Phosphorus Chemistry Research Articles

ChemInform Abstract: Diphosphazanes as Ligands. Symbiosis of Phosphorus Chemistry and Organometallic Chemistry

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A concise review of low coordinated organophosphorus compounds

Organophosphorus chemistry is organized around σ 3 and σ 4 phosphorus compounds and their derivatives. For a long time, this represented the core of phosphorus chemistry and, still today, the bulk of the work on phosphorus concerns this domain. Starting in the 1960s, a new realm of P-chemistry started to emerge. It concerns σ 1 and σ 2 phosphorus compounds. The aim of this concise review is to summarize the main advances in this new field.

Soil organic phosphorus in lowland tropical rain forests

Phosphorus is widely considered to constrain primary productivity in tropical rain forests, yet the chemistry of soil organic phosphorus in such ecosystems remains poorly understood. We assessed the composition of soil organic phosphorus in 19 contrasting soils under lowland tropical forest in the Republic of Panama using NaOH–EDTA extraction and solution 31P nuclear magnetic resonance spectroscopy. The soils spanned a strong rainfall gradient (1730–3404 mm y−1) and contained a wide range of chemical properties (pH 3.3–7.0; total carbon 2.8–10.4%; total phosphorus 74–1650 mg P kg−1). Soil organic phosphorus concentrations ranged between 22 and 494 mg P kg−1 and were correlated positively with total soil phosphorus, pH, and total carbon, but not with annual rainfall. Organic phosphorus constituted 26 ± 1% (mean ± STD error, n = 19) of the total phosphorus, suggesting that this represents a broad emergent property of tropical forest soils. Organic phosphorus occurred mainly as phosphate monoesters (68–96% of total organic phosphorus) with smaller concentrations of phosphate diesters in the form of DNA (4–32% of total organic phosphorus). Phosphonates, which contain a direct carbon–phosphorus bond, were detected in only two soils (3% of the organic phosphorus), while pyrophosphate, an inorganic polyphosphate with a chain length of two, was detected in all soils at concentrations up to 13 mg P kg−1 (3–13% of extracted inorganic phosphorus). Phosphate monoesters were a greater proportion of the total organic phosphorus in neutral soils with high concentrations of phosphorus and organic matter, whereas the proportion of phosphate diesters was greater in very acidic soils low in phosphorus and organic matter. Most soils did not contain detectable concentrations of either myo- or scyllo-inositol hexakisphosphate, which is in marked contrast to many temperate mineral soils that contain abundant inositol phosphates. We conclude that soil properties exert a strong control on the amounts and forms of soil organic phosphorus in tropical rain forests, but that the proportion of the total phosphorus in organic forms is relatively insensitive to variation in climate and soil properties. Further work is now required to assess the contribution of soil organic phosphorus to the nutrition and diversity of plants in these species-rich ecosystems.

ChemInform Abstract: Zirconium Species as Tools in Phosphorus Chemistry: [Cp2ZrMe2], a Useful Reagent

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Phosphorus fractionation in lowland tropical rainforest soils in central Panama

Abstract Phosphorus availability is commonly assumed to limit productivity in lowland tropical rainforests, yet there is relatively little information on the chemical forms of soil phosphorus in such ecosystems. We used the Hedley sequential fractionation scheme to assess phosphorus chemistry in five soils supporting tropical rainforest on Barro Colorado Island, Republic of Panama. The soils represented a range of orders (Inceptisols, Alfisols, and Oxisols) formed on contrasting geological substrates and topography, but under uniform climate and vegetation. Total phosphorus in surface horizons ranged between 315 and 1114 mg P kg− 1, being lowest on a soil derived from marine sediments and highest on soils derived from andesite. The majority of the phosphorus occurred in recalcitrant forms, although between 14% and 39% occurred as organic phosphorus. Readily-available phosphate, as extracted by anion-exchange membranes, occurred in small concentrations (4–13 mg P kg− 1), although labile phosphorus, defined as phosphate extracted by anion-exchange membrane plus inorganic and organic phosphorus extracted by 0.5 M NaHCO3, accounted for between 4.7% and 11.4% of the total soil phosphorus. Our results indicate a strong control of geology and topography on soil phosphorus in tropical rainforests, which may have important implications for understanding the diversity and distribution of plant species in such ecosystems. Further, some of the most common soils on Barro Colorado Island, including those on the 50 ha forest dynamics plot, are rich in phosphorus despite their relatively advanced stage of pedogenesis.

