Friday, June 11, 2010
19F - 13C HMQC
If one has an NMR spectrometer with hardware capable of synthesizing and amplifying the frequency of 19F from the 1H channel and a broadband NMR probe whose 1H channel can tune down to 19F, then one is able to do 19F - 13C HMQC experiments. The figure below shows an example of a 19F - 13C HMQC spectrum collected on a Bruker AVANCE 500 NMR spectrometer using a 5 mm broadband probe. The fluorine spectrum is plotted on the top and the 13C[19F] spectrum is plotted on the side. The panel on the left shows the spectrum optimized for one-bond coupling, while that on the right shows the spectrum optimized for two-bond coupling. Note that the protonated carbons are doublets as proton decoupling is not possible in this configuration. The large signal, off scale in the 13C[19F] spectrum is due to the solvent (benzene-d6).