Phosphorus Coupling Research Articles

Interactive effects of climate and nutrient enrichment on patterns of herbivory by different feeding guilds in mangrove forests

AbstractAimGlobal warming and eutrophication are major threats to coastal environments worldwide. As a result of differences between temperate and tropical ecosystems in nutrient availability, nitrogen (N):phosphorus (P) coupling and carbon retention, primary productivity and biotic interactions in the tropics are predicted to have stronger responses to increased nutrients than in temperate ecosystems. Habitats that occur across broad climatic ranges, such as mangrove forests, provide an opportunity to test this hypothesis by investigating the responses of herbivores to nutrient enrichment in temperate versus tropical latitudes on the same species.LocationAustralia and New Zealand.Time periodFertilization experiments were established at Port Douglas and Cape Cleveland in October 2000; Batemans Bay and Waikopua in August 2001; Whangapoua in January 2003; Tinchi Tamba in September 2005; and Garalia in October 2007. Herbivory was measured in 2009.Major taxa studiedInsect leaf miners; insect and fungal leaf gallers.MethodsWe used seven fertilization experiments in Australia and New Zealand across 20° of latitude to determine how increased nutrients affected herbivory and diversity of leaf miners and gallers of the mangrove Avicennia marina. Individual trees were fertilized annually with one of three treatments (Control, +N, +P); herbivory was measured in 2009.ResultsFertilization did not significantly affect herbivory or herbivore diversity. Leaf N:P, latitude and rainfall contributed significantly to herbivory, accounting for > 56% of the variation. Latitude, temperature, %P and salinity differentiated herbivory by feeding guild in the tropical versus subtropical and temperate latitudes. The effect of N fertilization on folivory differed across climatic regions; relative to Control trees, N‐fertilized trees in temperate areas had greater folivory than in tropical and subtropical latitudes. Species richness for leaf miners and gallers was correlated with latitude, with more species in subtropical and tropical latitudes than in temperate latitudes. The abundance of galls and mines differed by location, but differences were not correlated with latitude.Main conclusionsResults indicate that latitude and nutrients may have had an interactive effect on herbivory and herbivore diversity of A. marina. However, the strength of the interactions varied by climatic region and was not the same for all groups of herbivores.

Coupling of reactive riverine phosphorus and iron species during hot transport moments: impacts of land cover and seasonality

Spring runoff often comprises the majority of annual discharge and riverine phosphorus (P) export due to sustained high flow, and the magnitude of spring runoff can be a strong predictor of receiving water summer harmful algal bloom severity. Yet the loading of reactive forms of P during this time period remains poorly-characterized in time, space and geochemical partitioning. Here, we explore the hypothesis that riverine dissolved and suspended sediment P loads during spring runoff have a particularly high proportion of potentially reactive species due to unique hydrologic pathways and P association with iron (Fe).The concentration, distribution and temporal dynamics of dissolved P (DP), dissolved and colloidal Fe, and redox sensitive suspended sediment P (RSP) and Fe during spring runoff and summer storms were compared in forested and agricultural catchments of the same watershed. The dominant carrier of RSP was Fe (oxy)hydroxides across land cover and season, but Fe (oxy)hydroxide particles and colloids in agricultural catchments were strongly enriched in RSP and DP during spring runoff and summer storms, particularly at the onset of snowmelt. In 2014, 83% of DP and 74% of RSP were delivered to Missisquoi Bay during spring runoff. Suspended sediment was significantly more redox sensitive than typically input to limnological models, suggesting that the reactivity of this load may be systematically underestimated. Changes in the timing, provenance and severity of spring runoff associated with climate or land cover change will have dramatic impacts on total riverine P loads and their potential reactivity in receiving water ecosystems.

