Search results for "Phosphorus-31 NMR spectroscopy"

NMR spectroscopy in environmental chemistry:1H and13C NMR parameters of tricyclic polychlorinated C10 hydrocarbons and their oxy derivatives based on…

1999

Two-dimensional homo- and heteronuclear NMR chemical shift correlation techniques were applied in the characterization of five tricyclic polychlorinated C10 hydrocarbons, chlordene (1), heptachlor (2), trans-nonachlor (3), α-chlordene (4) and γ-chlordene (5), which are spread globally in the environment owing to their use as insecticides. Approximate and partly contradictory 1H and 13C NMR chemical shifts reported in the literature were corrected in this work. The chemical shift assignments of 1–5 were based on DQF COSY, HMQC and HMBC experiments. In addition, an INADEQUATE experiment was needed to ascertain the 13C chemical shifts assignment of 2. The nJ(H,H)s of 1–5 were solved by compute…

"Through-space" nuclear spin-spin J(PP) coupling in tetraphosphine ferrocenyl derivatives: a (31)P NMR and X-ray structure correlation study for coor…

2004

Herein, we report on (31)P(31)P solution-phase "through-space" nuclear spin-spin coupling constants (J(PP)) from a novel family of organometallic tetraphosphine nickel and palladium complexes. These J(PP) constants were accurately determined through NMR iterative simulation based on the second-order spectra obtained for the compounds. The corresponding solid-state X-ray structures of the complexes were determined, and the "through-space" P.P distances are reported. Due to the blocked conformation of the species in solution, a qualitative and semiquantitative experimental correlation is obtained, which links the geometric parameters and the intensity of the corresponding P.P coupling constan…

“Through-space” nuclear spin–spin couplings in ferrocenyl polyphosphanes and diphosphino cavitands: A new way of gathering structural information in …

2009

Abstract Nuclear magnetic resonance is an invaluable technique for investigating a variety of important issues ranging from the determination of molecular structure to therapeutic medical imaging. In this respect, the indirect nuclear spin–spin coupling involving common nuclei such as 1 H, 13 C or 31 P provides, via the J constant, conclusive data for compound characterization in solution. This electron-mediated nuclear spin coupling is usually regarded as being transmitted by covalently bonded magnetic atoms. However, several experimental and theoretical studies, first focused on constrained organofluorides, and more recently devoted to phosphane ligands highlighted the existence of very i…

Phosphorus NMR as a tool to study mineralization of organophosphonates—The ability of Spirulina spp. to degrade glyphosate

2007

Abstract A commercially available mixed culture of Spirulina spp. exhibited a remarkable ability to degrade the widely used organophosphorus herbicide glyphosate, that served as sole source of either phosphorus or nitrogen for cyanobacterial growth. 31P NMR analysis of spent media appeared to be an effective and simple technique to follow disappearance of the phosphonate and release of inorganic phosphate in biodegradation process(es).

1H, 13C and 17O NMR spectral study of chlorinated 3,4-dihydroxybenzaldehydes (protocatechualdehydes)

1995

Abstract Chlorinated 3,4-dihydroxybenzaldehydes have been studied by means of 1 H, 13 C and 17 O NMR spectroscopy. The 1 H and 13 C NMR spectral assignments are based on 2-dimensional 13 C- 1 H chemical shift correlation spectroscopy (COSY). The 17 O NMR measurements at natural isotope content in organic solvents are problematic owing to the poor solubility of the compounds and/or broadness of the resonance lines. In aqueous alkaline solutions, however, all protocatechualdehydes exhibit “easy-to-detect” 17 O NMR spectral characteristics. The 17 O NMR chemical shifts in the range of 140–480 p.p.m. are interpreted as arising from the different canonical structures of formyl substituted phenol…

13C and15N NMR study of substituted 1,2,4-triazines

1995

13C and 15N NMR spectra of eight substituted 1,2,4-triazines were measured and assigned. The assignments of the 13C NMR spectra were based on the substituent chemical shifts and nJ(C,H) coupling constants. 15N NMR chemical shifts generally showing well separated ranges were assigned by the proton coupled 15N NMR spectra. 15N NMR chemical shifts of N-4 in 3- and 5-methoxy or -thiomethyl-substituted 1,2,4-triazines were found to be related significantly (confidence level >99%) with the π-charge at N-4 calculated by a semi-empirical molecular orbital (AM1) procedure. For the 15N NMR chemical shifts of N-1 and N-2, no reliable correlations with the molecular electronic properties such as AM1 π-…

?-Phenylsulfonyl-N-arylacetamides (?-phenylsulfonylacetanilides):1H,13C and15N NMR spectral characterization

2000

Nuclear charge radii of the even sulphur isotopesS32,S34, andS36and ofP31using muonic atoms

1985

Energies of muonic x rays of the Lyman series of the even sulphur isotopes /sup 32/S, /sup 34/S, and /sup 36/S and of natural phosphorus have been determined with absolute precisions up to 23 parts/10/sup 6/. Equivalent Barrett charge radii R/sub k/,..cap alpha.. have been deduced. Their differences between the sulphur isotopes amount to ..delta..R/sub k/,..cap alpha..( /sup 34/S- /sup 32/ S) = 29.7(1.4) am and ..delta..R/sub k/,..cap alpha..( /sup 36/S- /sup 34/ S) = 18.7(1.5) am. Combining these results with recent elastic electron scattering data, we obtain in a model-independent way ..delta../sup 1/2/( /sup 34/S- /sup 3/ 2S) = 23.1(1.2) am and ..delta../sup 1/2/( /sup 36/S- /sup 3/ 4S) …

Lifetime measurements in mirror nuclei31S and31P: A test for isospin mixing

2011

Using the 20Ne + 12C fusion-evaporation reaction at E20Ne = 33 MeV and the multidetector array GASP in conjuction with the EUCLIDES charged particle detector, angular correlations of coincident pairs of γ transitions and lifetimes in mirror nuclei 31S and 31P have been measured at the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. A comparison of the determined B(E1) strengths of the analog mirror 7/2− → 5/2+ transitions indicates the presence of a violation of isospin symmetry.

Reevaluation of theP30(p,γ)S31astrophysical reaction rate from a study of theT=1/2mirror nuclei,S31andP31

2006

The $^{30}\mathrm{P}$($p,\ensuremath{\gamma}$)$^{31}\mathrm{S}$ reaction rate is expected to be the principal determinant for the endpoint of nucleosynthesis in classical novae. To date, the reaction rate has only been estimated through Hauser-Feschbach calculations and is unmeasured experimentally. This paper aims to remedy this situation. Excited states in $^{31}\mathrm{S}$ and $^{31}\mathrm{P}$ were populated in the $^{12}\mathrm{C}$($^{20}\mathrm{Ne}$,$n$) and $^{12}\mathrm{C}$($^{20}\mathrm{Ne}$,$p$) reactions, respectively, at a beam energy of 32 MeV, and their resulting $\ensuremath{\gamma}$decay was detected with the Gammasphere array. Around half the relevant proton unbound states …