess arsine present. The unstable [AlCl2{o-C6H4(AsMe2)2}][AlCl4] is also described, and shown to decompose rapidly in CH2Cl2 solution to form the diquaternised diarsine cation [o-C6H4(AsMe2)2(CH2)][AlCl4]2, which was fully characterised. Comparisons are drawn with the corresponding gallium(iii) systems (Cheng et al., Inorg. Chem., 2007, 46, 7215-7223) and with AlX3 complexes of Group 16 ligands (George et al., Dalton Trans., 2014, 43, 3637-3648), and it is concluded that the differences between the Al and Ga systems reflect the higher Lewis acidity of aluminium(iii) towards soft donor ligands. PMID:25140820

Burt, Jennifer; Levason, William; Light, Mark E; Reid, Gillian

2014-09-16

222

Diamond and Related Materials 7 (1998) 16511656 Influence of phosphine on the diamond growth mechanism  

E-print Network

a persistent obstacle towards the that the experimental doping efficiency (in the range development of diamond-like carbon (DLC) films can cal value calculated by Jin et al. (1Ã?10-4) [6]. These exhibit semiconducting films was found to be very their standard mixture of 0.15% CH 4 in H 2 . Hall effect low [5

Bristol, University of

223

Detection of phosphine: new aspects of the phosphorus cycle in the hydrosphere  

Microsoft Academic Search

The role of phosphorus in limiting organic matter production and in causing eutrophication has been in the forefront of hydrobiological research during the past 30-50 yr1-7. Comparing the cycles of major biogenic elements, it is evident that, with the exception of phosphorus, each of them contains gaseous substances (for example, CO2, CH4, O2, N2, NH3, H2S and volatile organic sulphur

István Dévai; Lajos Felföldy; Ilona Wittner; Sándor Plósz

1988-01-01

224

Role of lipophilicity in determining cellular uptake and antitumour activity of gold phosphine complexes  

Microsoft Academic Search

Purpose: The lipophilic cation [Au(I)(dppe)2]+ [where dppe is 1,2-bis(diphenylphosphino)ethane] has previously demonstrated potent in vitro antitumour activity. We wished\\u000a to determine the physicochemical basis for the cellular uptake of this drug, as well as of analogues including the 1:2 adducts\\u000a of Au(I) with 1,2-bis(di-n-pyridylphosphino)ethane (dnpype; n=2, 3 and 4), and to compare in vitro and in vivo antitumour\\u000a activity. Methods

Mark J. McKeage; Susan J. Berners-Price; Peter Galettis; Richard J. Bowen; Wandy Brouwer; Li Ding; Li Zhuang; Bruce C. Baguley

2000-01-01

225

Mechanistic Investigation of Catalytic Carbon-Carbon Bond Activation and Formation by Platinum and Palladium Phosphine  

E-print Network

Mechanistic Investigation of Catalytic Carbon-Carbon Bond Activation and Formation by Platinum). The breaking of C-C bonds is also crucial in coal liquefaction processes such as the Exxon Donor Solvent process or the Microcat Coal Liquefaction process. Presently cracking is achieved with heterogeneous

Jones, William D.

226

Intensely luminescent homoleptic alkynyl decanuclear gold(I) clusters and their cationic octanuclear phosphine derivatives.  

PubMed

Treatment of Au(SC(4)H(8))Cl with a stoichiometric amount of hydroxyaliphatic alkyne in the presence of NEt(3) results in high-yield self-assembly of homoleptic clusters (AuC(2)R)(10) (R = 9-fluorenol (1), diphenylmethanol (2), 2,6-dimethyl-4-heptanol (3), 3-methyl-2-butanol (4), 4-methyl-2-pentanol (4), 1-cyclohexanol (6), 2-borneol (7)). The molecular compounds contain an unprecedented catenane metal core with two interlocked 5-membered rings. Reactions of the decanuclear clusters 1-7 with gold-diphosphine complex [Au(2)(1,4-PPh(2)-C(6)H(4)-PPh(2))(2)](2+) lead to octanuclear cationic derivatives [Au(8)(C(2)R)(6)(PPh(2)-C(6)H(4)-PPh(2))(2)](2+) (8-14), which consist of planar tetranuclear units {Au(4)(C(2)R)(4)} coupled with two fragments [AuPPh(2)-C(6)H(4)-PPh(2)(AuC(2)R)](+). The titled complexes were characterized by NMR and ESI-MS spectroscopy, and the structures of 1, 13, and 14 were determined by single-crystal X-ray diffraction analysis. The luminescence behavior of both Au(I)(10) and Au(I)(8) families has been studied, revealing efficient room-temperature phosphorescence in solution and in the solid state, with the maximum quantum yield approaching 100% (2 in solution). DFT computational studies showed that in both Au(I)(10) and Au(I)(8) clusters metal-centered Au ? Au charge transfer transitions mixed with some ?-alkynyl MLCT character play a dominant role in the observed phosphorescence. PMID:22686420

Koshevoy, Igor O; Chang, Yuh-Chia; Karttunen, Antti J; Selivanov, Stanislav I; Jänis, Janne; Haukka, Matti; Pakkanen, Tapani; Tunik, Sergey P; Chou, Pi-Tai

2012-07-01

227

Extraction of transplutonium elements with diphenyl (alkyl)dialkyl-carbamoylmethyl phosphine oxides  

Microsoft Academic Search

Polydentate neutral organophosphorus compounds attract great interest as efficient extractants of transplutonium elements(TPE)\\u000a from acid waste nuclear fuel element solution. With the view of a further search, reagents R?R?-PO-CH2-CNO-R\\u000a 2\\u000a ?'\\u000a were synthetized and investigated. The solubility of R\\u000a 2\\u000a ?\\u000a POCH2CNOR\\u000a 2\\u000a ?'\\u000a vas investigated in organic solvents and in nitric acid solutions. This reagent was found to be

M. K. Chmutova; N. E. Kochetkova; O. E. Koiro; B. F. Myasoedov; N. P. Nesterova; M. I. Kabachnik

1983-01-01

228

Assembly of symmetrical and unsymmetrical platinum(ii) rollover complexes with bidentate phosphine ligands.  

PubMed

The reaction of the cyclometalated rollover complex [Pt(bpy-H)(Me)(DMSO)] (bpy-H = cyclometalated 2,2'-bipyridine) with two diphosphines, dppm (1,1-bis(diphenylphosphino)methane) and dppe (1,2-bis(diphenylphosphino)ethane), was investigated. According to the reaction conditions, dppm behaves as a monodentate, bridging or chelated ligand, whereas dppe gave only chelated species. Some aspects of the reactivity of the isolated species were studied, including protonation with [H3O·18-crown-6][BF4] and coordination reactions of mononuclear complexes, obtaining, inter alia, rare examples of unsymmetrical organometallic species with bridging dppm. PMID:25162179

Maidich, Luca; Zuri, Giuseppina; Stoccoro, Sergio; Cinellu, Maria Agostina; Zucca, Antonio

2014-09-16

229

Chiral Phosphinate Degradation by the Fusarium Species: Scope and Limitation of the Process  

PubMed Central

Biodegradable capacities of fungal strains of Fusarium oxysporum (DSMZ 2018) and Fusarium culmorum (DSMZ 1094) were tested towards racemic mixture of chiral 2-hydroxy-2-(ethoxyphenylphosphinyl) acetic acid—a compound with two stereogenic centres. The effectiveness of decomposition was dependent on external factors such as temperature and time of the process. Optimal conditions of complete mineralization were established. Both Fusarium species were able to biodegrade every isomer of tested compound at 30°C, but F. culmorum required 10 days and F. oxysporum 11 days to accomplish the process, which was continuously monitored using the 31P NMR technique. PMID:24324893

Brzezinska-Rodak, Malgorzata

2013-01-01

230

CHIRAL-AT-METAL OSMIUM(VI) PHOSPHINE COMPLEXES. (R829553)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

231

Extraction of Gold from Alkaline Gold Leaching Solution by Tertiary Amine N235 and Phosphine Oxide  

Microsoft Academic Search

Extraction of gold from alkaline gold leaching solution by N235-TRPO synergistic system was studied. The effects of the concentrations of Tri-akylphosphine oxide(TRPO) and tertiary amine(N235), the initial pH, and the concentration of gold on the extraction of gold and the extraction isotherm were inspected. The ability of extracting other metal elements by this system had been investigated. The effect of

Li Mingyu; Zhu Xiaoqiang; Zhou Li; Xie Yufei; Zheng Peikai

2011-01-01

232

The Mechanochemical Reaction of Palladium(II) Chloride with a Bidentate Phosphine  

ERIC Educational Resources Information Center

This experiment describes the reaction of palladium(II) chloride with 1,5-bis(diphenylphosphino)pentane by grinding the two powders together in the solid state. The product is the precursor for the metalation reaction at one of the methylene carbon atoms of the ligand's backbone. The final product is known to be a catalyst for Suzuki-Miyaura…

Berry, David E.; Carrie, Philippa; Fawkes, Kelli L.; Rebner, Bruce; Xing, Yao

2010-01-01

233

Variable Ag—O bonding patterns in silver cyclic amide tri-aryl-phosphine complexes  

Microsoft Academic Search

The solid-state structures of five new tri-arylphosphine silver cyclic amide complexes having a systematic variation in the ring structures have been resolved. Normal Ag—N bonding and variable, weaker Ag—O bonding interactions, which can be attributed to the ring modifications, form the basis of the bonding patterns. Reported here are the solid-state structures of silver complexes of tri-arylphosphine derivatives of silver

D. R. Whitcomb; M. Rajeswaran

2006-01-01

234

Complexes between hypohalous acids and phosphine derivatives. Pnicogen bond versus halogen bond versus hydrogen bond  

NASA Astrophysics Data System (ADS)

The complexes of HOBr:PH2Y (Y = H, F, Cl, Br, CH3, NH2, OH, and NO2), HOCl:PH2F, and HOI:PH2F have been investigated with ab initio calculations at the MP2/aug-cc-pVTZ level. Four types of structures (1, 2, 3a, and 3b) were observed for these complexes. 1 is stabilized by an O⋯P pnicogen bond, 2 by a P⋯X halogen bond, 3a by a H⋯P hydrogen bond and a P⋯X pnicogen bond, and 3b by H⋯P and H⋯Br hydrogen bonds. Their relative stability is related to the halogen X of HOX and the substituent Y of PH2Y. These structures can compete with interaction energy of -10.22 ? -29.40 kJ/mol. The Hsbnd O stretch vibration shows a small red shift in 1, a small irregular shift in 2, but a prominent red shift in 3a and 3b. The Xsbnd O stretch vibration exhibits a smaller red shift in 1, a larger red shift in 2, but an insignificant blue shift in 3a and 3b. The Psbnd Y stretch vibration displays a red shift in 1 but a blue shift in 2, 3a, and 3b. The formation mechanism, stability, and properties of these structures have been analyzed with molecular electrostatic potentials, orbital interactions, and non-covalent interaction index.

Li, Qingzhong; Zhu, Hongjie; Zhuo, Hongying; Yang, Xin; Li, Wenzuo; Cheng, Jianbo

2014-11-01

235

Chain-End-Functionalized Polyphosphazenes via a One-Pot Phosphine-Mediated Living Polymerization  

PubMed Central

A simple polymerization of trichlorophosphoranimine (Cl3P = N–SiMe3) mediated by functionalized triphenylphosphines is presented. In situ initiator formation and the subsequent polymerization progress are investigated by 31P NMR spectroscopy, demonstrating a living cationic polymerization mechanism. The polymer chain lengths and molecular weights of the resulting substituted poly(organo)phosphazenes are further studied by 1H NMR spectroscopy and size exclusion chromatography. This strategy facilitates the preparation of polyphosphazenes with controlled molecular weights and specific functional groups at the ?-chain end. Such well-defined, mono-end-functionalized polymers have great potential use in bioconjugation, surface modification, and as building blocks for complex macromolecular constructs. PMID:24700544

Wilfert, Sandra; Henke, Helena; Schoefberger, Wolfgang; Bruggemann, Oliver; Teasdale, Ian

2014-01-01

236

Phosphine-Catalyzed Formation of Carbon-Sulfur Bonds: Catalytic Asymmetric Synthesis of gamma-Thioesters  

E-print Network

A method for catalytic asymmetric ? sulfenylation of carbonyl compounds has been developed. In the presence of an appropriate catalyst, thiols not only add to the ? position of allenoates, overcoming their propensity to ...

Sun, Jianwei

237

Palladium/Tris(tert-butyl)phosphine-Catalyzed Suzuki Cross-Couplings in the Presence of Water  

E-print Network

Dipalladiumtris(dibenzylideneacetone)/tris(tert-butyl)phosphonium tetrafluoroborate/potassium fluoride dihydrate [Pd2(dba)3/[HP(t-Bu)3]BF4/KF?2?H2O] serves as a mild, robust, and user-friendly method for the efficient ...

Lou, Sha

238

Phosphine-catalyzed asymmetric additions of malonate esters to gamma-substituted allenoates and allenamides  

E-print Network

Because carbonyl groups are ubiquitous in organic chemistry, the ability to synthesize functionalized carbonyl compounds, particularly enantioselectively, is an important objective. We have developed a straightforward and ...

Sinisi, Riccardo

239

Study on the interaction of amino phosphine ester derivatives with DNA by spectroscopy, modeling and calorimetry  

NASA Astrophysics Data System (ADS)

The binding properties of amino phosphate ester derivatives, compound 1 and 2 with calf thymus DNA (CT-DNA) were investigated by UV spectra, fluorescence spectra, molecular modeling and isothermal titration calorimetry (ITC). The intrinsic binding constants Kb of compound 1 and 2 with CT-DNA were determined by fluorescence spectroscopy and ITC, respectively. The results indicated that the two compounds bind to CT-DNA with different binding affinity, which is in the order of compound 1 > compound 2. At the same time, fluorescence spectra suggested that the mechanism of the binding of the two compounds to CT-DNA is a static enhancing type. According to the ethidium bromide displacement experiments, UV spectra, molecular modeling and ITC studies, it can be concluded that compound 1 and 2 are intercalators that can slide into the G-C rich region of CT-DNA. Furthermore, ITC data showed that compound/DNA binding is enthalpy controlled.

Lu, Yan; Wang, Gongke; Tang, Wen; Hao, Xiaoxiao; Xu, Meihua; Li, Xiang

2011-11-01

240

Development of a redox-free Mitsunobu reaction exploiting phosphine oxides as precursors to dioxyphosphoranes.  

PubMed

The development of the first redox-free protocol for the Mitsunobu reaction is described. This has been achieved by exploiting triphenylphosphine oxide--the unwanted by-product in the conventional Mitsunobu reaction--as the precursor to the active P(V) coupling reagent. Multinuclear NMR studies are consistent with hydroxyl activation via an alkoxyphosphonium salt. PMID:24871529

Tang, Xiaoping; Chapman, Charlotte; Whiting, Matthew; Denton, Ross

2014-07-14

241

Inhibition of the Staphylococcus aureus sortase transpeptidase SrtA by phosphinic peptidomimetics  

Microsoft Academic Search

During pathogenesis, Gram-positive bacteria utilize surface protein virulence factors such as the MSCRAMMs (microbial surface components recognizing adhesive matrix molecules) to aid the initiation and propagation of infection through adherence to host endothelial tissue and immune system evasion. These virulence-associated proteins generally contain a C-terminal LPXTG motif that becomes covalently anchored to the peptidoglycan biosynthesis intermediate lipid II. In Staphylococcus

Ryan G Kruger; Salim Barkallah; Brenda A Frankel; Dewey G McCafferty

2004-01-01

242

A polymer-bound bidentate-phosphine-palladium complex as a catalyst in the Heck arylation  

SciTech Connect

Polymer-supported 1,2-bis(diisopropylphosphino)benzene Pd(II) complex 2 shows a higher level of catalytic activity than the structurally analogous monomeric Pd(II) complex 1 in the Heck arylation of methyl acrylate by iodobenzene. The polymer-supported Pd(II) complex has a much higher turnover number (by more than 1 order of magnitude) than either 1 or Pd(OAc){sub 2}/PPh{sub 3} at synthetically useful concentrations of reagents. The reaction rate of the monomeric Pd(II) complex 1 is enhanced by electrochemical prereduction of Pd(II) to Pd(0). Deactivation in homogeneous solution via aggregation of the reactive complex to insoluble palladium metal clusters or by equilibration to a sterically blocked tetraphosphino complex is proposed to explain the higher catalytic activity of the polymer-supported Pd(II) complex than of its structurally analogous soluble monomer.

Wang, P.W.; Fox, M.A. [Univ. of Texas, Austin, TX (United States)

1994-09-09

243

High-efficiency turquoise-blue electrophosphorescence from a Pt(II)-pyridyltriazolate complex in a phosphine oxide host  

Microsoft Academic Search

We demonstrate high-efficiency turquoise-blue electrophosphorescence from bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) [Pt(ptp)2] doped in 4-(diphenylphosphoryl)-N,N-diphenylaniline(HM-A1). Organic light-emitting diodes (OLEDs) with 5% Pt(ptp)2:HM-A1 attain peak power efficiency of 61.2 lm\\/W, versus 40.8 lm\\/W for analogous devices employing the standard turquoise-blue phosphor bis[(4,6-difluorophenyl)-pyridinato-N,C2'](picolinato)iridium(III) (FIrpic). Devices with x% Pt(ptp)2:HM-A1 exhibit blue emission maxima (lambdamax~480 nm) with monotonic increase in excimer\\/monomer intensity ratio at higher doping levels within

Unnat S. Bhansali; Evgueni Polikarpov; James S. Swensen; Wei-Hsuan Chen; Huiping Jia; Daniel J. Gaspar; Bruce E. Gnade; Asanga B. Padmaperuma; Mohammad A. Omary

2009-01-01

244

High-efficiency turquoise-blue electrophosphorescence from a Pt(II)-pyridyltriazolate complex in a phosphine oxide host  

NASA Astrophysics Data System (ADS)

We demonstrate high-efficiency turquoise-blue electrophosphorescence from bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) [Pt(ptp)2] doped in 4-(diphenylphosphoryl)-N ,N-diphenylaniline(HM-A1). Organic light-emitting diodes (OLEDs) with 5% Pt(ptp)2:HM-A1 attain peak power efficiency of 61.2 lm/W, versus 40.8 lm/W for analogous devices employing the standard turquoise-blue phosphor bis[(4,6-difluorophenyl)-pyridinato-N,C2'](picolinato)iridium(III) (FIrpic). Devices with x% Pt(ptp)2:HM-A1 exhibit blue emission maxima (?max˜480 nm) with monotonic increase in excimer/monomer intensity ratio at higher doping levels within 1%-10%, causing color shift toward green and less charge balance. This work represents a significant step toward optimizing future white OLEDs from the same phosphor via combination of low-doped and higher-doped or neat films.

Bhansali, Unnat S.; Polikarpov, Evgueni; Swensen, James S.; Chen, Wei-Hsuan; Jia, Huiping; Gaspar, Daniel J.; Gnade, Bruce E.; Padmaperuma, Asanga B.; Omary, Mohammad A.

2009-12-01

245

Low-temperature superstructure of [(N,N-diisobutyl-carbamo-yl)meth-yl]oct-yl(phen-yl)phosphine oxide (CMPO)  

PubMed Central

At 120?K, the title compound, C24H42NO2P, crystallizes in a unit cell with a doubled a parameter compared with the room-temperature structure. There are four mol­ecules in the asymmetric unit, one of which shows extensive disorder in a 0.588?(3):0.412?(3) ratio. In the crystal, numerous C—H?O inter­actions link the mol­ecules. PMID:22199779

Pojarova, Michaela; Fejfarova, Karla; Makrlik, Emanuel

2011-01-01

246

Dichlorido{[(diphenyl-phosphino)meth-yl]bis-(2-methyl-phen-yl)phosphine-?2 P,P?}palladium(II)  

PubMed Central

In the title compound, [PdCl2(C27H26P2)] or PdCl2[(C6H5)2PCH2P(C6H4CH3)2], the palladium center has a distorted square-planar geometry. There are two crystallographically independent mol­ecules in the asymmetric unit. The dihedral angle between the PdP2 and PdCl2 planes is 2.95?(4)° in one independent mol­ecule and 5.15?(4)° in the other. The P—Pd—P and P—C—P bond angles are significantly distorted because of the small bite angle of the chelating (bis­phosphino)methane ligand. The steric demands of the substituted rings in the mixed ligand cause a slight elongation of the Pd—P(C6H4CH3)2 bond relative to the Pd—P(C6H5)2 bond. In one molecule the tolyl ring shows positional disorder in a 0.58?(2):0.42?(2) ratio, in the other molecule the phenyl ring shows positional disorder in a 0.838?(9):0.162?(9) ratio. PMID:21577752

Badgett, Ansonia H.; Gray, Danielle L.; Shelby, Quinetta D.

2009-01-01

247

Transition-metal complexes containing parent phosphine or phosphinyl ligands and their use as precursors for phosphide nanoparticles.  

PubMed

P-H functional transition-metal complexes were synthesized without using hazardous PH3 gas in good yields by photolysis of the transition-metal carbonyl complexes M(CO)6-x (M = Cr, W, Fe; x = 0, 1) in tetrahydrofuran followed by reaction with P2(SiMe3)4 and subsequent methanolysis to give the bridging complexes [(CO)xM(?-PH2)]2 (M = Fe, x = 3 (1), M = Cr, x = 4 (2a), M = W, x = 4 (2b)). The photolysis of [(CO)4M(?-PH2)]2 (M = Cr (2a), M = W (2b)) with P(SiMe3)3 was applied followed by methanolysis to synthesize the PH2 bridging transition-metal binuclear complexes with terminal PH3 groups. The products [(CO)4M(?-PH2)2M(CO)3(PH3)] (M = Cr (3a), M = W (3b)) and [(CO)4W(?-PH2)2W(CO)2(PH3)2] (4b) were isolated in moderate yield. Another synthetic approach to this type of compounds is the direct photolysis of the complexes [(CO)3M(PH3)3] (M = Cr (5a), M = W (5b)). The products were comprehensively characterized by (31)P NMR and IR spectroscopy as well as by X-ray structural analysis. Additionally, the relevancy of 2a as single source precursor for the synthesis of stoichiometry-controlled CrP nanoparticles has been demonstrated. PMID:25329878

Bauer, Susanne; Hunger, Cornelia; Bodensteiner, Michael; Ojo, Wilfried-Solo; Cros-Gagneux, Arnaud; Chaudret, Bruno; Nayral, Céline; Delpech, Fabien; Scheer, Manfred

2014-11-01

248

Ni(II), Pd(II) and Pt(II) complexes of PNP and PSP tridentate amino-phosphine ligands.  

PubMed

The ligands D((CH(2))(2)NHPiPr(2))(2) (D = NH 1, S 2) react with (dme)NiCl(2) or (PhCN)(2)MCl(2) (M = Pd, Pt) to give complexes of the form [D((CH(2))(2)NHPiPr(2))(2)MX]X (X = Cl, I; M = Ni, Pd, Pt) which were converted to corresponding iodide derivatives by reaction with Me(3)SiI. Reaction of 1 or 2 with (COD)PdMeCl affords facile routes to [?(3)P,N,P-NH((CH(2))(2)NHPiPr(2))(2)PdMe]Cl (8a) and [?(3)P,S,P-S((CH(2))(2)NHPiPr(2))(2)PdMe]Cl (9a) in high yields. An alternative synthetic approach involves oxidative addition of MeI to a M(0) precursor yielding [?(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)NiMe]I (10), [?(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)MMe]I (M = Pd 8b Pt 11) and [?(3)P,S,P-S(CH(2)CH(2)NHPiPr(2))(2)MMe]I (M = Pd 9b, Pt 12). Alternatively, use of NEt(3)HCl in place of MeI produces the species [?(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)MH]X (X = Cl, M = Ni 13a, Pd 14a, Pt 16a). The analogs containing 2; [?(3)P,S,P-S((CH(2))(2)NHPiPr(2))(2)MH]X (M = Pd, X = PF(6)15: M = Pt, X = Br, 17a, PF(6)17b) were also prepared in yields ranging from 74-93%. In addition, aryl halide oxidative addition was also employed to prepare [?(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)MC(6)H(4)F]Cl (M = Ni 18, Pd 19) and [?(3)P,S,P-S((CH(2))(2)NHPiPr(2))(2)Pd(C(6)H(4)F)]Cl (20). Crystal structures of 3a, 4a, 5a, 6a, 8a, 9a, 14b and 16b are reported. PMID:22535417

Sgro, Michael J; Stephan, Douglas W

2012-06-14

249

Rigid P-chiral phosphine ligands with tert-butylmethylphosphino groups for rhodium-catalyzed asymmetric hydrogenation of functionalized alkenes.  

PubMed

Both enantiomers of 2,3-bis(tert-butylmethylphosphino)quinoxaline (QuinoxP*), 1,2-bis(tert-butylmethylphosphino)benzene (BenzP*), and 1,2-bis(tert-butylmethylphosphino)-4,5-(methylenedioxy)benzene (DioxyBenzP*) were prepared in short steps from enantiopure (S)- and (R)-tert-butylmethylphosphine-boranes as the key intermediates. All of these ligands were crystalline solids and were not readily oxidized on exposure to air. Their rhodium complexes exhibited excellent enantioselectivities and high catalytic activities in the asymmetric hydrogenation of functionalized alkenes, such as dehydroamino acid derivatives and enamides. The practical utility of these catalysts was demonstrated by the efficient preparation of several chiral pharmaceutical ingredients having an amino acid or a secondary amine component. A rhodium complex of the structurally simple ligand BenzP* was used for the mechanistic study of asymmetric hydrogenation. Low-temperature NMR studies together with DFT calculations using methyl ?-acetamidocinnamate as the standard model substrate revealed new aspects of the reaction pathways and the enantioselection mechanism. PMID:22192064

Imamoto, Tsuneo; Tamura, Ken; Zhang, Zhenfeng; Horiuchi, Yumi; Sugiya, Masashi; Yoshida, Kazuhiro; Yanagisawa, Akira; Gridnev, Ilya D

2012-01-25

250

Phosphine catalyzed alpha-arylation of enones and enals using hypervalent bismuth reagents: regiospecific enolate arylation via nucleophilic catalysis.  

PubMed

Exposure of enones and enals to 20 mol % tributylphosphine in the presence of triarylbismuth(V) dichlorides results in regiospecific aryl transfer to the alpha-position of the enone or enal pronucleophile. These results represent the first examples of enolate arylation under the conditions of nucleophilic catalysis. PMID:15113193

Koech, Phillip K; Krische, Michael J

2004-05-01

251

Dialkyl(Aryl) [Dialkylcarbamoylmethyl]Phosphine Oxides as Extractants for Concentrating of Transplutonium Elements from Acid Media  

Microsoft Academic Search

Dialkyl(aryl)carbamoylmethylphosphine oxides (CMPO), prepared by interaction of tervalent phosphorus acid esters with chloracetic amidesRRP(O)CHRC(O)NR , R, R, R, R = Alkyl or Aryl, can be used successfully for concentrating the transpluto-nium elements.

