Dually switchable heterotetracenes: addressing the photophysical properties and self-organization of the P-S system

New ladder-type, phosphorus- and sulfur-based heterotetracenes were synthesized, which allowed the engineering of the materials' properties by exploitation of the different reactivities between sulfur and phosphorus. (31)P NMR spectroscopy and X-ray crystallographic studies revealed that the different electronic effects of the secondary heteroatom, sulfur, influence not only the conjugation in the heterotetracene core but also the behavior of the phosphorus center. UV-vis and fluorescence spectroscopy showed that the scaffold's band gap is mainly controlled by the electronic nature of sulfur, while the fluorescence quantum yield highly depends on the electronic nature of phosphorus. Cyclic voltammetry indicated that the redox properties of the system could be altered by selective modification of the respective heteroatom (oxidation of sulfur and/or functionalization of trivalent phosphorus). Importantly, oxidation of the phosphorus center results in enhanced reduction features of the heterotetracene system, and oxidation of the sulfur center further enhances the electron acceptor character of the core. Theoretical calculations provided insights on both selectivity of phosphorus chemistry and communication between the two heteroatoms (sulfur and phosphorus). Macroscopic self-organization of the heterotetracenes was observed when the tetracene core is functionalized with pendant functional groups. Preliminary results showed that extension of the molecule with an alkyl chain along the long axis of molecules induces the formation of 1D microfibers, which was confirmed by fluorescence microscopy and scanning electron microscopy.     

Simultaneous spectrophotometric microdetermination of sulfur and phosphorus in organic compounds

A method is described for the simultaneous spectrophotometric microdetermination of sulfur and phosphorus in organic compounds. The interference of phosphorus in the determination of sulfur is avoided using a suitably modified barium chloranilate method. The samples analyzed include some pesticides and mixtures of organosulfur and organophosphorus compounds. The error does not exceed ±0.5% unlike the one reported in the earlier method.     

Improvements in flame photometric detector design and operation. Determination of organophosphorus pesticide residues at low picogram levels

The molecular emission of heteroelements such as phosphorus and sulfur is the basis of the selective response of the flame photometric detector. The behavior of the FPD towards phosphorus compounds has been studied and design improvements sought with regard to burner configuration and temperature distribution. The possibility of differentiating between compounds containing phosphorus atoms and those containing both phosphorus and sulfur atoms has also been examined. Detection limits and response characteristics have been reported for organophosphorus pesticide residues in samples of natural origin     

Application of a wavelength-dispersive particle-induced X-ray emission system to chemical speciation of phosphorus and sulfur in lake sediment samples

The chemical speciation of phosphorus and sulfur in lake sediment was performed by analyzing Kα X-ray spectra recorded with a high-resolution wavelength-dispersive particle-induced X-ray emission (WD-PIXE) system. The concentrations of phosphorus and sulfur in the sediment were 2500 and 7000 ppm, respectively. To measure both minor elements in a reasonable measurement time, a 2-MeV proton beam with a high current density (6 nA/mm²) was used for the chemical speciation. The possible chemical state change caused by the proton irradiation was studied in order to determine the maximal irradiation time without significant change. We found that the chemical states of phosphorus and sulfur were stable under a beam current density of 6 nA/mm² and a measurement time of 60 min (phosphorus) and 90 min (sulfur). The chemical states of phosphorus and sulfur were determined to be P⁵⁺ and a mixture of S²⁻ and S⁶⁺, respectively.     

Selective chemiluminescence detection of sulfur-containing compounds coupled with nitrogen—phosphorus detection for gas chromatography

A new sulfur and nitrogen—phosphorus detector for gas chromatography is described. The detector is an integrated thermionic ionization— chemiluminescence device permitting simultaneous detection of sulfur-containing and nitrogen- or phosphorus-containing compounds. This new flameless detector utilizes a heated rubidium-doped ceramic bead in a thermionic ionization chamber to produce sulfur monoxide from sulfur compounds. The SO is mixed with O₃ and the resulting chemiluminescence is monitored with a photomultiplier tube, providing sulfur-selective detection. The thermionic ionization detector signal serves as an independent second response channel, affording simultaneous selective and sensitive nitrogen—phosphorus detection. Two chromatograms are obtained, one in which selectivity is exhibited for nitrogen and phosphorus compounds, and the other for sulfur compounds present in the sample.     

Determination of silicon,phosphorus and sulfur in alloy steel by neutron activation analysis

Silicon, phosphorus, and sulfur in alloy steel were determined by neutron activation analysis involving rapid radiochemical separation procedures. The standard deviations for silicon, phosphorus, and sulfur were 1.6%, 2.3%, and 2.4% respectively; the sensitivity limits were 3.2, 0.20, and 2.50 p.p.m., respectively. The three constituents could be determined in alloy steel within 2 h of the irradiation.     

