The Semi-selective 2D HMBC experiment is a simple modification of the 2D HMBC pulse sequence in which one of the two carbon 90 degree pulses is applied selectively on a specified region. The main purpose is to achieve better resolution in the indirect dimension and therefore is recommended when high overlapped carbon spectra precludes an easy resonance assignment.

Easy implementation on any AVANCE spectrometer equipped with an inverse probehead.

General pulse sequences have been reported in 88JMR382-78 , 89JMR223-83 , 89JMR212-83 , 90JMR615-88 , 91MRC848 , 92MRC595 , 91JMR659-93 , 94JMRA100-111 and 94JMRB77-103 . A gradient-enhanced version has been also published ( 99JMR454-139 ).

In order to achieve improved resolution, the user can also use digital filtering in the acquired proton dimension and apply linear prediction when data processing.

The semi-selective 2D HMBC experiment can be recorded in routine/automation modes. The most important parameter to optimize is the semi-selective carbon pulse length which determines the carbon spectral width to be excited.

Tutorials: 2D inverse experiments

Tutorials: 2D gradient-based inverse experiments

The spectrum offers the same correlation map as the conventional HMBC experiment.

Related experiments:

2D Inverse experiments

2D Inverse gradient-enhanced experiments