M. K. Chmutova; G. A. Pribylova; N. P. Nesterova; B. F. Myasoedov; M. I. Kabachnik; A. N. Nesmeyanov

1990-01-01

252

Facile synthesis of uniform large-sized InP nanocrystal quantum dots using tris(tert-butyldimethylsilyl)phosphine  

PubMed Central

Colloidal III-V semiconductor nanocrystal quantum dots [NQDs] have attracted interest because they have reduced toxicity compared with II-VI compounds. However, the study and application of III-V semiconductor nanocrystals are limited by difficulties in their synthesis. In particular, it is difficult to control nucleation because the molecular bonds in III-V semiconductors are highly covalent. A synthetic approach of InP NQDs was presented using newly synthesized organometallic phosphorus [P] precursors with different functional moieties while preserving the P-Si bond. Introducing bulky side chains in our study improved the stability while facilitating InP formation with strong confinement at a readily low temperature regime (210°C to 300°C). Further shell coating with ZnS resulted in highly luminescent core-shell materials. The design and synthesis of P precursors for high-quality InP NQDs were conducted for the first time, and we were able to control the nucleation by varying the reactivity of P precursors, therefore achieving uniform large-sized InP NQDs. This opens the way for the large-scale production of high-quality Cd-free nanocrystal quantum dots. PMID:22289352

2012-01-01

253

Metal-polymer Hybrid Material as a Catalyst for the Heck Coupling Reaction Under Phosphine Free Conditions  

Microsoft Academic Search

A method is described for making a poly-aminophenol based hybrid material by in-situ polymerization of aminophenol using palladium acetate as the oxidant. The oxidative polymerization of aminophenol leads to the formation of poly-aminophenol, while the reduction of palladium acetate results in the formation of palladium nanoparticles. The palladium nanoparticles were found to be highly dispersed and stabilized throughout the polymer

Rafique Ul Islam; Michael J. Witcomb; Michael S. Scurrell; Willem Van Otterlo; Elma van der Lingen; Kaushik Mallick

2011-01-01

254

Metal–Polymer Hybrid Material as a Catalyst for the Heck Coupling Reaction Under Phosphine-Free Conditions  

Microsoft Academic Search

A method is described for making a poly-aminophenol-based hybrid material by in situ polymerization of aminophenol using palladium acetate as the oxidant. The oxidative polymerization of aminophenol leads to the formation of poly-aminophenol, while the reduction of palladium acetate results in the formation of palladium nanoparticles. The palladium nanoparticles were found to be highly dispersed and stabilized throughout the polymer

Rafique Ul Islam; Michael J. Witcomb; Michael S. Scurrell; Willem van Otterlo; Elma van der Lingen; Kaushik Mallick

2011-01-01

255

A Single Phosphine Ligand Allows Palladium-Catalyzed Intermolecular C-O Bond Formation with Secondary and Primary Alcohols  

E-print Network

Forging a bond: An efficient, general palladium catalyst for C-O bond-forming reactions of secondary and primary alcohols with a range of aryl halides has been developed using the ligand 1. Heteroaryl halides, and for the ...

Wu, Xiaoxing

256

A Bulky Biaryl Phosphine Ligand Allows for Palladium-Catalyzed Amidation of Five-Membered Heterocycles as Electrophiles  

E-print Network

The incredible bulk: The first palladium-catalyzed amidation of five-membered heterocyclic bromides with multiple heteroatoms was achieved using the Pd/1 catalyst system. N-Arylated imidazoles, pyrazoles, thiazoles, pyrroles, ...

Su, Mingjuan

257

Calix[4]arene-phosphine dimers: precursors of flexible metallo-capsules and self-compacting molecules.  

PubMed

The first diphosphines based on a double calixarene, namely 1,4 (or 1,3)-bis-(5-diphenylphosphino-25,26,27,28-tetrapropoxycalix[4]aren-17-yl)benzene (L(2), L(3)) were each prepared in four steps starting from 5,17-dibromo-25,26,27,28-tetrapropoxycalix[4]arene. Upon reaction of L(2) with [Au(tht)(thf)]BF(4), (tht = C(4)H(8)S) a rigid metallo-capsule was quantitatively formed, which adopts an oblique form owing to the distinct nature of the spacers linking the two calixarene half-spheres. In the solid state, the 1,4-substituted phenylene linker is turned towards the gold ion, suggesting the existence of weak bonding interactions between two aromatic CH protons of this ring and the metal centre (AuH =2.67 A). In contrast to this gold complex, the related silver complex shows dynamic behaviour in solution, the exchange between two enantiomeric oblique forms being facilitated by the greater stereochemical flexibility of Ag(I) vs. Au(I). A heteronuclear (109)Ag{(1)H} HMQC experiment established strong correlations between the CH protons of the phenylene linker and the (109)Ag ion. Dynamic behaviour similar to that observed for the silver complex was further observed in trans-[PtCl(2)L(2)], a chelate complex that could be obtained quantitatively from L(2) and [PtCl(2)(PhCN)(2)]. The intended formation of a chelate complex leading to a capsule with an endo-oriented metal centre was achieved by reacting L(3) with [Pd(allyl)(thf)(2)]BF(4). The complex thus formed constitutes the first organometallic transition metal complex embedded in a cavity with large portals. Binding of [RuCl(2)(p-cymene)] to L(2) and L(3) resulted in self-compacting bimetallic complexes in which each calixarene basket entraps a Ru(p-cymene) unit, thereby forming molecules occupying a minimal volume. PMID:19725082

Sameni, Soheila; Jeunesse, Catherine; Matt, Dominique; Toupet, Loïc

2009-10-12

258

Novel ligands for the separation of trivalent lanthanides and actinides-tetrakis(phosphane sulfide) and -(phosphinic acid) cavitands  

Microsoft Academic Search

Cavitands with phosphane sulfide moieties 4 and 8a,b were prepared in good yields from their phosphane oxide analogues, as more stable alternatives for the dithiophosphinic acids used at present. The cavitands 7a and 7b with flexible butoxyphosphane oxide ligating sites are more efficient than cavitand 3 having rigid methylphosphane oxide groups as was studied with EuIII picrate extractions. Due to

Harold Boerrigter; Tanja Tomasberger; Willem Verboom; David N. Reinhoudt

1999-01-01

259

New Ru complexes containing the N-tridentate bpea and phosphine ligands: consequences of meridional vs facial geometry.  

PubMed

The synthesis and isolation of the complex cis,fac-[RuIICl2(bpea)(PPh3)][3; bpea = N,N-bis(2-pyridylmethyl)ethylamine] and three geometrical isomers of the complex [RuIICl(bpea)(dppe)](BF4) [4; dppe = (1,2-diphenylphosphino)ethane], trans,fac (4a), cis,fac (4b), and mer(down) (4c), have been described (see Chart 1 for a drawing of their structures). These complexes have been characterized through analytical, spectroscopic (IR, UV/vis, and 1D and 2D NMR), and electrochemical (cyclic voltammetry) techniques. In addition, complexes 3, 4a, and 4b have been further characterized in the solid state through monocrystal X-ray diffraction analysis. The molecular and electronic structures of isomers 4a, 4b, 4c, and 4d (the mer(up) isomer) have also been studied by means of density functional theory (DFT) calculations. Furthermore, their low-energy electronic transitions have been simulated using time-dependent DFT approaches, which have allowed unraveling of their metal-to-ligand charge-transfer nature. Complexes 3 and 4a-c are capable of catalyzing H-transfer types of reactions between alcohols and aromatic ketones such as acetophenone and 2,2-dimethylpropiophenone (DP). A strong influence of the facial versus meridional geometry in the bpea ligand coordination mode is observed for these catalytic reactions, with the meridional isomer being much more active than the facial one. The meridional isomer is even capable of carrying out the H-transfer reaction of bulky substrates such as DP at room temperature. PMID:17173407

Mola, Joaquim; Rodríguez, Montserrat; Romero, Isabel; Llobet, Antoni; Parella, Teodor; Poater, Albert; Duran, Miquel; Solà, Miquel; Benet-Buchholz, Jordi

2006-12-25

260

Facile synthesis of uniform large-sized InP nanocrystal quantum dots using tris( tert-butyldimethylsilyl)phosphine  

NASA Astrophysics Data System (ADS)

Colloidal III-V semiconductor nanocrystal quantum dots [NQDs] have attracted interest because they have reduced toxicity compared with II-VI compounds. However, the study and application of III-V semiconductor nanocrystals are limited by difficulties in their synthesis. In particular, it is difficult to control nucleation because the molecular bonds in III-V semiconductors are highly covalent. A synthetic approach of InP NQDs was presented using newly synthesized organometallic phosphorus [P] precursors with different functional moieties while preserving the P-Si bond. Introducing bulky side chains in our study improved the stability while facilitating InP formation with strong confinement at a readily low temperature regime (210°C to 300°C). Further shell coating with ZnS resulted in highly luminescent core-shell materials. The design and synthesis of P precursors for high-quality InP NQDs were conducted for the first time, and we were able to control the nucleation by varying the reactivity of P precursors, therefore achieving uniform large-sized InP NQDs. This opens the way for the large-scale production of high-quality Cd-free nanocrystal quantum dots.

Joung, Somyoung; Yoon, Sungwoo; Han, Chang-Soo; Kim, Youngjo; Jeong, Sohee

2012-01-01

261

Synthesis and Application of New Ligands Derived from N-Heterocyclic Carbenes, Phosphines and Phosphites for Asymmetric Hydrogenations  

E-print Network

N-Heterocyclic carbene and phosphorus ligands have been synthesized and used for many catalytic reactions including chiral analogs of Crabtree’s catalyst for asymmetric hydrogenation. These catalysts have been studied extensively...

Khumsubdee, Sakunchai

2013-11-05

262

Interaction of Some Extreme-Pressure Type Lubricating Compounds with an Iron Surface.  

National Technical Information Service (NTIS)

An iron surface was exposed to the extreme-pressure type lubricant benzyl chloride, dichlorophenyl phosphine, dichlorophenyl phosphine sulfide, ophenyl phosphine oxide. Iron, in the sputter-cleaned state, was exposed to these materials statically and duri...

D. H. Buckley

1973-01-01

263

Boron in the primary and secondary coordination spheres of iron and nickel  

E-print Network

Motivated by the reported electronic versatility of anionic tris(phosphine)borate and tris- (phosphine)sily1 ligands, a new, neutral tris(phosphine)borane scaffold was prepared. The synthesis, spectroscopy and solid-state ...

MacMillan, Samantha Nicole

2013-01-01

264

Aryl-palladium-NHC complex: efficient phosphine-free catalyst precursors for the carbonylation of aryl iodides with amines or alkynes.  

PubMed

A series of aryl-palladium-NHC compounds was prepared according to the reported methods and their catalytic activity in the carbonylation of aryl iodides to synthesize ?-keto amides and alkynones was examined. These practical aryl-palladium-NHC complexes have shown highly efficient catalyzed carbonylation and Sonogashira carbonylation reactions, with high turnover number in synthesis of ?-keto amides (TON = 4300) and in synthesis of alkynones (TON = 980). PMID:25350346

Zhang, Chunyan; Liu, Jianhua; Xia, Chungu

2014-12-21

265

Tridentate Phosphine Linkers for Immobilized Catalysts: Development and Characterization of Immobilized Rhodium Complexes and Solid-State NMR Studies of Polymers  

E-print Network

of performance polymers with solid2state NMR techniques. First a brief overview of solid2state NMR and its relevance to the various areas of chemistry covered in this thesis is given. Following the synthesis, immobilization, and characterization of tridentate...

Guenther, Johannes 1983-

2012-08-16

266

Partitioning of Eu(III) between acidic aqueous Al(NO{sub 3}){sub 3} and tri-n-octyl phosphine oxide  

SciTech Connect

As the Hanford site undergoes remediation, significant economies could be realized if aluminum is kept from High-Level Waste glass. An acidic scrub of the Hanford sludge could enhance Al removal; however, a caveat is the potential mobilization of transuranic elements, which would require a secondary cleanup of the Al/Cr waste stream. Previous solvent extraction (SX) studies have shown that >99% of the Eu and U can be extracted from simulated acidic Al/Cr waste. This study examines the use of extraction chromatographic methods. Results indicate the systems behave comparably and either method could be considered for Hanford clean-up purposes. (authors)

Shafer, J.C.; Harrington, R.C.; Nash, K.L. [Chemistry Department, Washington State University, Pullman, WA (United States)

2008-07-01

267

Facile synthesis of phosphine free ultra-small PbSe nanocrystals and their light harvesting studies in ETA solar cells.  

PubMed

Ultra-small PbSe nanocrystals (NCs) were synthesized via a 'one-pot' approach in olive oil as the reaction medium and capping agent. The optical spectra showed discernible blue shifts in the absorption band edges (570-780 nm) due to strong quantum confinement effects and photoluminescence (PL) spectra showed significant strong emission peaks in the range of 780-850 nm. The broad peaks in the powder X-ray diffraction (p-XRD) pattern indicate the ultra-small size of the as-prepared NCs. These NCs were used to construct an extremely thin absorber (ETA) solar device after surface modification. The preliminary results indicate their potential as light harvesting entities in nanostructure based solar cells. PMID:25247625

Akhtar, Javeed; Banski, Mateusz; Malik, Mohammad Azad; Revaprasadu, Neerish; Podhorodecki, Artur; Misiewicz, Jan

2014-10-14

268

(6-Acetyl-1,3,7-trimethyl-lumazine-?3 O 4,N 5,O 6)bis-(triphenyl-phosphine-?P)copper(I) hexa-fluorido-phosphate  

PubMed Central

The title compound, [Cu(C11H12N4O3)(C18H15P)2]PF6, is the third example reported in the literature of a five-coordinated CuIP2NO2 system. The metal is coordinated to both PPh3 mol­ecules through the P atoms and to the pyrazine ring of the lumazine mol­ecule through an N atom in a trigonal–planar arrangement; two additional coordinated O atoms, at Cu—O distances longer than 2.46?Å, complete the coordination. The coordination environment can be described as an inter­mediate square-pyramidal/trigonal–bipyramidal (SP/TBP) polyhedron. PMID:21579625

Hueso-Urena, Francisco; Illan-Cabeza, Nuria A.; Jimenez-Pulido, Sonia B.; Moreno-Carretero, Miguel N.

2010-01-01

269

Dinuclear NHC-palladium complexes containing phosphine spacers: synthesis, X-ray structures and their catalytic activities towards the Hiyama coupling reaction.  

PubMed

Six dinuclear N-heterocyclic carbene (NHC) palladium complexes, [PdCl2(IMes)]2(?-dppe) (1), [PdCl2(IPr)]2(?-dppe) (2), [PdCl2(IMes)]2(?-dppb) (3), [PdCl2(IPr)]2(?-dppb) (4), [PdCl2(IMes)]2(?-dpph) (5), and [PdCl2(IPr)]2(?-dpph) (6) [IMes = N,N'-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene; IPr = N,N'-bis-(2,6-di(iso-propyl)phenyl)imidazol-2-ylidene; dppe = 1,2-bis(diphenylphosphino)ethane, dppb = 1,4-bis(diphenylphosphino)butane; and dpph = 1,6-bis(diphenylphosphino)hexane], have been synthesized through bridge-cleavage reactions of chloro-bridged dimeric compounds, [Pd(?-Cl)(Cl)(NHC)]2, with the corresponding diphosphine ligands. The obtained compounds were fully characterized by (1)H NMR, (13)C NMR and (31)P NMR spectroscopy, FT-IR, elemental analysis and single-crystal X-ray crystallography. Moreover, further explorations of the catalytic potential of the dinuclear carbene palladium complexes as catalysts for the Pd-catalyzed transformations have been performed under microwave irradiation conditions, and the complexes exhibited moderate to good catalytic activity in the Hiyama coupling reaction of trimethoxyphenylsilane with aryl chlorides. PMID:24671375

Yang, Jin; Li, Pinhua; Zhang, Yicheng; Wang, Lei

2014-05-21

270

Theoretical investigation on the electronic structures and phosphorescent properties of a series of Ir(III) complexes with the diphenyl(1-naphthyl)phosphine ancillary ligand  

NASA Astrophysics Data System (ADS)

The electronic structures, photophysical properties, and potential organic light-emitting diodes (OLEDs) applications of a series of Ir(III) complexes 1-6 have been theoretically investigated by using the density functional theory (DFT) method. The photophysical properties of these complexes are greatly affected by the different substituents on the cyclometalated ligands. The phosphorescence wavelength, quantum yields, and luminescent efficiency of these complexes also are closely related to the ?-conjugation length, substitution positions, and substituents inductive effect for the cyclometalated ligands. The designed complex 5 could be a potential candidate as a blue-emitting material with a high quantum efficiency.

Shang, Xiaohong; Han, Deming; Guan, Shuang; Wang, Xiaofeng; Zhang, Gang

2014-10-01

271

Flame retardancy mechanisms of aluminium phosphinate in combination with melamine polyphosphate and zinc borate in glass-fibre reinforced polyamide 6,6  

Microsoft Academic Search

The fire retardancy mechanisms of aluminium diethylphosphinate in combination with melamine polyphosphate and zinc borate was analysed in glass-fibre reinforced polyamide 6,6. The influence of phosphorus compounds on the polyamide decomposition pathways was characterized using thermal analysis (TG), evolved gas analysis (TG–FTIR), and FTIR–ATR analysis of the residue. The Lewis acid–base interactions between the flame retardants, the amide unit, and

Ulrike Braun; Bernhard Schartel; Mario A. Fichera; Christian Jäger

2007-01-01

272

Quantum chemical characterization and design of host materials based on phosphine oxide-substituted (triphenylamine) fluorene for (deep) blue phosphors in OLEDs.  

PubMed

We studied the electronic structures of a series of fluorene derivatives (p/mPODPFs and p/mPOAPFs) using density functional theory calculations and investigated their performances as host materials in organic light-emitting diodes from three aspects, i.e. triplet energy, ability of charge injection from neighboring organic layer or electrode, and match of the hosts and the reference guests (FIrpic and FCNIr) for efficient energy transfer (EF). Especially for the last aspect, the singlet/triplet (S(1)/T(1)) energies as well as the simulated host emission and guest absorption spectra are investigated to predict the possible emission mechanisms in the host-guest system and therefore to pursue the most suitable host for (deep) blue guest. From the investigated results, we deduced that pPODPF and pPOAPF are suitable for sky-blue FIrpic due to feasible Förster/Dexter energy transfers from pPODPF/pPOAPF to FIrpic, which agrees well with the experimental results. Furthermore, the higher external quantum efficiency (20.6%) of the pPOAPF-based device than that of the pPODPF-based device (13.2%) in experiments was inferred to be attributed to the matching S(1) energies between pPOAPF and FIrpic as well as good hole/electron injection abilities of pPOAPF in spite of a smaller overlap between the pPOAPF emission and FIrpic absorption spectra. By contrast, mPOAPF and mPODPF, designed in the work, may match with deep-blue FCNIr. In particular, mPOAPF may exhibit good performance as a host material for deep blue FCNIr as a consequence of its own balanced hole/electron injection ability and the matching S(1)/T(1) energies between mPOAPF and FCNIr. PMID:23295787

Wu, Jie; Wu, Shui-Xing; Wu, Yong; Kan, Yu-He; Geng, Yun; Su, Zhong-Min

2013-02-21

273

The strong-field tripodal phosphine donor, [PhB(CH2PiPr2)3]-, provides access to electronically and coordinatively unsaturated transition metal complexes.  

PubMed

This paper introduces a sterically encumbered, strong-field tris(diisopropylphosphino)borate ligand, [PhBP(iPr)(3)] ([PhBP(iPr)(3)] = [PhB(CH(2)P(i)Pr(2))(3)](-)), to probe aspects of its conformational and electronic characteristics within a host of complexes. To this end, the Tl(I) complex, [PhBP(iPr)(3)]Tl (1), was synthesized and characterized in the solid-state by X-ray diffraction analysis. This precursor proves to be an effective transmetallating agent, as evidenced by its reaction with the divalent halides FeCl(2) and CoX(2) (X = Cl, I) to produce the monomeric, 4-coordinate, high-spin derivatives [PhBP(iPr)(3)]FeCl (2) and [PhBP(iPr)(3)]CoX (X = Cl (3), I (4)) in good yield. Complexes 2-4 were each characterized by X-ray diffraction analysis and shown to be monomeric in the solid-state. For conformational and electronic comparison within a system exhibiting higher than 4-coordination, the 16-electron ruthenium complexes [[PhBP(iPr)(3)]Ru(mu-Cl)](2) (5) and [[PhBP(3)]Ru(mu-Cl)](2) (6) were prepared and characterized ([PhBP(3)] = [PhB(CH(2)PPh(2))(3)](-)). The chloride complexes 2 and 3 reacted with excess CO to afford the divalent, monocarbonyl adducts [PhBP(iPr)(3)]FeCl(CO) (7) and [PhBP(iPr)(3)]CoCl(CO) (8), respectively. Reaction of 4 with excess CO resulted in the monovalent, dicarbonyl product [PhBP(iPr)(3)]Co(I)(CO)(2) (9). Complexes 5 and 6 also bound CO readily, providing the octahedral, 18-electron complexes [PhBP(iPr)(3)]RuCl(CO)(2) (10) and [PhBP(3)]RuCl(CO)(2) (11), respectively. Dimers 5 and 6 were broken up by reaction with trimethylphosphine to produce the mono-PMe(3) adducts [PhBP(iPr)(3)]RuCl(PMe(3)) (12) and [PhBP(3)]RuCl(PMe(3)) (13). Stoichiometric oxidation of 3 with dioxygen provided the 4-electron oxidation product [PhB(CH(2)P(O)(i)Pr(2))(2)(CH(2)P(i)Pr(2))]CoCl (14), while exposure of 3 to excess oxygen results in the 6-electron oxidation product [PhB(CH(2)P(O)(i)Pr(2))(3)]CoCl (15). Complexes 2 and 4 were characterized via cyclic voltammetry to compare their redox behavior to their [PhBP(3)] analogues. Complex 4 was also studied by SQUID magnetization and EPR spectroscopy to confirm its high-spin assignment, providing an interesting contrast to its previously described low-spin relative, [PhBP(3)]CoI. The difference in spin states observed for these two systems reflects the conformational rigidity of the [PhBP(iPr)(3)] ligand by comparison to [PhBP(3)], leaving the former less able to accommodate a JT-distorted electronic ground state. PMID:12924878

Betley, Theodore A; Peters, Jonas C

2003-08-25

274

Activation of a (cyclooctadiene) rhodium(I) complex supported by a chiral ferrocenyl phosphine thioether ligand for hydrogenation catalysis: a combined parahydrogen NMR and DFT study.  

PubMed

The reaction of [RhCl(P,S(t)Bu)(COD)] (1) or [Rh(P,S(t)Bu)(COD)]BF4 (2) where (P,S(t)Bu) is CpFe[?(5)-1,2-C5H3(PPh2)(CH2S(t)Bu)] with H2 in MeOH gives rise to COD hydrogenation and formation of a solvent-stabilized product. The formation of hydride species cannot be observed in view of a very rapid H/D exchange between H2 and the solvent. Introduction of pyridine or acetonitrile slows down this exchange process and allows observation of diastereometric dihydride complexes, [Rh(P,S(t)Bu)(H)2(L)2](+), the stereochemistry of which was fully elucidated. The hydride site exchange rates have been derived from EXSY NMR experiments and used, with assistance from DFT calculation, to elucidate the isomerization and site exchange mechanisms. PMID:23851567

Kozinets, Ekaterina M; Fekete, Marianna; Filippov, Oleg A; Belkova, Natalia V; Shubina, Elena S; Poli, Rinaldo; Duckett, Simon B; Manoury, Eric

2013-08-28

275

Photooxidation of mixed aryl and biarylphosphines.  

PubMed

Arylphosphines and dialkylbiarylphosphines react with singlet oxygen to form phosphine oxides and phosphinate esters. For mixed arylphosphines, the most electron-rich aryl group migrates to form the phosphinate, while for dialkylbiarylphosphines migration of the alkyl group occurs. Dialkylbiarylphosphines also yield arene epoxides, especially in electron-rich systems. Phosphinate ester formation is increased at high temperature, while protic solvents increase the yield of epoxide. The product distribution provides evidence for Buchwald's recent conformational model for the aerobic oxidation of dialkylbiarylphosphines. PMID:20527907

Zhang, Dong; Celaje, Jeff A; Agua, Alon; Doan, Chad; Stewart, Timothy; Bau, Robert; Selke, Matthias

2010-07-01

276

Dual fluorescence from an isonido ReIII rhenacarborane phosphine complex, [7,10-mu-H-7-CO-7,7-(PPh3)2-isonido-7,8,9-ReC2B7H9].  

PubMed

The complex [7,10-mu-H-7-CO-7,7-(PPh3)2-isonido-7,8,9-ReC2B7H9] has been synthesized by treatment of the complex salt [NHMe3][3,3-Cl2-3,3-(CO)2-closo-3,1,2-ReC2B9H11] with PPh3 in refluxing THF (tetrahydrofuran) and isolated as intensely colored orange-red microcrystals. Spectroscopic NMR and IR data have suggested that the product has a highly asymmetric structure with two inequivalent PPh3 ligands and a single CO ligand. Measurement of 11B NMR spectra in particular have indicated seven distinct boron vertexes, although the resulting cage degradation by removal of two BH vertexes was confirmed only following X-ray crystallographic analysis, which revealed the pentadecahedral isonido-7,8,9-ReC2B7 architecture. The 11B NMR resonances span an enormous chemical shift range (Deltadelta = 113), and this appears to be a direct consequence of the deshielding of the boron vertex directly opposite the quadrilateral |ReCCB| aperture. The new complex has been shown by electrochemical measurements to undergo a reversible one-electron oxidation. Digitally simulated cyclic voltammograms support a proposed square scheme (E(1/2) = 0.58, 0.69 V vs ferrocene) involving a reversible isonido-closo transition of the metallacarborane cage. Most unusually for a metallacarborane complex, ambient temperature solutions in CH2Cl2 and DMF have been shown to be intensely turquoise-blue fluorescent (lambda(em) = 442 nm, Phi = 0.012). Fluorescence spectroscopy measurements in MeTHF (2-methyltetrahydrofuran) glass at 77 K have indicated that the likely cause of such a broad emission is dual fluorescence (lambda(em) = 404, 505 nm), with both emissions displaying vibronic structure. Following excited-state lifetime decay analysis, the emissive behavior has been accredited to metal-perturbed 1IL states, with the lower energy emission arising from a slight geometric distortion of the initially excited complex. PMID:16933936

Buckner, Steven W; Fischer, Matthew J; Jelliss, Paul A; Luo, Rensheng; Minteer, Shelley D; Rath, Nigam P; Siemiarczuk, Aleksander

2006-09-01

277

Synthesis, characterisation and thermal studies of ruthenium(II) carbonyl complexes of functionalised tripodal phosphine chalcogen donor ligands, [CH 3C(CH 2P(X)Ph 2) 3], where X = Se, S, O  

NASA Astrophysics Data System (ADS)

The polymeric ruthenium(II) carbonyl complex, [Ru(CO) 2Cl 2] n reacts with 1,1,1-tris-(diphenylphosphinomethyl)ethane trichalcogenide ligands, [CH 3C(CH 2P(X)Ph 2) 3], where X = Se( a), S( b) and O( c) in 1:1 (metal:ligand) molar ratio to afford hexa-coordinated complexes of the type ? 2-(X,X)-[Ru(CO) 2Cl 2P 3X 3] ( 1a- c). The complexes 1a- c exhibit two equally intense ?(CO) bands in the range 1979-2060 cm -1 indicating cis-disposition of the two terminal carbonyl groups. The values of ?(CO) frequencies containing different ligands, in general, follow the order: P 3O 3 > P 3S 3 > P 3Se 3 which may be explained in terms of 'Soft-Hard' (Ru(II)-O) and 'Soft-Soft' (Ru(II)-S/Se) interactions. The complexes have been characterized by elemental analyses, mass, 1H, 31P, 77Se and 13C NMR spectroscopy. The thermal stability of the complexes has also been studied.

