Effets des sels de terres rares sur quelques phosphates dérivés des metabolites de la glycolyse

1991 ◽  
Vol 69 (8) ◽  
pp. 1281-1287 ◽  
Author(s):  
Claude Rabiller ◽  
Philippe Eymard ◽  
Mahmoud Mesbahi
Keyword(s):  
Nmr Spectroscopy ◽  
Key Words ◽  
Fermentation Process ◽  
Chemical Shifts ◽  
Deuterium Nmr ◽  
Sugar Fermentation ◽  
Phosphoglyceric Acid ◽  
Spectroscopy Studies ◽  
Sugar Derivatives ◽  
Derivatives Of

Phosphate derivatives of glucose and fructose are well-known intermediates in sugar fermentation. Proton and deuterium NMR spectroscopy studies of the fermentation process provide information about proton (deuteron) transfers that are likely to occur in such biotransformations. In this paper we describe the influence of complexation of those metabolites with praseodymium trichloride and of pH on their proton NMR chemical shifts. We determine the conditions under which all the protons of both the α. and β forms of these cyclic sugars are separated. Glucose-1 phosphate was found to be the most suitable derivative for this type of study. Furthermore, comparing the behaviour of these compounds with 2-phosphoglyceric acid allows us to specify the exact conformation of the latter. Key words: phosphate sugar derivatives, NMR, LIS effects.

Cationic thiolate and selenolate complexes of platinum(IV)

2002 ◽  
Vol 80 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Michael C Janzen ◽  
Michael C Jennings ◽  
Richard J Puddephatt
Keyword(s):  
Nmr Spectroscopy ◽  
Key Words ◽  
Oxidative Addition ◽  
Competitive Reaction ◽  
Methyl Group ◽  
X Ray ◽  
Group Transfer ◽  
Structure Determinations ◽  
Derivatives Of ◽  
Methyl Group Transfer

The reaction of the adamantanoid compounds [Hg4(EPh)6(L)4][ClO4]2 (E = S or Se, L = PEt3 or PPh3) with [PtMe2(bu2bpy)] (bu2bpy = 4,4'-di-tert-butyl-2,2'-bipyridine) occurs easily to give the first examples of cationic thiolate or selenolate derivatives of platinum(IV), [PtMe2(EPh)L(bu2bpy)][ClO4], and the addition is shown to occur with trans stereochemistry. The new complexes are characterized by NMR spectroscopy and when L = PEt3 by X-ray structure determinations. When L = PPh3, a competitive reaction leads to methyl group transfer from platinum to mercury to give MeHgEPh (E = S or Se).Key words: oxidative-addition, platinum, thiolate, selenolate, mercury.

Study of Substituted Formylchromones

1994 ◽  
Vol 59 (7) ◽  
pp. 1673-1681 ◽  
Author(s):  
Hafez M. El-Shaaer ◽  
Pavol Zahradník ◽  
Margita Lácová ◽  
Mária Matulová
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Chemical ◽  
Chemical Method ◽  
Electron Distribution ◽  
Chemical Shifts ◽  
Aromatic Nucleus ◽  
Quantum Chemical Method ◽  
Pyrone Ring ◽  
H Nmr ◽  
Derivatives Of

Substituted derivatives of 2- and 3-formylchromone were synthesized and studied by IR, 13C and 1H NMR spectroscopy and the AM1 quantum chemical method. Energy and electron distribution calculations confirm the preference of the synplanar conformation in 3-formylchromones. The calculated charges on the carbon atoms correlate well with the experimental 13C chemical shifts. Substituents bonded to the aromatic nucleus have only small effect on the electron structure of the pyrone ring.

The Synthesis of 10-Halo-Substituted Derivatives of nido-7,8,9-PC2B8H11 and [nido-7,8,9-PC2B8H10]- and New Linear Correlations Between NMR Parameters

2005 ◽  
Vol 70 (11) ◽  
pp. 1861-1872 ◽  
Author(s):  
Josef Holub ◽  
Mario Bakardjiev ◽  
Bohumil Štíbr
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Proton Sponge ◽  
Nmr Chemical Shifts ◽  
Nmr Parameters ◽  
Neutral Compounds ◽  
Experimental Errors ◽  
Derivatives Of ◽  
Linear Correlations ◽  
Individual Cluster

Halogenation of the eleven-vertex phosphadicarbaborane nido-7,8,9-PC2B8H10 (1) with CCl4, Br2 or I2 in the presence of anhydrous AlCl3 (solvents CCl4, CS2, and benzene, respectively) generated a series of 10-X-nido-7,8,9-PC2B8H10 (10-X-1) compounds (X = Cl, Br, and I) in yields 55, 65, and 63%, respectively. Anionic compounds [10-X-nido-7,8,9-PC2B8H10]- (10-X-2) (X = Cl, Br, I) were obtained by treatment of the corresponding neutral compounds with "proton sponge" (PS = 1,8-bis(dimethylamino)naphthalene). All compounds were characterized by multinuclear (11B, 1H, and 31P) NMR spectroscopy and [11B-11B]-COSY and 1H-{11B(selective)} NMR measurements that led to complete assignments of all 11B and 1H resonances to individual cluster positions. Interesting halo-substitution NMR effects are also discussed in terms of new linear correlations. All the changes in NMR chemical shifts (∆) induced at the various skeletal sites by halogeno substituents on specific sites can be related to an arbitrary reference skeleton and are, within experimental errors, linearly proportional to those induced at the substituted site (∆α) of the reference skeleton.

