Tributylphosphine Research Articles

A New Route to Zinc-Blende CdSe Nanocrystals: Mechanism and Synthesis

We report the possible mechanism of forming of CdSe nanocrystals in the high boiling point solvents with long alkane chains and a novel Non-TOP-Based route to zinc-blende CdSe nanocrystals. A new mechanism shows that there exits a redox reaction in the long alkane chain solvents: Se is reduced to H2Se gas; at the same time, the long alkane chains are oxidated to alkene chains; then, the Cd complex reacts with H2Se to form CdSe nanocrystals. Possible chemical reaction equations involved in the process of forming the CdSe nanocrystals have been discussed. The alkene chain and H2Se were detected respectively by a series of experiments to support the new mechanism. Under the guidance of this mechanism, we have developed a much cheaper and greener Non-TOP-Based route for the synthesis of a size series of high-quality zinc-blende (cubic) CdSe nanocrystals. Low-cost, green, and environmentally friendlier reagents are used, without use of expensive solvents such as trioctylphosphine (TOP) or tributylphosphine (TBP). The new route enables us to achieve high-quality CdSe nanocrystals with sharp ultraviolet and visible (UV-vis) absorption peaks, controllable size (2.0-5.0 nm), bright photoluminescence (PL), narrow PL full width of half-maximum (fwhm) (29-48 nm), and high PL quantum yield (up to 60%) without any size sorting.

Reactions of 4-ethoxy-l,l,l-trifluoro-3-buten-2-one with phosphorous nucleophiles: Diethyl phosphite, tributyl phosphine and tris(diethylamino) phosphine

The reaction of ( E)-4-ethoxy-l,l,l-trifluoro-3-buten-2-one EtOCH CHCOCF 3 1 with diethyl phosphite (EtO) 2P(O)H 2 afforded a 1:1 cis- and trans-mixture of diethyl(l-trifluomethyl-3-ethoxy)allyl-phosphate EtO–CH CH–CH(CF 3)OP(O)(OEt) 2 3 via the 1,2-λ 5-oxaphosphol-4-ene intermediate. While tributyl phosphine Bu 3P added to 1 giving the double addition product Bu 3P +CH 2–C −(COCF 3)–CH CH–COCF 3 5. Its resonance structure was fully identified by spectral methods and single crystal X-ray diffraction analysis. More strong phosphorous nucleophile tris(diethylamino) phosphine (Et 2N) 3P reacted with 1 to give the known compound ( E)-4-(diethylamino)-l,l,l-trifluoro-3-buten-2-one Et 2N–CH CH–COCF 3 10 in good yield.

Proteomic Profiling of Hepatic Endoplasmic Reticulum-associated Proteins in an Animal Model of Insulin Resistance and Metabolic Dyslipidemia

Hepatic insulin resistance and lipoprotein overproduction are common features of the metabolic syndrome and insulin-resistant states. A fructose-fed, insulin-resistant hamster model was recently developed to investigate mechanisms linking the development of hepatic insulin resistance and overproduction of atherogenic lipoproteins. Here we report a systematic analysis of protein expression profiles in the endoplasmic reticulum (ER) fractions isolated from livers of fructose-fed hamsters with the intention of identifying new candidate proteins involved in hepatic complications of insulin resistance and lipoprotein dysregulation. We have profiled hepatic ER-associated proteins from chow-fed (control) and fructose-fed (insulin-resistant) hamsters using two-dimensional gel electrophoresis and mass spectrometry. A total of 26 large scale two-dimensional gels of hepatic ER were used to identify 34 differentially expressed hepatic ER protein spots observed to be at least 2-fold differentially expressed with fructose feeding and the onset of insulin resistance. Differentially expressed proteins were identified by matrix-assisted laser desorption ionization-quadrupole time of flight (MALDI-Q-TOF), MALDI-TOF-postsource decay, and database mining using ProteinProspector MS-fit and MS-tag or the PROWL ProFound search engine using a focused rodent or mammalian search. Hepatic ER proteins ER60, ERp46, ERp29, glutamate dehydrogenase, and TAP1 were shown to be more than 2-fold down-regulated, whereas alpha-glucosidase, P-glycoprotein, fibrinogen, protein disulfide isomerase, GRP94, and apolipoprotein E were all found to be up-regulated in the hepatic ER of the fructose-fed hamster. Seven isoforms of ER60 in the hepatic ER were all shown to be down-regulated at least 2-fold in hepatocytes from fructosefed/insulin-resistant hamsters. Implications of the differential expression of positively identified protein factors in the development of hepatic insulin resistance and lipoprotein abnormalities are discussed.

