13C Satellite Observation with 1D 1H - 13C HSQC

Two dimensional ¹H - ¹³C or  ¹H - ¹⁵N HSQC spectra are typically used to obtain one-bond heteronuclear correlation information between ¹H and ¹³C or ¹H and ¹⁵N.  The data are proton detected and typically employ pulsed field gradients for coherence selection.  The technique uses an incremented delay for chemical shift correlation and essentially discards the very intense signals from protons bound to ¹²C or ¹⁴N while enhancing the remaining doublet signals for protons bound to ¹³C or ¹⁵N.  Usually the ¹H FIDs are collected with ¹³C or ¹⁵N decoupling to collapse the doublets into singlets in the F2 domain leaving a single correlation between proton signals in F2 at the ¹³C or ¹⁵N chemical shifts in F1 of the nuclei to which the protons are bound.   One can use a 1D version of this experiment (without the incremented delay for chemical shift correlation) to collect ¹H NMR spectra exclusively of the protons bound to ¹³C or ¹⁵N.  If used without ¹³C or ¹⁵N decoupling, it allows easy observation of the ¹³C or ¹⁵N satellites in the absence of the very intense signals due to protons bound to ¹²C or ¹⁴N and allows the precise measurement of one-bond  ¹H - ¹³C  or  ¹H - ¹⁵N coupling constants.  The top panel of the figure below shows the 300 MHz 1D  ¹H - ¹³C HSQC spectrum of ethyl acetate.  Clearly the ¹³C satellites are observed and the  ¹H - ¹²C signals are suppressed.  The ¹H spectrum of ethyl acetate is shown in the bottom panel of the figure for comparison.