31P NMR assessment of the phosvitin-iron complex in mayonnaise

Lipid oxidation is the main reason for the limited shelf life of mayonnaise. One of the main catalysts of this process is iron, which is introduced in its ferric (Fe(III)) form via phosvitin, an egg yolk phosphoprotein rich in phosphoserines. The binding of Fe(III) to phosvitin and its ability to establish a redox couple with Fe(II) is believed to determine the oxidation rate of unsaturated lipids. In this work, a ³¹P NMR based method was developed to quantify loading of phosvitin with Fe(III) and its reductive release. Both features could be quantified in model phosvitin solutions by exploiting the paramagnetic broadening of ³¹P NMR signal of phosphoserine residues by Fe(III). This method was then successfully applied to quantify the phosvitin-Fe(III) loading in mayonnaise water phase by liquid NMR, whereas ³¹P NMR MAS could only provide a qualitative measure. The ³¹P NMR method showed a direct relation between loading of the Fe(III)-phosvitin complex and lipid oxidation.     

Determination of 31P,31P coupling constants in cyclotriphosphazenes and their influence on 1H and 13C NMR spectra of phosphorus substituents

¹H and ¹³C NMR spectra of symmetrically substituted cyclotriphosphazenes exhibit second‐order effects. The influence of the ³¹P,³¹P coupling constants between ring phosphorus atoms on these effects was studied. Some values of this coupling constant between phosphorus bearing identical substituents were measured using ¹³C satellites of the ³¹P signals or by introduction of a chiral substituent on the third phosphorus atom. Copyright © 2003 John Wiley & Sons, Ltd.     

Application of <Superscript>31</Superscript>P NMR for added polyphosphate determination in pork meat

Application of ³¹P NMR for qualitative and quantitative determination of added phosphorus compounds in meat samples is described. Furthermore, usefulness of the proposed method for monitoring of poly- and pyrophosphates hydrolysis in meat is discussed. Calibration curves based on the ³¹P resonance line areas were elaborated for Na₃P₃O₉, Na₅P₃O₁₀, Na₂H₂P₂O₇, and K₄P₂O₇ resulting in linearity (R ² = 0.9976, 0.9953, 0.9974, and 0.9524, respectively), detection limits (DL from 0.0018 mol L⁻¹ for Na₃P₃O₉ to 0.0070 mol L⁻¹ for K₄P₂O₇), and quantification limits (QL from 0.0060 mol L⁻¹ for Na₃P₃O₉ to 0.0234 mol L⁻¹ for K₄P₂O₇). The developed procedure was applied for laboratory prepared meat samples and compared with the standard UV-VIS method. The minimal sample pretreatment, obtained within-day precision (CV ≤ 2.0 %) and accuracy (as recovery ≥ 95 %) suggest ³¹P NMR as an alternative method of phosphorus determination in food analysis.     

31P NMR Study on Some Phosphorus-Containing Compounds

In view of the facts that the phenomena of aggregation are inseparably related to life processes and that phosphorus-containing compounds are one of the essential building blocks of life, we have studied the aggregation behavior of some phosphonates and phosphinates1. The application of NMR to the problems in chemistry has become rather popular. In phosphorus-containing compounds, phosphorus is a central or backbone atom in molecular structures. 31P NMR is of importance and special value in …     

Solid‐state 31P NMR investigation on the status of guanine nucleotides in paclitaxel‐stabilized microtubules

Microtubule dynamics is a target for many chemotherapeutic drugs. In order to understand the biochemical effects of paclitaxel on the GTPase activity of tubulin, the status of guanine nucleotides in microtubules was investigated by ³¹P cross‐polarization magic angle spinning (CPMAS) NMR. Microtubules were freshly prepared in vitro in the presence of paclitaxel and then lyophilized in sucrose buffer for solid‐state NMR experiments. A ³¹P CPMAS NMR spectrum with the SNR of 25 was successfully acquired from the lyophilized microtubule sample. The broadness of the ³¹P spectral lines in the spectrum indicates that the molecular environments around the guanine nucleotides inside tubulin may not be as crystalline as reported by many diffraction studies. Deconvolution of the spectrum into four spectral components was carried out in comparison with the ³¹P NMR spectra obtained from five control samples. The spectral analysis suggested that about 13% of the nucleotides were present as GTP and 37% as GDP in the β‐tubulin (E‐site) of the microtubules. It was found that most of the GDPs were present as GDP‐P_i complex in the microtubules, which seems to be one of the effects of paclitaxel binding. Copyright © 2015 John Wiley & Sons, Ltd.     