Nitrogen, phosphorus, arsenic, antimony and bismuth

This chapter reviews the literature reported during 2009 on the chemistry of nitrogen, phosphorus, arsenic, antimony and bismuth.

Phospha-organic chemistry: from molecules to polymers

Many parallels have been drawn between the chemistry of low-valent phosphorus and carbon. This Perspective is intended to highlight some emerging reactivity of phosphaalkenes, that is phospha-analogues of alkenes, in the areas of asymmetric catalysis and polymer science.

Differing effects of catchment land use on water chemistry explain contrasting behaviour of a diatom index in tropical northern and temperate southern Australia

The DSIAR biotic index for freshwater diatoms, regarded as a potential indicator of impact from agricultural and urban land use on rivers in temperate south-eastern Australia, did not correlate significantly with an index of catchment condition in a tropical region of northern Australia. However, the relationships between the index and water chemistry, especially pH, salinity and concentrations of nitrogen and phosphorus, were consistent in both regions. The variable relationship between the index and catchment conditions can be explained by differing effects of catchment land use on stream-water chemistry in northern and southern Australia. In the south, land use has commonly resulted in increases in stream pH, salinity and nutrients, whereas in the north its impact on pH and salinity appears weak. These findings emphasise the need to interpret biological and ecological indices in the context of the varying causal pathways by which human activities affect stream ecosystems in different circumstances.

Exploring organic reactions using simple cyclodiphosphazanes

Phosphine-activated reactions of alkynes/alkenes/allenes as well as the Mitsunobu reaction involve a rich phosphorus chemistry. With the aid of simple cyclodiphosphazanes, characterization of many compounds analogous to the proposed intermediates in such reactions has been accomplished. Use of a cyclodiphosphazane in Pd-catalyzed N-arylation reactions is highlighted. Results on molecular non-stoichiometry in phosphorus compounds and on the use of chiral phosphorus systems are discussed. Synthesis of allenylphosphoramides involving a cyclodiphosphazane is also described. X-ray structures of the new compounds [( t-BuNH)(PhCH 2CH(CN)CH 2–)P(μ-N- t-Bu) 2P(NH- t-Bu)] +[HCO 3] − ( 13), [( t-BuNH)P(μ-N- t-Bu) 2P( N- t-Bu)-C( CH 2)CH(C 6H 4-4-Me)-P(O)(OCH 2CMe 2CH 2O)] ( 18), [( i-PrNH)P(μ-N- t-Bu) 2P( N- i-Pr)-N(CO 2- i-Pr)-NH(CO 2- i-Pr)] ( 24), [( S)-(2-OH-1-C 10H 6-1′-C 10H 6-2′-O-P(O)(NH- t-Bu) 2] ( 36) and [( t-BuNH)(O)P(μ-N- t-Bu) 2P(O)(CH C CMe 2)] ( 40) are also reported.

How nitrate leaching from agricultural lands provokes phosphate eutrophication in groundwater fed wetlands: the sulphur bridge

Increased phosphorus availability may provoke serious eutrophication problems in wetlands. Strong evidence indicates that sulphate induced mobilization of phosphate (internal eutrophication) has been responsible for a strong decline of the biodiversity in wetlands during the last decades. It is currently underestimated, however, that the wide spread leaching of nitrate from agricultural lands can indirectly provoke strong internal phosphate eutrophication in wetlands, via its interference with sulphur and iron biogeochemistry in the subsoil. Nitrate can mobilize sulphate from geological pyrite deposits by the oxidation of FeSx in the aquifer, leading to a decrease of nitrate and an increase of groundwater sulphate concentrations. Furthermore nitrate immobilizes iron in the subsoil by oxidizing reduced (dissolved) iron. Increased sulphate concentrations may provoke strong phosphate eutrophication in wetlands fed directly or indirectly (via surface water) with groundwater as sulphate strongly interferes with iron phosphorus chemistry and stimulates anaerobic decomposition of organic matter. Management of wetlands should therefore be approached at a broader scale which includes the landscape-scale management of groundwater systems. Leaching of nitrate to the groundwater, for instance, should not only receive attention for its potential effects on drinking water quality but above all because of the resulting large scale mobilization of sulphate from geological pyrite deposits and the immobilization of ferrous iron.