Deb, Biswajit; Sarmah, Bhaskar Jyoti; Borah, Bibek Jyoti; Dutta, Dipak Kumar

2009-03-01

278

Theoretical Studies of Structures and Mechanisms in Organometallic and Bioinorganic Chemistry: Heck Reaction with Palladium Phosphines, Active Sites of Superoxide Reductase and Cytochrome P450 Monooxygenase, and Tetrairon Hexathiolate Hydrogenase Model  

E-print Network

The electronic structures and reaction mechanisms of transition-metal complexes can be calculated accurately by density functional theory (DFT) in cooperation with the continuum solvation model. The palladium catalyzed Heck reaction, iron...

Surawatanawong, Panida

2010-07-14

279

SYNTHESIS AND STRUCTURE OF THE MESOCYCLIC COMPOUNDS, 5-PHENYL-l-THIA-5-PHOSPHACYCLOOCTANE, CIS AND TRANS1,5DIPHENYL1,5-DIPHOSPHACYCLOOCTANE AND THEIR PHOSPHINE OXIDES  

Microsoft Academic Search

Three 1.5-disubstituted eight-membered ring meSocycles, 5-phenyl-l-thia-5-phosphacyclooctane, 2, cis-and trans-1,5-diphenyl-1,5-diphosphacyclooctane. 5a and 5b, have been synthesized. The diastereomers 5a and 5b were separated by preparative HPLC and the stereochemical assignments confirmed by an X-ray crystal structure of 5b. The X-ray crystal structures of 5-phenyl-1-thia-5-phosphacyclooctane 5-oxide, 1, and trans-l,5-diphenyl-l,5-diphosphacyclooctane 1.5-dioxide, 3b, are also reported. MeSocycles 1, 3b and 5b are in the

Susan D. Toto; Brian W. Arbuckle; Parimal K. Bharadwaj; Joyce Takahashi Doi; W. Kenneth Musker

1991-01-01

280

Synthesis, characterization, and reactivity studies of iridium complexes bearing the ligand diphenylphosphidoboratabenzene  

E-print Network

The synthesis, structure, and reactivity properties of three iridium square planar complexes bearing the anionic phosphine ligand diphenylphosphidoboratabenzene (DPB) are described. Reactivity studies show a rate enhancement ...

Arizpe, Luis (Luis Alfredo)

2011-01-01

281

Préparation de matériaux catalytiques bien définis à site unique de type complexe carbénique N-hétérocyclique d’Au(I) : application à la réaction d’addition des alcools sur les alcynes.  

E-print Network

??Les ligands carbéniques N-hétérocycliques sont généralement décrits comme des analogues aux ligands phosphines car ils présentent des propriétés électroniques comparables, bien que leur caractère ?-donneur… (more)

Bouhrara, Mohamed

2010-01-01

282

Improved rhodium hydrogenation catalysts immobilized on silica? C. Merckle and J. Blu mel*  

E-print Network

Improved rhodium hydrogenation catalysts immobilized on silica? C. Merckle and J. Blu¨ mel Wilkinson-type rhodium catalysts with various mono and bidentate phosphine ligands have been synthesized catalysts with monodentate, as well as dppe- and dppp-type phosphine linkers all showed similar activity

Bluemel, Janet

283

Hydroformylation: An Old Yet New Industrial Route to Alcohols.  

ERIC Educational Resources Information Center

Discusses trends in hydroformylation chemistry, considering these catalysis and ligands: (1) cobalt, (2) cobalt-phosphine, and (3) rhodium-phosphine. Indicates that rhodium technology will grow in domination of hydroformylation practice. In addition, processes adapted to special cases of functional olefins and to higher olefins can be expected.…

Pruett, Roy L.

1986-01-01

284

Methods for removing contaminant matter from a porous material  

DOEpatents

Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

Fox, Robert V. (Idaho Falls, ID) [Idaho Falls, ID; Avci, Recep (Bozeman, MT) [Bozeman, MT; Groenewold, Gary S. (Idaho Falls, ID) [Idaho Falls, ID

2010-11-16

285

Systems and strippable coatings for decontaminating structures that include porous material  

DOEpatents

Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

Fox, Robert V. (Idaho Falls, ID); Avci, Recep (Bozeman, MT); Groenewold, Gary S. (Idaho Falls, ID)

2011-12-06

286

A synthetic model for the inhibition of glutathione peroxidase by antiarthritic gold compounds.  

PubMed

In this paper, inhibition of the glutathione peroxidase activity of two synthetic organoselenium compounds, bis[2-(N,N-dimethylamino)benzyl]diselenide (5) and bis[2-(N,N-dimethylamino)benzyl]selenide (9), by gold(I) thioglucose (1), chloro(triethylphosphine)gold(I), chloro(trimethylphosphine)gold(I), and chloro(triphenylphosphine)gold(I) is described. The inhibition is found to be competitive with respect to a peroxide (H(2)O(2)) substrate and noncompetitive with respect to a thiol (PhSH) cosubstrate. The diselenide 5 reacts with PhSH to produce the corresponding selenol (6), which upon treatment with 1 equiv of gold(I) chlorides produces the corresponding gold selenolate complexes 11-13. However, the addition of 1 equiv of selenol 6 to complexes 11-13 leads to the formation of bis-selenolate complex 14 by ligand displacement reactions involving the elimination of phosphine ligands. The phosphine ligands eliminated from these reactions are further converted to the corresponding phosphine oxides (R(3)P=O) and selenides (R(3)P=Se). In addition to the replacement of the phosphine ligand by selenol 6, an interchange between two different phosphine ligands is also observed. For example, the reaction of complex 11 having a trimethylphosphine ligand with triphenylphosphine produces complex 13 by phosphine interchange reactions via the formation of intermediates 15 and 16. The reactivity of selenol 6 toward gold(I) phosphines is found to be similar to that of selenocysteine. PMID:19267501

Bhabak, Krishna P; Mugesh, Govindasamy

2009-03-16

287

Simple Method for generating substituted phosphide and phosphinite anions and syntheses based on them  

SciTech Connect

This paper attempts to improve the methods for the generation of anions of PH acids. The improvements are based on an investigation involving the quantitative determination of the PH acidity of compounds of the type RPH/sub 2/, R/sub 2/PH, and R/sub 2/PHO in dimethyl sulfoxide (DMSO). Secondary and tertiary phosphines, polyphosphines, and functionally substituted phosphines, as well as phosphine oxides of similar structure have been obtained by the alkylation of phosphide and phosphinite anions. Various solvents were used in the presence of concentrated aqueous potassium hydroxide and tetrabutylammonium iodide as a phase-transfer catalyst.

Tsvetkov, E.N.; Bondarenko, N.A.; Kabachnik, M.I.; Malakhova, I.G.

1985-06-01

288

Combined (Super 31)P and (Super 1)H NMR Experiments in the Structural Elucidation of Polynuclear Thiolate Complexes  

ERIC Educational Resources Information Center

A facile synthesis of two gold(I) complexes with 1,2-benzenedithiolate ligand and two different bidentate phosphines are described. A detailed sequence of NMR experiments is suggested to determine the structure of the compounds.

Cerrada, Elena; Laguna, Mariano

2005-01-01

289

78 FR 6274 - Withdrawal of Pesticide Petitions for Residues of Pesticide Chemicals in or on Various Commodities  

Federal Register 2010, 2011, 2012, 2013

...225 for residues of phosphine, in or on asparagus; cherimoya; dates, fresh; figs, fresh; globe artichokes; pawpaws; pineapple, water chestnuts and watercress, and for all fresh fruit and vegetable crop groups (including berry and small fruit;...

2013-01-30

290

Macrocyclization by Nickel-Catalyzed, Ester-Promoted, Epoxide-Alkyne Reductive Coupling: Total Synthesis of (?)-Gloeosporone  

E-print Network

Ringing the changes: The total synthesis of the title compound centers around a novel strategy that employs a nickel(0)–phosphine complex and triethyl borane in an efficient closure of a 14-membered ring through C--C bond ...

Trenkle, James?D.

291

Palladium-Catalyzed Conversion of Aryl and Vinyl Triflates to Bromides and Chlorides  

E-print Network

The palladium-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) has been developed using dialkylbiaryl phosphine ligands. A variety of aryl, heteroaryl, and vinyl halides ...

Shen, Xiaoqiang

2010-01-01

292

An Improved Synthesis of BrettPhos- and RockPhos-Type Biarylphosphine Ligands  

E-print Network

Improved processes for the preparation of biphenyl-based phosphine ligands t-BuBrettPhos, RockPhos, and BrettPhos are presented. The new methods, featuring the use of Grignard reagents and catalytic amounts of copper, are ...

Hoshiya, Naoyuki

293

Synthesis, structural characterization and properties of aluminum (III) meso-tetraphenylporphyrin complexes axially  

E-print Network

Synthesis, structural characterization and properties of aluminum (III) meso, France. RECEIVED DATE (will be automatically inserted after manuscript is accepted) Aluminum (III) meso-tetraphenylporphyrins axially bonded to phosphinate anions have been synthesized and characterized by NMR and UV

Paris-Sud XI, Université de

294

Asymmetric Hydrovinylation of Unactivated Linear 1,3-Dienes Rakesh K. Sharma and T. V. RajanBabu*  

E-print Network

-phosphines; X ) halogen) as catalysts in the presence of Lewis acids such as aluminum alkyls as promoters.1c was formed as ascertained by NMR and gas chromatography.12 The only contaminant (7%) has been identified

RajanBabu, T. V. "Babu"

295

Chemical Agents  

MedlinePLUS

... Methyl isocyanate Nicotine Nitrogen mustard Opioids Organic solvents Osmium tetroxide Paraquat Phosgene Phosgene oxime Phosphine Phosphorus Ricin ... HN-1, HN-2, HN-3) O Opioids Osmium tetroxide P Paraquat Phosgene (CG) Phosgene oxime (CX) ...

296

Enantioselective carbon–sulfur bond formation: ? additions of aryl thiols to allenoates catalyzed by a chiral phosphepine  

E-print Network

An effective phosphine-catalyzed method was developed for the enantioselective addition of aryl thiols to the ? position of allenoates, thereby providing ready access to aryl alkyl sulfides in very good ee. The array of ...

Fujiwara, Yuji

297

Nickel-Catalyzed Allylic Substitution of Simple Alkenes  

E-print Network

This report describes a nickel-catalyzed allylic substitution process of simple alkenes whereby an important structural motif, a 1,4-diene, was prepared. The key to success is the use of an appropriate nickel–phosphine ...

Matsubara, Ryosuke

298

Copper-catalyzed conjugate reduction  

E-print Network

Chapter 1. A highly enantioselective catalyst for the asymmetric conjugate reduction of a,- unsaturated cyclic ketones was generated upon combination of catalytic amounts of CuCl, NaOt-Bu, and a chiral bis-phosphine with ...

Jurkauskas, Valdas, 1966-

2004-01-01

299

Composition of Jupiter  

NASA Technical Reports Server (NTRS)

The chemistry of Jupiter's atmosphere is reviewed. The various molecules that were discovered on Jupiter are summarized. The compounds: methane, ammonia water, ethane, acetylene, carbon monoxide, phosphine, and germane.

Prinn, R.

1982-01-01

300

Re and (99m)Tc complexes of BodP3- multi-modality imaging probes.  

PubMed

A fluorescent tridentate phosphine, BodP3 (2), forms rhenium complexes which effectively image cancer cells. Related technetium analogues are also readily prepared and have potential as dual SPECT/fluorescent biological probes. PMID:25248386

Davies, Laura H; Kasten, Benjamin B; Benny, Paul D; Arrowsmith, Rory L; Ge, Haobo; Pascu, Sofia I; Botchway, Stan W; Clegg, William; Harrington, Ross W; Higham, Lee J

2014-12-21

301

Catalytically active gold: The role of cluster morphology T.V. Choudhary a  

E-print Network

dispersion and activity on the catalyst synthesis procedures, supports and pre-treatment conditions make-workers involving the grafting of Au phosphine complexes on different as-precipitated metal hydroxide supports has

Goodman, Wayne

302

Chemoselective ligation  

DOEpatents

The present invention features a chemoselective ligation reaction that can be carried out under physiological conditions. In general, the invention involves condensation of a specifically engineered phosphine, which can provide for formation of an amide bond between the two reactive partners resulting in a final product comprising a phosphine moiety, or which can be engineered to comprise a cleavable linker so that a substituent of the phosphine is transferred to the azide, releasing an oxidized phosphine byproduct and producing a native amide bond in the final product. The selectivity of the reaction and its compatibility with aqueous environments provides for its application in vivo (e.g., on the cell surface or intracellularly) and in vitro (e.g., synthesis of peptides and other polymers, production of modified (e.g., labeled) amino acids).

Saxon, Eliana (Albany, CA); Bertozzi, Carolyn Ruth (Berkeley, CA)

2010-11-23

303

Chemoselective ligation  

DOEpatents

The present invention features a chemoselective ligation reaction that can be carried out under physiological conditions. In general, the invention involves condensation of a specifically engineered phosphine, which can provide for formation of an amide bond between the two reactive partners resulting in a final product comprising a phosphine moiety, or which can be engineered to comprise a cleavable linker so that a substituent of the phosphine is transferred to the azide, releasing an oxidized phosphine byproduct and producing a native amide bond in the final product. The selectivity of the reaction and its compatibility with aqueous environments provides for its application in vivo (e.g., on the cell surface or intracellularly) and in vitro (e.g., synthesis of peptides and other polymers, production of modified (e.g., labeled) amino acids).

Saxon, Eliana (Albany, CA); Bertozzi, Carolyn (Berkeley, CA)

2003-05-27

304

Chemoselective ligation  

DOEpatents

The present invention features a chemoselective ligation reaction that can be carried out under physiological conditions. In general, the invention involves condensation of a specifically engineered phosphine, which can provide for formation of an amide bond between the two reactive partners resulting in a final product comprising a phosphine moiety, or which can be engineered to comprise a cleavable linker so that a substituent of the phosphine is transferred to the azide, releasing an oxidized phosphine byproduct and producing a native amide bond in the final product. The selectivity of the reaction and its compatibility with aqueous environments provides for its application in vivo (e.g. on the cell surface or intracellularly) and in vitro (e.g., synthesis of peptides and other polymers, production of modified (e.g., labeled) amino acids).

Saxon, Eliana (Albany, CA); Bertozzi, Carolyn R. (Berkeley, CA)

2010-02-23

305

77 FR 29341 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...  

Federal Register 2010, 2011, 2012, 2013

...Alternatives for which such information is needed include: Sulfuryl fluoride, propylene oxide (PPO), phosphine, and/or controlled...Alternatives for which such information is needed include: Sulfuryl fluoride, micro-sanitation, and/or heat. The applicant...

2012-05-17

306

78 FR 32646 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...  

Federal Register 2010, 2011, 2012, 2013

...nomination process indicate that sulfuryl fluoride is effective against key pests. The industry has mostly converted to sulfuryl fluoride and no market disruption has occurred...products can be treated with sulfuryl fluoride or phosphine and be held for...

2013-05-31

307

76 FR 34700 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...  

Federal Register 2010, 2011, 2012, 2013

...producers when converting to alternatives such as: sulfuryl fluoride and phosphine. If relevant, the applicant should also include...producers when converting to alternatives such as: sulfuryl fluoride, micro-sanitation, and heat. If relevant, the...

2011-06-14

308

Catalyst for the selective production of ethanol and methanol directly from synthesis gas  

SciTech Connect

Alkanols are selectively produced as the major product directly from synthesis gas under mild conditions using a homogeneous ruthenium catalyst, a halogen or halide promoter and a phosphine oxide compound as solvent.

Warren, B.K.

1982-06-08

309

Preparation and catalytic hydrogenation properties of some rhodium and ruthenium complexes with chiral tridentate phosphine ligands ( S, S)PhP(CH 2CHMeCH 2PPh 2) 2 and ( S)Ph 2PCH 2CH(PPh 2)CH 2CH 2PPh 2)  

Microsoft Academic Search

Treatment of RhCl(ttp*) (ttp*=(S,S)-PhP(CH2CHMeCH2PPh2)2) with NaBH4 produced Rh(BH4)(ttp*). The reaction of RuCl2(ttp*) with NaBH4 produced RuH(BH4)(ttp*). The complexes RhCl(ttp*), RuCl2(ttp*), Rh(BH4)(ttp*), and RuH(BH4)(ttp*) were found to be catalytically active for the hydrogenation of ?-acetamidocinnamic acid.

Hon Man Lee; Chuluo Yang; Guochen Jia

2000-01-01

310

Trimesityl phosphoniumyl cation radical: electrogeneration and evolution  

Microsoft Academic Search

The electrochemical oxidation of tris (2,4,6-tri-methyl-phenyl) phosphine (TMP) in acetonitrile was investigated on a platinum electrode. A fast mono-electronic transfer (Ep = 0.71 V vs sce) gives rise to the corresponding long-lived phosphoniumyl cation radical. This electrochemically generated radical undergoes a slow reaction with residual water, generating the corresponding phosphine oxide (TMPO) and hydro phosphonium (TMPH+). The kinetics of the

Belabbes Merzougui; Yves Berchadsky; Paul Tordo; Gérard Gronchi

1997-01-01

311

UPTAKE OF GOLD FROM HYDROCHLORIC ACID SOLUTIONS BY POLYMERIC RESINS BEARING VARIOUS PHOSPHORUS CONTAINING LIGANDS  

Microsoft Academic Search

Polymeric resins with phosphonate esters, phosphinate esters, and phosphine oxide ligands are synthesized via Arbusov reaction, characterized and used in the removal of Au(III) from hydrochloric acid solutions. It is found that phosphonate ethyl and butyl esters are able to adsorb as much as 100–120 mg Au\\/g of the resin. Affinity of these two resins towards gold, measured as the logarithm

Andrzej W. Trochimczuk

2002-01-01

312

Nickel-catalyzed C-P cross-coupling of arylboronic acids with P(O)H compounds.  

PubMed

A novel and efficient Ni-catalyzed coupling of a wide range of arylboronic acids with H-phosphites, H-phosphinate esters, and H-phosphine oxides has been developed, providing a general and powerful tool for the synthesis of various aryl-phosphorus compounds, especially for valuable triarylphosphine oxides, in good to excellent yield. This protocol is the first Ni-catalyzed C-P bond-forming reaction between arylboronic acids and P(O)H compounds. PMID:24099283

Hu, Gaobo; Chen, Weizhu; Fu, Tingting; Peng, Zhimin; Qiao, Hongwei; Gao, Yuxing; Zhao, Yufen

2013-10-18

313

Exploring the chemistry of N,N'-diamidocarbenes with organophosphorus compounds.  

PubMed

A readily available N,N'-diamidocarbene (DAC) was found to insert into the P-H bonds of primary and secondary phosphines as well as a phosphonate ester. In contrast, tertiary phosphines catalyzed the ring contraction of the DAC to an iminopyrrolidinedione. Treating the DAC with trimethyl phosphite afforded the corresponding diamidophosphonate ester and olefinic products expected from an Arbuzov-type reaction. PMID:24422680

Chase, Daniel T; Moerdyk, Jonathan P; Bielawski, Christopher W

2014-02-01

314

Redox-Neutral ?-C-H Bond Functionalization of Secondary Amines with Concurrent C-P Bond Formation/N-Alkylation  

PubMed Central

Redox-neutral formation of C–P bonds in the ?-position of amines was achieved via a process that features a combination of an oxidative ?-C–H bond functionalization and a reductive N-alkylation. Benzoic acid functions as an efficient catalyst in this three-component reaction of cyclic secondary amines, aldehydes and phosphine oxides to provide rapid access to ?-amino phosphine oxides not easily accessible by classic Kabachnik-Fields reactions. PMID:23957378

Das, Deepankar; Seidel, Daniel

2013-01-01

315

The Kabachnik-Fields reaction: synthetic potential and the problem of the mechanism  

Microsoft Academic Search

The published data of the last decade concerning the mechanism of the Kabachnik-Fields reaction and its significance for the chemistry of organophosphorus compounds as a method for the synthesis of alpha-amino phosphonates and their numerous functionally substituted derivatives and analogues, such as phosphinates and phosphine oxides, are generalised and systematised. The review discusses the classical version of the Kabachnik-Fields reaction,

Rafael A. Cherkasov; Vladimir I. Galkin

1998-01-01

316

Redox-neutral ?-C-H bond functionalization of secondary amines with concurrent C-P bond formation/N-alkylation.  

PubMed

Redox-neutral formation of C-P bonds in the ?-position of amines was achieved via a process that features a combination of an oxidative ?-C-H bond functionalization and a reductive N-alkylation. Benzoic acid functions as an efficient catalyst in this three-component reaction of cyclic secondary amines, aldehydes and phosphine oxides to provide rapid access to ?-amino phosphine oxides not easily accessible by classic Kabachnik-Fields reactions. PMID:23957378

Das, Deepankar; Seidel, Daniel

2013-09-01

317

Polymer-based separations: Synthesis and application of polymers for ionic and molecular recognition  

SciTech Connect

The object of this research is to develop an understanding of the mechanisms by which polymers interact with ions and molecules in solution and, in so doing, design polymers with high levels of selectivity for target substrates. Research thus continues for the synthesis of polymers with enhanced ionic and molecular recognition. Polymers studied and discussed include phosphinic acid resins, dimethyl amine/phosphinic acid, phosphonate monoester/diester resins, and sulfonic acid resins. 6 refs.

Alexandratos, S.D.

1991-04-01

318

Homolytic substitution at phosphorus for C-P bond formation in organic synthesis  

PubMed Central

Summary Organophosphorus compounds are important in organic chemistry. This review article covers emerging, powerful synthetic approaches to organophosphorus compounds by homolytic substitution at phosphorus with a carbon-centered radical. Phosphination reagents include diphosphines, chalcogenophosphines and stannylphosphines, which bear a weak P–heteroatom bond for homolysis. This article deals with two transformations, radical phosphination by addition across unsaturated C–C bonds and substitution of organic halides. PMID:23843922

2013-01-01

319

New Phosphorus Chemistry Leads to Unnatural Aminoacid Trimers  

Microsoft Academic Search

Unnatural or modified amino acids have become important biochemical vectors because of their potential utility in diagnostic or therapeutic medicine. Our ongoing research in hydroxymethyl phosphine chemistry has provided unique reaction pathways to produce unnatural aminoacid. The reaction of tris(hydroxymethyl)phosphine (THP) with chiral aminoacid L-alanine produced trimeric alanine in excellent yields. The X-ray crystal structure of 1 shows an unusual

Kattesh V. Katti; Raghuraman Kannan; Kavita K. Katti; Nagavarakishore Pillarsetty; Charles L. Barnes

2002-01-01

320

ACID HYDROLYSIS OF AZIRIDINYL PHOSPHORAMIDES  

Microsoft Academic Search

The acid hydrolysis of two model aziridinyl phosphoramides, l-aziridinylbis(dimethylamino)phosphine oxide (11) and bis(l-aziridinyl) (dimethylamino)phosphine oxide (16), in aqueous acetic acid proceeded by an initial aziridine ring opening to give 2-hydroxyethyl phosphoramides 12 and 17, respectively. These intermediates rapidly cyclized to an oxazaphospholidine ring structure 13 or 18, with the subsequent loss of dimethylamine or aziridine. Analysis of ongoing hydrolysis showed

Jerry B. Stokes; Charles W. Woods; Alexej B. Borkovec

1981-01-01

321

Real-time bioluminescence imaging of glycans on live cells.  

PubMed

Cell-surface glycans are attractive targets for molecule imaging due to their reflection of cellular processes associated with development and disease progression. In this paper, we describe the design, synthesis, and biological application of a new phosphine probe for real-time imaging of cell-surface glycans using bioluminescence. To accomplish this goal, we took advantage of the bioorthogonal chemical reporter technique. This strategy uses a two-step labeling procedure in which an unnatural sugar analogue containing a functional handle is (1) incorporated into sugar-bearing proteins via the cell's own biosynthetic machinery and then (2) detected with an exogenously added probe. We designed phosphine-luciferin reagent 1 to activate bioluminescence in response to Staudinger ligation with azide-labeled glycans. We chose to use a phosphine probe because, despite their slow reaction kinetics, they remain the best-performing reagents for tagging azidosugars in mice. Given the sensitivity and negligible background provided by bioluminescence imaging (BLI), we reasoned that 1 might be able to overcome some of the limitations encountered with fluorescent phosphine probes. In this work, we synthesized the first phosphine-luciferin probe for use in real-time BLI and demonstrated that azide-labeled cell-surface glycans can be imaged with 1 using concentrations as low as single digit nanomolar and times as little as 5 min, a feat that cannot be matched by any previous fluorescent phosphine probes. Even though we have only demonstrated its use in visualizing glycans, it can be envisioned that this probe could also be used for bioluminescence imaging of any azide-containing biomolecule, such as proteins and lipids, since azides have been previously incorporated into these molecules. The phosphine-luciferin probe is therefore poised for many applications in real-time imaging in cells and whole animals. These studies are currently in progress in our laboratory. PMID:20527879

Cohen, Allison S; Dubikovskaya, Elena A; Rush, Jason S; Bertozzi, Carolyn R

2010-06-30

322

A comparison of the relative activities of a number of GABAB antagonists in the isolated vas deferens of the rat.  