Complete 1H, 13C, 19F and 31P NMR data assignment of CWC‐related chemicals N,N‐dialkyl‐P‐alkyl phosphonamidic fluorides

The complete multinuclear ¹H, ¹³C, ³¹P and ¹⁹F NMR data of symmetrically substituted amines containing N,N‐dialkyl‐P‐alkyl phosphonamidic fluorides are presented. Assignment was achieved, using various one‐and two‐dimensional NMR experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

1D to 3D NMR study of microporous alumino‐phosphate AlPO4‐40

From one‐ to two‐ and three‐dimensional MAS NMR solid‐state experiments involving ³¹P and ²⁷Al, we show that the structure of microporous alumino‐phosphate AlPO₄‐40 contains at least four times more sites than expected, and we attribute two types of Al_IV sites. The newly described ²⁷Al‐³¹P MQ‐HMQC opens new possibilities of describing details of three‐dimensional bounded networks. Copyright © 2009 John Wiley & Sons, Ltd.     

Phosphorus NMR Characterisation of P–N Bond Rotamers of a α‐P4S3 Amide with a Conformationally Constrained Chiral Substituent

Reactions of bicyclic α‐P₄S₃I₂ with Hpthiq gave solutions containing α‐P₄S₃(pthiq)I and α‐P₄S₃(pthiq)₂, where Hpthiq is the conformationally constrained chiral secondary amine 1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline. The expected diastereomers have been characterised by complete analysis of their ³¹P{¹H} NMR spectra. Hindered P–N bond rotation in the amide iodide α‐P₄S₃(pthiq)I caused greater broadening of peaks in the room‐temperature spectrum of one diastereomer than in that of the other. At 183 K, spectra of two P–N bond rotamers for each diastereomer were observed and analysed. The minor rotamers showed strong evidence for steric crowding, having large diastereomeric differences in ¹J(P–P) and ²J(P–S–P) couplings (49 Hz, 16 % of value, and 4.4 Hz, 19 % of value, respectively).     

Phosphorus NMR and Ab Initio Modelling of P–N Bond Rotamers of a Sterically Crowded Chiral β‐P4S3 Diamide

Reaction of bicyclic β‐P₄S₃I₂ with enantiomerically pure (R)‐Hpthiq (1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline) and Et₃N gave a solution of a single diastereomer of the unusually stable diamide β‐P₄S₃(pthiq)₂, accounting for 83 % of the phosphorus content. Despite the steric bulk of the substituents, each amide group of this could adopt either of two rotameric positions about their P–N bonds, so that, at 183 K, ³¹P NMR multiplets for four rotamers could be observed and the spectra of three of them analysed fully. The large ²J(P–P–P) coupling became greater (253, 292, 304 Hz) with decreasing abundance of the individual rotamers. The rotamers were modelled at the ab initio RHF/3–21G* level, and relative NMR chemical shifts predicted by the GIAO method using a locally dense basis set, allowing the observed spectra to be assigned to structures. Calculations at the same level for the model compound α‐P₄S₃(pthiq)Cl confirmed the assignments of low‐temperature rotamers of α‐P₄S₃(pthiq)I reported previously. Changes in observed P–P coupling constants and ³¹P chemical shifts, on rotating a pthiq substituent, could then be compared between β‐P₄S₃(pthiq)₂ and α‐P₄S₃(pthiq)I, confirming both sets of assignments. The most abundant rotamer of β‐P₄S₃(pthiq)₂ was not the one with the least sterically crowded sides of both pthiq substituents pointing towards the P₄S₃ cage, because of interaction between the two substituents. Only by using a DFT method could relative abundances of rotamers of β‐P₄S₃(pthiq)₂ be predicted to be in the observed order. Use of racemic Hpthiq gave also the two diastereomers of β‐P₄S₃(pthiq)₂ with C_s symmetry, for which the room temperature ³¹P{¹H} NMR spectra were analysed fully.     

^31P NMR Studies on the Ligand Dissociation of Trinuclear Molybde-num Cluster Compounds

A series of carboxylate-substituted trinudear molybdenum dus-ter compounds formulated as Mo3S4(DTP)3(RCO2)(L), where RffiH, CH3, C2H5, CH2Cl, CCl3, R^1C6H4(R^1 is the group on the benzene ring of aromatic carboxylate ), L=pyridine,CH3CN, DMF, have been synthesized by the ligand substitu-tion reaction. The dissociation of the loosely-coordinated ligand L from the cluster core was studied by ^31p NMR. The dissocia-tion process of L is related to the solvent, temperature, and acidity of carboxylate groups, so as to affect the solution struc-ture and reactive properties of the duster. The long-distance in-teraction between ligands RCO2 and L is transported by Mo3S4 core.     