Improvement of two-dimensional gel electrophoresis proteome maps of the haloarchaeonHaloferax volcanii

Proteins of haloarchaea are remarkably unstable in low-ionic-strength solvents and tend to aggregate under standard two-dimensional (2-D) gel electrophoresis conditions, causing strong horizontal streaking. We have developed a new approach to generate 2-D maps of halophilic proteins which included washing cells with 1.5 M Tris-HCl buffer. In addition, proteins were precipitated with acetone, solubilized with urea and thiourea in the presence of the sulfobetaine detergent 3-[(3-cholamidopropyl)dimethylamino]-1-propanesulfonate (CHAPS), reduced with tributylphosphine (TBP), and separated with microrange strips of immobilized pH gradients (pH 3.9-5.1). This combination enabled the construction of highly reproducible 2-D maps of Haloferax volcanii proteins.

Influence of reducing agents on the integrity of selenocompounds. Exploratory work for selenoproteome analysis

Three selenium species (selenomethionine, selenocystine and selenocystamine) were studied for their behaviour in the presence of the reducing agents dithiothreitol and tributylphosphine, and of a derivatising agent, iodoacetic acid. These chemicals are commonly used in proteome analysis by means of gel electrophoresis. To study the effect of these chemicals on the selenospecies, two separation techniques were used, capillary electrophoresis and liquid chromatography, both with ICP-MS as an element-specific detector. Electrospray-mass spectrometry provided molecular information. Tributylphosphine (TBT) was shown to partly reduce selenocystine to selenocysteine, and iodoacetic acid to derivatise all the species, with conservation of the species information. Dithiothreitol (DTT), on the contrary, partly sequestered selenium from the species to form a DTT–Se molecule.

Synergistic extraction of uranium( VI) in presence of 2,2' -dipyridyl and neutral donors by absorption spectrophotometric method

The extraction behaviour of uranyl ion from dilute nitric acid medium employing 2,2'-dipyridyl and their mixture with several neutral donor, viz. trioctyl phosphine oxide (TOPO), tributyl phosphine oxide (TBPO), triphenylphosphine oxide (TPPO), tributyl phosphate (TBP), trioctyl amine (TOA) and Amberlite LA-2 was investigated. The extraction constant (log k e x ) for the binary species [UO 2 (dipy)(NO 3 ) 2 (H 2 O) 2 ] was determined to be 14.06. The overall extraction constant (log K) for the ternary species for various donors are : 15.55 (TOPO), 15.49 (TBPO), 15.44 (TPPO), 15.35 (TBP), 17.14 (TOA) and 17.11 (Amberlite LA-2).

Harvesting of Organic Triplet Emissions in Metal Diynes and Polyynes of Group 10−12 Transition Elements Containing the Conjugation-Interrupting Diphenylfluorene Unit

Soluble and thermally stable group 10 platinum(II) and group 12 mercury(II) polyyne polymers containing the diphenylfluorene moiety trans-[−Pt(PBu3)2C⋮CRC⋮C−]n and [−HgC⋮CRC⋮C−]n (R = 9,9-diphenylf...

Praseodymium nitrate and neodymium nitrate complexation with organophosphorus reagents in supercritical carbon dioxide solvent

