Comparison of1H-19F two-dimensional NMR scalar coupling correlation pulse sequences

2014 ◽  
Vol 52 (4) ◽  
pp. 183-189 ◽  
Author(s):  
Alexander A. Marchione ◽  
Rebecca J. Dooley ◽  
Breanna Conklin
Keyword(s):  
Pulse Sequences ◽  
Scalar Coupling ◽  
Two Dimensional ◽  
Coupling Correlation

Total assignment of the 1H and 13C spectra of mikanokryptin and comparison of its solution and solid state conformations

1985 ◽  
Vol 63 (4) ◽  
pp. 849-853 ◽  
Author(s):  
William F. Reynolds ◽  
Raul G. Enríquez ◽  
Marco A. Chavez ◽  
Ana L. Silba ◽  
Miguel A. Martinez
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Pulse Sequences ◽  
Detailed Comparison ◽  
Coupling Constants ◽  
Dihedral Angles ◽  
Two Dimensional ◽  
Spectral Editing ◽  
One Dimensional ◽  
Inversion Recovery Pulse

The 1H and 13C spectra of mikanokryptin are unambiguously assigned using a variety of one-dimensional nmr experiments (selective homonuclear decoupling, use of inversion–recovery pulse sequences to reveal hidden peaks, and DEPT spectral editing) in conjunction with normal and "long range" two-dimensional heteronuclear correlated experiments. Detailed comparison of vicinal, allylic, and homoallylic 1H—1H coupling constants with dihedral angles determined from an earlier crystal structure determination indicates that solution and solid state configurations are similar.

scholarly journals Sequential NMR assignments of labile protons in DNA using two-dimensional nuclear-Overhauser-enhancemnt spectroscopy with three jump-and-return pulse sequences

1987 ◽  
Vol 166 (1) ◽  
pp. 215-220 ◽  
Author(s):  
Gottfried OTTING ◽  
Rolf GRUTTER ◽  
Werner LEUPIN ◽  
Kurt WUTHRICH ◽  
Carlo MINGANTI ◽  
...  
Keyword(s):  
Nmr Assignments ◽  
Pulse Sequences ◽  
Two Dimensional ◽  
Nuclear Overhauser

Notizen: Geminal Coupling Constants 2.J(15N13C) in 2-Substituted Pyridines, Measured by Hahn-Echo Extended (HEED) Pulse Sequences

1993 ◽  
Vol 48 (10) ◽  
pp. 1433-1436
Author(s):  
Bernd Wrackmeyer ◽  
Gerald Kehr
Keyword(s):  
High Resolution ◽  
Nmr Spectra ◽  
Pulse Sequences ◽  
Coupling Constants ◽  
Positive Sign ◽  
Two Dimensional ◽  
H Nmr ◽  
Substituted Pyridines ◽  
Geminal Coupling

Coupling constants 2J(15N13CR) and nJ(15N1HR) in 2-substituted pyridines [R = Me (1), CH=CH2 (2), C≡CH (3), C(O)H (4), C(O)Me (5)] have been measured by using Hahn-echo extended (HEED) pulse sequences for one- (1 D) and two-dimensional (2D) 13C/1H NMR (HEED-INEPT, HEED-HETCOR). The magnitude of |2J(15N13CR)| is hardly affected by the hybridization of 13CR. 15N NMR spectra, measured under conditions of ultra high resolution (UHR) confirm the values 2J(15N13CR). 2D 13C/1H HEED-HETCOR experiments show that the sign of 3J(15Ν1HR) is negative in 1, whereas the coupling constants 3J(15N1HR) in 4 and 4J(15N1HR) in 3 have a positive sign

Practical Aspects of the Preparation of the Derivatives

2015 ◽  
Author(s):  
Josi M. Seco ◽  
Emilio Quiqoa ◽  
Ricardo Riguera
Keyword(s):  
Low Temperature ◽  
Acid Chloride ◽  
Nmr Spectra ◽  
Pulse Sequences ◽  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
Priority Rules ◽  
Conformational Composition ◽  
Nmr Spectrum ◽  
Priority Order

