September 3, 2008
by Arvin Moser, Team Manager, Application Scientists, ACD/Labs
Certain experimental conditions, such as varying the temperature or using different solvents, can influence the interpretation of NMR data. Although it can be useful to collect data with different solvents (e.g. DMSO-d6 or Chloroform-d) or temperatures to decrease peak overlap in a particular region, it can complicate the structure elucidation process by increasing the amount of spectral data at hand. When it comes to referencing 2D NMR data, use the 1D NMR data collected at the same temperature and solvent.
The 1H NMR spectra below are for the same compound quinine prepared with different deuterated solvents. The shifts in the peaks are a result of the different effects of the solute-to-solvent interactions. When analyzing 2D NMR data for an elucidation, be sure to use the 1D NMR with the same experimental conditions to ensure all peaks and correlations are aligned correctly.
TIP: the best data to work with is the one with the least amount of peak overlap.