Complex formation reactions of praseodymium nitrate hexahydrate, and neodymium nitrate hexahydrate salts with tri- n-butyl phosphate (TBP) and several other neutral organophosphorus reagents were investigated in supercritical carbon dioxide. The concentration of the metal complexes in the supercritical fluid (SCF) phase was determined using UV-Vis and luminescence spectroscopies. The stoichiometry of the complexes was determined using the mole-ratio method. Extraction equilibrium constants were calculated from the spectral data using least-squares regression and hard-equilibria models. UV-Vis absorbance data indicate that praseodymium nitrate and neodymium nitrate both form 1:4 lanthanide–tributyl phosphate complexes in supercritical carbon dioxide at 308 K. The conditional extraction coefficients for those two systems were calculated to be log K ex=7.45±0.06 for the praseodymium system and log K ex=7.52±0.03 for the neodymium system. For comparison, neodymium nitrate complexation reactions with tri- n-butyl phosphate and tributyl phosphite (TBPO 3) were studied in hexane under ambient conditions. UV-Vis data indicate that a 1:4 neodymium–tributyl phosphate complex is formed in hexane with a conditional extraction coefficient of log K ex=3.4±0.2. Tributyl phosphite forms a 1:8 complex with neodymium in hexane with a conditional extraction coefficient of log K ex=11.0±0.1. Neodymium nitrate was titrated with other organophosphorus reagents, tributyl phosphite and tributyl phosphine oxide (TBPO), in supercritical carbon dioxide to investigate differences between neutral oxygen donor ligands and neutral phosphorus donor ligands. UV-Vis and luminescence data indicate that neodymium nitrate forms a 1:8 complex with tributyl phosphite and a 1:5 complex with tributyl phosphine oxide, compared to a 1:4 complex with tri- n-butyl phosphate. The conditional extraction coefficient for the 1:8 neodymium–tributyl phosphite system was calculated as log K ex=21.4±0.2 from UV-Vis data, and log K ex=19.8±0.2 from luminescence data. The conditional extraction coefficient for the 1:5 neodymium–tributyl phosphine oxide complex was calculated as log K ex=7.83±0.05.

Determination of 3-amino-5-mercapto-1,2,4-triazole in serum

A high performance liquid chromatography (HPLC) method using fluorescence detection to determine 3-amino-5-mercapto-1,2,4-triazole (AMT) levels in serum has been developed. Sample preparation involved treatment with tributylphosphine (TBP) to reduce disulfides formed during storage, precipitation of proteins with acetonitrile (ACN), and precolumn derivatization using the thiol reactive fluorescent probe monobromobimane (MBB). The conjugate (AMT-MBB) was resolved by gradient elution from a C 18 reversed-phase column. The assay method was linear over a concentration range of 0.78–50 μg/ml and had a limit of detection (LOD) of 0.05 μg/ml AMT (10 μl injection). This method provides a sensitive and specific tool for the determination of AMT in serum and may have potential industrial hygiene application.

Synergistic effect of neutral donors on the extraction of zirconium(IV) by salicylaldoxime in dichloromethane

Liquid–liquid extraction of zirconium(IV) was investigated from dilute hydrochloric acid medium by salicyaldoxime (HA) in dichloromethane. The metal was spiked with 95 Zr and analyzed by its radioactivity. The effects of different donors, like trioctyl phosphine oxide (TOPO), triphenyl phosphine oxide (TPPO), tributyl phosphine oxide (TBPO), tributyl phosphate (TBP), trioctyl amine (TOA) and Amberlite LA-2 were studied. The adduct formation constants for both binary species (metal–ligand) and ternary species (metal–ligand–donor) were also calculated form the distribution data.

N-methyl-D-glucamine improves the laser-induced fluorescence capillary electrophoresis performance in the total plasma thiols measurement.

We describe an ultrarapid capillary electrophoresis with laser-induced fluorescence (CE-LIF) method for total plasma thiols measurement. Reduced thiols by 10% tri-n-butylphosphine (TBP) were derivatized in 10 min at room temperature with 5-iodoacetamidofluorescein (5-IAF) as fluorescent reagent. We show that CE-LIF allows a baseline separation of total plasma cysteinylglycine, homocysteine, cysteine, and glutathione in less than 5 min when N-methyl-D-glucamine in run buffer was added. CE was compared with high-performance liquid chromatography (HPLC) with fluorescence detection. The Bland-Altman test and Passing-Bablok regression demonstrates that the results obtained by CE-LIF and by HPLC are highly comparable. The simplified procedure of sample preparation, the short incubation and fast separation times, the high specificity, sensitivity and reproducibility, and the lower cost of analysis suggest that our proposed method can be considered valuable for the automation analysis in a routine laboratory.