Investigation of Reaction Mechanism of Amino Acids and Phosphorus Trichloride by 31P NMR and ESI‐MS/MS

The reaction of amino acids and phosphorus trichloride in THF was studied by ³¹P NMR tracing and ESI‐MS/MS. A series of hydridophoranes and cyclic dipeptides were obtained. The reaction presented interesting diversity and the reaction mechanism was proposed. The mechanism suggests that phosphorus plays an important role in the synthesis of amino acid hydridophorane and cyclic dipeptides. The results also show that ³¹P NMR and ESI‐MS/MS are useful tools for the investigation of reaction mechanism.     

1H, 13C and 31P NMR spectral analysis of monoalkyl (α‐anilinobenzyl)phosphonates and their dipalladium(II) metallocyclic complexes

A ¹H, ¹³C and ³¹P NMR study of monoethyl (HL1) and monobutyl (HL2) esters of (α‐anilinobenzyl)phosphonic acid and their metallocyclic dipalladium complexes (Pd₂L₄,L = L1, L2) in DMSO‐d₆ was performed, based on 1D and 2D homo‐ and heteronuclear experiments including ¹H,¹³C,³¹P,APT,¹H–¹H COSY, ¹H–¹³C COSY, gs‐HMQC and gs‐HMBC NMR techniques. The results obtained are discussed with respect to those for some palladium(II) complexes reported for various anilinobenzylphosphonate derivatives. Copyright © 2002 John Wiley & Sons, Ltd.     

用31P NMR研究硫代磷酸酯水解反应历程

磷酸酯的水解反应是一类较为重要的反应,了解这类反应历程及机理对研究农药的毒性、环境保护、及指导农药的生产与合成具有十分重要的意义。~(31)PNMR灵敏度高,化学位移范围宽,偶合常数大.~(31)P NMR的化学位移对于分子中磷原子的价态、与磷原子直接相连的原子或基团的类型、数量、性质及构型的变化十分敏感.是研究有关含磷化合物结构问题的有效手段之一,因此本文采用~(31)P NMR方法研究了疏代磷酸酯的水解反应历程。本文所研究的化合物是一种新合成的含七元环的二硫代磷酸酯。其结构式如下:     

Layered metal(IV) phosphonate materials: Solid‐state 1H, 13C, 31P NMR spectra and NMR relaxation

Multinuclear solid‐state NMR and powder X‐ray diffraction data collected for phosphonate materials Zr(O₃PC₆H₄PO₃) · 3.6H₂O and Sn(O₃PC₆H₄PO₃)_0.85(O₃POH)_0.30 · 3.09H₂O have resulted in the layered structure, where the phosphonic acids cross‐link the layers. The main structural motif (the 111 connectivity in the PO₃ group) has been established by determination of chemical shift anisotropy parameters for phosphorus nuclei in the phosphonate groups. An analysis of the variable‐temperature ³¹P T₁ measurements and the shapes of the phosphorus resonances in the ³¹P static NMR spectra have resulted in the dipolar mechanism of the phosphorus spin‐lattice relaxation, where the rotating phenylene rings reorient dipolar vectors P^…H as a driving force of the relaxation process. It has been found that water protons do not affect the ³¹P T₁ times. The activation energy of the phenylene rotation in both compounds has been determined as low as 12.5 kJ/mol. The interpretation of the phosphorus relaxation data has been independently confirmed by the measurements of ¹H T₁ times for protons of the phenylene rings.     

31P NMR spectroscopy in the quality control and authentication of extra-virgin olive oil: a review of recent progress

This review is a brief account on the application of a novel methodology to the quality control and authentication of extra-virgin olive oil. This methodology is based on the derivatization of the labile hydrogens of functional groups, such as hydroxyl and carboxyl groups, of olive oil constituents with the phosphorus reagent 2-chloro-4,4,5,5-tetramethyldioxaphospholane, and the use of the (31)P chemical shifts to identify the phosphitylated compounds. Various experimental aspects such as pertinent instrumentation, sample preparation, acquisition parameters and properties of the phosphorus reagent are reviewed. The strategy to assign the (31)P signals of the phosphitylated model compounds and olive oil constituents by employing 1D and 2D NMR experiments is presented. Finally, the capability of this technique to assess the quality and the genuineness of extra-virgin olive oil and to detect fraud is discussed.     

