NMR SPECTROSCOPY

¹³C-APT (attached proton test)

Determines ¹³C chemical shifts and differentiates between C_q, CH, CH₂, CH₃ groups (positive/negative signals)

O: S. Patt, J.N. Shoolery, J. Magn. Reson. 46, 535-539 1982  

¹³C-DEPT (distorsionless enhancement by polarization transfer)

Determines ¹³C chemical shifts and differentiates between CH, CH₂, CH₃ groups (positive/negative signals). 

The signals of C_q and solvent signals are suppressed.

O: M.R. Bendall, D.M. Doddrell, D.T. Pegg, J. Am. Chem. Soc. 103, 4603-4605 1981

¹³C-DEPTQ (distorsionless enhancement by polarization transfer including quaternary carbons)

Determines ¹³C chemical shifts and differentiates between CH, CH₂, CH₃ and C_q groups (positive/negative signals).

O: R. Burger, P. Bigler, J. Magn. Reson. 135, 529-534 1998 DOI: 10.1006/jmre.1998.1595
V: P. Bigler, R. Kümmerle, W. Bermel, Magn. Reson. Chem. 45, 469-472 2007 DOI: 10.1002/mrc.1993
P. Bigler, Spectroscopy Letters 41, 162-165 2008 DOI: 10.1080/00387010802008005

Note:
The edited DEPTQ spectra with Cq/CH signals in one and CH₂/CH₃ signals in the other are stored as follows:

¹H{¹H}-NOE (nuclear Overhauser enhancement)

NOEs take advantage of direct (dipolar) spin-spin couplings and allow to detect and measure intra- and intermolecular spatial proximity among protons.
O: D. Neuhaus, M. Williamson, The Nuclear Overhauser Effect, VCH, Weinheim 1989

Note:
So-called steady-state NOEs are measured, in contrast to the inherently weaker transient effects obtained with 2D techniques, such as NOESY and ROESY

For small molecules NOEs are positive (with a maximum of +0.5); for large (bio-) molecules NOEs are negative (with a maximum of –1.0) but spin diffusion occurs and complicates the interpretation.

Difference spectra are calculated which allow even weak NOEs to be recognized most conveniently

Reference spectrum and NOE-difference spectra are calculated automatically and are stored under the same filename but with different extensions (experimental numbers or “expnos” ):

¹H/¹H-COSY (correlation spectroscopy)

Detects homonuclear coupling interactions (indirect coupling) among protons of a molecule and allows coupling (J-connectivity) networks to be established most efficiently.

O: W.P. Aue, E. Bartholdi, R.R. Ernst, J. Chem. Phys. 64, 2229-2246 1976 DOI: 10.1063/1.432450
V: R.E. Hurd, J. Magn. Reson. 87, 422-428 1990
A. Derome, Williamson, J. Magn. Reson. 88, 177 - 185 1990  (MQ-filtered, phaseable version)

¹H/¹H-NOESY (NOE correlation spectroscopy)

Detects intra- and intermolecular spatial proximity (via direct coupling) among protons and allows to establish the corresponding dipolar network most efficiently. The same experiment (EXCSY) may be used to detect chemical and dynamic exchange among protons.

O: J. Jeener, B.H. Meier, P. Bachmann, R.R. Ernst, J. Chem. Phys. 71, 4546-4563 1979 DOI: 10.1063/1.438208
V: D.J. States, R.A. Haberkorn, D.J. Ruben, J. Magn. Reson. 48, 286-292 1982  

Note:
NOEs are dependent on molecular size and tumbling rates characterized by correlation times. For small molecules NOEs are positive (with a maximum of +0.385); for large (bio-)molecules NOEs are negative (with a maximum of –1.0). 

For molecules of intermediate size NOEs may be close to zero even for closely spaced protons. The ROESY experiment is used in such situations.

So-called transient NOEs are measured, in contrast to the stronger steady-state NOEs obtained with the 1D NOE experiment.  

¹H/¹H-ROESY (ROE correlation spectroscopy)

Detects intra- and intermolecular spatial proximity (via direct coupling) among protons and allows to establish the corresponding dipolar network most efficiently. The same experiment (EXCSY) may be used to detect chemical and dynamic exchange among protons.

