The 2D NOESY-Relayed experiment is an hybrid experiment consisting of consecutive NOESY and one-step RELAY building blocks. In the first step, magnetization is transferred between protons via NOE effect. In the second step, such magnetization is propagated to the J-coupled spins as described in RELAY-type experiments.

Easy implementation on AVANCE spectrometers.

The basic pulse sequence of the NOESY-Relayed experiment consists of a convetional 2D NOESY  pulse sequence followed by a RELAY building block ( 88MRC919 ). However, in this way, the resulting 2D spectrum cannot be phase corrected to pure phases. A better version includes a double-quantum filter (DQF) prior to acquisition ( 88JMR401-77 ) in order to obtain a uniform absorptive line shape for cross-peaks and diagonal. However, this DQF causes an extra 50% decrease in signal-to-noise ratio.

Modified experiments:

• A related ROESY-RELAY experiment has also been proposed ( 88JMR401-77 ) in which the NOESY block is simply replaced by a ROESY block.
• On the other hand, the two blocks can be reversed to obtain a 2D RELAY-NOESY experiment.
• Improved results are obtained from a 2D NOESY-TOCSY experiment.

The 2D NOESY-Relayed experiment can be recorded in routine/automation modes. The most important parameter to consider is the length of the NOESY mixing and the RELAY periods. See 2D NOESY and 2D RELAY experiments for more details.

Tutorials: 2D homonuclear experiments

Tutorials: 2D gradient-based homonuclear experiments

Tutorials: 2D gradient-based homonuclear experiments in H₂O

In the NOESY-RELAY experiment, the two-step magnetization transfer from a spin 1 (in F1) via spin 2 to a spin 3 (in F2) requires a NOE transfer between 1 and 2 and a J-coupling between 2 and 3. However, the requeriments for a transfer from spin 3 (in F1) via spin 2 to a spin 1 are different. That means NOESY-RELAY spectra are asymmetrical with respect to the diagonal. In addition, cross-peaks can suffer from antiphase cancellation (in-phase pattern in F1 and anti-phase pattern in F2) as found in COSY-type spectra. These disadvantages can  be partially overcomed performing 2D NOESY-TOCSY or 2D ROESY-TOCSY experiments.

Related experiments:

2D homonuclear experiments

2D gradient-based homonuclear experiments