NMR study of heterogeneity in pyridine-N-oxide...HCl crystal

Open Physics ◽  
2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Vytautas Balevicius ◽  
Alexandar Gacesa ◽  
Janez Plavec
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Solid Phase ◽  
Mixing Time ◽  
Exchange Process ◽  
2D Nmr ◽  
Spin Coupling ◽  
Nmr Study ◽  
2D Nmr Spectra ◽  
Heterogeneous Phase

AbstractAn origin of narrow 1H NMR signals in pyridine-N-oxide (PyO)...HCl crystal has been investigated by means of MAS, SPEDAS, NOESY and COSY techniques. Spectra of crystalline samples are compared with those of solid phase obtained from liquid PyO...HCl solutions (in acetonitile/H2O) after the heterogeneous phase separation. It has been concluded that partially resolved peaks in 1H NMR spectra of solids are related with heterogeneity of spin system and presence of different H-bond clusters of water molecules. NOESY spectra show no cross-peaks even at very long mixing time (500 ms). This indicates there is no exchange process between spins causing different peaks, and thus the corresponding molecular aggregates are captured in “islands of mobility8 without any channels sufficient for exchange. Appearance of MAS side bands as “pseudo8 cross-peaks in 2D NMR spectra using MAS/COSY technique is reported. In the case of accidental coincidence of spinning frequency (ωMAS) with spectral distances between some diagonal signals, intensive non-diagonal peaks are observed at the corresponding cross-positions. A misleading conclusion concerning spin coupling is easy to avoid using various ωMAS.

scholarly journals Ultrafast 2D 1H-1H NMR spectroscopy of DNP-hyperpolarised substrates for the analysis of mixtures

2021 ◽  
Author(s):  
Kawarpal Singh ◽  
Corentin Jacquemmoz ◽  
Patrick Giraudeau ◽  
Lucio Frydman ◽  
Jean-Nicolas Dumez
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
2D Nmr ◽  
Multiple Quantum ◽  
Dynamic Nuclear Polarisation ◽  
Nuclear Polarisation ◽  
2D Nmr Spectra

We show that TOCSY and multiple-quantum (MQ) 2D NMR spectra can be obtained for mixtures of substrates hyperpolarised by dissolution dynamic nuclear polarisation (D-DNP). This is achieved by combining optimised...

A 15N, 13C, and 1H NMR study of reaction products from arylguanidines and chloroformate esters

1991 ◽  
Vol 56 (7) ◽  
pp. 1505-1511 ◽  
Author(s):  
Antonín Lyčka ◽  
Karel Palát
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Reaction Products ◽  
H Nmr ◽  
Nmr Study

The 15N, 13C, and 1H NMR spectra of the reaction products from arylguanidines with two mols of chloroformate esters have been measured. With application of the corresponding 15N isotopomer it has been proved that the reaction products have the structures IIIa-IIIc.

Differential Analysis of 2D NMR Spectra: New Natural Products from a Pilot-Scale Fungal Extract Library

2007 ◽  
Vol 46 (6) ◽  
pp. 901-904 ◽  
Author(s):  
Frank C. Schroeder ◽  
Donna M. Gibson ◽  
Alice C. L. Churchill ◽  
Punchapat Sojikul ◽  
Eric J. Wursthorn ◽  
...  
Keyword(s):  
Natural Products ◽  
Nmr Spectra ◽  
2D Nmr ◽  
Pilot Scale ◽  
Differential Analysis ◽  
Fungal Extract ◽  
2D Nmr Spectra

scholarly journals New Antimalarial and Antimicrobial Tryptamine Derivatives from the Marine Sponge Fascaplysinopsis reticulata

Marine Drugs ◽  
2019 ◽  
Vol 17 (3) ◽  
pp. 167 ◽  
Author(s):  
Pierre-Eric Campos ◽  
Emmanuel Pichon ◽  
Céline Moriou ◽  
Patricia Clerc ◽  
Rozenn Trépos ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Minimum Inhibitory Concentration ◽  
Marine Sponge ◽  
Nmr Spectra ◽  
Inhibitory Concentration ◽  
Chemical Study ◽  
2D Nmr ◽  
Antimicrobial Activities ◽  
2D Nmr Spectra ◽  
Ic50 Values