Synthesis, spectroscopic and structural studies of O-methyl and O-isopropyl monothiocarbonate (monoxanthate) derivatives of dimethyl-and diphenyltellurium(IV). Crystal structures of Me2Te[SCO2(i-Pr)]2, Ph2Te[SCO2(i-Pr)]2, Me2TeCl[SCO2Me], and Me2TeBr[SCO2(i-Pr)]

1996 ◽  
Vol 74 (11) ◽  
pp. 1968-1982 ◽  
Author(s):  
John E. Drake ◽  
Robert J. Drake ◽  
Layla N. Khasrou ◽  
Anil G. Mislankar ◽  
Raju Ratnani ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Key Words ◽  
Lone Pair ◽  
Supramolecular Interactions ◽  
Equatorial Position ◽  
Structural Studies ◽  
Cell Parameters ◽  
Distorted Trigonal Bipyramid ◽  
Derivatives Of ◽  
Oxygen Atoms

Monothiocarbonate derivatives of diorganotellurium(IV), R2Te[SCO2R′]2, and R2TeX[SCO2R′], where R = Me, Ph; R′ = Me, i-Pr; X = Cl, Br, and I, have been prepared and characterized by vibrational and 1H, 13C, and 125Te NMR spectroscopy. Me2Te[SCO2(i-Pr)]2 (2): P21/n (No. 14) with cell parameters a = 6.942(6) Å, b = 25.599(3) Å, c = 9.404(6) Å, β = 94.48(6)°, V = 1666(1) Å3, Z = 4, R = 0.0648, Rw = 0.0624; Ph2Te[SCO2(i-Pr)]2 (4): P21/n (No. 14) with a = 12.360(4) Å, b = 12.277(3) Å, c = 15.066(3) Å, β = 102.82(2)°, V = 2229.1(9) Å3, Z = 4, R = 0.0368, Rw = 0.0312; Me2TeCl[SCO2Me] (5); P21/c (No. 14) with a = 5.193(2) Å, b = 18.118(4) Å, c = 9.613(5) Å, β = 91.31(6)°, V = 904.2(6) Å3, Z = 4, R = 0.0396, Rw = 0.0361; and Me2TeBr[SCO2(i-Pr)] (8): P21/n (No. 14) with a = 11.701(2) Å, b = 6.250(2) Å, c = 16.152(2) Å, β = 98.43(1)°, V = 1168.4(4) Å3, Z = 4, R = 0.0369, Rw = 0.0325. In all molecules, the immediate environment about tellurium is that of the saw-horse structure in which the lone pair is assumed to be stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. In 2 and 5, the terminal oxygen atoms are oriented toward tellurium, whereas in 4, one O(i-Pr) group is oriented toward tellurium, as it is in 8. In the latter cases, the terminal oxygen atoms act as weak bridges to form a pseudo dimeric species in 4 and a pseudo polymer in 8. Supramolecular interactions in 2 and 5 lead to a sulfur-bridged dimer in the former and a chlorine-bridged polymer in the latter. Key words: structure, tellurium, dimethyl, diphenyl, monothiocarbonates.

Monitoring the encapsulation of chlorin e6 derivatives into polymer carriers by NMR spectroscopy

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1576-1586 ◽  
Author(s):  
Sara Pfister ◽  
Luca Sauser ◽  
Ilche Gjuroski ◽  
Julien Furrer ◽  
Martina Vermathen
Keyword(s):  
Relaxation Time ◽  
Nmr Spectroscopy ◽  
Core Region ◽  
Chlorin E6 ◽  
Polypropylene Glycol ◽  
Polymer Carriers ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Dynamic Methods ◽  
Derivatives Of

The encapsulation of five derivatives of chlorin e6 with different hydrophobicity and aggregation properties into a series of five poloxamer-type triblock copolymer micelles (BCMs) with varying numbers of polyethylene and polypropylene glycol (PEG, PPG) units was monitored using 1H NMR spectroscopy. NMR chemical shift and line shape analysis, as well as dynamic methods including diffusion ordered spectroscopy (DOSY) and T1 and T2 relaxation time measurements of the chlorin and the polymer resonances, proved useful to assess the chlorin–BCM compatibility. The poloxamers had high capability to break up aggregates formed by chlorins up to intermediate hydrophobicity. Physically entrapped chlorins were always localized in the BCM core region. The loading capacity correlated with chlorin polarity for all poloxamers among which those with the lowest number of PPG units were most efficient. DOSY data revealed that relatively weakly aggregating chlorins partition between the aqueous bulk and micellar environment whereas more hydrophobic chlorins are well retained in the BCM core region, rendering these systems more stable. T1 and T2 relaxation time measurements indicated that motional freedom in the BCM core region contributes to encapsulation efficiency. The BCM corona dynamics were rather insensitive towards chlorin entrapment except for the poloxamers with short PEG chains. The presented data demonstrate that 1H NMR spectroscopy is a powerful complementary tool for probing the compatibility of porphyrinic compounds with polymeric carriers such as poloxamer BCMs, which is a prerequisite in the development of stable and highly efficient drug delivery systems suitable for medical applications like photodynamic therapy of tumors.