Preparation of the [(DippNP)2(P4)2]2+-Dication by the Reaction of [DippNPCl]2 and a Lewis Acid with P4

The controlled activation of white phosphorus, P(4), provides a key entry point into many aspects of phosphorus chemistry. The activation and functionalization of P(4) by N-heterocyclic carbenes and carbene-like main group element fragments is of considerable current interest. In this communication, we report on the first use of a disguised bifunctional Lewis acid [DippNP](2)(2+) obtained from the cyclo-1,3-diphospha-2,4-diazane [DippNPCl](2) for P(4) functionalization. This has enabled the targeted preparation of novel mono- and dicationic phosphorus-rich clusters [(DippNP)(2)(P(4))Cl](+) and [(DippNP)(2)(P(4))(2)](+). The utilization of such a bifunctional phosphenium cation represents a rational and potentially versatile synthetic method for the assembly of large clusters using P(4) as a building block.

Lightning-induced reduction of phosphorus oxidation state

Phosphorus is frequently the limiting nutrient in marine and terrestrial ecosystems. Analysis of lightning-derived glassy compounds from North America, Africa and Australia suggests that cloud-to-ground lightning increases the bioavailability of this nutrient. Phosphorus is frequently the limiting nutrient in marine and terrestrial ecosystems, largely owing to its poor solubility and slow movement through the rock cycle1,2. Phosphorus is viewed to exist in geological systems almost exclusively in its fully oxidized state as orthophosphate. However, many microorganisms use the partially oxidized forms—phosphite and hypophosphite—as alternative phosphorus sources3,4,5, and genomic evidence suggests that this selectivity is ancient6. Elucidating the processes that reduce phosphate is therefore key to understanding the biological cycling of phosphorus. Here we show that cloud-to-ground lightning reduces phosphate in lightning-derived glass compounds, termed fulgurites. We analysed the phosphorus chemistry of ten fulgurites retrieved from North America, Africa and Australia, using microprobes and 31P nuclear magnetic resonance. Half of the fulgurites contained reduced phosphorus, mainly in the form of phosphite. The amount and type of reduced phosphorus was dependent on the composition of the fulgurite section examined: carbon-rich sections contained around 22% reduced phosphorus in the form of iron phosphide, whereas other fulgurites contained between 37 and 68% in the form of phosphite. We suggest that lightning provides some portion of the reduced phosphorus used by microbes, and that phosphate reduction by lightning can be locally important to phosphorus biogeochemistry.

New Adventures in the Molecular Chemistry of Phosphorus

Teaching old dogs new tricks: Recent developments in low-coordinate phosphorus chemistry reveal the capacity of this element for surprises. For example, P for CR substitution in new phosphaalkynes was used to stabilize purported intermediates in an important synthetic transformation, and also to form new diphosphacyclobutadiene sandwich complexes (see scheme).

Extractability of slurry and fertilizer phosphorus in soil after repeated freezing

The potential effects of freezing on phosphorus (P) chemistry in Finnish soils are not well known. We studied the effects of multiple freeze-thaw cycles on soil P chemistry in a laboratory incubation experiment with one organic and one mineral surface soil. The soils were incubated at +5°C or at alternating +5/–20°C temperatures for 24 weeks, either without amendment or amended with pig slurry or with commercial compound fertilizer (NPK 20–3–9). After incubation, the soils were analyzed for water-soluble reactive and unreactive P, and acid ammonium acetate soluble P (PAAA). Freezing and thawing of soils during the incubation had no significant effect on any of the water-soluble P fractions or PAAA. The outcome was most likely a consequence of the good P status of the soils, which masked the gentle effects of freezing. According to these results, the time of soil sampling (fall vs. spring) has no effect on P test results on soils with a good P status. Concentrations of soluble P after incubation were roughly twice as high in the slurry treatments than in the fertilizer treatments, demonstrating potentially better long-term availability of slurry P.;

Sensitivity of soil phosphorus tests in predicting the potential risk of phosphorus loss from pasture soil