Chemical study of the CH2Cl2-MeOH (1:1) extract of the sponge Fascaplysinopsis reticulata collected in Mayotte highlighted three new tryptophan derived alkaloids, 6,6′-bis-(debromo)-gelliusine F (1), 6-bromo-8,1′-dihydro-isoplysin A (2) and 5,6-dibromo-8,1′-dihydro-isoplysin A (3), along with the synthetically known 8-oxo-tryptamine (4) and the three known molecules from the same family, tryptamine (5), (E)-6-bromo-2′-demethyl-3′-N-methylaplysinopsin (6) and (Z)-6-bromo-2′-demethyl-3′-N-methylaplysinopsin (7). Their structures were elucidated by 1D and 2D NMR spectra and HRESIMS data. All compounds were evaluated for their antimicrobial and their antiplasmodial activities. Regarding antimicrobial activities, the best compounds are (2) and (3), with minimum inhibitory concentration (MIC) of 0.01 and 1 µg/mL, respectively, towards Vibrio natrigens, and (5), with MIC values of 1 µg/mL towards Vibrio carchariae. In addition the known 8-oxo-tryptamine (4) and the mixture of the (E)-6-bromo-2′-demethyl-3′-N-methylaplysinopsin (6) and (Z)-6-bromo-2′-demethyl-3′-N-methylaplysinopsin (7) showed moderate antiplasmodial activity against Plasmodium falciparum with IC50 values of 8.8 and 8.0 µg/mL, respectively.

scholarly journals Advanced solvent signal suppression for the acquisition of 1D and 2D NMR spectra of Scotch Whisky

2017 ◽  
Vol 55 (9) ◽  
pp. 785-796 ◽  
Author(s):  
Will Kew ◽  
Nicholle G.A. Bell ◽  
Ian Goodall ◽  
Dušan Uhrín
Keyword(s):  
Nmr Spectra ◽  
2D Nmr ◽  
Signal Suppression ◽  
2D Nmr Spectra ◽  
Solvent Signal Suppression ◽  
Scotch Whisky

scholarly journals Hierarchical Alignment and Full Resolution Pattern Recognition of 2D NMR Spectra: Application to Nematode Chemical Ecology

2011 ◽  
Vol 83 (5) ◽  
pp. 1649-1657 ◽  
Author(s):  
Steven L. Robinette ◽  
Ramadan Ajredini ◽  
Hasan Rasheed ◽  
Abdulrahman Zeinomar ◽  
Frank C. Schroeder ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Chemical Ecology ◽  
Nmr Spectra ◽  
2D Nmr ◽  
Full Resolution ◽  
2D Nmr Spectra

Pentacyclic Triterpenes and Other Constituents from Ficus cordata (Moraceae)

2008 ◽  
Vol 63 (11) ◽  
pp. 1335-1338 ◽  
Author(s):  
Herve M. P. Poumale ◽  
Rodrigue T. Kengap ◽  
Jean Claude Tchouankeu ◽  
Felix Keumedjio ◽  
Hartmut Laatsch ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Secondary Metabolites ◽  
Betulinic Acid ◽  
Nmr Spectra ◽  
2D Nmr ◽  
Stem Bark ◽  
Published Data ◽  
Pentacyclic Triterpenes ◽  
2D Nmr Spectra ◽  
Lupeol Acetate

Abstract Two new pentacyclic triterpenes 8,26-cyclo-urs-21-en-3β, 20β-diol (1) and 3β-acetoxy-8.26- cyclo-ursan-20β-ol (2) together with 3-friedelanone, oleanolic acid, betulinic acid, lupeol acetate, α- and β-amyrine, S.SJ^'-tetrahydroxyflavane, and 3,5,7,3',4'-pentahydroxyflavane were isolated from the stem bark of Ficus cordata (Moraceae). The structures of these secondary metabolites were established using ID and 2D NMR spectra and by comparison with published data or with authentic samples. Compounds 1 and 2 exhibited weak antibacterial and no antifungal activity.

Phloridzin Highly Accumulated in Malus rockii Rehder and Its Structure Revision and Hypolipidemic Activity

Planta Medica ◽  
2021 ◽  
Author(s):  
Li-Juan Lang ◽  
Min Wang ◽  
Chang Lei ◽  
Yi Shen ◽  
Qi-Jie Zhu ◽  
...  
Keyword(s):  
Analgesic Activity ◽  
Nmr Spectra ◽  
Antimalarial Activity ◽  
2D Nmr ◽  
Proton Exchange ◽  
Hypolipidemic Activity ◽  
Wild Plants ◽  
Lead Compound ◽  
Structure Revision ◽  
2D Nmr Spectra

Phloridzin is a lead compound of the prestigious antidiabetic gliflozins. The present study found that phloridzin highly accumulated in Malus rockii Rehder. The content of phloridzin in M. rockii was the highest among wild plants, with the percentage of 15.54% in the dry leaves. The structure of phloridzin was revised by proton exchange experiments and extensive 2D NMR spectra. Phloridzin exhibited significant hypolipidemic activity in golden Syrian hamsters maybe by increasing the expression of CYP7A1, at the doses of 50 mg/kg and 200 mg/kg. The total performance of anti-hyperlipidemic effect of phloridzin may be superior to that of lovastatin, though lovastatin was more active than phloridzin. In addition, phloridzin exhibited moderate antimalarial activity with inhibition ratio of 31.3±10.9% at a dose of 25 mg/kg/day, and showed moderate analgesic activity with 28.0% inhibition at a dose of 50 mg/kg.

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