PubMed Central

1. A series of GABAB receptor antagonists were tested against (+/-)-baclofen for activity on the presynaptic GABAB receptor in the rat vas deferens. 2. All the antagonists tested caused a rightward shift in the concentration-response curve to (+/-)-baclofen. 3. pA2 values calculated from full Schild analysis were as follows: phaclofen, pA2 = 4.3; delta-amino valeric acid, pA2 = 4.4; 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP 35348), pA2 = 5.0; 3-amino-propyl(n-hexyl)phosphinic acid (3-APHPA), pA2 = 4.5. 4. These results show that none of the above compounds possess potent antagonist activity at the GABAB receptor (i.e. pA2 > 6) in this peripheral tissue. In addition, the more recently available phosphinic acid antagonists, appear to offer no great advance over the GABAB antagonists previously available. PMID:1364830

Hills, J. M.; Larkin, M. M.; Howson, W.

1991-01-01

323

High Efficiency InP Solar Cells from Low Toxicity Tertiarybutylphosphine  

NASA Technical Reports Server (NTRS)

Large scale manufacture of phosphide based semiconductor devices by organo-metallic vapor phase epitaxy (OMVPE) typically requires the use of highly toxic phosphine. Advancements in phosphine substitutes have identified tertiarybutylphosphine (TBP) as an excellent precursor for OMVPE of InP. High quality undoped and doped InP films were grown using TBP and trimethylindium. Impurity doped InP films were achieved utilizing diethylzinc and silane for p and n type respectively. 16 percent efficient solar cells under air mass zero, one sun intensity were demonstrated with Voc of 871 mV and fill factor of 82.6 percent. It was shown that TBP could replace phosphine, without adversely affecting device quality, in OMVPE deposition of InP thus significantly reducing toxic gas exposure risk.

Hoffman, Richard W., Jr.; Fatemi, Navid S.; Wilt, David M.; Jenkins, Phillip P.; Brinker, David J.; Scheiman, David A.

1994-01-01

324

Structure-reactivity relationships in SHOP-type complexes: tunable catalysts for the oligomerisation and polymerisation of ethylene.  

PubMed

For over 30 years complexes with the general formula [NiPh(P,O)L] (L = tertiary phosphine; P,O = chelating phosphanylenolato ligand) have been used as highly efficient oligomerisation catalysts suitable for the production of linear alpha-olefins. The same complexes, which are usually referred to as SHOP-type catalysts (SHOP = Shell Higher Olefin Process) can also be used as ethylene polymerisation catalysts, provided they are treated with a phosphine scavenger that selectively removes the tertiary phosphine ligand (L). This Perspective examines the impact of various parameters (influence of the substituents, backbone size, solvent, use of co-catalysts, etc.) on the catalytic outcome of the complexes. Overall, this review shows that the selectivity and activity of the catalyst may be tuned efficiently through directed modification of the P,O chelator. PMID:17225902

Kuhn, Pierre; Sémeril, David; Matt, Dominique; Chetcuti, Michael J; Lutz, Pierre

2007-02-01

325

High efficiency InP solar cells from low toxicity tertiarybutylphosphine  

NASA Astrophysics Data System (ADS)

Large scale manufacture of phosphide based semiconductor devices by organo-metallic vapor phase epitaxy (OMVPE) typically requires the use of highly toxic phosphine. Advancements in phosphine substitutes have identified tertiarybutylphosphine (TBP) as an excellent precursor for OMVPE of InP. High quality undoped and doped InP films were grown using TBP and trimethylindium. Impurity doped InP films were achieved utilizing diethylzinc and silane for p and n type respectively. 16 percent efficient solar cells under air mass zero, one sun intensity were demonstrated with Voc of 871 mV and fill factor of 82.6 percent. It was shown that TBP could replace phosphine, without adversely affecting device quality, in OMVPE deposition of InP thus significantly reducing toxic gas exposure risk.

Hoffman, Richard W., Jr.; Fatemi, Navid S.; Wilt, David M.; Jenkins, Phillip P.; Brinker, David J.; Scheiman, David A.

1994-05-01

326

Reduction of proteins during sample preparation and two-dimensional gel electrophoresis of woody plant samples.  

PubMed

Protein extraction procedure and the reducing agent content (DTT, dithioerythritol, tributyl phosphine and tris (2-carboxyethyl) phosphine (TCEP)) of the sample and rehydration buffers were optimised for European beech leaves and roots and Norway spruce needles. Optimal extraction was achieved with 100 mM DTT for leaves and needles and a mixture of 2 mM TCEP and 50 mM DTT for roots. Performing IEF in buffers containing hydroxyethyldisulphide significantly enhanced the quality of separation for all proteins except for acidic root proteins, which were optimally focused in the same buffer as extracted. PMID:16456882

Vâlcu, Cristina-Maria; Schlink, Katja

2006-03-01

327

The Kabachnik-Fields reaction: synthetic potential and the problem of the mechanism  

NASA Astrophysics Data System (ADS)

The published data of the last decade concerning the mechanism of the Kabachnik-Fields reaction and its significance for the chemistry of organophosphorus compounds as a method for the synthesis of ?-amino phosphonates and their numerous functionally substituted derivatives and analogues, such as phosphinates and phosphine oxides, are generalised and systematised. The review discusses the classical version of the Kabachnik-Fields reaction, its modifications with the use of phosphorus chlorides, neutral esters and inorganic phosphorus acids, as well as chemical processes simulating separate steps of the reaction, viz., hydrophosphorylation of imines and amination of ?-hydroxy phosphonates. Data on the practical application of ?-amino phosphonates are presented. The bibliography includes 253 references.

Cherkasov, Rafael A.; Galkin, Vladimir I.

1998-10-01

328

Investigations on low-temperature MOVPE growth of InGaAs/InP using alternative sources (TBAs, TBP)  

SciTech Connect

Growth of high quality InP and InGaAs using the less hazardous liquid group V precursors, TBAs and TBP has been achieved. A systematic study compares the quality of InP and InGaAs epitaxial layers grown by low-pressure organometallic vapor phase epitaxy (MOVPE) using TMG and TEG trimethylindium (TMIn), phosphine (PH{sub 3}), arsino (AsH{sub 3}) and tetriarybutylophosphine (TBP) and tertriarybutylarsin (TBAs) sources. High quality InP Layers are obtained with both phosphorus sources for growth at high V/III ratio and at low temperatures with the TBP, TBAs sources than with the phosphine and arsine sources.

Czub, M.; Strupinski, W. [Inst. of Electronic Materials Technology, Warsaw (Poland); Weber, J.; Gyuro, I. [Alcatel SEL, Stuttgart (Germany). Research Center

1996-12-31

329

Zinc Phosphide Poisoning  

PubMed Central

Zinc phosphide has been used widely as a rodenticide. Upon ingestion, it gets converted to phosphine gas in the body, which is subsequently absorbed into the bloodstream through the stomach and the intestines and gets captured by the liver and the lungs. Phosphine gas produces various metabolic and nonmetabolic toxic effects. Clinical symptoms are circulatory collapse, hypotension, shock symptoms, myocarditis, pericarditis, acute pulmonary edema, and congestive heart failure. In this case presentation, we aim to present the intensive care process and treatment resistance of a patient who ingested zinc phosphide for suicide purposes. PMID:25101186

Dogan, Erdal; Guzel, Abdulmenap; Ciftci, Taner; Aycan, Ilker; Cetin, Bedri; Kavak, Gonul Olmez

2014-01-01

330

Extremely Electron-Rich, Boron-Functionalized, Icosahedral Carborane-Based Phosphinoboranes  

PubMed Central

We have prepared the first examples of B9-connected trivalent aryl and alkyl phosphinoborane species via Pd-catalyzed phosphination of 9-iodo-meta-carborane. Our studies highlight the unique electronic features of the B9-connected meta-carboranyl moiety as compared to its C1-based analogue. This work suggests that the B9-functionalized meta-carboranyl substituent in these ligands exhibits more electron-releasing character than any other known carbon-based substituent, ultimately laying the foundation for a new class of phosphine ligands with extremely electron-rich character. PMID:23667288

Spokoyny, Alexander M.; Lewis, Calvin D.; Teverovskiy, Georgiy; Buchwald, Stephen L.

2012-01-01

331

Radiation resistance of a series of organophosphorus extractants  

Microsoft Academic Search

Extraction of U(VI), TUE, and REE from acid process solution with solutions of mono-and bidentate neutral organophosphorus\\u000a compounds (NOPCs), phenyloctyl(N,N-diisobutylcarbamoylmethyl)phosphine oxide (CMPO), 2-ethylhexyl (N,N-dibutylcarbamoylmethyl)phenylphosphinate (CMPP), and unsymmetrical phosphine oxide (UPO) was studied as influenced by ?-irradiation\\u000a at different absorbed dose rates. In all cases extraction of the target radionuclides decreased with increasing absorbed dose\\u000a of ?-radiation. The resistance of the

M. V. Logunov; Yu. A. Voroshilov; N. P. Starovoitov; A. Yu. Shadrin; I. V. Smirnov; I. B. Kvasnitskii; I. G. Tananaev; B. F. Myasoedov; V. P. Morgalyuk; M. Kamiya; I. Koma; T. Koyama

2006-01-01

332

Synthesis and characterization of sodium bis(trimethylstannyl) amide and bis(trimethylsilyl) bis(trimethylstannyl) -phospha-tetrazene  

Microsoft Academic Search

Sodium bis(trimethylstannyl)amide NaN(SnMe3)2, isolated by the reaction of trimethylstannyldiethylamine with sodium amide, reacts with tris(trimethylsilyl)hydrazino—dichloro-phosphine to form bis(trimethylsilyl)bis(trimethylstannyl)-2-phospha-2-tetrazene, (Me3Si)2N-N=P-N(SnMe3)2. Both the molecules have been isolated and characterized.

S. K. Vasisht; Tripat P. Kaur; Jyotsna Kaushal; Seema Dixit

1997-01-01

333

Efficient synthesis of polysubstituted olefins using stable palladium nanocatalyst: applications in synthesis of tamoxifen and isocombretastatin A4.  

PubMed

A phosphine-free stable palladium nanocatalyst was used for an efficient synthesis of polysubstituted olefins from N-tosylhydrazones and aryl iodides. This methodology was successfully utilized in the synthesis of biologically important tamoxifen and isocombretastatin A4. The nanocatalyst was easily recovered and reused without any apparent loss in size and catalytic activity. PMID:25036297

Ganapathy, Dhandapani; Sekar, Govindasamy

2014-08-01

334

98 Organometallics 1988,7, 98-105 portant difference in chemical reactivity between Fe-  

E-print Network

and the resulting 17-electron intermediate is stabilized by the basic phosphines L, whereas Fe- (TMM. Cyclic voltammetry of 6a-c showed a reversible one- electron oxidation at negative potential was observed (Table VI). The latter oxidation can be attributed to the 6+/62+couple which may decompose

Goddard III, William A.

335

Polyurea-encapsulated palladium(II) acetate: a robust and recyclable catalyst for use in conventional and supercritical media.  

PubMed

Palladium(II) acetate microencapsulated in polyurea (MC-[Pd]) is an economical and versatile heterogeneous catalyst for a range of phosphine-free cross-coupling reactions in both conventional solvents and supercritical carbon dioxide (scCO2); the catalyst can be recovered by a simple filtration and recycled up to four times. PMID:12122701

Ley, Steven V; Ramarao, Chandrashekar; Gordon, Richard S; Holmes, Andrew B; Morrison, Angus J; McConvey, Ian F; Shirley, Ian M; Smith, Stephen C; Smith, Martin D

2002-05-21

336

Synthesis and Migratory-Insertion Reactivity of CpMo(CO)[subscript3](CH[subscript3]): Small-Scale Organometallic Preparations Utilizing Modern Glovebox Techniques  

ERIC Educational Resources Information Center

Experiments are described for the reliable small-scale glovebox preparation of CpMo(CO)[subscript 3](CH[subscript 3]) and acetyl derivatives thereof through phosphine-induced migratory insertion. The robust syntheses introduce students to a variety of organometallic reaction mechanisms and glovebox techniques, and they are easily carried out…

Whited, Matthew T.; Hofmeister, Gretchen E.

2014-01-01

337

The 1982 NASA/ASEE summer faculty fellowship research program, abstracts of research projects, 1st and 2nd-year fellows  

NASA Technical Reports Server (NTRS)

Phosphine photolysis in Jupiter's atmosphere is discussed in relation to organic chemical evolution. Workload in AFTI F-16 test flights, infrared observations of M17, and the relation between rock and vegetation types are presented. Orbiter transfer vehicle aerothermodynamics simulation problems are also discussed.

1982-01-01

338

New Perspectives for light alkanes isomerization. Robert Hubaut*  

E-print Network

palladium (or nickel)-cerium oxides and silica-supported HPAs have been realized and tested for the n-hexane isomerization. The solids were characterized before and after tests. Presence of Pt, Pd (or nickel) and Ce gives, the activity is in the same order as the acid strength. 1 H and 31 P solid-state NMR of trimethyl phosphine

Paris-Sud XI, Université de

339

SYNTHESIS OF SOME CARBONYL DERIVATIVES OF TRIS(AMINOMETHYL)PHOSPIE OXIDE  

Microsoft Academic Search

Miscellaneous phosphohrylated carbamates, ureas and thioureas of potential value as flame retardants for cotton have been synthesized from a key intermediate, tris(aminomethyl)phosphine oxide (1), whose synthesis we recently described. Reactions were carried out between 1 and representative chloroformates, isocyanates, thiocyanates and ureas, and with carbonyl sulfide and carbon disulfide. An improved procedure was developed for the thermal cyclization of the

Arlen W. Frank

1985-01-01

340

Simplified Chinese TRPO Process to Extract and Recover Transuranium Elements from High?Level Liquid Waste  

Microsoft Academic Search

The Chinese trialkyl phosphine oxides (TRPO) process is effective for recovery of transuranium elements from high?level liquid waste (HLLW). Integration of the TRPO process with the current Purex process will simplify both processes. With this viewpoint, a simplified TRPO process is proposed in this paper. The original process with two strip sections for U and Np + Pu has been changed to

Xuegang Liu; Junfu Liang; Jingming Xu

2004-01-01

341

Transport of chromium (VI) through a Cyanex 923–xylene flat-sheet supported liquid membrane  

Microsoft Academic Search

The present investigation deals with carrier-facilitated membrane transport of chromium (VI) from chloride media across a flat-sheet supported liquid membrane (FSSLM) using as organic reagent the phosphine oxide, Cyanex 923. The permeation of Cr (VI) has been studied under various experimental conditions: stirring speed of the source phase, initial metal and carrier concentrations, organic phase diluent, HCl concentration in the

F. J. Alguacil; A. G. Coedo; M. T. Dorado

2000-01-01

342

The Kabachnik-Fields reaction: mechanism and synthetic use.  

PubMed

The Kabachnik-Fields (phospha-Mannich) reaction involving the condensation of primary or secondary amines, oxo compounds (aldehydes and ketones) and >P(O)H species, especially dialkyl phosphites, represents a good choice for the synthesis of ?-aminophosphonates that are of significant importance due to their biological activity. In general, these three-component reactions may take place via an imine or an ?-hydroxy-phosphonate intermediate. The monitoring of a few Kabachnik-Fields reactions by in situ Fourier transform IR spectroscopy has indicated the involvement of the imine intermediate that was also justified by theoretical calculations. The Kabachnik-Fields reaction was extended to >P(O)H species, comprising cyclic phosphites, acyclic and cyclic H-phosphinates, as well as secondary phosphine oxides. On the other hand, heterocyclic amines were also used to prepare new ?-amino phosphonic, phosphinic and phosphine oxide derivatives. In most cases, the synthesis under solvent-free microwave (MW) conditions is the method of choice. It was proved that, in the cases studied by us, there was no need for the use of any catalyst. Moreover, it can be said that sophisticated and environmentally unfriendly catalysts suggested are completely unnecessary under MW conditions. Finally, the double Kabachnik-Fields reaction has made available bis(phosphonomethyl)amines, bis(phosphinoxidomethyl)amines and related species. The bis(phosphinoxidomethyl)amines serve as precursors for bisphosphines that furnish ring platinum complexes on reaction with dichlorodibenzonitriloplatinum. PMID:23117425

Keglevich, György; Bálint, Erika

2012-01-01

343

Organometallics 1987, 6, 1301-1311 1301 Preparation, Dynamic Behavior, and C-H and C-C Cleavage  

E-print Network

of cyclopentadiene at 0 "C for short periods of time. Continued photolysis results in the formation of CpRe(PPh3)H4 cyclopentadiene and a rhenium phosphine polyhydride. After the discovery of ferrocene, a number of other cy- clopentadienyl derivativeswere synthesized from reactions of metals with cyclopentadiene. In several instances

Jones, William D.

344

Photochemistry of intermolecular C-H bond activation reactions  

SciTech Connect

Goals at the onset were to obtain photophysical and photochemical data on transition-metal organometallic complexes which undergo light-induced intermolecular C-H bond activation reactions with hydrocarbon substrates. The complexes included these of rhodium and rhenium with such as cyclopentadiene, CO, phosphine, pyridines, etc.

Lees, A.J.

1994-09-01

345

Bifunctionalized allenes. Part XIII. A convenient and efficient method for regioselective synthesis of phosphorylated ?-hydroxyallenes with protected and unprotected hydroxy group.  

PubMed

The paper describes a convenient and efficient method for regioselective synthesis of phosphorylated ?-hydroxyallenes using an atom economical [2,3]-sigmatropic rearrangement of intermediate propargyl phosphites or phosphinites. These can be readily prepared via reaction of protected alkynols with dimethyl chlorophosphite or chlorodiphenyl phosphine respectively in the presence of a base. PMID:24840901

Ismailov, Ismail E; Ivanov, Ivaylo K; Christov, Valerij Ch

2014-01-01

346

Relativistic effects in homogeneous gold David J. Gorin1  

E-print Network

community. Cationic phosphine­gold(I) complexes are especially versatile and selective catalystsREVIEWS Relativistic effects in homogeneous gold catalysis David J. Gorin1 & F. Dean Toste1 Transition-metal catalysts containing gold present new opportunities for chemical synthesis

Toste, Dean

347

THE UNIVERSAL SOLVENT EXTRACTION (UNEX) PROCESS. I. DEVELOPMENT OF THE UNEX PROCESS SOLVENT FOR THE SEPARATION OF CESIUM, STRONTIUM, AND THE ACTINIDES FROM ACIDIC RADIOACTIVE WASTE  

Microsoft Academic Search

A synergistic extraction mixture containing chlorinated cobalt dicarbollide (CCD), carbamoylmethyl phosphine oxide (CMPO), and polyethylene glycol (PEG) has been investigated for the simultaneous recovery of cesium, strontium, lanthanides, and actinides from highly acidic media. The extraction properties of this mixture depend on the concentration ratio of the components. For recovery of all major radionuclides, the optimal ratio of [CCD]:[PEG]: [CMPO

Valeriy N. Romanovskiy; Igor V. Smirnov; Vasily A. Babain; Terry A. Todd; R. Scott Herbst; Jack D. Law; Ken N. Brewer

2001-01-01

348

Rhenium and technetium bi- and tricarbonyl complexes in a new strategy for biomolecule incorporation using click chemistry.  

PubMed

A versatile strategy to prepare fac-[M(I)(CO)3](+) and cis-[M(I)(CO)2](+) (M = Re, (99m)Tc) complexes was developed using Huisgen click chemistry and monodentate phosphine ligands to readily incorporate biomolecules and tailor the chemical properties. PMID:24710681

Hayes, Thomas R; Kasten, Benjamin B; Barnes, Charles L; Benny, Paul D

2014-05-21

349

Preparation of hydroborate complexes of copper and an investigation of the dependence of their structure on the nature of the organophosphorus ligands  

Microsoft Academic Search

1.A method has been developed for obtaining hydroborate complexes of copper with various organophosphorus ligands (tertiary and secondary phosphines, tertiary phosphites, phosphonites, amidophosphites) by the action of ionic hydroborates on the corresponding copper complexes in aprotic solvents. The IR absorption spectra of the obtained complexes have been measured.2.The influence of the electronic and steric properties of the organophosphorus ligands on

V. D. Makhaev; A. P. Borisov; É. B. Lobkovskii; V. B. Polyakova; K. N. Semenenko

1985-01-01

350

Domino hydroformylation/aldol condensation/hydrogenation catalysis: highly selective synthesis of ketones from olefins.  

PubMed

A general and highly chemo- and regioselective synthesis of ketones from olefins by domino hydroformylation/aldol condensation/hydrogenation reaction has been developed. A variety of olefins are efficiently converted into various ketones in good to excellent yields and regioselectivities in the presence of a specific rhodium phosphine/base-acid catalyst system. PMID:25331557

Fang, Xianjie; Jackstell, Ralf; Börner, Armin; Beller, Matthias

2014-11-24

351

Instructions for use A Palladium-Catalyzed Biaryl Coupling of Arylboronic Acids in Aqueous Media Using A  

E-print Network

-scale industrial processes because of the simplicity of catalyst-product separation and the economy and safety but also in several industrial processes by using palladium or rhodium homogeneous catalysts1 (Scheme 1 in a two-phase, basic aqueous-organic medium. The phosphine supported on a graft copolymer of styrene

Tachizawa, Kazuya

352

Asymmetric Formation of Quaternary Carbon Centers Catalyzed by Novel Chiral  

E-print Network

-cata- lyzed allylations,5 Heck reactions,6 Diels-Alder reac- tions,7 and cyclopropanations.8 Recently, we, 2, Figure 1). High enantioselectivities (>90% ee) have been obtained for Pd-catalyzed allylic do not proceed at room temperature. Because the nucleophilic addition of a phosphine to ethyl 2

Zhang, Xumu

353

ATP-dependent ligases in trypanothione biosynthesis kinetics of catalysis and inhibition  

E-print Network

1 ,N8 -bis(glutathionyl)spermidine] and trypa- nothione reductase, which replaces not only mechanism for glutathionyl- spermidine synthetase (EC 6.3.1.8) from Crithidia fasciculata (CfGspS) obeys that the phosphinate behaves as a slow-binding bisubstrate inhibitor [competitive with respect to GSH and spermidine

Schnaufer, Achim

354

TIER I CHEMICALS: 2.LABORATORY SAFETY PLAN  

E-print Network

-Butyllithium 109-72-8 Sodium Sulphide 1313-82-2 Phenyllithium 591-51-5 tert-Butyl hypochlorite 507-40-4 Phosphine chemicals, GT requires that each laboratory prepared (i) tailored laboratory safety plan, (ii) chemical-58-6 Dichlorosilane 4109-96-0 Magnesium Diamide 7803-54-5 Diethylaluminum chloride 96-10-6 Maneb 12427

Sherrill, David

355

Ligand-dependent scope and divergent mechanistic behavior in nickel-catalyzed reductive couplings of aldehydes and alkynes.  

PubMed

A new procedure for catalytic reductive coupling of aldehydes and alkynes has been developed. The procedure uses Ni(COD)2 with an imidazolium carbene ligand as the catalyst and triethylsilane as the reducing agent. A crossover deuterium-labeling experiment illustrated that variants involving trialkyl phosphines and imidazolium carbene ligands with a nickel catalyst proceed by different mechanisms. PMID:15038707

Mahandru, Gireesh M; Liu, Gang; Montgomery, John

2004-03-31

356

Organophosphorus esters causing delayed neurotoxic effects  

Microsoft Academic Search

Mechanism o\\/Action. Evidence is reviewed that the initial biochemical event leading to delayed neurotoxicity is phosphorylation of the active site of a specific enzyme called Neurotoxie Esterase. This is followed by a bondclcavage ( ? hydrolytic) leading to formation of a mono-substituted phosphoric acid residue on the protein. The mechanism by which some phosphinates protect hens against neurotoxic compounds is

M. K. Johnson

1975-01-01

357

The Classification of Transitions between Levels of Principal Quantum Numbers 2 and 3 in S X to XIV and of Isoelectronic Spectra in P, Cl and Ar  

Microsoft Academic Search

Emission lines which result from transitions betwen principal quantum numbers 2 and 3 in S X to XIV P X to XII, Cl XI to XIV and Ar XII and XIII are classified. The spectra were emitted from the plasma produced in a theta-pinch into which a small quantity of hydrogen sulphide, phosphine, chlorine or argon was added. Wavelength measurements

B C Fawcett; R W Hayes

1973-01-01

358

Development of a Lewis Base Catalyzed Selenocyclization Reaction  

ERIC Educational Resources Information Center

The concept of Lewis base activation of selenium Lewis acids has been effectively reduced to practice in the Lewis base catalyzed selenofunctionalization of unactivated olefins. In this reaction, the weakly acidic species, "N"-phenylselenyl succinimide, is cooperatively activated by the addition of a "soft" Lewis base donor (phosphine sulfides,…

Collins, William

2009-01-01

359

Ligand-controlled ?- and ?-arylation of acyclic N-Boc amines.  

PubMed

The palladium-catalyzed ligand-controlled arylation of ?-zincated acyclic amines, obtained by directed ?-lithiation and transmetalation, is described. Whereas PtBu3 gave rise to ?-arylated Boc-protected amines, more flexible N-phenylazole-based phosphine ligands induced major ?-arylation through migrative cross-coupling. PMID:24504659

Millet, Anthony; Dailler, David; Larini, Paolo; Baudoin, Olivier

2014-03-01

360

Preparation, structure, and dynamics of a nickel p-allyl cyanide Nicole M. Brunkan, William D. Jones *  

E-print Network

Preparation, structure, and dynamics of a nickel p-allyl cyanide complex Nicole M. Brunkan, William(h3 - allyl)]' [3] and Ni(phosphine)2(h3 -allyl)(halide) [4Á/7] are known, and a cyanide complex numerous allyl cyanide complexes of nickel during studies of the reaction of butadiene with HCN using Ni

Jones, William D.

361

Merging Gold and Organocatalysis: A Facile Asymmetric Synthesis of Annulated Pyrroles  

PubMed Central

The combination of cinchona-alkaloid-derived primary amine and AuI–phosphine catalysts allowed the selective C–H functionalization of two adjacent carbon atoms of pyrroles under mild reaction conditions. This sequential dual activation provides seven-membered-ring-annulated pyrrole derivatives in excellent yields and enantioselectivities. PMID:24590817

Hack, Daniel; Loh, Charles C. J.; Hartmann, Jan M.; Raabe, Gerhard; Enders, Dieter

2014-01-01

362

Synthesis and Characterization of Osmium(II) Trispyrazolylborate Paul W. Dickinson and Gregory S. Girolami*  

E-print Network

Synthesis and Characterization of Osmium(II) Trispyrazolylborate Complexes Paul W. Dickinson and actinides.4,5 Polypyrazolylborate osmium complexes remain less ex- plored than those of most other d reagents have also been used to prepare several osmium complexes bearing phosphine ligands; occasionally

Girolami, Gregory S.

