scholarly journals Optimisation of pyruvate hyperpolarisation using SABRE by tuning the active magnetisation transfer catalyst

2020 ◽  
Vol 10 (5) ◽  
pp. 1343-1355 ◽  
Author(s):  
Ben. J. Tickner ◽  
Olga Semenova ◽  
Wissam Iali ◽  
Peter J. Rayner ◽  
Adrian C. Whitwood ◽  
...  
Keyword(s):  
Magnetisation Transfer ◽  
Control Efficiency ◽  
Nmr Signals ◽  
C Nmr

SABRE catalysts [Ir(H)2(η2-pyruvate)(sulfoxide)(NCH) transfer magnetisation from para-hydrogen to pyruvate yielding hyperpolarised 13C NMR signals enhanced by >2000-fold. Properties of the catalyst control efficiency.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

scholarly journals Propionate stimulates pyruvate oxidation in the presence of acetate

2014 ◽  
Vol 307 (8) ◽  
pp. H1134-H1141 ◽  
Author(s):  
Colin Purmal ◽  
Blanka Kucejova ◽  
A. Dean Sherry ◽  
Shawn C. Burgess ◽  
Craig. R. Malloy ◽  
...  
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Energy Production ◽  
Nmr Spectra ◽  
Heart Tissue ◽  
Viable Myocardium ◽  
Normal Heart ◽  
Alternative Substrate ◽  
Isotopomer Analysis ◽  
Nmr Signals ◽  
C Nmr

Flux through pyruvate dehydrogenase (PDH) in the heart may be reduced by various forms of injury to the myocardium, or by oxidation of alternative substrates in normal heart tissue. It is important to distinguish these two mechanisms because imaging of flux through PDH based on the appearance of hyperpolarized (HP) [13C]bicarbonate derived from HP [1-13C]pyruvate has been proposed as a method for identifying viable myocardium. The efficacy of propionate for increasing PDH flux in the setting of PDH inhibition by an alternative substrate was studied using isotopomer analysis paired with exams using HP [1-13C]pyruvate. Hearts from C57/bl6 mice were supplied with acetate (2 mM) and glucose (8.25 mM). 13C NMR spectra were acquired in a cryogenically cooled probe at 14.1 Tesla. After addition of hyperpolarized [1-13C]pyruvate, 13C NMR signals from lactate, alanine, malate, and aspartate were easily detected, in addition to small signals from bicarbonate and CO2. The addition of propionate (2 mM) increased appearance of HP [13C]bicarbonate >30-fold without change in O2 consumption. Isotopomer analysis of extracts from the freeze-clamped hearts indicated that acetate was the preferred substrate for energy production, glucose contribution to energy production was minimal, and anaplerosis was stimulated in the presence of propionate. Under conditions where production of acetyl-CoA is dominated by the availability of an alternative substrate, acetate, propionate markedly stimulated PDH flux as detected by the appearance of hyperpolarized [13C]bicarbonate from metabolism of hyperpolarized [1-13C]pyruvate.

Neue Untersuchung über Inhaltsstoffe aus Aloe-und Rhamnus-Arten, XV [1] Homonataloin A und B aus Aloe lateritia: Reindarstellung, Konstitutions-und Konfigurationsaufklärung der Diastereomeren / A New Investigation on Constituents of Aloe and Rhamnus Species, XV [1] Hom onataloins A and B from Aloe lateritia: Isolation, Structure and Configurational Determ ination of the Diastereomers

1991 ◽  
Vol 46 (3-4) ◽  
pp. 177-182 ◽  
Author(s):  
Hans-W. Rauwald ◽  
Deo-D. Niyonzima
Keyword(s):  
Chemical Shifts ◽  
Optical Rotation ◽  
Coupling Constants ◽  
Cd Spectra ◽  
Large Coupling ◽  
H Nmr ◽  
Leaf Exudate ◽  
Hydroxyl Protons ◽  
Nmr Signals ◽  
C Nmr

From the leaf exudate of Aloe lateritia ENGLER the C-glucosyl com pounds homonataloin, aloeresin A and aloesin (synon. aloeresin B) were isolated together with the anthraquinone nataloeem odin-8-methylether and spectroscopically identified. Hom onataloin, widely distributed in Aloe species, was separated into homonataloin A and B by combined TLC and DCCC. In their 1 D and 2D 1H NMR spectra only the shifts of the 2′-hydroxyl protons of both glucosyl residues differ significantly, indicative of 10 S (A) resp. 10 S (B) configurations. In both com pounds the anthrone is in β-position of the D-glucopyranosyl, as determined by the large coupling constants of the anomeric protons. The 13C NMR signals are unambiguously assigned by the use of DEPT, APT and gated-decoupling methods. Only the chemical shifts of C -11 and C -14 show significant differences between both diastereomers due to the adjacent 2′-sugar hydroxyls. The two homonataloins differ mostly in optical rotation and circulardichroism due to different configurations at C - 10 of the anthrone part. The absolute configurations of the diastereomers are determined by correlation of their CD spectra with the CD spectra of the structural analogues 7-hydroxyaloins A and B, which shows that hom onataloin A is the 10 S, 1′S-compound and that homonataloin B has 10 R, 1′S-configuration.