Catalytic Synthesis of Organophosphorus Compounds from Inorganic Derivatives of Low Valence Phosphorus

<p>A variety of new reactions of inorganic compounds of elemental and low valence phosphorus (phosphine, white phosphorus, sodium hypophosphite) with various organic substrates (alcohols, olefins, quinones) catalysed by different transition metal (Pd<sup>II</sup>, Hg<sup>II</sup>, Pt<sup>II</sup>, Pt<sup>IV</sup>, Ag<sup>I</sup>, Fe<sup>III</sup>, Cu<sup>II</sup>) salts leading to the formation of valuable organophosphorus derivatives (trialkylphosphates, dialkylphosphites, trialkylphoshinoxides, phosphonium salts) are reviewed. The principal features of the oxidative phosphorylation reactions which are of great practical importance are described. The mechanisms of the catalytic oxidative P-O and P-C coupling of phosphine, white phosphorus and hypophosphite with alcohols, olefins and quinones are considered. It has been shown that this catalytic protocol allows to provide a highly selective conversion of relatively inexpensive feedstocks to desirable higher added-value products.</p>

New cyclopentadienyl molybdenum polynuclear clusters from ring opening of Woollins’ reagent via phosphorus–selenium bond scission, phosphorus–phosphorus coupling and deselenation pathways

Cothermolysis of [(Ph)P(Se)(μ-Se)]2 or Woollins’ reagent (WR) with Cp2Mo2(CO)4 (2) in toluene at 110°C led to the isolation of three different metal clusters, [Cp2Mo2{(μ-Se)2(PPh(Se))}{(μ-Se)(PPh)3] (3), Cp4Mo4(CO)3(μ-Se)4 (4) and a pair of isomer complexes of Cp3Mo3(CO)4[Se3(PPh)2] (5a and 5b) in 17.5%, 3.1% and 4.9% yields, respectively. A similar reaction at 70°C gave only 5a and 5b in 2.0% and 4.9% yields, respectively. All complexes have been fully characterized via NMR, IR and ESI mass spectroscopy. Molecular structures of 3, 4 and 5a were confirmed by single crystal X-ray diffraction analyses. A variable temperature 1H NMR study of 4 was carried out. Finally, a free-radical addition pathway by selenation of WR was postulated.

Highly Enantioselective Pd-Catalyzed Synthesis of P-Stereogenic Supramolecular Phosphines, Self-Assembly, and Implication

Metal-catalyzed asymmetric addition of a secondary phosphine to an aryl halide is one of the most efficient and reliable approaches for the construction of enantiopure carbon–phosphorus bonds. An isolated Pd(II) complex (5) catalyzes the carbon–phosphorus coupling reaction between tolylphenylphosphine (1a) and 3-iodophenylurea (2b), which proceeds with an unprecedented enantiomeric excess (ee) of 97%. The generality of the strategy has been demonstrated by preparing a small library of a new class of P-stereogenic phosphines with an in-built hydrogen bonding motif for the first time. The P-stereogenic phosphines self-assemble on a metal template via deliberately installed hydrogen-bonding motifs and mimic the bidentate ligand coordination. Interestingly, when it was employed in asymmetric hydrogenation, the supramolecular phosphine {1-(3-(phenyl(o-tolyl)phosphanyl)phenyl)urea} (6b) produced the corresponding hydrogenated product with the highest enantiomeric excess of 99% along with excellent conversion, d...

Nutrient resorption helps drive intra-specific coupling of foliar nitrogen and phosphorus under nutrient-enriched conditions

Aims Plant biomass growth, storage, and decomposition connect nitrogen (N) and phosphorus (P) cycles, yet we know relatively little about the dynamics of such coupling under nutrient enriched conditions, and our understanding of the interactive relationships between plant N and P in drylands remains particularly poor.

Coupling of dietary phosphorus and growth across diverse fish taxa: a meta‐analysis of experimental aquaculture studies