363

Two-electron mixed-valence complexes small molecule activation and photocatalytic hydrogen production  

E-print Network

Two-electron mixed-valence complexes of rhodium may be supported by diphosphazane ligands (RN(PY2)2). Whereas diphosphazane ligands with strongly [pi]-acidic phosphine groups (Y = F, OCH2CF3) react with RhI starting materials ...

Heyduk, Alan F. (Alan Frank), 1974-

2001-01-01

364

Diastereospecific synthesis of phosphinidene-capped cyclodextrins leading to "introverted" ligands.  

PubMed

alpha-Cyclodextrins (alpha-CDs) containing "PPh" units which cap the primary face of the CD were obtained in high yield by reaction of Li(2)PPh with A,B- or A,C-dimesylated and A,B,D,E-tetramesylated precursors; the resulting phosphines are diastereomerically pure and constitute valuable precursors for the synthesis of metallo-cavitands. PMID:15010755

Engeldinger, Eric; Poorters, Laurent; Armspach, Dominique; Matt, Dominique; Toupet, Loïc

2004-03-21

365

Current status of non-residual control methods against stored product pests  

Microsoft Academic Search

There is an increasing dichotomy between the demands of the first world for quality food uncontaminated by insecticidal residues, and the desperate need of third-world populations to maintain and protect their harvested grain from the deprivations of insects, so as to maintain a minimum level of food security. Fumigation is widely regarded as a non-residual treatment and fumigation with phosphine

Ezra Jonathan Donahaye

2000-01-01

366

Uranium extraction process  

SciTech Connect

Uranium is extracted from wet process phosphoric acid by extraction with a mixture of a diorganophosphate and a neutral phosphorus compound, which is preferably a triorgano phosphine oxide, in the presence of nitrate to form an organic extract layer containing uranium and an aqueous acid layer, which are separated.

Rose, M.A.

1983-05-03

367

A general and efficient copper catalyst for the double carbonylation reaction.  

PubMed

The use of (NHC)CuI complex in combination with a N-heterocyclic carbene precursor as catalyst for the double carbonylation of aryl Iodides and secondary amines solves the problem of using the precious metal Pd and phosphine ligands. The new protocol requires a nonprecious metal catalyst and has greater generality than those previously reported. PMID:19220013

Liu, Jianming; Zhang, Rongzhao; Wang, Shoufeng; Sun, Wei; Xia, Chungu

2009-03-19

368

Journal of Catalysis 207, 247255 (2002) doi:10.1006/jcat.2002.3525, available online at http://www.idealibrary.com on  

E-print Network

­oxidation treatment procedures (22). Recently, Iwasawa and co-workers obtained highly active CO oxidation catalysts by grafting Au­phosphine com- plexes (AuL3NO3 or Au9L8(NO3)3; L = PPh3) onto "as- precipitated" Ti(OH)4 (4

Goodman, Wayne

369

Catalytic platinum-initiated cation-olefin reactions with alkene terminating groups†  

PubMed Central

A series of phosphine–Pt2+-catalysts is reported, which enable the oxidative cascade cyclization of poly-alkene substrates. When the terminus is appropriately arranged and a catalyst reoxidation mediator is included, several polycyclic all carbon skeletons can be obtained. In one example, a chiral P2Pt+2 catalyst provides up to 79% ee. PMID:23619982

Sokol, Joseph G.; Cochrane, Nikki A.; Becker, Jennifer J.; Gagne, Michel R.

2013-01-01

370

Enantioselective aza-Morita-Baylis-Hillman reaction between acrylates and N-Boc isatin ketimines: asymmetric construction of chiral 3-substituted-3-aminooxindoles.  

PubMed

The first enantioselective aza-Morita–Baylis–Hillman reaction of acrylates with ketimines derived from isatins has been developed. With 2 mol% of chiral bifunctional phosphine-squaramide 4e, optically active 3-substituted-3-amino-2-oxindoles were obtained in excellent yields with up to 91% ee. PMID:25184554

Zhao, Xuan; Li, Tian-Ze; Qian, Jing-Ying; Sha, Feng; Wu, Xin-Yan

2014-10-28

371

Palladium-catalyzed asymmetric allylic alkylation using chiral hydrazone ligands with ferrocene skeleton  

Microsoft Academic Search

Palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (4) with a dimethyl malonate–BSA–LiOAc system has been successfully carried out in the presence of chiral phosphine–hydrazone ligands such as 3a in good yields with good enantioselectivities (up to 84% ee).

Takashi Mino; Hiroshi Segawa; Masakazu Yamashita

2004-01-01

372

HPLC-UV determination of total vitamin C in a wide range of fortified food products  

Microsoft Academic Search

A HPLC method for the quantification of total ascorbic acid (AA) and isoacorbic acid (isoAA) in fortified food products, premixes and duomixes has been developed. The method is based on the acidic extraction of AA in the presence of reducing agent Tris [2-carboxyethyl] phosphine (TCEP), which maintained AA in its reduced form. The separation was performed on a C18 column

Patric Fontannaz; Tamara Kilinç; Olivier Heudi

2006-01-01

373

Organotrifluoroborates and Monocoordinated Palladium Complexes as Catalysts--A Perfect Combination for Suzuki-Miyaura Coupling  

PubMed Central

Monocoordinated palladium catalysts derived from sterically hindered, electron-rich phosphines or N-heterocyclic carbenes have revolutionized the Suzuki–Miyaura coupling reaction. The emergence of organotrifluoroborates has provided important new perspectives for the organoboron component of these reactions. In combination, these two components prove to be extraordinarily powerful partners for cross-coupling reactions. PMID:19899086

Molander, Gary A.; Canturk, Belgin

2010-01-01

374

Cobalt catalysis at the crossroads: cobalt-catalyzed Alder-ene reaction versus [2 + 2] cycloaddition.  

PubMed

The application of bidentate phosphine ligands in cobalt-catalyzed transformations of cyclic alkenes such as cyclopentene and cycloheptene with internal alkynes led to a chemoselective Alder-ene or a [2 + 2] cycloaddition reaction depending on the electronic nature of the alkyne and the bite angle of the ligand used. PMID:20196545

Hilt, Gerhard; Paul, Anna; Treutwein, Jonas

2010-04-01

375

Palladium-catalyzed carboiodination of alkenes: carbon-carbon bond formation with retention of reactive functionality.  

PubMed

We report a palladium-catalyzed carbon-carbon bond-forming reaction between aryl iodides and alkenes. In contrast to traditional cross-coupling reactions, two new bonds are formed, and all of the atoms in the starting materials are incorporated into the product. The use of a palladium catalyst with bulky phosphine ligands is found to be crucial for reactivity. PMID:21265523

Newman, Stephen G; Lautens, Mark

2011-02-16

376

Extraction of cadmium and iodocadmat species by di(2-ethylhexyl) phosphoric acid from perchloric and phosphoric media.  

PubMed

We have investigated the extraction of cadmium with di(2-ethylhexyl) phosphoric acid (HDEHP) in various solvents from perchloric and phosphoric solutions. The distribution coefficient D obtained is not very dependent on the nature and the polarity of the diluent used. The extraction of Cd(II) by HDEHP dissolved in benzene, from sulfophosphoric solutions shows the absence of sulfuric or mixed sulfophosphoric complexes of the metal. However, the presence of iodide anions in aqueous perchloric or phosphoric media results in enhanced extraction coefficient of cadmium with HDEHP (HX) in benzene. The extracted species were found to be CdIX,3(HX)2 and CdI2,3(HX)2 and their formation constants are 0.033 and 0.036, respectively. The recovery of cadmium from phosphoric medium by tributylphosphate (TBP), trioctyl phosphine oxide (TOPO), triphenyl phosphine oxide (TPPO), diphenylamine or their mixtures with HDEHP is lesser than with HDEHP alone. PMID:11300405

Elyahyaoui, A; Bouhlassa, S

2001-06-01

377

When the Tolman electronic parameter fails: a comparative DFT and charge displacement study of [(L)Ni(CO)?](0/-) and [(L)Au(CO)](0/+).  

PubMed

In this study we have examined 42 [(L)M(CO)n](±/0) complexes (M = Ni and Au), including neutral ligands, such as phosphines and carbenes, and anionic ones. For each complex, the carbonyl stretching frequency (?(CO)) and the amount of charge donated from the ligand to the metal (CT) have been computed on the basis of DFT calculations. For nickel complexes, the two observables nicely correlate with each other, as expected from the theory underlying the Tolman electronic parameter. On the contrary, for gold complexes a more complex pattern can be observed, with an apparent differentiation between phosphine ligands and carbon-based ones. Such differences have been explained analyzing the Au-L bond in terms of Dewar-Chatt-Duncanson bonding constituents (? donation and ? back-donation). Our analysis demonstrates that in linear gold(I) complexes, ?(CO) depends only on the metal-to-ligand ? back-donation. PMID:25166741

Ciancaleoni, Gianluca; Scafuri, Nicola; Bistoni, Giovanni; Macchioni, Alceo; Tarantelli, Francesco; Zuccaccia, Daniele; Belpassi, Leonardo

2014-09-15

378

Multiple-episode conjunctivitis outbreak among workers at a nut-processing facility.  

PubMed

Workers in a Kern County almond and pistachio nut-packing facility sought medical care for eye irritation (conjunctivitis) on three separate occasions in 1987 and 1988. These incidents were investigated by the California Department of Health Services to identify the agent responsible for the eye irritation outbreak and to suggest possible remediation. The eye irritation incidents involved only the 30 to 35 workers in the preprocessor shed. Each of the three eye irritation incidents followed phosphine (Gastoxin) fumigation. Four plausible hypotheses were tested as explanations of the outbreaks of eye irritation: phosphine gas exposure, ammonia gas exposure, aluminum hydroxide dust exposure, and almond cleaning and hulling dust exposure, with or without contamination by propargite residues (Omite 6-E). None of these hypotheses received enough consistent support to be viewed as a probable cause for the illness outbreaks. PMID:2037905

Ames, R G

1991-04-01

379

MOVPE growth of high performance photodetector structures using TBA and TBP  

SciTech Connect

Tertiary-butyl-arsine (TBA) and tertiary-butyl-phosphine (TBP) are common alternative group V precursors for the replacement of the highly toxic arsine and phosphine. The authors demonstrate, that high performance devices like pin-photodetectors grown with TBA and TBP show excellent device characteristics. Extremely low dark currents of I{sub D} < 100 pA at {minus}5 V are found for 55 {micro}m planar pin-photodiodes with an yield of 99%. Also planar 300 {micro}m diodes and mesa pin photodetectors (40 {micro}m) were processed and investigated. In both cases very low dark currents of I{sub D} < 0.6 nA at {minus}5 V were measured. Beside safety aspects, the improvements in device properties together with high yields (>95%) demonstrate the suitability of TBA and TBP for the growth of high performance pin-photodetectors.

Weber, J.; Nowitzki, A.; Gyuro, I.; Scherb, J. [Alcatel Telecom, Stuttgart (Germany). Research Div.

1996-12-31

380

Temperature- and voltage-induced ligand rearrangement of a dynamic electroluminescent metallopolymer.  

PubMed

A dynamic-covalent metal-containing polymer was synthesized by the condensation of linear diamine and dialdehyde subcomponents around copper(I) templates in the presence of bidentate phosphine ligands. In solution, the red polymers undergo a sol-gel transition upon heating to form a yellow gel, a process that can be either reversible or irreversible depending on the solvent used. When fabricated into a light-emitting electrochemical cell (LEC), the polymer emits infrared light at low voltage. As the voltage is increased, a blue shift in the emission wavelength is observed until yellow light is emitted, a process which is gradually reversed over time upon lowering the voltage. The mechanism underlying these apparently disparate responses is deduced to be due to loss of the copper phosphine complex from the polymer. PMID:24962081

Asil, Demet; Foster, Jonathan A; Patra, Asit; de Hatten, Xavier; del Barrio, Jesús; Scherman, Oren A; Nitschke, Jonathan R; Friend, Richard H

2014-08-01

381

Quantum Dots: The New Little Nanosemiconductors  

NASA Astrophysics Data System (ADS)

The recent arrival of nanomaterials has brought a nifty device called the Quantum Dot. They have intriguing and useful properties. They release light when electricity, heat or light excites their electrons. Their tunable bandgaps allow for the wavelength range they release to be controlled. Free Dots can be attached to a variety of molecules via metal coordinating functional groups. Some of These groups include thiol, phosphine oxide, phosphonic acid, amine, nitrile, phosphine, carboxylic acid or others ligands. This allows the Dots to be dispersed or dissolved in almost any solvent as well as incorporated into a large number of inorganic and organic films. quantum dots can also be tuned to emit in sharp Gaussian peaks in visible or infrared light. Their uses vary from counter counterfeiting to tracking terrorist movement across a large empty landscape.

Harenza, Chance

2006-10-01

382

Isolable gold(I) complexes having one low-coordinating ligand as catalysts for the selective hydration of substituted alkynes at room temperature without acidic promoters.  

PubMed

Hydration of a wide range of alkynes to the corresponding ketones has been afforded in high yields at room temperature by using gold(I)-phosphine complexes as catalyst, with no acidic cocatalysts required. Suitable substrates covering alkyl and aryl terminal alkynes, enynes, internal alkynes, and propargylic alcohols, including enantiopure forms, are cleanly transformed to the corresponding ketones in nearly quantitative yields. Acid-labile groups present in the substrates are preserved. The catalytic activity strongly depends on both the nature of the phosphine coordinated to the gold (I) center and the softness of the counteranion, the complex AuSPhosNTf(2) showing the better activity. A plausible mechanism for the hydration of alkynes through ketal intermediates is proposed on the basis of kinetic studies. The described catalytic system should provide an efficient alternative to mercury-based methodologies and be useful in synthetic programs. PMID:19170603

Leyva, Antonio; Corma, Avelino

2009-03-01

383

Extraction of lanthanides and actinides from H. A. Waste by calix[4]arenes bearing CMPO units  

NASA Astrophysics Data System (ADS)

The decategorisation of radioactive liquid waste by removal of 90Sr, 137Cs and actinides (allowing the waste to be sent to a surface disposal after conditioning) or the separation of these long lived nuclides from solutions arising from the PUREX process (in order to destroy them by transmutation or to isolate them in high integrity matrixes) need very specific extractants. Carbamoylmethyl phosphine oxides are excellent extractants for actinides, especially the (N, N-di-isobutylcarbamoylmethyl) octyl phenyl phosphine oxide used in the TRUEX process. The species extracted contains three CMPO molecules per actinide cation. Thus, it seemed interesting to attach, in a suitable way and on an appropriate platform, three (or more) functional groups of the CMPO type, to better complex the trivalent cations.

Dozol, J. F.; Carrera, A. Garcia; Rouquette, H.

2000-07-01

384

Bis(pentamethylcyclopentadienyl)ytterbium: An investigation of weak interactions in solution using multinuclear NMR spectroscopy  

SciTech Connect

NMR spectroscopy is ideal for studying weak interactions (formation enthalpy {le}20 kcal/mol) in solution. The metallocene bis(pentamethylcyclopentadienyl)ytterbium, Cp*{sub 2}Yb, is ideal for this purpose. cis-P{sub 2}PtH{sub 2}complexes (P = phosphine) were used to produce slow-exchange Cp*{sub 2}YbL adducts for NMR study. Reversible formation of (P{sub 2}PtH){sub 2} complexes from cis-P{sub 2}PtH{sub 2} complexes were also studied, followed by interactions of Cp*{sub 2}Yb with phosphines, R{sub 3}PX complexes. A NMR study was done on the interactions of Cp*{sub 2}Yb with H{sub 2}, CH{sub 4}, Xe, CO, silanes, stannanes, C{sub 6}H{sub 6}, and toluene.

Schwartz, D.J.

1995-07-01

385

Feasibility of actinide separation from UREX-like raffinates using a combination of sulfur- and oxygen-donor extractants  

SciTech Connect

A synergistic combination of bis(o-trifluoromethylphenyl)dithios-phosphinic acid and trioctylphosphine oxide has been recently shown to selectively remove uranium, neptunium, plutonium and americium from aqueous environment containing up to 0.5 M nitric acid and 5.5 g/l fission products. Here the feasibility of performing this complete actinide recovery from aqueous mixtures is forecasted for a new organic formulation containing sulfur donor extractant of modified structure based on Am(III) and Eu(III) extraction data. A mixture of bis(bis-m,m-trifluoromethyl)phenyl)-dithios-phosphinic acid and TOPO in toluene enhances the extraction performance, accomplishing Am/Eu differentiation in aqueous mixtures up to 1 M nitric acid. The new organic recipe is also less susceptible to oxidative damage resulting from radiolysis. (authors)

Zalupski, P.R.; Peterman, D.R.; Riddle, C.L. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415 (United States)

2013-07-01

386

Coordination Chemistry of Cyclic Disilylated Stannylenes and Plumbylenes to Group 4 Metallocenes  

PubMed Central

Reduction of group 4 metallocene dichlorides with magnesium in the presence of cyclic disilylated stannylene or plumbylene phosphine adducts yielded the respective metallocene tetrylene phosphine complexes. Under the same conditions the use of the respective dimerized stannylene or plumbylene gave metallocene ditetrylene complexes. A computational analysis of these reactions revealed for all investigated compounds multiple-bonded character for the M–E(II) linkage, which can be rationalized in the case of the monotetrylene complex with the classical ?-donor/?-acceptor interaction. The strength of the M–E(II) bond increases descending group 4 and decreases going from Sn to its heavier congener Pb. The weakness of the Ti–E(II) bonds is caused by the significantly reduced ability of the titanium atom for d–p ?-back-bonding. PMID:22716501

2012-01-01

387

Controlling charge transport in blue organic light-emitting devices by chemical functionalization of host materials  

SciTech Connect

Generation of white light from OLEDs for general lighting applications requires a highly efficient blue component. However, a stable and power efficient blue OLED component with simple device architecture remains a significant challenge partly due to lack of appropriate host materials. Here we report the photophysical and device properties of ambipolar host phosphine oxide based materials. In this work, we studied the effect of the structural modification made to phosphine oxide-based hosts on the charge balance. We observed significant changes in charge transport within the host occurred upon small modifications to their chemical structure. As a result, an alteration of the chemical design of these materials allows for the control of charge balance of the OLED.

Polikarpov, Evgueni; Koech, Phillip K.; Wang, Liang; Swensen, James S.; Cosimbescu, Lelia; Rainbolt, James E.; Von Ruden, Amber L.; Gaspar, Daniel J.; Padmaperuma, Asanga B.

2011-01-18

388

Extractant Assisted Synthesis of Polymer Stabilized Platinum and Palladium Metal Nanoparticles for Sensor Applications  

Microsoft Academic Search

Extractant?assisted synthesis of platinum and palladium polymer?stabilized metal nanoparticles (PSMNP) was carried out for the first time. The synthesis included the following sequential steps: a) loading of extractant (tributyl?phosphine oxide, TBPO) with the desired metal ion; b) preparation of a membrane “cocktail” by mixing a metal?containing extractant, solution of the polymer (PVC or polysulfone) and plastisizer; c) membrane deposition and

Dmitri N. Muraviev; Maria Isabel Pividory; José Luis Montañez Soto; Salvador Alegret

2006-01-01

389

A chemical investigation into the catalytic site of aspartate transcarbamylase  

E-print Network

functional group which can react with nucleo- phillic amino acid side chains while the reagent is bound to the enzyme. Aspartate transcarbamylase catalyzes the reaction be- tween carbamyl phosphate and L-aspartate to form carbamyl- L... (dimethylamino) phosphine Tribenzyl phosphite Benzyl hydrogen N-(chloroacetyl)? phosphoramidate Dilithium N- (chloroacetyl)? phosphoramidate Inhibition Studies Determination of Carbamyl Aspartic Acid Stock solutions Inhibitor solutions 19 19 20 22...

Kaeder, Gerald Raymond

2012-06-07

390

Efficient hydroxycarbonylation of aryl iodides using recoverable and reusable carbon aerogels doped with palladium nanoparticles as catalyst  

Microsoft Academic Search

Electron-rich and electron-poor aryl iodides are converted, in high to excellent yields, into the corresponding carboxylic acids through a hydroxycarboxylation reaction catalyzed by a recoverable and reusable phosphine free palladium–carbon aerogel catalyst using lithium formate and acetic anhydride as an internal condensed source of carbon monoxide. The catalyst system can be reused several times without any appreciable loss of activity.

Sandro Cacchi; Cosmin L. Cotet; Giancarlo Fabrizi; Giovanni Forte; Antonella Goggiamani; Laura Martín; Sandra Martínez; Elies Molins; Marcial Moreno-Mañas; Francesco Petrucci; Anna Roig; Adelina Vallribera

2007-01-01

391

Optimizing the connectivity in disulfide-rich peptides: ?-conotoxin SII as a case study  

Microsoft Academic Search

We describe a strategy for the efficient, unambiguous assignment of disulfide connectivities in ?-conotoxin SII, of which ?30% of its mass is cysteine, as an example of a generalizable technique for investigation of cysteine-rich peptides. ?-Conotoxin SII was shown to possess 3–8, 2–18, and 4–14 disulfide bond connectivity. Sequential disulfide bond connectivity analysis was performed by partial reduction with Tris(2-carboxyethyl)phosphine

Jon-Paul Bingham; Natalie M. Broxton; Bruce G. Livett; John G. Down; Alun Jones; Edward G. Moczydlowski

2005-01-01

392

Electron microscopy of ultra-thin buried layers in InP and InGaAs  

Microsoft Academic Search

The large-angle convergent-beam electron diffraction (LACBED) technique has been used to measure layer thicknesses and strain of ultra-thin arsenic and phosphorus-rich layers produced by temporary arsine and phosphine purges in the metal-organic vapour phase epitaxy growth of InP and InGaAs. The paper describes how the technique, previously used to investigate single quantum wells of thickness between 8 and 30 Å,

N. Grigorieff; D. Cherns; M. J. Yates; M. Hockly; S. D. Perrin; M. R. Aylett

1993-01-01

393

CCMR: New Iridium Complexes for the Dehydrogenation of Alkanes  

NSDL National Science Digital Library

To introduce small variations on the previously investigated iridium P-C-P pincer complexes. The variations include substitution of cyclohexyl groups for the tert-butyl and the iso-propyl groups found on the phosphines.Thus, synthesis of these new iridium P-C-P pincer complexes was performed with the aim of improved catalytic dehydrogenation activity as well as a better understand of the influence that ligand sterics and electronics have on the active species.

Wang, David

2004-08-17

394

Chiral Palladacycle Catalysts Generated on a Single-Handed Helical Polymer Skeleton for Asymmetric Arylative Ring Opening of 1,4-Epoxy-1,4-dihydronaphthalene.  

PubMed

Post-polymerization C?H activation of poly(quinoxaline-2,3-diyl)-based helically chiral phosphine ligands (PQXphos) with palladium(II) acetate afforded chiral phosphapalladacycles quantitatively. In?situ generated palladacycles exhibited enantioselectivities up to 94?%?ee in the palladium-catalyzed asymmetric ring-opening arylation of 1,4-epoxy-1,4-dihydronaphthalenes with arylboronic acids. PMID:25251609

Yamamoto, Takeshi; Akai, Yuto; Suginome, Michinori

2014-11-17

395

Development of a practical photochemical energy storage system. Quarterly report. [Interconversion between norbornadiene and quadricyclene for thermochemical heat storage  

Microsoft Academic Search

Research on polymer organic sensitizers and polymer inorganic sensitizers for the conversion of norbornadiene to quadricyclene for thermochemical storage of solar heat is described. Also, research on the catalysis of the conversion of quadricyclane to norbornadiene is described. Polymer-anchored cobalt(II) porphyrin catalysts, polymer-anchored palladium(II) phosphine catalysts, and triphenylcyclopropenyl nickel complexes as catalysts were studied, and results are discussed. (WHK)

R. R. Hautala; C. R. Kutal

1977-01-01

396

BrettPhos Ligand Supported Palladium-Catalyzed C?O Bond Formation through an Electronic Pathway of Reductive Elimination: Fluoroalkoxylation of Activated Aryl Halides.  

PubMed

We report an unprecedented BrettPhos ligand supported Pd-catalyzed C?O bond-forming reaction of activated aryl halides with primary fluoroalkyl alcohols. We demonstrate that the Phosphine ligand (BrettPhos) possesses the property of altering the mechanistic pathway of reductive elimination from nucleophile to nucleophile. The Pd/BrettPhos catalyst system facilitates the reductive elimination of the oxygen nucleophile through an electronic pathway. PMID:25236851

Rangarajan, T M; Singh, Rajendra; Brahma, Raju; Devi, Kavita; Singh, Rishi Pal; Singh, R P; Prasad, Ashok K

2014-10-27

397

Recent Progress in Polymeric Palladium Catalysts for Organic Synthesis  

Microsoft Academic Search

Recent progress in the design, preparation, and application of polymer-supported palladium complexes is reviewed. In particular, the preparation of various supported palladium-phosphine complexes used in a variety of carbon–carbon bond forming reactions such as the Heck reaction, the Suzuki–Miyaura coupling, and -allylic substitution is discussed. Immobilization of the palladium complexes has often been achieved by anchoring phosphorus-based ligands on functionalized

Yasuhiro Uozumi

398

Molecular design of luminescent dinuclear gold(I) thiolate complexes: from fundamentals to chemosensing  

Microsoft Academic Search

A number of dinuclear gold(I) phosphine thiolates have been synthesized and characterized. Detailed spectroscopic and luminescence studies have provided a fundamental understanding on their spectroscopic origins, which serves as the basis for the design of versatile spectrochemical and luminescence chemosensors as well as molecular optoelectronic ‘on-off’ switching devices based on the switching on and off of weak metal?metal interactions using

Vivian Wing-Wah Yam; Chui-Ling Chan; Chi-Kwan Li; Keith Man-Chung Wong

2001-01-01

399

Preparation of Concentrated Stable Fluids Containing Silver Nanoparticles in Nonpolar Organic Solvent  

Microsoft Academic Search

Stable fluids containing silver nanoparticles in kerosene have been prepared by the extraction?reduction method. Silver nitrate was extracted in nonpolar solvent by thio?substituted phosphinic acid extractant Cyanex 302, and then Ag was reduced by solid KBH4. In order to enhance the loading content of silver nanoparticles in the fluids, a tri?block copolymer (PEO)20(PPO)70(PEO)20 was added into the organic phase before

Fu Xun; Yu Wei; Lin Yusheng; Wang Debao; Shi Huaqiang; Yan Fengyuan

2005-01-01

400

Dynamic tests for actinide/lanthanide separation by CMPO solvent in fluorinated diluents  

SciTech Connect

Actinide and lanthanide extraction by new solvent: 0.2 M phenyl-octyl-N,N-diiso-butylcarbamoyl-phosphine oxide (CMPO) + 30% TBP + formal of octafluoro-pentanol was studied. A dynamic test with this solvent was performed. It was shown that americium and lanthanides are effectively extracted from PUREX process raffinate. The separation of americium from light lanthanides was confirmed in the modified SETFICS flowsheet with this new solvent. (authors)

Tkachenko, L.; Babain, V.; Alyapyshev, M.; Vizniy, A.; Il'in, A. [V. G. Khlopin Radium Institute, 2nd Murinskiy Ave 28., St. Petersburg 194021 (Russian Federation); Shadrin, A. [A.A. Bochvar High-technology Research Institute of Inorganic Materials, 5-a, Rogova str., Moscow 123098 (Russian Federation)

2013-07-01

401

The role of hydrogen dilution of silane and phosphorus doping on hydrogenated microcrystalline silicon (?c-Si:H) films prepared by hot-wire chemical vapor deposition (HW-CVD) technique  

Microsoft Academic Search

The electrical, structural and optical properties of undoped and phosphorus doped ?c-Si:H films prepared by a HW-CVD technique have been studied. The hydrogen (H2) dilution of silane has been varied carefully to produce undoped ?c-Si:H films. The amorphous-to-microcrystalline transition was observed for a hydrogen dilution ratio >0.75. The phosphorus doped ?c-Si:H films were deposited by varying the phosphine (PH3) gas

S. R Jadkar; J. V Sali; M. G Takwale; D. V Musale; S. T Kshirsagar

2001-01-01

402

RING-CHAIN HALOGENOTROPIC TAUTOMERISM. 2,2DIPHENYL1,2?-THIAPHOSPHOLANIUM BROMIDE 3-BROMOPROPYLDIPHENYLPHOSPHINE SULFIDE  

Microsoft Academic Search

A new type of ring-chain anionotropic tautomerism for cyclic thiaphospholanium bromide 2A and isomeric phosphine sulfide 2B was investigated. Both of the tautomers were isolated in crystalline form. Their structures were proved by IR, Raman, H, P NMR spectroscopy and X-ray analysis. In solution the equilibrium position doesn't depend on the kind of dissolved tautomer. The effect of the solvent.