Determination of dissolved thiols using solid-phase extraction and liquid chromatographic determination of fluorescently derivatized thiolic compounds

A method employing solid-phase extraction coupled with HPLC separation of thiol-monobromobimane (mBBr) derivatives was developed and optimized to quantify dissolved thiols at concentrations as low as 0.1 n M for glutathione (GSH) and γ-glutamylcysteine (γEC) in natural waters. The reducing reagent, tri- n-butylphosphine (TBP), is needed for complete derivatization. At the optimal addition of TBP ([TBP]/[mBBr]=0.4–1.6), no interference from copper was observed. The thiol fluorescence signal was totally suppressed if the mole ratio of TBP to mBBr was 2.6 or greater. Consistent recovery of thiols standards in a NaCl solution (0.5 M) was obtained using the Waters HLB reversed-phase resin, and blank levels of GSH and γEC were extremely low (less than 0.03 n M). The detection limits for GSH, γEC and phytochelatin-2 (PC-2) were 0.03, 0.03, and 0.06 n M, respectively.

Biologically active polymers. V. Synthesis and antimicrobial activity of modified poly(glycidyl methacrylate‐co‐2‐hydroxyethyl methacrylate) derivatives with quaternary ammonium and phosphonium salts

AbstractAntimicrobial copolymers bearing quaternary ammonium and phosphonium salts based on a copolymer of glycidyl methacrylate and 2‐hydroxyethyl methacrylate were synthesized. Poly(glycidyl methacrylate‐co‐2‐hydroxyethyl methacrylate) was modified for the introduction of chloromethyl groups by its reaction with chloroacetyl chloride. The chloroacetylated copolymer was modified for the production of quaternary ammonium or phosphonium salts. The antimicrobial activity of the obtained copolymers was studied against gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella sp., and Salmonella typhae), gram‐positive bacteria (Bacillus subtilus and B. cereus), and the fungus Trichophyton rubrum by the cut‐plug method. The results showed that the three copolymers had high antimicrobial activity. A control experiment was carried out on the main polymer without ammonium or phosphonium groups. The copolymer bearing quaternary salt made from tributyl phosphine was the most effective copolymer against both gram‐negative and gram‐positive bacteria and the fungus T. rubrum. The diameters of the inhibition zones ranged between 20 and 60 mm after 24 h. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2384–2393, 2002

A Tin-119 NMR investigation of phosphine and phosphine oxide adducts of organotin chlorides

The stoichiometry and structure of phosphine and phosphine oxide adducts of Ph 3SnCl, R 2SnCl 2 (R=Et, Pr, Bu, t-Bu, and Ph), and RSnCl 3 (R=Bu and Ph) were studied with Sn-119 spectroscopy. The shift of the Sn-119 resonance to a lower frequency upon adduct formation, the multiplicity of the resonance, the variation of P-31-Sn-119 coupling with the nature of the substituent, and the change in structure of the peaks with concentration and temperature were all used to determine stoichiometry and structure. The organotin chloride adducts readily exchange with base or with other adducts. The diorganotin dichlorides form only 1:1 adducts with tributylphosphine (TBP), even at high base to acid ratios, but most form 1:2 adducts (as several geometric isomers) with phosphine oxides at mole ratios above 1:1. The lower dialkyltin dichlorides prefer to form 1:1 adducts (at 1:1 mole ratios) with TBP rather than tributylphosphine oxide (TBPO), whereas diphenyltin dichloride and di( t-butyl)tin dichloride prefer TBPO adduct formation. The reactions of the trihalides with TBP and TBPO are complicated by aryl transfer or displacement of chloride by base and consequent ion formation.

Cross-coupling reactions of carbamoyl chlorides and Grignard reagents: a new rapid synthesis of tertiary amides

Tributyl phosphine or nickel catalysts allow the cross-coupling reaction between N, N-dialkylcarbamoyl chlorides and alkyl or aryl Grignard reagents. This convenient and simple method affords tertiary amides with moderate to excellent yields in short reaction times.