The objective of this study was to examine the effects of urine and dung additions on the phosphorus (P) chemistry of pasture land and to compare the sensitivity of two soil extraction methods in assessing the P-loading risk. In a field experiment, urine and dung were added to soil in amounts corresponding to single excrement portions and the soil samples, taken at certain intervals, were analysed for pHH2O, acid ammonium acetate extractable P (PAc) and water extractable total P (TPw), and molybdate reactive P (MRPw). Urine additions immediately increased soil pH and MRPw, but no such response was observed in PAc extraction due to the low pH (4.65) of the extractant enhancing the resorption of P. The PAc responded to the dunginduced increase in soil total P similarly as did Pw, which suggests that both tests can serve to detect areas of high P concentration. However, water extraction was a more sensitive method for estimating short-term changes in P solubility. In pasture soils, the risk of P loss increases as a result of the interaction of urination and high P concentration in the topsoil resulting from continuous dung excretion.;

Constraining Phosphorus Chemistry in Carbon‐ and Oxygen‐Rich Circumstellar Envelopes: Observations of PN, HCP, and CP

Millimeter-wave observations of PN, CP, and HCP have been carried out toward circumstellar envelopes of evolved stars using the Arizona Radio Observatory (ARO). HCP and PN have been identified in the carbon-rich source CRL 2688 via observations at 1 mm using the Submillimeter Telescope (SMT) and 2-3 mm with the Kitt Peak 12 m. An identical set of measurements were carried out toward IRC +10216, as well as observations of CP at 1 mm. PN was also observed toward VY Canis Majoris (VY CMa), an oxygen-rich supergiant star. The PN and HCP line profiles in CRL 2688 and IRC +10216 are roughly flat topped, indicating unresolved, optically thin emission; CP, in contrast, has a distinct U shape in IRC +10216. Modeling of the line profiles suggests abundances, relative to H2, of f(PN) ~ (3–5) × 10−9 and f(HCP) ~ 2 × 10−7 in CRL 2688, about an order of magnitude higher than in IRC +10216. In VY CMa, f(PN) is ~4 × 10−8. The data in CRL 2688 and IRC +10216 are consistent with LTE formation of HCP and PN in the inner envelope, as predicted by theoretical calculations, with CP a photodissociation product at larger radii. The observed abundance of PN in VY CMa is a factor of 100 higher than LTE predictions. In IRC +10216, the chemistry of HCP/CP mimics that of HCN/CN and suggests an N2 abundance of f ~ 1 × 10−7. The chemistry of phosphorus appears active in both carbon- and oxygen-rich envelopes of evolved stars.

Evaluation of Organophosphorus Chemicals‐Degrading Enzymes: A Comparison of Escherichia coli and Human Cytosolic Aminopeptidase P

An enzyme capable of hydrolyzing organophosphate compounds is of biological as well as environmental significance. We evaluated the possibility of human cytosolic aminopeptidase P (hcAMPP) as an attractive bioscavenger candidate by measuring the enzymatic rates of hydrolysis for a wide variety of organophosphorus compounds. The comparison of substrate specificity exhibited by hcAMPP and E. coli aminopeptidase P (E. coli AMPP) was studied. We cloned, expressed, and purified hcAMPP from HeLa cells and AMPP from Escherichia coli. The pH-rate profiles of hcAMPP were measured in the presence of organophosphate compound 3 or 5. All of the organophosphorus compounds, 1-19, were synthesized by using the approach of phosphorus chemistry described in a previous publication. The relative activity of hcAMPP and E. coli AMPP in hydrolyzing a series of organophosphorus analogues, 1-17, was evaluated in a spectrophotometric assay by monitoring the difference of accumulation of 4-nitrophenol at 400 nm. The overall substrate preference of hcAMPP is as follows: methylphosphonates>ethylphosphonates> or =organophosphates. Interestingly, the observed enhancement in the activity of hcAMPP with methyl phosphonates, 8, 10, 12, and 13, suggests that there is particularly special about the substructure of both methyl moiety and P=O ligand, since the values of specific activity with hcAMPP for the methylphosphonates 8, 10, 12, and 13 are 2- to 73-fold greater than those for the ethylphosphonates 14-17 and the organophosphates 1-7. Similarly, in E. coli AMPP toward ethylphosphonates 14-17, the results indicate that the regions of both MeO moiety and P=O ligand may be located in the vicinity of the substrate-binding site, which have not been altered within the active site of enzyme upon mutation of Trp88, Arg153, and Arg370. These studies demonstrate that E. coli AMPP and hcAMPP display different substrate preference toward organophosphorus compounds. Evidence here, therefore, represents the first example of hcAMPP that might serve as a valuable bioscavenger candidate as E. coli AMPP due to the promise from the hydrolysis of these toxic chemicals.