O: A.A.Bothner-By, R.L. Stephens, J.-M. Lee, C.D. Warren, R.W.Jeanloz, J. Am. Chem. Soc. 106, 811-813 1984 DOI: 10.1021/ja00315a069
A. Bax, D.G. Davis, J. Magn. Reson. 63, 207-213 1985

Note:
In contrast to the NOESY experiment with the NOE built up under the influence of the strong static magnetic field, ROEs are built up in the much weaker “rotating field”. 

As a consequence ROEs are positive throughout (no zero-crossing) irrespective of the molecular size, but yield weaker effects for large molecules (<0.7 compared to –1.0 for NOEs)

So-called transient ROEs are measured, in contrast to the stronger steady-state NOEs obtained with the 1D NOE experiment.  

¹³C/¹H-HSQC (Heteronuclear single quantum correlation spectroscopy)

Detects heteronuclear coupling interactions (indirect coupling) between protons and directly bound carbons (1JCH) of a molecule and allows coupling (1JCH-connectivity) networks to be established most efficiently.

O: G. Bodenhausen, D.J. Ruben, Chem. Phys. Lett. 69, 185-188 1980 DOI: 10.1016/0009-2614(80)80041-8
V: L.E. Kay, P. Keifer, T. Saarinen, J. Am. Chem. Soc. 114, 10663-10665 1992 (gradient selected version) DOI: 10.1021/ja00052a088
W. Willker, D. Leibfritz, R. Kerssebaum, W. Bermel, Magn. Reson. Chem. 31, 287-292 1993
J. Schleucher et al. J. Biomol. NMR 4, 301-306 1994 DOI: 10.1007/BF00175254

Note:
¹³C chemical shifts are detected indirectly by taking advantage of single quantum t1-evolution

¹³C/¹H-HMQC (Heteronuclear multiple quantum correlation spectroscopy)

Detects heteronuclear coupling interactions (indirect coupling) between protons and directly bound carbons (1JCH) of a molecule and allows coupling (1JCH-connectivity) networks to be established most efficiently. 

O: L. Müller, J. Am. Chem. Soc. 101, 4481-4484 1979 DOI: 10.1021/ja00510a007
V: A. Bax, S. Subramanian, J. Magn. Reson. 67, 565-569 1986
R.E. Hurd, B.K. John, J. Magn. Reson. 91, 648-653 1991 (gradient selected version)

Note:
¹³C chemical shifts are detected indirectly by taking advantage of multiple quantum t1-evolution.  

¹³C/¹H-HMBC (Heteronuclear multiple bond correlation spectroscopy)

Detects heteronuclear coupling interactions (indirect coupling) between protons and remote carbons (mainly 2JCH, 3JCH) of a molecule and allows “long-range” coupling networks to be established most efficiently.

O: A. Bax, M.F. Summers, J. Am. Chem. Soc. 108, 2093-2094 1986 (gradient selected version) DOI: 10.1021/ja00268a061
V: D.O. Cicero, G. Barbato, R. Bazzo, J. Magn. Reson. 148, 209-213 2001 (F1 phased version) DOI: 10.1006/jmre.2000.2234

Note:
in contrast to HSQC, HMQC heteronuclear “long-range” connectivities include also quaternary carbons.   

¹³C/¹H-HMSC (Heteronuclear multiple and single bond correlation spectroscopy)

Detects heteronuclear coupling interactions (indirect coupling) through one (1JCH)  and more (2JCH, 3JCH) bonds 

simultaneously. The two types of connectivities are disentangled and the corresponding two spectra are calculated automatically.

O: R. Burger, C. Schorn, P. Bigler, J. Magn. Reson.148 (1), 88-94 2001 DOI: 10.1006/jmre.2000.2223

Note:
The two spectra with the 1JCH- and the 2JCH/3JCH- connectivities will be stored with “expnos” 900 and 902 respectively

The spectra are measured without ¹³C broadband decoupling. As a consequence doublets (spitted by 1JCH) are obtained in the 1JCH subspectrum.

¹⁹F

Note:
Since the internal calibration of our NMR spectrometers is very accurate (<0.05 ppm) and stable (using the lock signal), no additional ¹⁹F spectrum of 80% CFCl3  in CDCl3 will be provided anymore. 

³¹P

Note:
Since the internal calibration of our NMR spectrometers is very accurate (<0.05 ppm) and stable (using the lock signal), no additional ³¹P spectrum of 85% H3PO4 in H2O will be provided anymore.