Dmitrii I. Lobanov; Inga M. Aladzheva; Olga V. Bykhovskaya; Pavel V. Petrovskii; Konstantin A. Lyssenko; Mikhail Yu. Antipin; Tatyana A. Mastryukova; Martin I. Kabachnik

1997-01-01

403

A convenient synthesis of triflate anion ionic liquids and their properties.  

PubMed

A solvent- and halogen-free synthesis of high purity triflate ionic liquids via direct alkylation of organic bases (amines, phosphines or heterocyclic compounds) with methyl and ethyl trifluoromethanesulfonate (methyl and ethyl triflate) has been developed. Cheap and non-toxic dimethyl and diethyl carbonate serve as source for the methyl and ethyl groups in the preparation of methyl and ethyl triflate by this invented process. The properties of ionic liquids containing the triflate anion are determined and discussed. PMID:22565482

Ignat'ev, Nikolai V; Barthen, Peter; Kucheryna, Andryi; Willner, Helge; Sartori, Peter

2012-01-01

404

Control of Ge/Si intermixing during Ge island growth  

NASA Astrophysics Data System (ADS)

The surface energy and growth kinetics during Ge deposition on Si(001) were modified by growing the films in a phosphine environment. Islands were formed under a H2 flux as well as in a PH3/H2 atmosphere, but the morphologies were different. The presence of PH3 not only affects the island shape and size but also the composition profile. The dramatical inhibition of Ge/Si intermixing during growth leads to islands richer in Ge compared to undoped islands.

Leite, Marina S.; Kamins, T. I.; Medeiros-Ribeiro, G.

2009-02-01

405

The effective recovery of praseodymium from mixed rare earths via a hollow fiber supported liquid membrane and its mass transfer related  

Microsoft Academic Search

The recovery of praseodymium from mixed rare earths via a hollow fiber supported liquid membrane (HFSLM) was examined. Bis(2,4,4-trimethylpentyl) phosphinic acid – known as Cyanex 272 – was used as an extractant carrier. The stripping solution was hydrochloric acid solution. The experiments examined in functions of the concentrations of the carrier in liquid membrane, the (initial) pH's of initial feed

Pharannalak Wannachod; Srestha Chaturabul; Ura Pancharoen; Anchaleeporn W. Lothongkum; Weerawat Patthaveekongka

2011-01-01

406

Triple-helical transition state analogues: a new class of selective matrix metalloproteinase inhibitors.  

PubMed

Alterations in activities of one family of proteases, the matrix metalloproteinases (MMPs), have been implicated in primary and metastatic tumor growth, angiogenesis, and pathological degradation of extracellular matrix (ECM) components, such as collagen and laminin. Since hydrolysis of the collagen triple-helix is one of the committed steps in ECM turnover, we envisioned modulation of collagenolytic activity as a strategy for creating selective MMP inhibitors. In the present study, a phosphinate transition state analogue has been incorporated within a triple-helical peptide template. The template sequence was based on the alpha1(V)436-450 collagen region, which is hydrolyzed at the Gly(439)-Val(440) bond selectively by MMP-2 and MMP-9. The phosphinate acts as a tetrahedral transition state analogue, which mimics the water-bound peptide bond of a protein substrate during hydrolysis. The phosphinate replaced the amide bond between Gly-Val in the P1-P1' subsites of the triple-helical peptide. Inhibition studies revealed Ki values in the low nanomolar range for MMP-2 and MMP-9 and low to middle micromolar range for MMP-8 and MMP-13. MMP-1, MMP-3, and MT1-MMP/MMP-14 were not inhibited effectively. Melting of the triple-helix resulted in a decrease in inhibitor affinity for MMP-2. The phosphinate triple-helical transition state analogue has high affinity and selectivity for the gelatinases (MMP-2 and MMP-9) and represents a new class of protease inhibitors that maximizes potential selectivity via interactions with both prime and nonprime active site subsites as well as with secondary binding sites (exosites). PMID:17672455

Lauer-Fields, Janelle; Brew, Keith; Whitehead, John K; Li, Shunzi; Hammer, Robert P; Fields, Gregg B

2007-08-29

407

Reactivity patterns of stibine and trisdimethylaminoantimony precursors for chemical beam epitaxial growth and etching  

Microsoft Academic Search

The handling and use of stibine in a CBE environment has been investigated and found to be very straightforward, permitting its use as a CBE precursor. Growth studies of GaSb and InSb on GaAs and SiO2 substrates using this precursor are reported. The compound displays a similar surface reactivity pattern to arsine and phosphine, necessitating the use of thermal pre-crackers

J. S Foord; F. P Howard; G. S McGrady; G. J Davies

1998-01-01

408

Synthesis and self-organization of Au nanoparticles  

Microsoft Academic Search

Monodisperse (diameter 10 nm) Au nanoparticles have been synthesized by the reduction of AuCl3 at high temperatures, in commercial oleyl amine, in the presence of tri-octyl phosphine oxide (TOPO). The oleyl amine molecule has multiple roles, acting as high-boiling-point solvent, capping agent and reducing agent. The Au nanocrystalline particles have been studied by powder x-ray diffraction (XRD) and transmission electron

S. Pyrpassopoulos; D. Niarchos; G. Nounesis; N. Boukos; I. Zafiropoulou; V. Tzitzios

2007-01-01

409

Enynylation of 2-iodo-4-(phenylchalcogenyl)-1-butenes via intramolecular chelation: approach to the synthesis of conjugated dienynes or trienynes.  

PubMed

[reaction: see text] 2-Iodo-4-(phenylchalcogenyl)-1-butenes 3 and 4, which are derived from methylenecyclopropanes 1, can be enynylated with alkynes catalyzed by Pd(OAc)(2) to give conjugated dienynes 5 and 6 in the absence of any phosphine ligand and copper salt, and trienyne 9a can be obtained by oxidation of compound 5a. A plausible reaction mechanism has been proposed. PMID:15987211

Shi, Min; Liu, Le-Ping; Tang, Jie

2005-07-01

410

High performance of a palladium phosphinooxazoline catalyst in the asymmetric arylation of cyclic N-sulfonyl ketimines.  

PubMed

A cationic palladium complex with a chiral phosphine-oxazoline ligand (iPr-phox) showed high catalytic activity and enantioselectivity in the asymmetric addition of arylboronic acids to six-membered cyclic N-sulfonyl ketimines to give high yields of the corresponding chiral cyclic sulfamidates with 96-99.9%?ee. The products have tetrasubstituted stereogenic centers with an amino group and a triaryl or alkyldiaryl group as substituents. PMID:25044954

Jiang, Chunhui; Lu, Yixin; Hayashi, Tamio

2014-09-01

411

Reduction of Crosshatch Roughness and Threading Dislocation Density in Metamorphic GaInP Buffers and GaInAs Solar Cells  

Microsoft Academic Search

Surface crosshatch roughness typically develops during the growth of lattice-mismatched compositionally graded buffers and can limit misfit dislocation glide. In this study, the crosshatch roughness during growth of a compressive GaInP\\/GaAs graded buffer is reduced by increasing the phosphine partial pressure throughout the metamorphic growth. Changes in the average misfit dislocation length are qualitatively determined by characterizing the threading defect

R. M. France; J. F. Geisz; M. A. Steiner; B. To; M. J. Romero; W. J. Olavarria; R. R. King

2012-01-01

412

Avidin and Plant Biotechnology to Control Pests  

Microsoft Academic Search

\\u000a The urgency of the global food crisis, coupled with the environmental impact of global warming and fuel shortages, indicate\\u000a that transgenic methods may be required to enhance food production and quality. Widely used chemical insecticides, such as\\u000a phosphine and methyl bromide, are losing their utility either due to insect resistance or to the environmental damage they\\u000a cause. It is most

Harry Martin; Elisabeth P. J. Burgess; Michal Masarik; Karl J. Kramer; Miroslava Beklova; Vojtech Adam; Rene Kizek

413

Solvent Extraction of Actinides and Lanthanides by CMP(O)? and N?Acyl(thio)urea?tetrafunctionalized Cavitands: Strong Synergistic Effect of Cobalt Bis(dicarbollide) Ions  

Microsoft Academic Search

The synthesis of two carbamoylmethylphosphate (CMP)? and ?phosphine oxide (CMPO)?tetrafunctionalized cavitands with a propyl spacer between the cavitand platform and the chelating sites is described. Liquid–liquid extractions with CMP(O)?and N?acyl(thio)urea?tetrafunctionalized cavitands were performed from aqueous nitric acid into dichloromethane or o?nitrophenyl hexyl ether (NPHE). The extraction of americium (III) and europium (III) from aqueous nitric acid into NPHE was studied

Willem Verboom; David N. Reinhoudt; Fre´deric Brisach; Karine Liger

2005-01-01

414

Phosphinoferrocenylaminophosphines as novel and practical ligands for asymmetric catalysis.  

PubMed

[structure: see text] A new series of ligands with a novel phosphine-aminophosphine ligation design as depicted in structure 1 has been prepared on a ferrocenylethyl backbone. These BoPhoz ligands of structure 2 have afforded exceedingly high activity and enantioselectivity in the rhodium-catalyzed asymmetric hydrogenation of dehydro-alpha-amino acid derivatives, itaconic acids, and alpha-ketoesters. These air-stable ligands are readily prepared from cost-effective and non-pyrophoric intermediates. PMID:12098262

Boaz, Neil W; Debenham, Sheryl D; Mackenzie, Elaine B; Large, Shannon E

2002-07-11

415

EXTRACTION CHROMATOGRAPHIC SEPARATION OF PROMETHIUM FROM HIGH ACTIVE WASTE SOLUTIONS OF PUREX ORIGIN  

Microsoft Academic Search

An extraction chromatographic procedure for the separation of Pm from High Active Waste solutions of Purex process has been developed. Octy1(pheny1)-N,N-diisobutylcarbamoylmethy1phosphine oxide(CMPO) and 2-ethylhexy1-2-ethylhexylphosphonic acid (KSM-17), both sorbed separately on an inert support(chromosorb-102) have been sequentially employed for this purpose. In the CMPO column, the rare earths and the trivalent actinides are sorbed together with uranium, plutonium and traces of

A. Ramanujam; P. V. Achuthan; P. S. Dhami; V. Gopalakrishnan; R. Kannan; J. N. Mathur

1995-01-01

416

Importance of co-donor field strength in the preparation of tetradentate ?-diimine nickel hydrosilylation catalysts.  

PubMed

Although bis(?-diimine)Ni complexes were prepared when amine-substituted chelates were added to Ni(COD)2, the incorporation of strong-field phosphine donors allowed the isolation of (?(4)-N,N,P,P-DI)Ni hydrosilylation catalysts. The crystallographic investigation of two different (?(4)-N,N,P,P-DI)Ni compounds revealed that the geometry about nickel influences the observed degree of ?-diimine reduction. PMID:24030659

Porter, Tyler M; Hall, Gabriel B; Groy, Thomas L; Trovitch, Ryan J

2013-10-01

417

Potency and selectivity of RXP407 on human, rat, and mouse angiotensin-converting enzyme  

Microsoft Academic Search

By screening phosphinic peptide libraries, we recently reported the discovery of RXP407 (Ac-Asp-PheY(PO2-CH2)LAla-Ala-NH2), a potent N-domain-selective inhibitor of recombinant human angiotensin-converting enzyme (ACE). Preliminary studies to evaluate the in vivo activity of RXP407 in rat led us to suspect possible differences in the binding property of RXP407 between human and rat ACE. The aim of the present study was thus

Gille Vazeux; Joël Cotton; Philippe Cuniasse; Vincent Dive

2001-01-01

418

Synthesis and Characterization of Gold Clusters Ligated with 1,3-Bis(dicyclohexylphosphino)propane  

SciTech Connect

In this multidisciplinary study we combine chemical reduction synthesis of novel gold clusters in solution with high-resolution analytical mass spectrometry (MS) to gain insight into the composition of the gold clusters and how their size, ionic charge state and ligand substitution influences their gas-phase fragmentation pathways. Ultra small cationic gold clusters ligated with 1,3-bis(dicyclohexylphosphino)propane (DCPP) were synthesized for the first time and introduced into the gas phase using electrospray ionization (ESI). Mass-selected cluster ions were fragmented employing collision induced dissociation (CID) and the product ions were analysed using MS. The solutions were found to contain the multiply charged cationic gold clusters Au9L43+, Au13L53+, Au6L32+, Au8L32+ and Au10L42+ (L = DCPP). The gas-phase fragmentation pathways of these cluster ions were examined systematically employing CID combined with MS. In addition, CID experiments were performed on related gold clusters of the same size and ionic charge state but capped with 1,3-bis(diphenylphosphino)propane (DPPP) ligands containing phenyl functional groups at the two phosphine centers instead of cyclohexane rings. It is shown that this relatively small change in the molecular substitution of the two phosphine centers in diphosphine ligands (C6H11 versus C6H5) exerts a pronounced influence on the size of the species that are preferentially formed in solution during reduction synthesis as well as the gas-phase fragmentation channels of otherwise identical gold cluster ions. The mass spectrometry results indicate that in addition to the length of the alkyl chain between the two phosphine centers, the substituents at the phosphine centers also play a crucial role in determining the composition, size and stability of diphosphine ligated gold clusters synthesized in solution.

Johnson, Grant E.; Priest, Thomas A.; Laskin, Julia

2013-09-01

419

Degradation of [ 14 C]phosphinothricin (glufosinate) in soil under laboratory conditions: Effects of concentration and soil amendments on 14 CO 2 production  

Microsoft Academic Search

Degradation of the herbicide phosphinothricin (L-homoalanine-4-yl-(methyl)-phosphinic acid) in a phaeozem was investigated by monitoring the 14CO2 release from [1-14C] and [3,4-14C]phosphinothricin. The degradation was largely due to microbial activity, since the rate decreased by more than 95% when the soil was sterilized by ?-radiation. Data obtained with both labels suggested that decarboxylation of phosphinothricin preceded oxidation of its C-atoms 3

C. C. Tebbe; H. H. Reber

1991-01-01

420

UNIVERSITE JOSEPH FOURIER GRENOBLE I N attribu par la bibliothque  

E-print Network

. Autres complexes polyazamacrocycliques 26 III. Autres complexes 27 1. Les complexes phosphine 27 2. Les) et dérivés 63 3. [Re(L)(CO)3Cl] (L = dmbpy, L2) 69 III. Propriétés électrochimiques et 1. Caractérisations physico-chimiques des complexes contenant les ligands «innocents » 83 2

Paris-Sud XI, Université de

421

Catalytic anomeric aminoalkynylation of unprotected aldoses.  

PubMed

A copper(I)-catalyzed anomeric aminoalkynylation reaction of unprotected aldoses was realized. Use of an electron-deficient phosphine ligand, boric acid to stabilize the iminium intermediate, and a protic additive (IPA) to presumably enhance reversible carbohydrate-boron complexation were all essential for efficient conversion. The reaction proceeded well even with a natural disaccharide substrate, suggesting that the developed catalytic reaction could be useful for the synthesis of glycoconjugates with minimum use of protecting groups. PMID:23901780

Kimura, Yasuaki; Ito, Soichi; Shimizu, Yohei; Kanai, Motomu

2013-08-16

422

Phosphylation kinetic constants and oxime?induced reactivation in acetylcholinesterase from fetal bovine serum, bovine caudate nucleus, and electric eel  

Microsoft Academic Search

Kinetic constants for selected phosphonate and phosphinate inhibitors of fetal bovine serum acetylcholinesterase (FBS AChE; EC 3.1.1.7), bovine caudate nucleus AChE (BCN AChE), and eel AChE have been determined. Oxime reactivation of the phosphylated enzymes has also been evaluated. In general a rank order with respect to organophosphorus compound (OP) inhibition of the enzymes was observed: soman (pinacolyl methylphosphonofluoridate) was

Dan W. Hanke; Michael A. Overton

1991-01-01

423

Supramolecular Allosteric Cofacial Porphyrin Complexes  

SciTech Connect

Nature routinely uses cooperative interactions to regulate cellular activity. For years, chemists have designed synthetic systems that aim toward harnessing the reactivity common to natural biological systems. By learning how to control these interactions in situ, one begins to allow for the preparation of man-made biomimetic systems that can efficiently mimic the interactions found in Nature. To this end, we have designed a synthetic protocol for the preparation of flexible metal-directed supramolecular cofacial porphyrin complexes which are readily obtained in greater than 90% yield through the use of new hemilabile porphyrin ligands with bifunctional ether-phosphine or thioether-phosphine substituents at the 5 and 15 positions on the porphyrin ring. The resulting architectures contain two hemilabile ligand-metal domains (Rh{sup I} or Cu{sup I} sites) and two cofacially aligned porphyrins (Zn{sup II} sites), offering orthogonal functionalities and allowing these multimetallic complexes to exist in two states, 'condensed' or 'open'. Combining the ether-phosphine ligand with the appropriate Rh{sup I} or Cu{sup I} transition-metal precursors results in 'open' macrocyclic products. In contrast, reacting the thioether-phosphine ligand with RhI or CuI precursors yields condensed structures that can be converted into their 'open' macrocyclic forms via introduction of additional ancillary ligands. The change in cavity size that occurs allows these structures to function as allosteric catalysts for the acyl transfer reaction between X-pyridylcarbinol (where X = 2, 3, or 4) and 1-acetylimidazole. For 3- and 4-pyridylcarbinol, the 'open' macrocycle accelerates the acyl transfer reaction more than the condensed analogue and significantly more than the porphyrin monomer. In contrast, an allosteric effect was not observed for 2-pyridylcarbinol, which is expected to be a weaker binder and is unfavorably constrained inside the macrocyclic cavity.

Oliveri, Christopher G.; Gianneschi, Nathan C.; Nguyen, Son Binh T.; Mirkin, Chad A.; Stern, Charlotte L.; Wawrzak, Zdzislaw; Pink, Maren (NWU); (Indiana)

2008-04-12

424

Synthesis of the Tricyclic Core in Stemonamine Alkaloids via One-Pot Gold(I)-Catalyzed Cyclization and Schmidt Rearrangement: Formal Synthesis of (±)-Stemonamine.  

PubMed

An efficient synthesis of the tricyclic cyclopenta[1,2-b]pyrrolo[1,2-a]azepine nucleus of stemonamine alkaloids is reported. The key reaction utilizes a one-pot gold(I)-catalyzed cyclization and SnCl4-mediated Schmidt rearrangement. Notably, the phosphine ligand had a crucial effect on the gold(I)-catalyzed cyclization. As an application of this new methodology, the formal synthesis of (±)-stemonamine has been accomplished. PMID:25322172

Kim, Cheoljae; Kang, Soyeong; Rhee, Young Ho

2014-11-21

425

Direct Pd-catalyzed cross-coupling of functionalized organoaluminum reagents.  

PubMed

A handsome couple: Through the use of the simple Pd catalyst [Pd(tmpp)(2)Cl(2)] (tmpp = tris(2,4,6-trimethoxyphenyl)phosphine) and THF/DMF as solvent, various aryl-, heteroaryl-, benzyl- and alkylaluminum reagents can be readily cross-coupled with aryl or heteroaryl iodides, bromides, and nonaflates, and in special cases even with chlorides and triflates. This cross-coupling tolerates free NH(2) groups, aldehydes, ketones, esters, and nitro functions. PMID:23037856

Groll, Klaus; Blümke, Tobias D; Unsinn, Andreas; Haas, Diana; Knochel, Paul

2012-10-29

426

Evaluation of Degradation Inhibitors in Poly(Hexafluoropropene Oxide) Fluids  

NASA Technical Reports Server (NTRS)

The action of various alloys: 440C steel, M-50 steel, Pyrowear 675, Cronidur 30 and Ti(4Al,4Mn); the effect of decradation inhibitors: mono- and diphospha-s-triazines, diphosphatetraazacyclooctatetraene, phosphate esters, phosphate/ diester rust inhibiting mixtures, and a phosphine were evaluated in two poly(hexafluoropropene oxide) fluids (143AC and 16256). The degradation promoting action of the ferrous alloys in 16256 fluid were comparable; Ti(4Al,4Mn) alloy was significantly more detrimental. The overall rating of the additives was: phosphates (greater than) phosphate/diester mixture (greater than) phosphine (greater than or equal to) phospha-s-triazines. The 16256 fluid was less responsive to additive inhibition than 143AC. Phosphate esters were fully effective over 24 hour exposure in the 16256/440C steel and the 16256/Ti(4Al,4Mn) systems at 330 C. In general, the phosphine was less effective in the presence of ferrous alloys than the phosphates and phospha-s-triazines.

Jones, William R., Jr.; Paciorek, Kazimiera J. L.; Lin, Wen-Huey; Masuda, Steven R.; Nakahara, James H.

1996-01-01

427

Chemical Methods for the Direct Detection and Labeling of S-Nitrosothiols  

PubMed Central

Abstract Significance: Posttranslational modification of proteins through phosphorylation, glycosylation, and oxidation adds complexity to the proteome by reversibly altering the structure and function of target proteins in a highly controlled fashion. Recent Advances: The study of reversible cysteine oxidation highlights a role for this oxidative modification in complex signal transduction pathways. Nitric oxide (NO), and its respective metabolites (including reactive nitrogen species), participates in a variety of these cellular redox processes, including the reversible oxidation of cysteine to S-nitrosothiols (RSNOs). RSNOs act as endogenous transporters of NO, but also possess beneficial effects independent of NO-related signaling, which suggests a complex and versatile biological role. In this review, we highlight the importance of RSNOs as a required posttranslational modification and summarize the current methods available for detecting S-nitrosation. Critical Issues: Given the limitations of these indirect detection methods, the review covers recent developments toward the direct detection of RSNOs by phosphine-based chemical probes. The intrinsic properties that dictate this phosphine/RSNO reactivity are summarized. In general, RSNOs (both small molecule and protein) react with phosphines to yield reactive S-substituted aza-ylides that undergo further reactions leading to stable RSNO-based adducts. Future Directions: This newly explored chemical reactivity forms the basis of a number of exciting potential chemical methods for protein RSNO detection in biological systems. Antioxid. Redox Signal. 17, 981–991. PMID:22356122

Bechtold, Erika

2012-01-01

428

Ruthenium Hydrides Containing the Superhindered Polydentate Polyphosphine Ligand P(CH2CH2P(t)Bu2)3.  

PubMed

The complex RuH2(N2)(P(2)P3(tBu)) (1) containing the extremely bulky PP3-type ligand P(2)P3(tBu) = P(CH2CH2P(t)Bu2)3 was synthesized by reduction of RuCl2(P(2)P3(tBu)) (2) with Na/NH3 under a N2 atmosphere. Like other complexes containing the P(2)P3(tBu) ligand, only three of the four donor phosphines are coordinated, and one of the phosphines remains as a dangling pendant phosphine. Reduction of RuCl2(P(2)P3(tBu)) (2) with a range of the more usual hydride reducing agents afforded the previously unknown ruthenium hydride complexes RuHCl(P(2)P3(tBu)) (3), RuH(BH4)(P(2)P3(tBu)) (6), RuH(AlH4)(P(2)P3(tBu)) (7), and the ruthenium(II) trihydride K[Ru(H)3(P(2)P3(tBu))] (8). The ruthenium tetrahydride containing a coordinated H2 ligand RuH2(H2)(P(2)P3(tBu)) (10) was synthesized by exchange of N2 in 1 by H2. Complexes 1, 3, 6, 7, and 8 were characterized by crystallography and multinuclear NMR spectroscopy. PMID:25390508

Gilbert-Wilson, Ryan; Field, Leslie D; Bhadbhade, Mohan

2014-12-01

429

Redox chemistry in the phosphorus biogeochemical cycle  

PubMed Central

The element phosphorus (P) controls growth in many ecosystems as the limiting nutrient, where it is broadly considered to reside as pentavalent P in phosphate minerals and organic esters. Exceptions to pentavalent P include phosphine—PH3—a trace atmospheric gas, and phosphite and hypophosphite, P anions that have been detected recently in lightning strikes, eutrophic lakes, geothermal springs, and termite hindguts. Reduced oxidation state P compounds include the phosphonates, characterized by C?P bonds, which bear up to 25% of total organic dissolved phosphorus. Reduced P compounds have been considered to be rare; however, the microbial ability to use reduced P compounds as sole P sources is ubiquitous. Here we show that between 10% and 20% of dissolved P bears a redox state of less than +5 in water samples from central Florida, on average, with some samples bearing almost as much reduced P as phosphate. If the quantity of reduced P observed in the water samples from Florida studied here is broadly characteristic of similar environments on the global scale, it accounts well for the concentration of atmospheric phosphine and provides a rationale for the ubiquity of phosphite utilization genes in nature. Phosphine is generated at a quantity consistent with thermodynamic equilibrium established by the disproportionation reaction of reduced P species. Comprising 10–20% of the total dissolved P inventory in Florida environments, reduced P compounds could hence be a critical part of the phosphorus biogeochemical cycle, and in turn may impact global carbon cycling and methanogenesis. PMID:25313061

Pasek, Matthew A.; Sampson, Jacqueline M.; Atlas, Zachary

2014-01-01

430

Molecular determinants of a selective matrix metalloprotease-12 inhibitor: insights from crystallography and thermodynamic studies.  

