The application of double-quantum and spin echo nuclear magnetic resonance spectroscopy to the assignment of 1H chemical shifts of RNA oligomers

1984 ◽  
Vol 62 (6) ◽  
pp. 1214-1222 ◽  
Author(s):  
Donald W. Hughes ◽  
Thomas Neilson ◽  
Jan M. Coddington ◽  
Russell A. Bell
Keyword(s):  
Pulse Sequence ◽  
Chemical Shifts ◽  
Spin Echo ◽  
Anomeric Proton ◽  
Scalar Coupling ◽  
Double Quantum ◽  
Resonance Spectroscopy ◽  
Single Experiment ◽  
Second Procedure ◽  
Specific Assignment

Specific assignment of the non-exchangeable base and ribose anomeric protons is difficult for oligoribonucleotides with a high pyrimidine content. Problems arise from the narrow range of pyrimidine H-6 chemical shifts and the overlap of pyrimidine H-5 resonances with the ribose anomeric proton signals. To solve these problems two multiple pulse methods were used which depend on the scalar coupling between H-6 and H-5. The first method was double-quantum nmr which established the connectivity between specific pyrimidine H-6 and H-5 resonances. A refocussing pulse was added to the end of the double-quantum pulse sequence to improve the identification of several H-6 and H-5 connectivities in a single experiment. The second procedure involved homonuclear decoupled spin echo nmr to remove H-5 signals selectively from the ribose anomeric proton region. These techniques are illustrated by the assignment of the spectra of the oligoribonucleotides UpUpC, UpUpU, GpCpUpC, and UpApGpCpUpU.

scholarly journals Physicochemical properties and structural dynamics of organic–inorganic hybrid [NH3(CH2)3NH3]ZnX4 (X = Cl and Br) crystals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ae Ran Lim ◽  
Sun Ha Kim ◽  
Yong Lak Joo
Keyword(s):  
Structural Dynamics ◽  
Chemical Shifts ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Scanning Calorimetry ◽  
Inorganic Hybrid ◽  
Halogen Atoms

AbstractThe physical properties of the organic–inorganic hybrid crystals having the formula [NH3(CH2)3NH3]ZnX4 (X = Cl, Br) were investigated. The phase transition temperatures (TC; 268K for Cl and 272K for Br) of the two crystals bearing different halogen atoms in their skeletons were determined through differential scanning calorimetry. The thermodynamic properties of the two crystals were investigated through thermogravimetric analysis. The structural dynamics, particularly the role of the [NH3(CH2)3NH3] cation, were probed through 1H and 13C magic-angle spinning nuclear magnetic resonance spectroscopy as a function of temperature. The 1H and 13C NMR chemical shifts did not show any changes near TC. In addition, the 1H spin–lattice relaxation time (T1ρ) varied with temperature, whereas the 13C T1ρ values remained nearly constant at different temperatures. The T1ρ values of the atoms in [NH3(CH2)3NH3]ZnCl4 were higher than those in [NH3(CH2)3NH3]ZnBr4. The observed differences in the structural dynamics obtained from the chemical shifts and T1ρ values of the two compounds can be attributed to the differences in the bond lengths and halogen atoms. These findings can provide important insights or potential applications of these crystals.

T2-weighted spin-echo pulse sequence with variable repetition and echo times for reduction of MR image acquisition time.

Radiology ◽  
1991 ◽  
Vol 180 (2) ◽  
pp. 551-556 ◽  
Author(s):  
R K Butts ◽  
F Farzaneh ◽  
S J Riederer ◽  
J N Rydberg ◽  
R C Grimm
Keyword(s):  
Pulse Sequence ◽  
Spin Echo ◽  
Image Acquisition ◽  
Acquisition Time ◽  
Mr Image ◽  
Image Acquisition Time ◽  
Echo Pulse

Studies of specifically fluorinated carbohydrates. Part II. Nuclear magnetic resonance studies of pentopyranosyl fluoride derivatives

1969 ◽  
Vol 47 (1) ◽  
pp. 19-30 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Resonance Spectroscopy ◽  
Magnetic Resonance Studies ◽  
Conformational Model ◽  
Nuclear Magnetic