Detection of the CCP Radical ( X 2 Π r ) in IRC +10216: A New Interstellar Phosphorus-containing Species

The CCP radical (X2Πr) has been detected in the circumstellar gas of IRC +10216, the fifth phosphorus-bearing molecule identified in interstellar space. This identification was made on the basis of new laboratory millimeter/submillimeter direct absorption measurements, conducted in the range 120-413 GHz. Four rotational transitions of this species were observed using the Arizona Radio Observatory (ARO) 12 m telescope on Kitt Peak at 2 and 3 mm in wavelength. Each transition consists of lambda-doublets, which are well-separated in frequency in IRC +10216; five of these eight possible lines of CCP were clearly detected, while the remaining three were contaminated by stronger emission from other species. The column density derived for CCP was Ntot= 1.2 × 1012 cm−2 and Trot = 21 K. Modeling of the line profiles suggests that CCP arises from an extended shell with a maximum radius of ~40''. The abundance of this radical, relative to H2, is f ~ 1 × 10−9—roughly comparable to that of PN and CP in this source. CCP may be produced from radical-radical reactions of CP, or ion-molecule chemistry involving P+ and HCCH. The identification of CCP is additional evidence that phosphorus chemistry is active in carbon-rich circumstellar gas.

Organic chemistry in circumstellar envelopes: Setting the stage for prebiotic synthesis

AbstractOne of the few carbon-rich environments found in interstellar space is the ejecta of asymptotic giant branch (AGB) stars. Such material, which forms a circumstellar envelope, becomes enriched in carbon due to “dredge-up” phenomena associated with nucleosynthesis. A unique organic synthesis flourishes in the gas phase in these envelopes, and radio and millimeter observations have identified a wide range of C-bearing compounds, including long acetylenic chains such as HC5N, HC7N, C4H, C6H, C8H, C6H−, C8H−, and C3O. Oxygen-rich envelopes also have a non-negligible carbon chemistry, fostering species such as HCN and HCO+. Phosphorus chemistry appears to be active as well in circumstellar shells, as evidenced by the recent detections of HCP, CCP, and PO. Radio observations also indicate that some fraction of the circumstellar molecular material survives into the planetary nebula stage, and then becomes incorporated into diffuse, and eventually, dense clouds. The complex organic molecules found in dense clouds such as Sgr B2(N) may be the products of “seed” material that can be traced back to the carbon-enriched circumstellar gas.

Biologically Relevant Phosphoranes: Hypervalent Phosphorus as Applied to Phosphoryl Transfer Enzymes

The coordination tendencies of phosphorus to form a hexacoordinated state from a pentacoordinated state, which might assist in describing the mechanistic action of phosphoryl transfer enzymes, are delineated. In view of the work reported here and recent work on enzyme promiscuity and moonlighting activities, it is suggested that donor action should play a role in determining active site interactions in phosphoryl transfer enzyme mechanisms. Biochemists studying phosphoryl transfer enzymes outline mechanisms of nucleophilic attack at phosphorus that take place by way of proposed trigonal bipyramidal intermediates or transition states. However, recent work has shown the ready availability of higher coordinate forms of phosphorus, particularly the ease of formation of hexacoordinate phosphorus. Our recent work established the X-ray structure of several biorelevant phosphoranes. Included are the structures of a xylofuranose based phosphorane 1 and a thymidine based phosphorane. Dynamic equilibrium between two isomeric forms exists in solution for 1. In addition, bicyclic phosphorane 3 exists in equilibrium between pentacoordinated and hexacoordinated isomeric forms. The rapid exchange process between these two geometries reorients the nucleotidyl or carbohydrate component of the trigonal bipyramidal phosphorane. At an active site, this type of pseudorotational behavior provides a mechanism that could bring another active site residue into play and account for a means for phosphoryl transfer enzymes to express promiscuous behavior. Pseudorotation, a well-founded process in non-enzymatic phosphorus chemistry may have an application in the future of phosphoryl transfer enzyme chemistry.