Organoboranes and tetraorganoborates studied by 11B and 13C NMR spectroscopy and DFT calculations

2015 ◽  
Vol 70 (6) ◽  
pp. 421-424 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
Dft Calculations ◽  
13C Nmr ◽  
Quantum Chemical ◽  
13C Nmr Spectroscopy ◽  
Coupling Constants ◽  
Line Widths ◽  
Nmr Signals ◽  
C Nmr ◽  
Extract Information

AbstractCare should be taken on recording the sometimes elusive 13C NMR signals for boron-bonded carbon atoms, since it is easy to extract information about coupling constants 1J(13C,11B) by measuring the respective line widths of 13C(B-C) and 11B NMR signals. This information can be confirmed by quantum-chemical calculations [B3LYP (6-311+G(d,p) level of theory] of nJ(13C,11B) in organoboranes and tetraorganoborates. For the latter, the signs for n = 2, 3, 4 were experimentally determined.

Electronic structure of low-spin six-coordinate iron(III) meso-tetrapropylchlorin complexes

2014 ◽  
Vol 18 (08n09) ◽  
pp. 778-791 ◽  
Author(s):  
Akira Ikezaki ◽  
Jyunpei Ono ◽  
Yoshiki Ohgo ◽  
Mari Fukagawa ◽  
Takahisa Ikeue ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Ground State ◽  
Nmr Spectra ◽  
Spectroscopic Properties ◽  
H Nmr ◽  
Axial Ligands ◽  
Splitting Parameter ◽  
Nmr Signals ◽  
Electronic Ground ◽  
C Nmr

Low-spin iron(III) tetrapropylchlorins [ Fe ( T n PrC ) L 2]± (L = HIm, 1-MeIm, DMAP, CN-, 4-CNPy, tBuNC) adopt the dxy-type ground state regardless of the nature of axial ligands. Among the complexes examined, [ Fe ( T n PrC )( t BuNC )2]+ has shown quite unique spectroscopic properties as described below. (1) 1 H NMR signals were extremely broad as compared with those of other complexes. In particular, 5,20- CH 2(α) signal was too broad to detect. (2) No signals except C γ were observed in 13 C NMR spectra. (3) Tetragonal splitting parameter (|Δ|) estimated by the EPR g values at 4.2 K reached as much as 12.4 λ, which is the largest |Δ| value among all the low-spin iron(III) porphyrins and porphyrinoids reported previously. On the basis of these results, we have concluded that [ Fe ( T n PrC )( t BuNC )2]+ adopts the low-spin iron(III) with (dxz, dyz)4(dxy)1 electronic ground state at 4.2–30 K where the EPR spectra are taken, while it should be expressed as the low-spin Fe ( II ) chlorin π-radical cation [ Fe II ( T n PrC .)( t BuNC )2]+ at ambient temperature where the NMR spectra are taken.

scholarly journals Complete Assignment of the 1H and 13C NMR Spectra of Carthamin Potassium Salt Isolated from Carthamus Tinctorius L.

2021 ◽  
Author(s):  
Maiko Sasaki ◽  
Keiko Takahashi
Keyword(s):  
Potassium Salt ◽  
Nmr Spectra ◽  
Carthamus Tinctorius ◽  
Ionization Mass ◽  
13C Nuclear Magnetic Resonance ◽  
Complete Assignment ◽  
Pure Product ◽  
Atomic Adsorption Spectroscopy ◽  
Nmr Signals ◽  
C Nmr

Carthamin potassium salt isolated from Carthamus tinctorius L. was purified by an improved traditional Japanese method, without using column chromatography. The 1H and 13C nuclear magnetic resonance (NMR) signals of the pure product were fully assigned using one- and two-dimensional NMR spectroscopy, while the high purity of the potassium salt and deprotonation at the 3’ position of carthamin were confirmed by atomic adsorption spectroscopy and nano-electrospray ionization mass spectrometry.

scholarly journals Substituent Effects on NMR Spectroscopy of 2,2-Dimethylchroman-4-one Derivatives: Experimental and Theoretical Studies

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2061
Author(s):  
Daniela Iguchi ◽  
Davide Ravelli ◽  
Rosa Erra-Balsells ◽  
Sergio M. Bonesi
Keyword(s):  
Density Functional ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Heterocyclic Ring ◽  
Functional Theory ◽  
1H And 13C Nmr ◽  
Meta Position ◽  
Experimental And Theoretical Studies ◽  
Nmr Signals ◽  
C Nmr

The attribution of 1H and 13C NMR signals of a library of 5-, 6- and 7-substituted 2,2-dimethylchroman-4-one derivatives is reported. Substituent effects were interpreted in terms of the Hammett equation, showing a good correlation for carbons para- to the substituent group, not for the meta- ones. Similarly, the Lynch correlation shows the additivity of the substituent chemical shifts in the case of both H and C nuclei, again with the exception of the carbons in the meta- position. Density Functional Theory (DFT)-predicted 1H and 13C chemical shifts correspond closely with experimentally observed values, with some exceptions for C NMR data; however, the correlation is valid only for the aromatic moiety and cannot be extended to the heterocyclic ring of the chroman-4-one scaffold.