Most of the NMR spectra shown in this book and in the literature have been recorded at 250 or 300 MHz, with a few being obtained at 500 MHz for 1H NMR (the equivalent for 13C NMR). No special pulse sequences are necessary, just standard one-dimensional (1D) spectra although two-dimensional (2D) experiments (e.g., correlation spectroscopy; COSY) may be necessary in some cases in order to get an unambiguous identification of the signals relevant for the assignment. In general, 5–10 mg or less of CDA derivative dissolved in 0.5 mL of deuterated solvent are sufficient to obtain a good NMR spectrum. Temperature, solvent, and concentration used in the NMR experiments should be adequate for each CDA-substrate pair and methodology, because the method is based on the conformational composition of the AMAA derivatives in precise conditions. With the exception of the low-temperature procedure (single derivatization), a NMR probe temperature around 300 K has always been used. In general, the spectra for double-derivatization assignments should be taken in deuterated chloroform. Different NMR solvents are required only in two of the single-derivatization methods. In the assignment by low-temperature NMR, the most convenient solvent is a CS2/CD2Cl2 (4:1) mixture, which allows the use of temperatures low enough (i.e., 213 K) to obtain relevant shifts. In the procedure based on the complexation with Ba2+, the NMR solvent should be deuterated acetonitrile. The barium salt is anhydrous Ba(ClO4)2, which can be added directly to the tube by using a spatula. No weighing is necessary after shaking, as the excess salt will remain at the bottom of the NMR tube and will not disturb the experiment. (R)- and (S)-MPA, MTPA, and Boc-phenylglycine (BPG) are commercially available and can be used without further purification. The first two (MPA and MTPA) can also be purchased as acid chlorides. When using MTPA or the corresponding acid chloride [85] for the derivatization of an alcohol or amine, it should be noted that the Cahn-Ingold-Prelog priority rules assign different R/S descriptors to the acid and to the corresponding chloride; this is due to the different priority order generated by the substituents [i.e., (R)-MTPA generates the (S)-acid chloride and vice versa].

Analysis of generalized two-dimensional homonuclear nmr spectra

1981 ◽  
Vol 59 (4) ◽  
pp. 723-730 ◽  
Author(s):  
Alex D. Bain ◽  
Jacques Bornais ◽  
Sydney Brownstein
Keyword(s):  
Chemical Shift ◽  
Nmr Spectra ◽  
Pulse Sequences ◽  
Spin Coupling ◽  
Spectral Information ◽  
Spectral Features ◽  
Two Dimensional ◽  
Free Induction ◽  
The Common

Analysis of the free induction decays from 90°–90° two-dimensional homonuclear pulse sequences gives complete spectral information from each transition in the f2 dimension. Theoretical intensities and frequencies are illustrated for the common cases AX, A2X, AMX, A2X2, AA′XX′, and A2X3 along with experimental examples of each. An analysis of intensities is given. From these examples it should be possible to determine chemical shift and spin-coupling values even when many lines in the f2 dimension are obscured by other spectral features.

Two-dimensional POMMIE carbon–proton chemical shift correlated 13C NMR spectrum editing

1990 ◽  
Vol 68 (7) ◽  
pp. 1145-1150 ◽  
Author(s):  
Bruce Coxon
Keyword(s):  
Chemical Shift ◽  
Pulse Sequences ◽  
Coupling Constants ◽  
Data Sets ◽  
Proton Chemical Shift ◽  
Two Dimensional ◽  
Chemical Shift Correlation ◽  
Linear Combinations ◽  
Nmr Spectrum ◽  
C Nmr

Two pulse sequences are described for acquisition of two-dimensional, carbon–proton chemical shift correlated 13C NMR spectra by the "phase oscillations to maximize editing technique". One of these sequences provides two-dimensional, carbon–proton chemical shift correlated spectra in which the 1H–1H coupling constants are present in the 1H chemical shift dimension, whereas the other sequence includes a bilinear rotation decoupling unit that removes the vicinal 1H–1H couplings in this dimension. Extensions of these techniques to generation of two-dimensional, carbon–proton chemical shift correlated CH, CH2, and CH313C NMR subspectra from linear combinations of three two-dimensional data sets are described. Decreased residual signals in the edited 2D subspectra have been achieved by Pascal programs that include six floating point coefficients, and a method for their calibration is discussed. Results are reported for troleandomycin (1). Keywords: 13C nuclear magnetic resonance, carbon–proton chemical shift correlation, DEPT, Pascal programs, POMMIE, two-dimensional NMR spectrum editing, troleandomycin.

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