Synthesis and application of chiral cyclopropane-based ligands in palladium-catalyzed allylic alkylation

A series of chiral, cyclopropane-based phosphorus/sulfur ligands have been synthesized and evaluated in the palladium-catalyzed allylic alkylation of 1,3-diphenylpropenyl acetate with dimethyl malonate. Variation of the ligand substituents at phosphorus, sulfur, and the carbon backbone revealed 24d to have the optimal configuration for this reaction, giving the product in high yield and with good enantioselectivity (93%). A model for the observed enantioselectivity is discussed within the context of existing models, using X-ray crystallographic data, solution-phase NMR studies, and the absolute stereochemistry of the products. Selected ligands were also evaluated in the palladium-catalyzed intermolecular Heck reaction and the rhodium-catalyzed hydrogenation of a dehydroamino acid.     

Organophosphorus compounds: I. Simple,rapid, and reliable method for the simultaneous microdeterminaton of carbon,hydrogen, and phosphorus by the rapid straight empty tube method

A method for the simultaneous microdetermination of C, H, and P is presented. The organophosphorus compound is pyrolyzed in a 80-mm long silica sample capsule using the rapid straight empty tube method. Carbon and hydrogen are determined by conventional gravimetry. Oxides of phosphorus are quantitatively retained on the walls of the capsule. The P₅O₂, uptake is determined gravimetrically for the phosphorus determination.Organophosphorus compounds containing sulfur can also be analyzed following the same procedure. Electrolytic silver, heated at 550 °C, absorbs the oxides of sulfur. The results obtained fall within the acceptable limits of error.     

Nonmetals in the argon-inductively coupled plasma-optical emission spectrometry: I. Phosphorus, sulfur and carbon

The behavior of phosphorus, sulfur and carbon in the argon-ICP-OES was systematically investigated for a wide range of nebulizer gas flows and observation heights. Five lines of phosphorus, four lines of sulfur and three lines of carbon, which have analytical usable detection limits, were taken into consideration. The further parameter set was inspired by the needs of every-day-analysis in the laboratory, especially the low integration time that is necessary for analysis of large amounts of samples. For each element line a signal-to-noise plot was obtained with a method described earlier. The optimum conditions for the combined analysis were determined from signal-to-noise plots of those element lines with the lowest detection limits. The lowest detection limits for phosphorus (0.13 mg/L) and carbon (0.01 mg/L) are useful for solving many analytical problems. However, even the best detection limit for sulfur (2.97 mg/L) is only of limited use without further preconcentration. A major problem was the background of carbon, most probably from carbon dioxide, which increased the available detection limit to about 0.04 mg/L. Surprisingly, the best detection limits were obtained at very low observation heights, which were only a couple of millimeters above the load coil. Fortunately, all elements showed a similar behavior and so the detection limits at compromise conditions were only slightly higher compared with the single-element detection limits.     

Novel Approach to the Synthesis of Phosphorus Sulfur Organic Compounds and Their Metal Complexes

Abstract

The reaction of elemental phosphorus (P_{ti 4}) and sulfur with protonodonor reagents (alcohols, phenols, and thiols) has been studied in the presence of amines and complexes based on trialkyltrithiophosphites and transition metal halides. A novel approach to the synthesis of phosphorus sulfur organic compounds has been proposed on the basis of these reactions.     

中国煤中磷的分布特征

以“中国煤种资源数据库”为基础,结合新采集煤样,对中国不同煤田1117个煤层煤样的磷含量数据进行了统计分析.结果表明,中国煤中磷可采储量加权平均质量分数为224x10-6,大约90％的煤中磷质量分数低于500x10-6,为特低磷煤或低磷煤,全国总体上呈“北低南高”的趋势.按不同聚煤区、不同成煤时代和不同煤炭类别讨论了中...     

Monosaccharides with Phosphorus in the Sugar Ring

Abstract

In recent years attention has been directed toward the synthesis of modified sugars wherein the oxygen atom in the sugar ring is replaced by sulfur, selenium or phosphorus. Synthesis of sugar analogs with phosphorus as the ring heteroatom is interesting from the point of view of their possible biological activity.     

微波消解-电感耦合等离子体发射光谱法测定植物样品中的磷、硫

本方法采用微波消解处理样品,电感耦合等离子体发射光谱法测定植物样品中的磷、硫的含量,选用优化微波消解条件进行消解,磷和硫方法最低检出限分别为0.925mg/kg、1.82 mg/kg。精密度RSD和相对误差RE均小于3%,对新鲜植物样品进行加标回收试验,加标回收率为90.5%~107%,证明本方法既可用于检测干植物样品,又可检测新鲜植物样品。     

The effects of sulfur substitution for the nucleophile and bridging oxygen atoms in reactions of hydroxyalkyl phosphate esters