PubMed

The molecular determinants responsible for the potency of the RXP470.1 phosphinic peptide inhibitor toward matrix metalloprotease-12 (MMP-12) remain elusive. To address this issue, structure-activity study, X-ray crystallography, and isothermal titration calorimetry (ITC) experiments were performed. The crystal structure of MMP-12/inhibitor complex (1.15 Å) reveals that the inhibitor establishes multiple interactions with the MMP-12 active site, with its long P(1)' side chain filling most of the S(1)' deep cavity. ITC experiments indicate that the binding of this inhibitor to MMP-12 is mostly entropy driven (?G° = -13.1 kcal/mol, ?H° = -2.53 kcal/mol, and -T?S° = -10.60 kcal/mol) and involves a proton uptake from the buffer. Comparing phosphinic versus hydroxamate inhibitors reveals that the chelation of the zinc ion is slightly different, leading the inhibitor backbone to adopt a position in which the hydrogen bonding with the MMP-12 active site is less favorable in phosphinic inhibitor while maintaining high affinity. PMID:23343195

Czarny, Bertrand; Stura, Enrico A; Devel, Laurent; Vera, Laura; Cassar-Lajeunesse, Evelyne; Beau, Fabrice; Calderone, Vito; Fragai, Marco; Luchinat, Claudio; Dive, Vincent

2013-02-14

431

Redox chemistry in the phosphorus biogeochemical cycle.  

PubMed

The element phosphorus (P) controls growth in many ecosystems as the limiting nutrient, where it is broadly considered to reside as pentavalent P in phosphate minerals and organic esters. Exceptions to pentavalent P include phosphine-PH3-a trace atmospheric gas, and phosphite and hypophosphite, P anions that have been detected recently in lightning strikes, eutrophic lakes, geothermal springs, and termite hindguts. Reduced oxidation state P compounds include the phosphonates, characterized by C-P bonds, which bear up to 25% of total organic dissolved phosphorus. Reduced P compounds have been considered to be rare; however, the microbial ability to use reduced P compounds as sole P sources is ubiquitous. Here we show that between 10% and 20% of dissolved P bears a redox state of less than +5 in water samples from central Florida, on average, with some samples bearing almost as much reduced P as phosphate. If the quantity of reduced P observed in the water samples from Florida studied here is broadly characteristic of similar environments on the global scale, it accounts well for the concentration of atmospheric phosphine and provides a rationale for the ubiquity of phosphite utilization genes in nature. Phosphine is generated at a quantity consistent with thermodynamic equilibrium established by the disproportionation reaction of reduced P species. Comprising 10-20% of the total dissolved P inventory in Florida environments, reduced P compounds could hence be a critical part of the phosphorus biogeochemical cycle, and in turn may impact global carbon cycling and methanogenesis. PMID:25313061

Pasek, Matthew A; Sampson, Jacqueline M; Atlas, Zachary

2014-10-28

432

Effect of surface ligands on optical and electronic spectra of semiconductor nanoclusters.  

PubMed

We investigate the impact of ligands on the morphology, electronic structure, and optical response of the Cd(33)Se(33) cluster, which overlaps in size with the smallest synthesized CdSe nanocrystal quantum dots (QDs). Our density functional theory calculations demonstrate significant surface reorganization for both the bare cluster and the cluster capped with amine or phosphine oxide model ligands. We observe strong surface-ligand interactions leading to substantial charge redistribution and polarization effects on the surface. These effects result in the development of hybridized states, for which the electronic density is spread over the cluster and the ligands. The loss of one of the passivating ligands leads to either optically dark or bright additional states inside of the band gap, depending on the position of the leaving ligand on the QD surface. However, for fully ligated QDs, neither the ligand-localized nor hybridized molecular orbitals appear as trap states inside or near the band gap of the QD. Instead, being mostly optically dark, dense hybridized states could open new relaxation channels for high-energy photoexcitations. Comparing QDs passivated by different ligands, we also found that hybridized states are denser at the edge of the conduction band of the cluster ligated with phosphine oxide molecules than that with primary amines. Such a different manifestation of ligand binding may potentially lead to faster electron relaxation in QDs passivated by phosphine oxide than by amine ligands. PMID:19425603

Kilina, Svetlana; Ivanov, Sergei; Tretiak, Sergei

2009-06-10

433

An update on toxicology of aluminum phosphide  

PubMed Central

Aluminum phosphide (AlP) is a cheap solid fumigant and a highly toxic pesticide which is commonly used for grain preservation. In Iran it is known as the “rice tablet”. AlP has currently aroused interest with increasing number of cases in the past four decades due to increased use in agricultural and non-agricultural purposesand also its easy availability in the markets has increased its misuse to commit suicide. Upon contact with moisture in the environment, AlP undergoes a chemical reaction yielding phosphine gas, which is the active pesticidal component. Phosphine inhibits cellular oxygen utilization and can induce lipid peroxidation. It was reported that AlP has a mortality rate more than 50% of intoxication cases. Poisoning with AlP has usually occurred in attempts to suicide. It is a more common case in adults rather than teen agers. In some eastern countries it is a very common agent with rapid action for suicide. Up to date, there is no effective antidote or treatment for its intoxication. Also, some experimental results suggest that magnesium sulfate, N-acetyl cysteine (NAC), glutathione, vitamin C and E, beta-carotenes, coconut oil and melatonin may play an important role in reducing the oxidative outcomes of phosphine. This article reviews the experimental and clinical features of AlP intoxication and tries to suggest a way to encounter its poisoning. PMID:23351193

2012-01-01

434

Synthesis, characterization, and photophysical properties of heteroleptic copper(I) complexes with functionalized 3-(2'-pyridyl)-1,2,4-triazole chelating ligands.  

PubMed

A new series of mononuclear copper(I) complexes (1-9) with functionalized 3-(2'-pyridyl)-1,2,4-triazole chelating ligands, as well as the halide and/or phosphine ancillary ligands, have been synthesized. Complexes 1-9 were fully characterized by elemental analysis, NMR spectroscopy, mass spectroscopy, electronic absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and X-ray crystallography (1-8). They adopt a distorted tetrahedral configuration, and are considerably air-stable in solid state and in solution. All these Cu(I) complexes display a comparatively weak low-energy absorption in CH2Cl2 solution, assigned to charge-transfer transitions with appreciable MLCT character, as supported by TD-DFT studies. Cu(I) halide complexes 1-4 each shows bright solid-state emission at room temperature, although they are nonemissive in fluid solutions, in which the emission markedly depends on the halide and the substituent on the 2-pyridyl ring. Complexes 5-9 bearing 2-pyridyl functionalized 1,2,4-triazole and phosphine exhibit good photoluminescence properties in solution and solid states at ambient temperature, which are well-modulated via the alteration of the auxiliary phosphine ligand and the structural modification of 3-(2'-pyridyl)-1,2,4-triazole. Interestingly, cationic complex 6 and neutral derivative 7 can readily be interconverted through the ring inversion of the 1,2,4-triazolyl regulated by the NH???N(-) transformation. PMID:23962338

Chen, Jing-Lin; Cao, Xing-Fu; Wang, Jin-Yun; He, Li-Hua; Liu, Zong-Yong; Wen, He-Rui; Chen, Zhong-Ning

2013-09-01

435

Tempering the Reactivities of Postulated ?-Oxo Gold Carbenes by Bidentate Ligands: Implication of Tricoordinated Gold Intermediates and the Development of an Expedient Bimolecular Assembly of 2,4-Disubstituted Oxazoles  

PubMed Central

2,4-Oxazole is an important structural motif in various natural products. An efficient modular synthesis of this structure is achieved via a [3+2] annulation between a terminal alkyne and a carboxamide by using a gold-catalyzed oxidation strategy. The postulated reactive intermediate, a terminal ?-oxo gold carbene, previously known to be highly electrophilic and hence impropable to be trapped by stoichiometric external nucleophiles, is coerced to react smoothly with a carboxamide en route to the oxazole ring by a P,N- or P,S-bidentate ligand such as Mor-DalPhos; in stark contrast, often used ligands including monodentate phosphines and NHCs are totally ineffective. The role of these bidentate phosphines in this reaction is attributed to the formation of a tricoordinated gold carbene intermediate, which is less electrophilic and hence more chemoselective when reacting with nucleophiles. The success in using bidentate phosphine ligands to temper the reactivities of in-situ generated gold carbenes would likely open many new opportunities to apply the oxidative gold catalysis to the development of novel methods, and the implication of tricoordinated gold intermediates in homogeneous gold catalysis should stimulate further advance in gold catalysis. PMID:23039251

Luo, Yingdong; Ji, Kegong; Li, Yuxue

2012-01-01

436

Photoinitiated polymerization of PEG-diacrylate with lithium phenyl-2,4,6-trimethylbenzoylphosphinate: polymerization rate and cytocompatibility  

PubMed Central

Due to mild reaction conditions and temporal and spatial control over material formation, photopolymerization has become a valuable technique for the encapsulation of living cells in three dimensional, hydrated, biomimetic materials. For such applications,2-hydroxy-1-[4-(2-hydroxyethoxy) phenyl]-2-methyl-1-propanone (I2959) is the most commonly used photoinitiator (by virtue of its moderate water solubility), yet this initiator has an absorption spectrum that is poorly matched with wavelengths of light generally regarded as benign to living cells, limiting the rate at which it may initiate polymerization in their presence. In contrast, acylphosphine oxide photoinitiators, generally exhibit absorption spectra at wavelengths suitable for cell encapsulation, yet commercially available initiators of this class have low water solubility. Here, a water soluble lithium acylphosphinate salt is evaluated for its ability to polymerize diacrylated poly(ethylene glycol) (PEGDA) monomers rapidly into hydrogels, while maintaining high viability during direct encapsulation of cells. Through rheometric measurements, the time to reach gelation of a PEGDA solution with the phosphinate initiator is one tenth the time for that using I2959 at similar concentrations, when exposed to 365 nm light. Further, polymerization with the phosphinate initiator at 405 nm visible light exposure is achieved with low initiator concentrations and light intensities, precluded in polymerizations initiated with I2959 by its absorbance profile. When examined 24 hours after encapsulation, survival rates of human neonatal fibroblasts encapsulated in hydrogels polymerized with the phosphinate initiator exceed 95%, demonstrating the cytocompatibility of this initiating system. PMID:19783300

Fairbanks, Benjamin D.; Schwartz, Michael P.; Bowman, Christopher N.; Anseth, Kristi S.

2009-01-01

437

Pd-catalyzed copolymerization of methyl acrylate with carbon monoxide: structures, properties and mechanistic aspects toward ligand design.  

PubMed

Full details are provided for the alternating copolymerization of acrylic esters with carbon monoxide (CO) catalyzed by palladium species bearing a phosphine-sulfonate bidentate ligand. The copolymer of methyl acrylate (MA) and CO had complete regioregularity with stereocenters that slowly epimerize in the presence of methanol. In the presence of ethylene, terpolymers of MA/ethylene/CO were also prepared. The glass transition temperatures of the co- and terpolymers were higher than that of the ethylene/CO copolymer. Both experimental and theoretical investigations were performed to clarify the superior nature of the palladium phosphine-sulfonate system compared to an unsuccessful conventional palladium diphosphine system: (i) The reversible insertion of CO was directly observed with the isolated alkylpalladium complexes, [{o-((o-MeOC(6)H(4))(2)P)C(6)H(4)SO(3)}PdCH(CO(2)Me)CH(2)COMe], whereas it was not observed with the corresponding complex bearing 1,2-bis(diphenylphosphino)ethane (DPPE). (ii) The transition state of the subsequent MA insertion, the rate-determining step of the catalytic cycle, was lower in energy in the phosphine-sulfonate system than in the DPPE system. This stabilization could be attributed to the less hindered sulfonate moiety as well as the stronger back-donation from palladium to the electron-deficient olefin, which is located trans to the sulfonate. PMID:21480592

Nakamura, Akifumi; Munakata, Kagehiro; Ito, Shingo; Kochi, Takuya; Chung, Lung Wa; Morokuma, Keiji; Nozaki, Kyoko

2011-05-01

438

Flavin-linked Erv-family sulfhydryl oxidases release superoxide anion during catalytic turnover.  

PubMed

Typically, simple flavoprotein oxidases couple the oxidation of their substrates with the formation of hydrogen peroxide without release of significant levels of the superoxide ion. However, two evolutionarily related single-domain sulfhydryl oxidases (Erv2p; a yeast endoplasmic reticulum resident protein and augmenter of liver regeneration, ALR, an enzyme predominantly found in the mitochondrial intermembrane) release up to ~30% of the oxygen they reduce as the superoxide ion. Both enzymes oxidize dithiol substrates via a redox-active disulfide adjacent to the flavin cofactor within the helix-rich Erv domain. Subsequent reduction of the flavin is followed by transfer of reducing equivalents to molecular oxygen. Superoxide release was initially detected using tris(3-hydroxypropyl)phosphine (THP) as an alternative reducing substrate to dithiothreitol (DTT). THP, and other phosphines, showed anomalously high turnover numbers with Erv2p and ALR in the oxygen electrode, but oxygen consumption was drastically suppressed upon the addition of superoxide dismutase. The superoxide ion initiates a radical chain reaction promoting the aerobic oxidation of phosphines with the formation of hydrogen peroxide. Use of a known flux of superoxide generated by the xanthine/xanthine oxidase system showed that one superoxide ion stimulates the reduction of 27 and 4.5 molecules of oxygen using THP and tris(2-carboxyethyl)phosphine (TCEP), respectively. This superoxide-dependent amplification of oxygen consumption by phosphines provides a new kinetic method for the detection of superoxide. Superoxide release was also observed by a standard chemiluminescence method using a luciferin analogue (MCLA) when 2 mM DTT was employed as a substrate of Erv2p and ALR. The percentage of superoxide released from Erv2p increased to ~65% when monomeric mutants of the normally homodimeric enzyme were used. In contrast, monomeric multidomain quiescin sulfhydryl oxidase enzymes that also contain an Erv FAD-binding fold release only 1-5% of their total reduced oxygen species as the superoxide ion. Aspects of the mechanism and possible physiological significance of superoxide release from these Erv-domain flavoproteins are discussed. PMID:22148553

Daithankar, Vidyadhar N; Wang, Wenzhong; Trujillo, Joliene R; Thorpe, Colin

2012-01-10

439

Synthesis, characterization and catalytic activity of saturated and unsaturated N-heterocyclic carbene iridium(i) complexes.  

PubMed

Both saturated and unsaturated N-benzyl substituted heterocyclic carbene (NHC) iridum(i) complexes were synthesized. The unsaturated carbene complex [(un-NHC-Bn)Ir(CO)(2)Cl] in the cis form was prepared via the carbene transfer from the corresponding silver complex to [Ir(COD)(2)Cl](2) followed by ligand substitution with CO, whereas the saturated complex was obtained via the transfer from (sat-NHC-Bn)W(CO)(5). The treatment of phosphines with (NHC)Ir(CO)(2)Cl complexes yielded the products with the phosphine ligand trans to the carbene moiety via substitution. X-Ray structural determination shows that distances of Ir-C((carbene)) in both (un-NHC-Bn)Ir(CO)(PR(3))Cl and (un-NHC-Bn)Ir(CO)(PR(3))Cl are essentially the same. Analyses of spectroscopic and crystal structural data of iridium complexes [(NHC)Ir(CO)(PR(3))Cl] and Vaska's complex show similar corresponding data in both types of complexes, suggesting that the studied NHC ligands and phosphines have similar bonding with Ir(i) metal center. All iridium complexes studied in this work illustrated their catalytically activity on N-alkylation of amine with alcohol via hydrogen transfer reduction. It appears no dramatic difference on the catalytic activity among these iridium carbene complexes; but the saturated carbene complex (sat-NHC-Bn)Ir(CO)(PR(3))Cl appears to be slightly more active. For example, the reaction of benzyl alcohol with aniline in the presence of catalyst (1 mol%) under basic conditions at 100 degrees C provided the secondary amine (N-benzylaniline) in 96% yield. PMID:19156280

Chang, Yung-Hung; Fu, Ching-Feng; Liu, Yi-Hong; Peng, Shei-Ming; Chen, Jwu-Ting; Liu, Shiuh-Tzung

2009-02-01

440

A computational study of the activation of allenoates by Lewis bases and the reactivity of intermediate adducts.  

PubMed

Several chemical properties of Lewis base-allenoate adducts (LB·allenoate), such as solvent effect, basicity, nucleophilicity and cycloaddition, are studied to provide a detailed foundation for the analysis of LB-catalyzed reactions of allenoates. The zwitterionic LB·allenoates formed between methyl allenoate and Lewis bases, such as N-heterocyclic carbenes (NHCs), phosphines, amines and aza-heterocycles, are studied at the M06-2X/6-31+G* level. The addition of the LBs to the allenoate can yield Z- or E-type adducts. The formation of the Z-type adducts is more favorable in the gas phase due to electrostatic interactions. The yield of the E-type adducts increases with the permittivity of the solvent. The lowest barriers for the addition and the most stable adducts are observed with NHCs as catalysts. It is also shown that the ?-carbon atom of the allenic moiety in LB·allenoate is more nucleophilic than the ?-carbon atom. Aza-arenes, phosphines and NHCs stabilize the [3 + 2]-ylides formed by the cycloaddition of LB·allenoate to ethylene; therefore, these LBs thermodynamically support the [3 + 2] cycloadditions. The detailed analysis of [3 + 2]-, [2 + 4]-, [2 + 2]- and [2 + 2 + 2]-cycloadditions with enones/ketones shows that the amine-catalyzed reactions follow the kinetically preferred path, and that the exergonic formation of the P-ylide favors the [3 + 2] cycloaddition in the phosphine-catalyzed reaction. The thermodynamically preferred pathway is followed with NHCs whereas the high stability of NHC·allenoate adducts reduces the overall catalytic efficiency of NHCs. PMID:25110957

Huang, Gou-Tao; Lankau, Timm; Yu, Chin-Hui

2014-10-01

441

Synthesis and activity of ruthenium olefin metathesis catalysts coordinated with thiazol-2-ylidene ligands.  

PubMed

A new family of ruthenium-based olefin metathesis catalysts bearing a series of thiazole-2-ylidene ligands has been prepared. These complexes are readily accessible in one step from commercially available (PCy3)2Cl2Ru=CHPh or (PCy3)Cl2Ru=CH(o-iPrO-Ph) and have been fully characterized. The X-ray crystal structures of four of these complexes are disclosed. In the solid state, the aryl substituents of the thiazole-2-ylidene ligands are located above the empty coordination site of the ruthenium center. Despite the decreased steric bulk of their ligands, all of the complexes reported herein efficiently promote benchmark olefin metathesis reactions such as the ring-closing of diethyldiallyl and diethylallylmethallyl malonate and the ring-opening metathesis polymerization of 1,5-cyclooctadiene and norbornene, as well as the cross metathesis of allyl benzene with cis-1,4-diacetoxy-2-butene and the macrocyclic ring-closing of a 14-membered lactone. The phosphine-free catalysts of this family are more stable than their phosphine-containing counterparts, exhibiting pseudo-first-order kinetics in the ring-closing of diethyldiallyl malonate. Upon removing the steric bulk from the ortho positions of the N-aryl group of the thiazole-2-ylidene ligands, the phosphine-free catalysts lose stability, but when the substituents become too bulky the resulting catalysts show prolonged induction periods. Among five thiazole-2-ylidene ligands examined, 3-(2,4,6-trimethylphenyl)- and 3-(2,6-diethylphenyl)-4,5-dimethylthiazol-2-ylidene afforded the most efficient and stable catalysts. In the cross metathesis reaction of allyl benzene with cis-1,4-diacetoxy-2-butene increasing the steric bulk at the ortho positions of the N-aryl substituents results in catalysts that are more Z-selective. PMID:18220390

Vougioukalakis, Georgios C; Grubbs, Robert H

2008-02-20

442

Bonding and activation of N2 in Mo(0) complexes supported by hybrid tripod ligands with mixed dialkylphosphine/diarylphosphine donor groups: interplay of steric and electronic factors.  

PubMed

Molybdenum dinitrogen complexes are presented which are supported by novel hybrid tripod ligands of the type Me-C(CH2PPh2)2(CH2P(i)Pr2) (trpd-1) and H-C(CH2PPh2)(CH2P(i)Pr2)2 (trpd-2) having mixed dialkylphosphine/diarylphosphine donor groups. Reaction of the ligand trpd-1 with [MoI3(thf)3] followed by sodium amalgam reduction in the presence of the dppm gives the dinitrogen complex [Mo(N2)(trpd-1)(dmpm)] where trpd-1 is coordinated in a ?(3) fashion. The complex exhibits a moderate activation of N2 which enables its protonation under retention of the pentaphosphine ligation. Replacement of dmpm by the sterically more demanding coligand dppm is found to hamper coordination of N2 and leads to [Mo(trpd-1)(dppm)], the first structurally characterized five-coordinate Mo(0) complex with a phosphine-only ligand sphere. Employing the ligand trpd-2 along with the diphosphines dmpm and dppm in an analogous synthetic route results in a mixture of the bis(dinitrogen) complexes trans-[Mo(N2)2(?(2)-trpd-2)(diphosphine)] and trans-[Mo(N2)2(iso-?(2)-trpd-2)(diphosphine)] where the tripod ligand trpd-2 coordinates with two phosphine arms and one phosphine group (PPh2 or P(i)Pr2, respectively) is free. Similar results are obtained with the pure alkyl- and arylphosphine tripod ligands H-C(CH2P(i)Pr2)3 (trpd-3) and H-C(CH2PPh2)3 (tdppmm), leading to trans-[Mo(N2)2(?(2)-trpd-3)(diphos)] and trans-[Mo(N2)2(?(2)-tdppmm)(dmpm)], respectively. The electronic and steric reasons for the experimental findings are considered, and the implications of the results for the area of synthetic nitrogen fixation with molybdenum phosphine systems are discussed. PMID:23697992

Söncksen, Ludger; Gradert, Christian; Krahmer, Jan; Näther, Christian; Tuczek, Felix

2013-06-01

443

A polymeric flame retardant additive for rubbers  

SciTech Connect

Synthesis of a polyphosphonate by the interfacial polymerization of bisphenol-A (BPA) and dichloro-phenyl phosphine oxide (DCPO) using cetyltrimethyl ammonium chloride (TMAC) as phase transfer catalyst (PTC) was reported. The polyphosphonate was characterized by elemental analysis, IR, TGA, DSC and 1H-NMR spectroscopy. The flame retardancy of the polymer was done by OI study. The polymer was used as a fire retardant additive to rubbers such as natural rubber (NR), styrene-butadiene rubber(SBR), nitrile rubber (NBR) and chloroprene rubber (CR). The efficiency of the fire retardant property of this additive was determined by LOI measurements of the various rubber samples.

Ghosh, S.N.; Maiti, S. [Indian Institute of Technology, Kharagpur (India)

1993-12-31

444

Ruthenium-catalyzed N-alkylation of amines and sulfonamides using borrowing hydrogen methodology.  

PubMed

The alkylation of amines by alcohols has been achieved using 0.5 mol % [Ru(p-cymene)Cl(2)](2) with the bidentate phosphines dppf or DPEphos as the catalyst. Primary amines have been converted into secondary amines, and secondary amines into tertiary amines, including the syntheses of Piribedil, Tripelennamine, and Chlorpheniramine. N-Heterocyclization reactions of primary amines are reported, as well as alkylation reactions of primary sulfonamides. Secondary alcohols require more forcing conditions than primary alcohols but are still effective alkylating agents in the presence of this catalyst. PMID:19191700

Hamid, M Haniti S A; Allen, C Liana; Lamb, Gareth W; Maxwell, Aoife C; Maytum, Hannah C; Watson, Andrew J A; Williams, Jonathan M J

2009-02-11

445

Synthesis and Properties of a Novel Family of Fluorous Triphenylphosphine Derivatives  

Microsoft Academic Search

A novel approach to the preparation of perfluorotail-functionalized triarylphosphines using a p-silyl substituent as the branching point has been developed. This approach enabled the attachment of between three and nine perfluorotails per phosphorus atom, resulting in the production of highly fluorous tris[p-(1H,1H,2H,2H-perfluoroalkylsilyl)aryl]phosphines, P[C6H4-p-SiMe3-n(CH2CH2CxF2x+1)n]3 (n = 1, 2, 3; x = 6, 8), containing between 50 and 67 wt % fluorine.

G. van Koten; B. Richter; E. de Wolf; Berth-Jan Deelman

2000-01-01

446

Substituent Effects In a Series of 1,7-C60(RF)2 Compounds (RF = CF3, C2F5, n-C3F7, i-C3F7, n-C4F9, s-C4F9, n-C8F17): Electron Affinities, Reduction Potentials, and E(LUMO) Values Are Not Always Correlated  

SciTech Connect

Substituent effects are of paramount importance in virtually all fields of fundamental and applied chemistry. Classical and modern examples can be found in organic chemistry (Hammett parameters and Charton steric parameters), inorganic chemistry (trans effect and trans influence), organometallic chemistry (phosphine cone angles), physical chemistry (linear free energy relationships and DFT), biochemistry (protein tertiary structure), medicinal chemistry (SAR maps and BioMAP analysis), polymer chemistry (nonlinear optical and permeation properties and glass transition temperatures), and materials chemistry (stability and luminescent properties of electroluminescent devices and light-to-power conversion efficiencies of fullerene-derivative-based OPV devices).

Kuvychko, Igor V.; Whitaker, James B.; Larson, Bryon W.; Folsom, Travis; Shustova, Natalia; Avdoshenko, Stanislav; Chen, Yu-Sheng; Wen, Hui; Wang, Xue B.; Dunsch, Lothar; Popov, Alexey A.; Boltalina, Olga V.; Strauss, Steven H.

2012-05-01

447

Preparation and properties of fluorenylidenephosphines bearing an electron-donating substituent, 2-alkoxy-4,6-di- t-butylphenyl or 2-(alkoxymethyl)-4,6-di- t-butylphenyl  

Microsoft Academic Search

Fluorenylidenephosphines having a 2,4-di-t-butyl-6-methoxyphenyl, 2,4-di-t-butyl-6-(methoxymethyl)phenyl or 2,4-di-t-butyl-6-(phenoxymethyl)phenyl group were prepared. 31P NMR chemical shifts of the fluorenylidenephosphines indicated that electron-donating effects through space are not so strong between the alkoxy group and the double-bonded phosphorus atom. The structure of a tungsten carbonyl complex of [2,4-di-t-butyl-6-(phenoxymethyl)phenyl](fluorenylidene)phosphine was analyzed by X-ray crystallography.