scholarly journals Structure of Nanobody Nb23

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3567
Author(s):  
Mathias Percipalle ◽  
Yamanappa Hunashal ◽  
Jan Steyaert ◽  
Federico Fogolari ◽  
Gennaro Esposito
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Solution Structure ◽  
Chemical Shifts ◽  
Molecular Size ◽  
Side Chain ◽  
3D Nmr ◽  
Target Antigen ◽  
Internuclear Distances ◽  
2D And 3D

Background: Nanobodies, or VHHs, are derived from heavy chain-only antibodies (hcAbs) found in camelids. They overcome some of the inherent limitations of monoclonal antibodies (mAbs) and derivatives thereof, due to their smaller molecular size and higher stability, and thus present an alternative to mAbs for therapeutic use. Two nanobodies, Nb23 and Nb24, have been shown to similarly inhibit the self-aggregation of very amyloidogenic variants of β2-microglobulin. Here, the structure of Nb23 was modeled with the Chemical-Shift (CS)-Rosetta server using chemical shift assignments from nuclear magnetic resonance (NMR) spectroscopy experiments, and used as prior knowledge in PONDEROSA restrained modeling based on experimentally assessed internuclear distances. Further validation was comparatively obtained with the results of molecular dynamics trajectories calculated from the resulting best energy-minimized Nb23 conformers. Methods: 2D and 3D NMR spectroscopy experiments were carried out to determine the assignment of the backbone and side chain hydrogen, nitrogen and carbon resonances to extract chemical shifts and interproton separations for restrained modeling. Results: The solution structure of isolated Nb23 nanobody was determined. Conclusions: The structural analysis indicated that isolated Nb23 has a dynamic CDR3 loop distributed over different orientations with respect to Nb24, which could determine differences in target antigen affinity or complex lability.

scholarly journals Resolving Entangled JH-H-Coupling Patterns for Steroidal Structure Determinations by NMR Spectroscopy

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2643
Author(s):  
Danni Wu ◽  
Kathleen Joyce Carillo ◽  
Jiun-Jie Shie ◽  
Steve S.-F. Yu ◽  
Der-Lii M. Tzou
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Atomic Level ◽  
Molecular Structures ◽  
Naturally Occurring ◽  
Structure Determinations ◽  
Ligand Interactions ◽  
Synthetic Steroids ◽  
The Individual

For decades, high-resolution 1H NMR spectroscopy has been routinely utilized to analyze both naturally occurring steroid hormones and synthetic steroids, which play important roles in regulating physiological functions in humans. Because the 1H signals are inevitably superimposed and entangled with various JH–H splitting patterns, such that the individual 1H chemical shift and associated JH–H coupling identities are hardly resolved. Given this, applications of thess information for elucidating steroidal molecular structures and steroid/ligand interactions at the atomic level were largely restricted. To overcome, we devoted to unraveling the entangled JH–H splitting patterns of two similar steroidal compounds having fully unsaturated protons, i.e., androstanolone and epiandrosterone (denoted as 1 and 2, respectively), in which only hydroxyl and ketone substituents attached to C3 and C17 were interchanged. Here we demonstrated that the JH–H values deduced from 1 and 2 are universal and applicable to other steroids, such as testosterone, 3β, 21-dihydroxygregna-5-en-20-one, prednisolone, and estradiol. On the other hand, the 1H chemical shifts may deviate substantially from sample to sample. In this communication, we propose a simple but novel scheme for resolving the complicate JH–H splitting patterns and 1H chemical shifts, aiming for steroidal structure determinations.

23. A new adult rat brain slice preparation for ex vivo NMR spectroscopy studies of stroke

1994 ◽  
Vol 52 (1) ◽  
pp. A11
Author(s):  
M.T. Espanol ◽  
L. Litt ◽  
L.-H. Chang ◽  
T.L. James ◽  
P.R. Weinstein ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Rat Brain ◽  
Brain Slice ◽  
Ex Vivo ◽  
Slice Preparation ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Spectroscopy Studies ◽  
Rat Brain Slice ◽  
Brain Slice Preparation

Reversal of order of chemical shifts. Differential solvent effects in the hydrogen shifts of toluene,m-xylene ando-xylene as determined by 320 MHz tritium NMR spectroscopy

1984 ◽  
Vol 22 (10) ◽  
pp. 665-667 ◽  
Author(s):  
Mervyn A. Long ◽  
John K. Saunders ◽  
Philip G. Williams ◽  
Allan L. Odell ◽  
R. Wayne Martin
Keyword(s):  
Nmr Spectroscopy ◽  
Solvent Effects ◽  
Chemical Shifts ◽  
Tritium Nmr ◽  
Hydrogen Shifts
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