Separation of divalent transition metal β-diketonates and their adducts by supercritical fluid chromatography

A method for separation and detection of divalent transition metal β-diketonates by adduct formation/supercritical fluid chromatography (SFC) with an open-tubular capillary column and a FID detector is described. The crystal structures of copper (Cu)-hexafluoro-acetylacetone (HFA) and Cu bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (THD) complexes have been determined by X-ray crystallography. The SFC behavior of Cu β-diketonates shows a strong correlation with the structure of the complexes. The hydrated cu β-diketonate complexes usually exhibit strong intermolecular interactions or decomposition in SFC. Formation of adducts with a neutral donor, such as tributyl phosphine oxide (TBPO), can greatly improve the SFC behavior and detection sensitivity of Cu(II) and Mn(II) β-diketonates. The stoichiometry and thermal stability of the adducts Cu(II) and Mn(II) β-diketonates with TBPO in supercritical CO 2 have also been investigated. The implications of utilizing adduct formation for supercritical fluid extraction (SFE) of divalent transition metals and for on-line coupled SFE/SFC analysis of divalent transition metals are discussed.

Analysis of biogenic thiols in natural water samples by high-performance liquid chromatographic separation and fluorescence detection with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD-F)

A sensitive and reliable reversed-phase high-performance liquid chromatography (HPLC) method has been developed to analyze naturally occurring low-molecular weight thiols using pre-column derivatization with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD-F) and fluorescence detection in a gradient elution. The derivatization procedure and separation conditions were optimized by careful control of the reaction conditions in terms of time, temperature, pH and reducing agent. A linear calibration in the nM range was obtained for all the standard compounds, allowing measurement of thiols in natural water samples. Results show that the reducing agent tri- n-butylphosphine (TBP) not only acts as an anti-oxidant/disulfide cleaving agent, but also enables the SBD-F to react with thiols complexed by soft metals. This is the first study reported using the SBD-F labeling technique to measure phytochelatin concentrations. The methodology has been successfully applied to estuarine water samples from Galveston Bay.

CdTe/CdS Clusters with “Core−Shell” Structure in Colloids and Films: The Path of Formation and Thermal Breakup

A new organometallic “cold−slow” route to strongly fluorescing CdTe/CdS (core−shell) colloids and transparent films is presented. Based on the optical absorption, fluorescence, FTIR, micro-Raman, XPS, and XRD data collected on these nanostructures before and after thermal annealing, a mechanistic path of the core−shell formation and thermal break up is proposed and discussed. The processing of the CdTe/CdS nanostructures starts with 0.5 M tributylphosphine (TBP) stabilized CdS colloid in dichloromethane as a solvent. This yellow colloidal oil composed of 3−4 nm CdS clusters is reacted with liquid Bis(trimethylsilyl)-telluride (TMS2Te) in the presence of excess insoluble CdCl2 salt. During this reaction, a rapid chalcogen atom exchange occurs within a few seconds which produces a new CdTe “core”. The expelled sulfide reacts slowly with the CdCl2 salt to form new CdS clusters after several hours. Furthermore, this “CdS-formation-driven CdCl2 salt dissolution” activates a strong green-yellow fluorescence indicating a possible evolution of a “core−shell”-like CdTe/CdS structure. Thermal sintering of the subsequently prepared CdTe/CdS films between 100 and 200 °C completely suppresses the fluorescence and initiates CdTe cluster growth, reflecting a high thermal sensitivity of the “core−shell” interfaces. By further raising the sintering temperature to 300−400 °C, the TBP ligands are released and, consequently, bare CdS- and CdTe nanocrystals, as well as ternary nanocrystalline CdTexS1-x phases, start forming. Above 400 °C, the CdTe part of the nanostructures sublimates, yielding (111)-oriented CdTe films.

New Olefination of Acetals with TMSCH2Cu(PBu3) · LiI under the Influence of BF3· OEt2

New Olefination of Acetals with TMSCH₂Cu(PBu₃) · LiI under the Influence of BF₃· OEt₂

A facile one-pot cyanation of primary and secondary alcohols. Application of some new Mitsunobu reagents

Some new Mitsunobu reagents, especially N,N,N′,N′-tetramethylazodicarboxamide (TMAD)-tributylphosphine (TBP) and cyanomethylenetrimethylphosphorane (CMMP), mediated the direct transformation of primary and secondary alcohols into the corresponding nitriles in the presence of acetone cyanohydrin. This type of cyanation process can convert 3β-cholestanol to 3α-cyanocholestane in high yield with complete Walden inversion.