Imbalances in phosphorus (P) intake relative to demand negatively affect animal growth, but their consequences are less understood for vertebrates, in which bone represents a significant and potentially flexible pool of P. Flexibility in body‐P content could buffer vertebrates from the effects of imbalances between P intake and demand, reducing the likelihood of a sharp stoichiometric “knife‐edge” in the relationship between growth rate and diet‐P level. We conducted a meta‐analysis of published aquaculture experiments that tested effects of diet %P on fish growth rate (49 studies, 28 species) and body‐P content (27 of the studies in the main data set, 20 species). Our meta‐analysis revealed significant P limitation of growth, as well as significant negative effects of excess P on growth rate. Diet‐P thresholds for these effects occurred at ecologically relevant levels (optimal diet‐P of 1.2% ± 0.45%, mean ± SD, under experimental conditions of high ration). Finally, the analysis also suggested a pattern of relatively shallow relationships between growth rate and diet‐P level, coupled with surprisingly flexible body‐P content in fishes. This result is consistent with fish using flexible body‐P content (presumably mediated through bone P) to buffer imbalances between P intake and demand. Together, our results provide evidence for a relatively “dull” stoichiometric “knife‐edge” in fishes, driven in part by flexible body‐P content.

Factors controlling spatial distributions and relationships of carbon, nitrogen, phosphorus and sulphur in sediments of the stratified and eutrophic Gulf of Gdansk

Spatial distribution and coupling of carbon, nitrogen, phosphorus and sulphur were studied in sediments of the Gulf of Gdansk, southern Baltic Sea. We report data on sedimentary contents of total and organic carbon (TC and OC), total nitrogen (TN), total and organic phosphorus (TP and OP) and total sulphur (TS), as well as pore water concentrations of ammonium, phosphate and hydrogen sulphide. The lowest values of all the investigated parameters were observed in coastal area, while the highest were noted in sediments below halocline which is attributed to changing hydrodynamic conditions and sedimentation regimes with depth. The contents of TC, OC, TN, TP, OP and TS in sediments and their molar ratios were also noted to vary spatially in relation to distance from land and oxygen conditions in near-bottom water. As a result of high organic matter supply to the sediments caused by eutrophication we observed increased contents of TC, OC, TN, TP and OP in the upper few centimetres of sediment. Results obtained for the Gdansk Deep indicate that sediments in this area are site of accumulation of sulphur and redox-dependent phosphorus release.We analysed relationships between the investigated parameters and organic matter content in sediments measured as loss-on-ignition (LOI). Regression analysis indicated that LOI was a good estimator of contents of OC, TN and OP in the Gulf of Gdansk sediments and may be used as a screening tool when planning geochemical investigations. However, calculated equations can only be applied to LOI results obtained at similar temperature and exposure time (550°C, 6h). In addition to this, the method was unreliable for prediction of TS content in euxinic environments where, as in the Gdansk Deep sediments, accumulation of sulphur occurs due to the formation of iron (II) sulphides.

Degradation of CYANEX 301 in Contact with Nitric Acid Media

The nature of the degradation product obtained upon contacting CYANEX 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) with nitric acid has been elucidated and found to be a disulfide derivative. The first step to the degradation of CYANEX 301 in toluene has been studied using 31P{1H} NMR after being contacted with nitric acid media. The spectrum of the degradation product exhibits a complex multiplet around δP = 80 ppm. A succession of purifications of CYANEX 301 has resulted in single crystals of the acidic form and the corresponding ammonium salt. Unlike the original CYANEX 301, which consists of a complex diastereomeric mixture displaying all possible combinations of chiral orientations at the 2-methyl positions, the purified crystals were shown by single-crystal X-ray diffraction to be racemates, containing 50:50 mixtures of the [R;R] and [S;S] diastereomers. The comparison between the 31P {1H} NMR spectra of the degradation products resulting from the diastereomerically pure CYANEX 301 and the original diastereomeric mixture has elucidated the influence of the isomeric composition on the multiplicity of the 31P {1H} NMR peak. These NMR data indicate the initial degradation leads to a disulfide-bridged condensation product displaying multiple resonances due to phosphorus–phosphorus coupling, which is caused by the inequivalence of the two P atoms as a result of their different chirality. A total of nine different NMR resonances, six of which display phosphorus–phosphorus coupling, could be assigned, and the identity of the peaks corresponding to phosphorus atoms coupled to each other was confirmed by 31P {1H} homodecoupled NMR analysis.

