The 2D Selective J-INEPT (SINEPT) experiment is the 2D version of the selective 1D INEPT experiment. It allows to measure accurate long-range proton-carbon coupling constants directly from the F1 columns of a heteronuclear J-resolved spectrum.

Easy implementation on any AVANCE spectrometer.

The basic pulse sequence of the 2D SINEPT experiment can be easily derived from the 1D SINEPT experiment, in which the first fixed defocusing period is made variable ( 86JMR344-66 ).


In addition, in order to reduce the number of changes of decoupler power levels during the experiment, it has been proposed to make all proton pulses selective for the desired proton ( 89JCC389 and 92MRC823 ). Application: 94MRC1 .

Alternatively of these approaches, it can be derived another version in which the second delay in the 1D SINEPT experiment is made variable while the first delay is fixed. In this case, similar results are obtained for CH systems but different  multiplicities are observed in the F1 dimension in CH2 (triplets) and CH3 (quartets) systems. Other approach uses the different T1 relaxation times of several overlapped protons in order to select one of them ( 89MRC1052 ) although sensitivity gain is  greatly reduced.

Similar approaches have been also proposed for DEPT-based ( 92BMR263 , 94MRC657 , and 95MRC196 ) and PENDANT-based ( 95JMRB275-109 ) J-resolved experiments. There are two versions of the selective 2D J-DEPT experiment, depending if the evolution period is inserted before or after  the multiquantum evolution period. The more conventional is the former, in which the resulting spectra has the same characteristics of the 2D SINEPT experiment.

Related selective 2D inverse J-resolved experiments has also been proposed.

The 2D SINEPT experiment can be recorded in routine/automation modes. The parameters to be consider are the offset and the selectivity of the selective inversion proton pulse. The refocusing delay must be optimized to 1/2*ⁿJ(CH).

Tutorials: 2D X-detected experiments

As all selective 2D J-resolved experiments, the main benefit of the 2D SINEPT experiment is the simple spectral analysis. In the F2 dimension we have a conventional decoupled 13C spectrum. Each 13C signal is splitted as a doublet in the F1 dimension. This splitting affords the long-range proton-carbon coupling constant value. Because the F1 dimension can be set to a minimum value, the resolution of this measurement can be about 0.1-0.3 Hz. Intensity signal is proporcional to nJ(CH) optimization value and, therefore, signals arising from non-coupled carbons do not appear and, therefore, a cleaner 2D spectrum results.

 Selective 2D J-resolved experiment

2D X-detected experiments