The effects of sulfur substitution on the reactions of hydroxyalkyl phosphate esters are examined. These compounds are models for the intramolecular phosphoryl transfer reaction involved in the cleavage of the internucleotide bond in RNA. The models studied here lack the ribose ring and their conformational flexibility results in greater stability and the availability of different reaction pathways. Sulfur in the nucleophilic position shows no nucleophilic reaction at phosphorus, instead rapidly attacking at the beta carbon atom, forming thiirane with departure of a phosphomonoester. Sulfur substitution at either of the two bridging positions leads to cleavage of the diester via formation of a cyclic intermediate, but with significant rate acceleration when compared to the oxygen analogues. The bridge-substituted models react substantially slower than the analogous ribose compounds with sulfur substitution at comparable positions. Kinetic isotope effects reveal significant differences in the transition state depending on which bridging position sulfur occupies. When sulfur is in the scissile bridging position, a highly associative transition state is indicated, with a largely formed bond to the nucleophile and the scissile P-S bond is little changed. When sulfur occupies the other bridging position, the isotope effects imply a very early transition state in a concerted reaction.     

Novel Effectively Carbonaceous and Sulfurated Hydrogen Corrosion Inhibitors on the Basis of Organosulfurphosphorus Compounds

Abstract

Novel ammonium salts of O,O-dialkyl dithiophosphoric acids were obtained by one-pot synthesis from white phosphorus, elemental sulfur, industrial alcohols or phenols, and amines. Long-chain S-alkyl O,O-dialkyldithiophosphonates were prepared by the reaction of red phosphorus with elemental sulfur, alcohols, and the cheap industrial fractions of С₁₆–С₁₈ and С₂₀–С₂₆ of higher α-olefins in the presence of Lewis acid catalyst. The dithiophosphates obtained possess the high anticorrosion activities toward mild steel.     

Flame photometric detection inside of a capillary gas chromatography column

A novel micro-flame photometric detector (FPD) employing a miniature counter-current flame is described. The micro-FPD flame, encompassing a volume of about 30 nL, is operated inside the end of a capillary gas chromatography column (i.e. on-column) or inside of a quartz capillary after the column (i.e. post-column). Either air or oxygen can support a hydrogen flame in the device, although oxygen is far preferable. The detector can be operated for several hours without any observed degradation in performance or flame stability. The optimal gas flows established for the detection of sulfur and phosphorus are in the range of 4 mL min(-1) of oxygen and 9 to 13 mL min(-1) of hydrogen. The fuel-rich micro-FPD flame generates chemiluminescent blue S2* emission for sulfur and green HPO* emission for phosphorus, similar to a conventional FPD. Sulfur response in the micro-FPD is quadratic over nearly 3 orders of magnitude while that of phosphorus is linear over nearly 5 orders of magnitude. The micro-FPD detection limit for sulfur is 1 x 10(-9) g S s(-1), and that of phosphorus is 2 x 10(-10) g P s(-1). The properties established for the initial prototype of the micro-FPD make this counter-current flame method potentially suitable for integration with on-chip gas chromatography or other micro-analytical devices where flame-based detection methods are desirable.     

The Simple Synthesis of Tetra-Alkyl Sym-Monothiopyrophosphates

Abstract

This poster is a part of our continuing interest in the synthesis and properties of phosphorus acid anhydride analogs, particulary those containing sulfur bridge between two phosphorus atoms (1). Recently we have found that sulfur dichloride reacts with dialkyl trimethylsilyl phosphites 1 to form the tetra-alkyl sym-monothiopyrophosphates 2 in high yield.     

Determination of Nitrogen,Sulfur, Phosphorus,and Carbon in Solid Ecological Materials Via Hydrogenation and Element-Selective Detection

Abstract

Element-selective detectors for carbon, sulfur, phosphorus, and nitrogen are used to determine methane, hydrogen sulfide, phosphine and ammonia in the effluent from a pyrolytic hydrogenator. Solid ecological field samples, e.g., forest floor litter, plant stream particulate, and insects, require no chemical pretreatment. These are pyrolyzed and the pyrolyzates pass through a catalyst bed which reduces the elements to the corresponding hydrides. Data are given for sulfur, carbon, and nitrogen.     

Ammonium sulfatophosphate producing from the phosphorites of Central Kyzylkum

The necessity of using sulfur-containig fertilizers in agricultural production is evidenced. By neutralizaation with gaseous amonia of a mixture of extractive phosphoric and sulfuric acids the ammonium sulfatophosphates are produced, containing nitrogen, phosphorus and sulfur in various ratio. The regimes for producing them are described and material flows in the industrial manufacturing are given.     

New Biomimetic Catalysts for the Electrochemical Processes on the Basis of Redox-Active Macrocyclic Frame Structures

Abstract

Efficient catalytic systems mimicking the action of metalloenzymes based on cyclic frame structures containing phosphorus, nitrogen, and sulfur coordinating atoms for hydrogen oxidation or reduction under mild conditions are proposed.