The ge-2D Inverse J-Resolved experiment is the gradient-enhanced proton-detected version of the heteronuclear 2D J-resolved experiment in which coherence selection is achieved by means of PFG. The method allows to measure direct (¹J_CH) and long-range proton-carbon coupling constants (ⁿJ_CH ) in a similar way as known for J-Resolved experiments. In addition, all advantages of PFG-based inverse experiments are retained: good sensitivity, optimal dynamic range, improved artefact suppression, and reduced t1 noise.

Easy implementation on any AVANCE spectrometer equipped with pulsed field gradients (PFGs) and inverse probehead.

The ge-2D inverse J-resolved pulse sequence is based on the HSQC pulse train. The main difference is the variable evolution period: In the HSQC experiment, a  hard 180º 1H pulse is placed at the middle of the variable period in order to allow the evolution of the carbon chemical shift whereas heteronuclear coupling evolution is refocused. In the J-resolved experiment, a simultaneous 180º 13C pulse is applied to the 1H pulse in order to refocus carbon chemical shift whereas heteronuclear couplins evolve. When the 1H 180º pulse is made selective for a selecte proton, only heteronuclear coupling constants from this proton will evolve during t1, allowing the accurate measurement of ⁿJ_CH  by direct analysis of specific columns ( 95JMRB275-109 ).

The ge-2D inverse J-resolved experiment can be recorded in routine/automation modes and minor changes are required if a predefined parameter set is available. In the selective version, the features of the proton selective inversion must be specified.

Tutorials: 2D inverse experiments

Tutorials: 2D gradient-based inverse experiments

The resulting spectra shown the typical J-resolved display. Proton chemical shift are along the F2 dimension whereas J_CH  are displayed as a clean doublets in the F1 dimension. The measured ⁿJ_CH values are between the carbon directly-attached to the selectively pulsed proton and the proton which chemical shift is being analyzed.

Related experiments:

2D Inverse experiments

2D Inverse gradient-enhanced experiments