Kozo Toyota; Subaru Kawasaki; Masaaki Yoshifuji

2002-01-01

448

Organometallic chemistry of bimetallic compounds. Annual progress report  

SciTech Connect

Research is reported under 5 headings: reactions of heterobimetallic dihydrides (hydrogenation of alkynes by Re, Pt complex), metal-metal double bonds (Re=Re), C{sub 5}Me{sub 5}Co=CoC{sub 5}Me{sub 5} is actually (C{sub 5}Me{sub 5}){sub 3}Co{sub 3}({mu}{sub 2}-H){sub 3}({mu}{sub 3}-H), reactions of (C{sub 5}Me{sub 5}){sub 3}Co{sub 3}({mu}{sub 2}-H){sub 3}({mu}{sub 3}-H), and wide bite angle phosphines in hydroformylation.

Casey, C.P.

1993-07-01

449

Acetylene Hydrogenation on Au-Based Catalysts  

Microsoft Academic Search

Hydrogenation of acetylene has been investigated on Au\\/TiO2, Pd\\/TiO2 and Au-Pd\\/TiO2 catalysts at high acetylene conversion levels. The Au\\/TiO2 catalyst (avg. particle size: 4.6 nm) synthesized by the temperature-programmed reduction-oxidation of an Au-phosphine complex on TiO2 showed a remarkably high selectivity to ethylene formation even at 100% acetylene conversion. Au\\/TiO2 prepared by the conventional incipient wet impregnation method (avg. particle

T. V. Choudhary; C. Sivadinarayana; A. K. Datye; D. Kumar; D. W. Goodman

2003-01-01

450

Dramatic effect of N-substituents in viologens on single electron transfer from tributylphosphine.  

PubMed

A single electron transfer (SET) takes place from tributylphosphine (1a) to 1-alkyl-1'-methylviologens in acetonitrile containing a large amount of methanol under an argon atmosphere. In contrast, no SET takes place from 1a to viologens whose alkyl groups on the nitrogens are larger than the methyl group under the same conditions, 1a instead nucleophilically attacking the viologen to form a covalent adduct. This dramatic substituent effect is discussed in terms of SET occurring within a tight encounter complex formed between the phosphine and the viologen. PMID:16294246

Yasui, Shinro; Itoh, Kenji; Ohno, Atsuyoshi; Tokitoh, Norihiro

2005-12-01

451

Pd-catalyzed carbonylation for the construction of tertiary and quaternary carbon centers with sp(3) carbon partners.  

PubMed

The first examples of a Pd-catalyzed carbonylation of aryl boronic acids with sp(3) carbon partners are presented. Various boronic acids were shown to react with 1,3-diesters and 1,3-diketones to afford structurally unique carbonyl compounds. By employing 2-substituted 1,3-diesters, synthetically-challenging quaternary carbon centres were accessed. In total, 42 examples of aryl carbonyl compounds were prepared in moderate to good yields. The catalytic system features the use of a bidentated phosphine ligand and a relatively low CO pressure (5 atm), providing an easy, alternative method for the preparation of triketones. PMID:24922089

Lu, Wei; Li, Yang; Wang, Chao; Xue, Dong; Chen, Jian-Gang; Xiao, Jianliang

2014-07-28

452

Small bite-angle P-OP ligands for asymmetric hydroformylation and hydrogenation.  

PubMed

A series of small bite-angle phosphine-phosphite (P-OP) ligands have been synthesized by a two-step method. The key intermediate was prepared by an unprecedented asymmetric carbonyl reduction of a phosphamide using the CBS (Corey-Bakshi-Shibata) catalyst. The topology of these ligands (a configurationally stable stereogenic carbon with two heteroatom substituents) and their small bite-angle (created by the close proximity of the two ligating groups to the metal center) together provide a rigid asymmetric environment around this center, enabling high stereoselectivity in hydroformylations and hydrogenations of standard substrates. PMID:23815635

Fernández-Pérez, Héctor; Benet-Buchholz, J; Vidal-Ferran, Anton

2013-07-19

453

A tris(pyrazolyl)borate rhodium phosphite complex that undergoes an Arbusov-like rearrangement.  

PubMed

Tp'Rh[P(OMe)3](Me)H, loses methane in pentane solution containing CH2F2 to give the scorpionate complex bis(?-dimethyl phosphito)-?(2)P:O;?(2)O:P-bis{methyl[tris(3,5-dimethyl-1H-pyrazol-1-yl-?N(2))borato]rhodium(III)}, [Rh2(CH3)2(C2H6O3P)2(C15H22BN6)2], in which the phosphine O-Me bond is cleaved. The product is dimeric and resembles the Arbusov-type rearrangement product known to form from trimethyl phosphite. PMID:24005495

Jiao, Yunzhe; Brennessel, William W; Jones, William D

2013-09-01

454

Chiral rhodium complexes covalently anchored on carbon nanotubes for enantioselective hydrogenation.  

PubMed

Chiral rhodium hybrid nanocatalysts have been prepared by covalent anchorage of pyrrolidine-based diphosphine ligands onto functionalized CNTs. This work constitutes the first attempt at covalent anchoring of homogeneous chiral catalysts on CNTs. The catalysts, prepared with two different chiral phosphines, were characterized by ICP, XPS, N2 adsorption and TEM, and have been tested in the asymmetric hydrogenation of two different substrates: methyl 2-acetamidoacrylate and ?-acetamidocinnamic acid. The hybrid nanocatalysts have shown to be active and enantioselective in the hydrogenation of ?-acetamidocinnamic acid. A good recyclability of the catalysts with low leaching and without loss of activity and enantioselectivity was observed. PMID:24590206

Gheorghiu, C C; Machado, B F; Salinas-Martínez de Lecea, C; Gouygou, M; Román-Martínez, M C; Serp, P

2014-05-28

455

Potential role of tubulin tyrosine ligase-like enzymes in tumorigenesis and cancer cell resistance.  

PubMed

Polyglutamylation of tubulin and other non-tubulin substrates is a reversible posttranslational modification brought about by tubulin tyrosine-like ligases. Altered polyglutamylation is linked to tumorigenesis and resistance to chemotherapeutic drugs that target the microtubule, and therefore is a potential pharmacological target in cancer therapy. Despite the large amount of research focused on the development of anticancer agents, only a small number of well-characterized inhibitors of polyglutamylases have been identified, including the phosphinic acid-based inhibitors of Ttll7. In this minireview, we summarize the role of polyglutamylation in cancer, and draw attention to the largely unexplored area of polyglutamylase inhibition in the treatment of cancer. PMID:24814394

Das, Viswanath; Kanakkanthara, Arun; Chan, Ariane; Miller, John H

2014-08-01

456

Suggestions for Controlling Insects in Farm-Stored Grain.  

E-print Network

pellets or tablets containing aluminum phosphide (Phostoxin? ) can be used to fumigate farm-stored grain. Tablets or pellets properly placed in the grain mass are activated by moisture in the air to release highly toxic aluminum phosphide gas which... contains the active ingredient phosphine. The tablets may be hand fed or machine metered into the grain stream as it is being stored. The pellets may be used in a similar manner or probed down into the 15 1 .. grain after storage. Standard application...

Hamman, Philip J.

1982-01-01

457

Enantioselective organocatalytic aldol reaction of ynones and its synthetic applications.  

PubMed

[Structure: see text] For the first time, unmodified ynones were used in organocatalytic asymmetric aldol reactions delivering monoprotected anti-alpha,beta-dihydroxyynones in high yields, dr's up to 19:1, and ee's up to 95%. These products can be either reduced to afford enantioenriched unsaturated anti,anti-triol or cyclized using a novel intramolecular phosphine-catalyzed alpha-addition to the ynone. This organocatalytic sequential aldol-cyclization process provides a concise entry to unusual enantioenriched oxygenated heterocycles, which can be used for subsequent structural manipulations. PMID:17078732

Silva, Franck; Sawicki, Marcin; Gouverneur, Véronique

2006-11-01

458

Synthesis of aryl group-modified DIOP dioxides (Ar-DIOPOs) and their application as modular Lewis base catalysts.  

PubMed

Treatment of an optically pure tartaric acid-derived diiodide and various secondary phosphine oxides with LHMDS provides the corresponding aryl group-modified DIOP dioxides (Ar-DIOPOs). The activities of Ar-DIOPOs as Lewis base catalysts were investigated for several asymmetric transformations using chlorosilane reagents. The p-tolyl-substituted DIOPO (p-tolyl-DIOPO) was most effective for the reductive aldol reaction of chalcone and aldehydes with trichlorosilane, whereas the 2,8-dimethylphenoxaphosphine-derived DIOPO (DMPP-DIOPO) afforded the best enantioselectivity for the phosphonylation of conjugated aldehydes and the chlorinative aldol reaction of an ynone and benzaldehyde. PMID:22569566

Ohmaru, Yusuke; Sato, Norimasa; Mizutani, Makoto; Kotani, Shunsuke; Sugiura, Masaharu; Nakajima, Makoto

2012-06-21

459

Temperature and composition of Saturn's polar hot spots and hexagon.  

PubMed

Saturn's poles exhibit an unexpected symmetry in hot, cyclonic polar vortices, despite huge seasonal differences in solar flux. The cores of both vortices are depleted in phosphine gas, probably resulting from subsidence of air into the troposphere. The warm cores are present throughout the upper troposphere and stratosphere at both poles. The thermal structure associated with the marked hexagonal polar jet at 77 degrees N has been observed for the first time. Both the warm cyclonic belt at 79 degrees N and the cold anticyclonic zone at 75 degrees N exhibit the hexagonal structure. PMID:18174438

Fletcher, L N; Irwin, P G J; Orton, G S; Teanby, N A; Achterberg, R K; Bjoraker, G L; Read, P L; Simon-Miller, A A; Howett, C; de Kok, R; Bowles, N; Calcutt, S B; Hesman, B; Flasar, F M

2008-01-01

460

Dissolution of [RhCl(PPh 3) 3] in the ionic liquid, 1-ethyl-3-methyl imidazolium chloroaluminate(III), and its reaction with H 2. The stabilization of Rh(I) species in an ionic liquid  

Microsoft Academic Search

The solution of [RhCl(PPh3)3] in acidic 1-ethyl-3-methylimidazolium chloroaluminate(III) ionic liquid (AlCl3 molar fraction, xAlCl3=0.67) was investigated by 1H and 31P{1H} NMR. One triphenyl phosphine is lost from the complex and is protonated in the acidic media, and cis-[Rh(PPh3)2ClX], (2), where X is probably [AlCl4]?, is formed. On, standing, 2 is converted to trans-[Rh(H)(PPh3)2X], (3). The reaction of 2 and H2

Brian E. Mann; Maira H. Guzman

2002-01-01

461

Hydroformylation of naphthas with a rhodium complex in biphasic medium  

Microsoft Academic Search

The chlorocarbonyl bis-[butylphenyl (meta-sulfonate-phenyl)phosphine] rhodium (I) complex shows catalytic hydroformylation\\u000a activity in toluene\\/water biphasic medium for 1-hexene, cyclohexene, 2,3-dimethyl-2-butene and 2-methyl-2-pentene, their binary\\u000a mixtures and a real Venezuelan naphtha, under standardized reaction conditions (1000 psi of syngas (1:1 H2\\/CO), 100C, substrate\\/catalyst molar ratio (600:1) and 4 h reaction time), obtaining high percent conversion to oxygenated\\u000a products.

Marisela Reyes; Daniel Mercades; Bernardo Fontal; Trino Suárez; Fernando Bellandi; Ricardo R. Contreras; Isolda Romero; Yuraima Fonseca; Pedro Cancines

2007-01-01

462

Green route synthesis of high quality CdSe quantum dots for applications in light emitting devices  

NASA Astrophysics Data System (ADS)

Investigation was made on light emitting diodes fabricated using CdSe quantum dots. CdSe quantum dots were synthesized chemically using olive oil as the capping agent, instead of toxic phosphine. Room temperature photoluminescence investigation showed sharp 1st excitonic emission peak at 568 nm. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting devices were fabricated by solution process. The electroluminescence study showed low turn on voltage (˜2.2 V) .The EL peak intensity was found to increase by increasing the operating current.

Bera, Susnata; Singh, Shashi B.; Ray, S. K.

2012-05-01

463

Gel Electrophoresis of Gold-DNA Nano-Conjugates  

SciTech Connect

Single stranded DNA of different lengths and different amounts was attached to colloidal phosphine stabilized Au nanoparticles. The resulting conjugates were investigated in detail by a gel electrophoresis study based on 1200 gels. We demonstrate how these experiments help to understand the binding of DNA to Au particles. In particular we compare specific attachment of DNA via gold-thiol bonds with nonspecific adsorption of DNA. The maximum number of DNA molecules that can be bound per particle was determined. We also compare several methods to used gel electrophoresis for investigating the effective diameter of DNA-Au conjugates, such as using a calibration curve of particles with known diameters and Ferguson plots.

Pellegrino, T.; Sperling, R.A.; Alivisatos, A.P.; Parak, W.J.

2006-01-10

464

Palladium-catalyzed cross-coupling reactions of 2-iodo-4-(phenylchalcogenyl)-1-butenes.  

PubMed

[reaction: see text] 2-Iodo-4-(phenylchalcogenyl)-1-butenes 2 or 3, which are derived from the ring-opening reaction of methylenecyclopropanes (MCPs) 1 by iodine, can be applied to some palladium-catalyzed cross-coupling reactions such as the Sonogashira, Heck, Kumada, Suzuki, and Negishi reactions under mild conditions to give the corresponding coupling products in good yields. These reactions proceeded smoothly at room temperature (20 degrees C) in most cases without any phosphine ligand and additive. The phenylchalcogenyl group plays an important role in the reactions and a plausible reaction mechanism has been proposed. PMID:16323852

Shi, Min; Liu, Le-Ping; Tang, Jie

2005-12-01

465

A Double Asymmetric Hydrogenation Strategy for the Reduction of 1,1-Diaryl Olefins Applied to an Improved Synthesis of CuIPhEt, a C2-Symmetric N-Heterocyclic Carbenoid  

PubMed Central

A library of iridium and rhodium phosphine catalysts have been screened for the double asymmetric hydrogenation of 2,6-di-(1-phenylethenyl)-4-methyl aniline to produce the C2-symmetric aniline precursor of the N-heterocyclic carbenoid CuIPhEt. The best catalyst produced the desired enantiomer in 98.6% selectivity. This rare example of a highly selective hydrogenation of a 1,1-diaryl olefin enables a 4 step asymmetric synthesis of the C2-symmetric phenylethyl imidazolium ion (IPhEt) from p-toluidine and phenylacetylene, and its conversion to the hydrosilylation catalyst CuIPhEt. PMID:23383707

Spahn, Elizabeth; Albright, Abigail; Shevlin, Michael; Pauli, Larissa; Pfaltz, Andreas; Gawley, Robert E.

2013-01-01

466

Control contaminants in olefin feedstocks and products. Part 2  

SciTech Connect

Impurities in polymer feedstocks affect new, site-specific, third-generation catalysts. To increase productivity and to manufacture value-added resins, polymer operators are using newer polymerization processes and subsequently converting to site-specific catalysts. Consequently, olefin producers must offer feedstocks that are nearly contaminant-free. An overview of innovative removal systems shows how to cost-effectively clean up process streams. The paper describes impurity removal systems for acetylene, CO{sub 2}, CO, H{sub 2}, CH{sub 4}, ethane in ethylene, and ethylene in propylene. It also discusses specific poisons to catalysts: ammonia, arsine, phosphine, and carbonyl sulfide.

Reid, J.A.; McPhaul, D.R. [Stone and Webster Engineering Corp., Houston, TX (United States)

1996-09-01

467

Structures and catalytic properties of complexes of bis(diphenylphino)methane dioxide with scandium and lanthanide trifluoromethane sulfonates  

Microsoft Academic Search

Complexes of scandium and lanthanide triflates with bis(diphenylphosphino)methane dioxide (Ph2P(O)CH2P(O)Ph2?L) have been prepared and have the general formulae Sc(OTf)3L3, La(OTf)3L41.5H2O and Ln(OTf)3L3H2O3.5H2O. The structures show that the phosphine oxides act as bidentate chelates, and whilst triflate ions are not coordinated to the metals some hydrogen bond with the methylene protons in the ligand. The solution properties have been investigated using

John Fawcett; Andrew W. G Platt

2003-01-01

468

R-(-)-beta-phenyl-GABA is a full agonist at GABAB receptors in brain slices but a partial agonist in the ileum.  

PubMed

R-(-)-beta-phenyl-GABA has been compared at GABAB receptors using cortical and ileal preparations. R-(-)-beta-phenyl-GABA (EC50 = 25 microM) was a less potent full agonist than R,S-(+/-)-baclofen (EC50 = 2.5 microM), in depressing CA1 population spikes of rat hippocampal slices, and 5 times less potent in attenuating the spontaneous discharges of rat neocortex. However, R-(-)-beta-phenyl-GABA (100-400 microM) was only a weak partial agonist in the ileum. All these actions were sensitive to CGP 35348 (3-aminopropyl-(P-diethoxymethyl)-phosphinic acid) and therefore mediated by GABAB receptors. PMID:8386087

Ong, J; Kerr, D I; Doolette, D J; Duke, R K; Mewett, K N; Allen, R D; Johnston, G A

1993-03-16

469

EXTRACTION AND SEPARATION OF Ti(IV) USING THIOPHOSPHINIC ACIDS AND ITS RECOVERY FROM ILMENITE AND RED MUD  

Microsoft Academic Search

This paper embodies details on the extraction behavior of Ti(IV) along with Mg(II), Mn(II), Fe(III), Al(III), Ce(IV), and V(V) from hydrochloric acid medium employing mono- and di-sulphur analogues of bis-(2,4,4-trimethylpentyl) phosphinic acid, namely bis-(2,4,4-trimethylpentyl)monothiophosphinic acid (Cyanex 302) and bis-(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301). The effect of various parameters, such as the concentration of the acid, metal ion, and extractant, and the

Akash Deep; Poonma Malik; Bina Gupta

2001-01-01

470

Dual Emissive-Reflective Display Materials with Large Emission Switching Using Highly Luminescent Lanthanide(III) Complex and Electrochromic Material  

NASA Astrophysics Data System (ADS)

Electroswitching of emission and coloration was achieved by a combination of a luminescent Eu(III) complex and an electrochromic molecule of diheptyl viologen (HV2+), in order to utilize them as novel display devices with dual emissive-reflective modes. The coloration was associated with the HV2+ electrochromism. Emission control was also achieved by the HV2+ electrochromism via intermolecular energy transfer from the excited state of the Eu(III) ion to the HV+. In order to improve ON-OFF contrast in emission, the emission quantum yield of Eu(III) complex were considerably improved using low vibrational phosphine oxide ligands, resulting in the large control of emission switching.

Kanazawa, Kenji; Nakamura, Kazuki; Kobayashi, Norihisa

2013-05-01

471

Ligand effects on the electronic structure, spectra, and electrochemistry of tetracobalt carbonyl clusters  

Microsoft Academic Search

Self-consistent field X..cap alpha.. calculations using the discrete variational method (SCF-X..cap alpha..-DV) have been performed for Co⁴(CO)ââ (I) and the C\\/sub 3nu\\/ symmetry model clusters (eta-CâHâ)Coâ(CO)â((PHâ)âCH) (III), and (eta-CâHâ)Coâ(CO)â((PHâ)âCH) (IV) to explore the effect of phosphine and arene ligands on cluster electronic structures. Density of states plots have been used to simplify analysis of bonding trends in these complex clusters.

Gary F. Holland; Donald E. Ellis; William C. Trogler

1986-01-01

472

Redox chemistry of Pd 2+, Pt 2+, Rh 3+–TPPTS systems in water: pH influence on the preparation of low valent TPPTS complexes  

Microsoft Academic Search

The redox process of the water-soluble systems: TPPTS–Pd(OAc)2, PdSO4, PtCl2, Rh2(SO4)3, and RhCl3, have been investigated at room temperature by 31P-NMR spectroscopy, polarography and pH measurement. (TPPTS: 3,3?,3?-phosphinidynetris(benzenesulfonic acid) trisodium salt, or the usual name: tris(m-sulfophenyl)phosphine trisodium salt). For a particular given value of pH, controlled by NaOH addition, except for Rh2(SO4)3 which leads to a Rh(OH)3 precipitate, every system

E. G. Kuntz; O. M. Vittori

1998-01-01

473

Separation of actinides from lanthanides  

DOEpatents

An organic extracting solution and an extraction method useful for separating elements of the actinide series of the periodic table from elements of the lanthanide series, where both are in trivalent form is described. The extracting solution consists of a primary ligand and a secondary ligand, preferably in an organic solvent. The primary ligand is a substituted monothio-1,3-dicarbonyl, which includes a substituted 4-acyl-2-pyrazolin-5-thione, such as 4-benzoyl-2,4- dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (BMPPT). The secondary ligand is a substituted phosphine oxide, such as trioctylphosphine oxide (TOPO).

Smith, B.F.; Jarvinen, G.D.; Ryan, R.R.

1988-03-31

474

Domino-Hydroformylation/Aldol Condensation Catalysis: Highly Selective Synthesis of ?,?-Unsaturated Aldehydes from Olefins.  

PubMed

A general and highly chemo-, regio-, and stereoselective synthesis of ?,?-unsaturated aldehydes by a domino hydroformylation/aldol condensation reaction has been developed. A variety of olefins and aromatic aldehydes were efficiently converted into various substituted ?,?-unsaturated aldehydes in good to excellent yields in the presence of a rhodium phosphine/acid-base catalyst system. In view of the easy availability of the substrates, the high atom-efficiency, the excellent selectivity, and the mild conditions, this method is expected to complement current methodologies for the preparation of ?,?-unsaturated aldehydes. PMID:25179918

Fang, Xianjie; Jackstell, Ralf; Franke, Robert; Beller, Matthias

2014-10-01

475

Synthesis of New Elastomers with Controlled Structures Based on Alkylene Oxides, Grafted by ROMP  

NASA Astrophysics Data System (ADS)

Poly(propylene oxide-ran-allyl glycidyl ether) (PPO-AGE) copolymers have been prepared using as initiating system an alkyl aluminum compound, controlled amounts of water and different organic compounds that act as cocatalysts, e.g. ethers, diols, phosphines, salicylic acid derivatives, and organozinc compounds. Among the investigated catalysts the most productive systems showed to be the ternary systems derived from triisobutylaluminum (TIBA) and water having Zn(acac)2 as a third component. These copolymers have subsequently been grafted by ringopening metathesis polymerization (ROMP) with cyclooctene in the presence of Grubbs first-generation ruthenium (Ru) catalyst to produce new comblike copolymers.

Spurcaciu, Bogdan; Dragutan, Ileana; Nicolae, Cristian-Andi; Buzdugan, Emil; Dragutan, Valerian

476

The effects of metals and inhibitors on thermal oxidative degradation reactions of unbranched perfluoroalkylethers  

NASA Technical Reports Server (NTRS)

Thermal oxidative degradation studies were performed on unbranched perfluoroalkylethers at 288 C in oxygen. Metals and alloys studied included Ti, Al, and Ti (4 Al, 4 Mn). The mechanism of degradation was by chain scission. Ti and Al promoted less degradation than Ti (4 Al, 4 Mn). The two inhibitors investigated (a perfluorophenyl phosphine and a phosphatriazine) reduced degradation rates by several orders of magnitude. Both inhibitors were effective for the same duration (75 to 100 hours). The phosphatriazine appeared to provide more surface protection.

Jones, W. R., Jr.; Paciorek, K. J. L.; Harris, D. H. L.; Smythe, M. E.; Kratzer, R. H.

1983-01-01

477

Synthesis and In Vitro Evaluation of Aspartate Transcarbamoylase Inhibitors  

PubMed Central

The design, synthesis, and evaluation of a series of novel inhibitors of aspartate transcarbamoylase (ATCase) are reported. Several submicromolar phosphorus-containing inhibitors are described, but all-carboxylate compounds are inactive. Compounds were synthesized to probe the postulated cyclic transition-state of the enzyme-catalyzed reaction. In addition, the associated role of the protonation state at the phosphorus acid moiety was evaluated using phosphinic and carboxylic acids. Although none of the synthesized inhibitors is more potent than N-phosphonacetyl-L-aspartate (PALA), the compounds provide useful mechanistic information, as well as the basis for the design of future inhibitors and/or prodrugs. PMID:19828320

Coudray, Laetitia; Pennebaker, Anne F.; Montchamp, Jean-Luc

2009-01-01

478

Separation of actinides from lanthanides  

DOEpatents

An organic extracting solution and an extraction method useful for separating elements of the actinide series of the periodic table from elements of the lanthanide series, where both are in trivalent form. The extracting solution consists of a primary ligand and a secondary ligand, preferably in an organic solvent. The primary ligand is a substituted monothio-1,3-dicarbonyl, which includes a substituted 4-acyl-2-pyrazolin-5-thione, such as 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (BMPPT). The secondary ligand is a substituted phosphine oxide, such as trioctylphosphine oxide (TOPO).

Smith, Barbara F. (Los Alamos, NM); Jarvinen, Gordon D. (Los Alamos, NM); Ryan, Robert R. (Los Alamos, NM)

1989-01-01

479

Extractant composition  

DOEpatents

An organic extracting solution useful for separating elements of the actinide series of the periodic table from elements of the lanthanide series, where both are in trivalent form. The extracting solution consists of a primary ligand and a secondary ligand, preferably in an organic solvent. The primary ligand is a substituted monothio-1,3-dicarbonyl, which includes a substituted 4-acyl-2-pyrazolin-5-thione, such as 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (BMPPT). The secondary ligand is a substituted phosphine oxide, such as trioctylphosphine oxide (TOPO).

Smith, Barbara F. (Los Alamos, NM); Jarvinen, Gordon D. (Los Alamos, NM); Ryan, Robert R. (Los Alamos, NM)

1990-01-01

480

Diverse reactions of PhI(OTf)2 with common 2-electron ligands: complex formation, oxidation, and oxidative coupling.  

PubMed

The crystal structures of bis-pyridine stabilized iodine dications [PhI(pyr)(2)](2+) are reported as triflate salts, representing the first ligand supported iodine dications to be structurally characterized. The pyridine complexes are susceptible to ligand exchange in reaction with stronger N-based donors such as 4-dimethylaminopyridine. Attempts to extend this reactivity to N-heterocyclic carbene and phosphine ligands, as has been accomplished in the earlier p-block groups, resulted in redox chemistry, with oxidation of the ligands rather than coordination. PMID:23148595

Pell, Thomas P; Couchman, Shannon A; Ibrahim, Sara; Wilson, David J D; Smith, Brian J; Barnard, Peter J; Dutton, Jason L

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