1. Purpose

The INEPT sandwich forms a basic building-block in many modern 2D and 3D sequences, such as the HSQC technique (see Exp. 10.17). It transfers proton magnetization to an X nucleus. The reverse transfer is usually also achieved by an INEPT type sandwich, which is shown in the educational experiment given here. Starting from ¹³C magnetization, the C,H doublet is observed by proton detection. Signals of protons bonded to ¹²C are suppressed.

2. Literature

R. Freeman, T. H. Mareci, G. A. Morris, J. Magn. Reson. 1981, 42, 341–345.

3. Pulse Scheme and Phase Cycle

Reverse INEPT pulse sequence and phase cycle

4. Acquisition

Time requirement: 10 min

Sample: 10% CHCl₃ in [D₆]acetone.

Record normal ¹³C and ¹H NMR spectra and note the offsets of CHCl₃. Set the instrument to ¹H observation with ¹³C decoupling (inverse mode on older instruments) and load the reverse INEPT pulse program. You have to set:

td	4 k
sw	500 Hz
o1	on resonance of ¹H NMR signal
o2	on resonance of ¹³C NMR signal