The influence of structural modification on progesterone and androgen receptor binding of norethisterone. Correlation with nuclear magnetic resonance signals

1987 ◽  
Vol 115 (3) ◽  
pp. 406-412 ◽  
Author(s):  
H.-O. Hoppen ◽  
P. Hammann
Keyword(s):  
Androgen Receptor ◽  
Double Bond ◽  
Progesterone Receptor ◽  
Substituent Effects ◽  
Binding Affinities ◽  
Rough Approximation ◽  
Methylene Group ◽  
Nmr Signals ◽  
C Nmr

Abstract. The relative binding affinities (RBA) of eight progestogens structurally derived from 17α-ethinyl-19-nortestosterone (norethisterone) have been estimated a) for the progesterone receptor from human premenopausal endometrium and b) for the androgen receptor in human mammary carcinoma in vitro. Introduction of a methylene group at C-11, a methyl group at C-18, or a double bond between C-15 and C-16 of the norethisterone molecule increases the RBA to the progesterone receptor. As a rough approximation, the substituent effects seem to be additive. RBA to the androgen receptor follows a more complex pattern when norethisterone is structurally modified. An additional methyl at C-18 enhances affinity to the androgen receptor. The double bond between C-15 and C-16 has no effect except when introduced into desogestrel, where it reduces RBA to the lowest value in the study. The methylene group at C-11 increases androgen RBA when present as the only substituent, but reduces androgen RBA when together with any other substituent. The complete assignment of 13C-NMR signals has been achieved for all 8 steroids investigated. The 13C-resonance signal of C-17 shows a correlation with the RBA to the progesterone receptor, and with the progestogen/androgen RBA ratios.

13C nuclear magnetic resonance studies. 61. The effect of solute–solvent association on internal rotation in substituted benzaldehydes

1976 ◽  
Vol 54 (20) ◽  
pp. 3267-3271 ◽  
Author(s):  
R. E. Klinck ◽  
J. B. Stothers
Keyword(s):  
Steric Effect ◽  
Methylene Chloride ◽  
Activation Parameters ◽  
Formyl Group ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Group Rotation ◽  
Substituted Benzaldehydes ◽  
Nmr Signals ◽  
C Nmr

Complete lineshape analyses of the 13C nmr signals of the ortho and meta carbons have been carried out for two p-substituted benzaldehydes in methylene chloride-d2 and toluene-d8 solutions over a wide temperature range. The activation parameters have been determined for the formyl group rotation and large negative values are found for ΔS≠ when the latter solvent is used. These results suggest that solute–solvent association has a steric effect on the transition state.

Bicyclo[3.2.1]octa-2,6-dienyllithium and -potassium Chemistry Solvation, Aggregation, and 119Sn-7Li Coupling of Stannylated Derivatives

1990 ◽  
Vol 45 (6) ◽  
pp. 848-856 ◽  
Author(s):  
Norbert Hertkorn ◽  
Frank H. Köhler
Keyword(s):  
Nmr Spectra ◽  
Ion Pair ◽  
Lithium Cation ◽  
H Nmr ◽  
Triple Ions ◽  
Nmr Signals ◽  
Independent Confirmation ◽  
Triple Ion ◽  
C Nmr ◽  
Very Low Temperature

The 13C NMR spectra of bicyclo[3.2.1]octa-2,6-dienyl anion (1) as the lithium (1 Li) and the potassium salt (1 K) were recorded at various temperatures and in different solvents. The results show 1K to exist as a contact ion pair (CIP), whereas for 1 Li solvent separated ions (SSIP) are also found as the temperature is lowered and when the solvating power of the solvent is increased. In the 7Li NMR spectra at very low temperature the signals of the SSIP disappear and only those of a monomeric CIP and a triple ion (1 Li 1) consisting of two carbanions and one lithium cation are present. For independent confirmation, the hitherto unknown 6-, 7-, and 3-trimethylstannyl substituted bicyclo[3.2.1]octa-2,6-dienyllithium derivatives 2 a Li, 2 b Li, and 3 Li were synthesized and also studied by 119Sn, 13C, and 1H NMR. According to the temperature dependence of the δ(13C)-values the CIP/SSIP-equilibrium of 2 a Li in THF/TMEDA is shifted to the CIP side. The observation of a unique 119Sn-7Li coupling (6.2 Hz) shows that at –90 °C a species containing 2 a and lithium exists under slow exchange conditions. A similar coupling of 3.5 Hz can be estimated for 3Li. A mixture of the epimeric carbanions 2a and 2 b yields two sets of 13C NMR signals which are due to the diastereomeric triple ions 2 aLi 2 a and 2 aLi 2 b.

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