Synthesis of triethylphosphite complexes of nickel(II) and palladium(II) with tridentate Schiff base ligand for catalytic application in carbon–carbon coupling reactions

Abstract Air stable Ni(II) and Pd(II) complexes viz. [Ni(LS)(P(OEt)3)] (1), [Ni(LN)(P(OEt)3)] (2), [Pd(LS)(P(OEt)3)] (3) and [Pd(LN)(P(OEt)3)] (4) [where LS and LN are dianions of N–(2–mercaptophenyl)salicylideneimine and N–(2–mercaptophenyl)naphthylideneimine respectively] have been synthesized and characterized by analytical and spectral (electronic, FT–IR, 1H, 13C and 31P NMR) methods. The 1H–31P HMBC spectrum established the coupling of phosphorus with the azomethine proton of the Schiff base and the aliphatic protons of triethylphosphite. Novel Ni(II) and Pd(II) complexes exhibited good catalytic activity in Kumada–Tamao–Corriu and Suzuki–Miyaura coupling reactions respectively.

P‐OR Functional Phosphanido and/or Li/OR Phosphinidenoid Complexes?

AbstractP‐H,P‐OR‐substituted phosphane complexes 3a–e have been synthesized by two methods: (1) the thermal reaction of 2H‐azaphosphirene complex 1 with methanol, n‐butanol, or ethylene glycol monomethyl ether (3b,c,e) or (2) the reaction of P‐chlorophosphane complex 2 with appropriate sodium phenolate salts (3a,d). All the complexes 3a–e were obtained in good yields and fully characterized by NMR, IR, MS, and elemental analysis. Furthermore, the structures of 3a, 3d and 3e were confirmed unambiguously by X‐ray analysis. The deprotonation of complexes 3a–e by using lithium diisopropylamide in the presence of 12‐crown‐4 led to phosphinidenoid complexes 4a–e, which exhibit downfield 31P resonances and small tungsten–phosphorus coupling constants. Studies on the reactivity of complexes 4a–c,e revealed a “phosphanido‐type” reactivity, and only for complex 4d, a thermally labile complex, was evidence found for a “phosphinidene‐type” reactivity.

Effects of water, nitrogen and phosphorus coupling on starch paste properties of winter wheat

为了解豫西半干旱区不同水、肥条件对小麦淀粉品质的调控效应, 于2009—2010年度和2010—2011年度在河南省洛阳市农业科学研究院以“洛旱2号”小麦为材料, 采用防雨棚池栽种植方式, 研究了不同灌水量、施氮量和施磷量及其互作对小麦淀粉糊化特性的影响。结果表明: 施氮量和施磷量对小麦淀粉糊化特性均有显著影响(<i>P</i>≤0.05或<i>P</i>≤0.01); 随施氮量的增加, 淀粉各黏度参数呈增大趋势, 施氮量为105 kg·hm^-2时达最大值, 之后增加施氮量各黏度参数又有所下降; 黏度参数在施磷量为168 kg·hm^-2时达最大值。在豫西半干旱生态条件下, 灌水量对淀粉黏度参数影响不显著, 但存在灌水量×施氮量的显著互作效应(<i>P</i>≤0.05或<i>P</i>≤0.01)。从不同水肥处理组合看, 淀粉糊化特性以处理组合N105P168W217.5[施氮量105 kg(N)·hm^-2、施磷量168 kg(P<sub>2M/sub>O₅)·hm^-2和全生育期灌水量217.5 mm]最优。相关分析表明, 淀粉黏度参数与籽粒产量在2009—2010年度呈显著正相关, 而在2010—2011年度相关不显著, 说明产量与淀粉品质间存在着协同提高的可能性。

Structures, Energies, and Spin–Spin Coupling Constants of Methyl-Substituted 1,3-Diborata-2,4-diphosphoniocyclobutanes: Four-member B–P–B–P Rings B2P2(CH3)nH8–n, with n = 0, 1, 2, 4