Phosphorylated amino acids: model compounds for solid-state 31P NMR spectroscopic studies of proteins

Solid-state 31P NMR spectroscopy was applied to measure the isotropic chemical shifts, chemical shift anisotropies and asymmetry parameters of three phosphorylated amino acids, O-phospho-L-serine, O-phospho-L-threonine and O-phospho-L-tyrosine. The cross-polarization buildup rates and longitudinal relaxation times of 31P and 1H were-determined and compared with the values measured for a triphosphate (GppCH2p) bound to a crystalline protein (Ras). It is shown that the phosphorylated amino acids are well-suited model compounds, e.g. for the optimization of experiments on crystalline proteins. Two-dimensional exchange experiments on O-phospho-L-tyrosine indicate the existence of an exchange between the two different conformations of the molecule.     

Recent advances in computational 31P NMR: Part 1. Chemical shifts

This is the first part of two closely related reviews dealing with the computation of phosphorus-31 nuclear magnetic resonance chemical shifts in a wide series of organophosphorus compounds including complexes, clusters, and bioorganic phosphorus compounds. In particular, the analysis of the accuracy factors, such as substitution effects, solvent effects, vibrational corrections, and relativistic effects, is presented. This review is dedicated to the Full Member of the Russian Academy of Sciences Professor Boris A. Trofimov in view of his invaluable contribution to the field of synthesis, nuclear magnetic resonance, and computation studies of organophosphorus compounds.     

Simultaneous determination of phenolic compounds and triterpenic acids in oregano growing wild in Greece by 31P NMR spectroscopy

³¹P nuclear magnetic resonance (NMR) spectroscopy was used to detect and quantify simultaneously a large number of phenolic compounds and the two triterpenic acids, ursolic acid and oleanolic acid, extracted from two oregano species Origanum onites and Origanum vulgare ssp. Hirtum using two different organic solvents ethanol and ethyl acetate. This analytical method is based on the derivatization of the hydroxyl and carboxyl groups of these compounds with the phosphorous reagent 2‐chloro‐4,4,5,5‐tetramethyl‐1,3,2‐dioxa phospholane and the identification of the phosphitylated compounds on the basis of the ³¹P chemical shifts. Unambiguous assignment of the ³¹P NMR chemical shifts of the dihydroxy‐ and polyhydroxy‐phenols in oregano species as well as those of the triterpenic acids was achieved upon comparison with the chemical shifts of model compounds assigned by using two‐dimensional NMR techniques. Furthermore, the integration of the appropriate signals of the hydroxyl derivatives in the corresponding ³¹P NMR spectra and the use of the phosphitylated cyclohexanol as an internal standard allowed the quantification of these compounds. The validity of this technique for quantitative measurements was thoroughly examined. Copyright © 2012 John Wiley & Sons, Ltd.     

Bildung und Struktur des [{η2‐tBu2P–P}Pt(PHtBu2)(PPh3)]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XX Formation and Structure of [{η²‐^tBu₂P–P}Pt(PH^tBu₂)(PPh₃)] [{η²‐^tBu₂P¹–P²}Pt(P³Ph₃)(P⁴Ph₃)] ( 2 ) reacts with ^tBu₂PH exchanging only the P³Ph₃ group to give [{η²‐^tBu₂P¹–P²}Pt(P³H^tBu₂)(P⁴Ph₃)] ( 1 ). The crystal stucture determination of 1 together with its ³¹P{¹H} NMR data allow for an unequivocal assignment of the coupling constants in related Pt complexes. 1 crystallizes in the triclinic space group P1 (no. 2) with a = 1030.33(15), b = 1244.46(19), c = 1604.1(3) pm, α = 86.565(17)°, β = 80.344(18)°, γ = 74.729(17)°.     

Solid-state 31P and 109Ag CP/MAS NMR as a powerful tool for studying of silver(I) complexes with N-thiophosphorylated thiourea and thioamide ligands

A family of three- and four-coordinated silver(I) complexes of formulas [Ag(PPh₃)₂L], [Ag(PPh₃)L], and [AgL]_n with N-thiophosphorylated thiourea and thioamide ligands of general formula RC(S)NHP(S)(OPri)₂ [R = Ph, PhNH, iPrNH, tBuNH, NH₂] have been studied by solid-state ¹⁰⁹Ag and ³¹P CPMAS NMR spectroscopy. ¹⁰⁹Ag NMR spectra have provided valuable structural information about Ag coordination, which is in good accordance with the available crystal structure data. The data presented in this work represent a significant addition to the available ¹⁰⁹Ag chemical shifts and chemical shifts anisotropies. The silver chemical shift ranges for different P,S-environments and coordination state were discussed in detail. The ¹J(³¹P–^107/109Ag) and ²J(³¹P–³¹P) values were determined and analyzed.