Detailed studies, by 1H and 19F nuclear magnetic resonance spectroscopy, of a series of fully esterified pentopyranosyl fluorides, show that all such derivatives favor that conformer in which the fluorine substituent is axially oriented. This conclusion is supported by separate considerations of the vicinal and geminal19F–1H and 1H–1H coupling constants, of the long-range (4J) 1H–1H and 19F–1H coupling constants and of the 19F chemical shifts. The limitations of the above conformational model are discussed.

scholarly journals Study of the biologically active acyclic ureas by nuclear magnetic resonance

2020 ◽  
Vol 100 (4) ◽  
pp. 60-74
Author(s):  
А.А. Bakibaev ◽  
◽  
М.Zh. Sadvakassova ◽  
V.S. Malkov ◽  
R.Sh. Еrkasov ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Functional Groups ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Biologically Active ◽  
Resonance Spectroscopy ◽  
13C Nmr Spectra ◽  
Nuclear Magnetic

A wide variety of acyclic ureas comprising alkyl, arylalkyl, acyl, and aryl functional groups are investigated by nuclear magnetic resonance spectroscopy. In general, spectral characteristics of more than 130 substances based on acyclic ureas dissolved in deuterated dimethyl sulfoxide at room temperature are studied. The re-sults obtained based on the studies of 1H and 13C NMR spectra of urea and its N-alkyl-, N-arylalkyl-, N-aryl- and 1,3-diaryl derivatives are presented, and the effect of these functional groups on the chemical shifts in carbonyl and amide moieties in acyclic urea derivatives is discussed. An introduction of any type of substitu-ent (electron-withdrawing or electron-donating) into urea molecule is stated to result in a strong upfield shift in 13C NMR spectra relatively to unsubstituted urea. A strong sensitivity of NH protons to the presence of acyl and aryl groups in nuclear magnetic resonance spectra is pointed out. In some cases, qualitative depend-encies between the chemical shifts in the NMR spectra and the structure of the studied acyclic ureas are re-vealed. A summary of the results on chemical shifts in the NMR spectra of the investigated substances allows determining the ranges of chemical shift variations of the key protons and carbon atoms in acyclic ureas. The literature describing the synthesis procedures are provided. The results obtained significantly expand the methods of reliable identification of biologically active acyclic ureas and their metabolites that makes it promising to use NMR spectroscopy both in biochemistry and in clinical practice.

scholarly journals Studies on 13C magnetic resonance spectroscopy. XV. Correlation between 13C NMR chemical shifts and charge densities of diaza-benzenes.

1979 ◽  
Vol 27 (9) ◽  
pp. 2105-2110 ◽  
Author(s):  
TOSHIO TSUJIMOTO ◽  
CHIZUKO KOBAYASHI ◽  
TOSHIRO NOMURA ◽  
MAKIKO IIFURU ◽  
YOSHIO SASAKI
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
13C Nmr ◽  
Chemical Shifts ◽  
Resonance Spectroscopy ◽  
Nmr Chemical Shifts ◽  
Charge Densities ◽  
13C Nmr Chemical Shifts ◽  
13C Magnetic Resonance Spectroscopy

Carbon magnetic resonance studies of some phenyl, furyl and thienyl organometallics. Some comments on carbon-metal scalar coupling

1974 ◽  
Vol 27 (2) ◽  
pp. 417 ◽  
Author(s):  
D Doddrell ◽  
KG Lewis ◽  
CE Mulquiney ◽  
W Adcock ◽  
W Kitching ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Scalar Coupling ◽  
Coupling Constant ◽  
Aryl Substituent ◽  
Magnetic Resonance Studies ◽  
Thienyl Group ◽  
13C Chemical Shift

13C chemical shift variations within a series of phenyl, furyl and thienyl Group IVB organometallics appear to be best understood in terms of the usual alkyl and aryl substituent effects on 13C chemical shifts and not variations in dπ ?pπ metal-aryl interactions. Large changes in 13C-metal scalar coupling constants have been observed suggesting that other factors besides the s-character of the carbon-metal bond is responsible in determining the coupling constant.

Sign in / Sign up

Export Citation Format

Share Document