An ab initio study has been carried out to determine the structures, relative stabilities, and spin-spin coupling constants of a set of 17 methyl-substituted 1,3-diborata-2,4-diphosphoniocyclobutanes B(2)P(2)(CH(3))(n)H(8-n), for n = 0, 1, 2, 4, with four-member B-P-B-P rings. The B-P-B-P rings are puckered in a butterfly conformation, in agreement with experimental data for related molecules. Isomers with the CH(3) group bonded to P are more stable than those with CH(3) bonded to B. If there is only one methyl group or if two methyl groups are bonded to two different P or B atoms, isomers with equatorial bonds are more stable than those with axial bonds. However, when two methyl groups are present, the gem isomers are the most stable for molecules B(2)P(2)(CH(3))(2)H(6) with P-C and B-C bonds, respectively. Transition structures present barriers to the interconversion of two equilibrium structures or to the interchange of axial and equatorial positions in the same isomer. These barriers are very low for the isomer with two methyl groups bonded to B in axial positions for the isomer with four axial bonds and for the isomer with geminal B-C bonds at both B atoms. Coupling constants (1)J(B-P), (1)J(P-C), (1)J(B-C), (2)J(P-P), and (3)J(P-C) are capable of providing structural information. They are sensitive to the number of methyl groups present and can discriminate between axial, equatorial, and geminal bonds, although not all do this to the same extent. The one-bond coupling constants (1)J(B-P), (1)J(P-C), and (1)J(B-C) are similar in equilibrium and transition structures, but (3)J(P-C) and (2)J(P-P) are not. These coupling constants and those of the corresponding fluoro-derivatives of the 1,3-diborata-2,4-diphosphoniocyclobutanes demonstrate the great sensitivity of phosphorus coupling to structural and electronic effects.

Directing Alkyl Chain Ordering of Functional Phosphorus Coupling Agents on ZrO2

ZrO(2) powder (6.6 m(2)/g) was modified using polymerizable phosphorus-based coupling agents (P-CAs) (i.e., phosphonic acid, phosphoric acid, and bis-phosphonic acid), resulting in densely grafted layers as determined by thermogravimetry and elemental analysis (up to 4.2 molecules/nm(2)). The applied P-CAs contained a methacrylate group, which led to the covalent incorporation of a polymerizable moiety into the grafted layer. To direct the ordering of the alkyl chains in the layer, three different approaches were evaluated with respect to their structure-directing ability by means of FT-IR and nitrogen sorption at 77 K: (i) variation of the chain length, (ii) variation of the anchoring group and (iii) comodification with a defined amount of a nonfunctional phosphonic acid (variation of the functional/nonfunctional acid ratio). It was shown that the chain length and anchoring group size have significant effects on the alkyl chain ordering and morphology of the layer.

A new approach to coordination chemistry involving phosphorus-selenium based ligands. Ring opening, deselenation and phosphorus–phosphorus coupling of Woollins’ Reagent

The facile reaction of [CpCr(CO)3]2 (1) with an equivalent of 2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide or Woollins’ Reagent (WR) at ambient temperature gave mainly [CpCr(CO)2]2Se (3) as the main product. A similar reaction with an excess of 1 gave 3 (58%) and trans-[CpCr(CO)2(SePPh)]2 (5, 25%). However reaction with an equivalent of the triply bonded congener Cp2Cr2(CO)4 (2) at 60°C took 3h to complete and led to the isolation of trans-[CpCr(CO)2(SePPh)]2 (5, 3%), CpCr(CO)2(SeP(H)Ph) (4, 18%) and [CpCr(Se2P(O)Ph)]2 (6, 2%). The ring-opening reaction of WR via an initial homolytic P–Se bond cleavage by CpCr(CO)n· (n=2 (2A) or 3 (1A)) depicts a new approach to coordination chemistry involving P–Se based ligands. A mechanistic pathway was proposed according to the evidences obtained from thermolysis, NMR and mass spectra studies. All the products of 4, 5 and 6 have been structurally characterized by single-crystal X-ray diffraction analysis.

Long range phosphorus–phosphorus coupling constants in bis(phosphorylhydroxymethyl)benzene derivatives

Abstract Long range spin–spin couplings found between two phosphorus atoms are quite rare phenomena. A new example of such a coupling through seven bonds is described for 1-[(diethoxyphosphoryl)butyryloxymethyl]-4-[(diethoxyphosphoryl)hydroxymethyl]benzene and 1,4-bis[phosphorylhydroxymethyl]benzene and through six bonds for tetraethyl phenylene-1,3-(bishydroxymethylphosphonate). Coupling constants in this system are also well predicted by theoretical studies.

NMR and X-ray crystallographic studies of unsymmetrical 25,26;27,28-dibridged para-tert-butyl calix[4]arene bisphosphites with a large “through-space” P–P coupling

Three 25,26-bridged para-tert-butyl-calix[4]arene phosphites, 1–3, have been synthesized by linking two proximal phenolic oxygen atoms of para-tert-butyl-calix[4]arene to a P(OR) [R = 2,6-But2–4-Me-C6H2 (1), 2,6-Pri2-C6H3 (2) or 2,4-But2-C6H3 (3)] moiety. NMR spectroscopic data and X-ray crystallographic studies (1 and 2 only) show that the calixarene framework in 1 adopts a cone conformation, whereas in 2 and 3 it assumes a partial cone conformation. Unsymmetrical 25,26;27,28-dibridged para-tert-butyl-calix[4]arene bisphosphites 5–7 have been synthesized by the reaction of 25,26-bridged para-tert-butyl-calix[4]arene phosphite 1 with (R′O)PCl2 [R′ = 2,4-But2-C6H3 (5), 2,6-Pri2-C6H3 (6) or (1R,2S,5R)-(−)menthyl (7)]. NMR investigations (homonuclear 31P COSY) revealed an unprecedented “through-space” phosphorus–phosphorus coupling of 223–244 Hz for these unsymmetrical 25,26;27,28-dibridged para-tert-butyl-calix[4]arene bisphosphites. The molecular structure of unsymmetrical 25,26;27,28-bridged bisphosphite 5 was determined by X-ray crystallography; the two phosphorus atoms are in close proximity and the P⋯P distance (3.543(2) Å) is less than the sum of their van der Walls radii.

Measurement of Δ 1J( 199Hg, 31P) in [HgPCy 3(OAc) 2] 2 and relativistic ZORA DFT investigations of mercury–phosphorus coupling tensors

Using 31P solid-state NMR spectroscopy, anisotropy in the indirect 199Hg- 31P spin–spin coupling tensor (Δ J) for powdered [HgPCy 3(OAc) 2] 2 ( 1) has been measured as 4700±300 Hz. Zeroth-order regular approximation (ZORA) density functional theory (DFT) calculations, including scalar and spin-orbit relativistic effects, performed on 1 and a series of other related compounds show that Δ J( 199Hg, 31P) arises entirely from the ZORA Fermi-contact–spin-dipolar cross term. The calculations validate assumptions made in the spectral analysis of 1 and in previous determinations of Δ J in powder samples, namely that J is axially symmetric and shares its principal axis system with the direct dipolar coupling tensor ( D). Agreement between experiment and theory for various 199Hg, 31P spin–spin coupling anisotropies is reasonable; however, experimental values of 1 J( 199Hg, 31P) iso are significantly underestimated by the calculations. The most important improvements in the agreement were obtained as a result of including more of the crystal lattice in the model used for the calculations, e.g., a change of 43% was noted for 1 J( 199Hg, 31P) iso in [HgPPh 3(NO 3) 2] 2 depending on whether the two or three nearest nitrate ions are included in the model. Finally, we have written a computer program to simulate the effects of non-axial symmetry in J and of non-coincidence of the J and D on powder NMR spectra. Simulations clearly show that both of these effects have a pronounced impact on the 31P NMR spectrum of 199Hg– 31P spin pairs, suggesting that the effects should be observable experimentally if a suitable compound can be identified.

Synthesis and Mechanism Studies on Amide Bond Formation by Hexamethylphosphoramide (HMPA)

In this paper, hexamethylphosphoramide (HMPA) was used as the organic phosphorus coupling reagent for the synthesis of amide bond. The reaction mechanism was tracked and investigated through 31P NMR.

A Reactive Niobium Phosphinidene P8 Cluster Obtained by Reductive Coupling of White Phosphorus

A Reactive Niobium Phosphinidene P₈ Cluster Obtained by Reductive Coupling of White Phosphorus