Fig. 3.

Proton and carbon resonance assignment of HDF using heteronuclear correlation NMR spectroscopy. (A) Expanded region (δF2 7.7–6.5 ppm and δF1 140–100 ppm) and (B) (δF2 5.5–3.5 ppm and δF1 75–65 ppm) of the ¹H-¹³C HSQC and H2BC spectra of U-[¹⁵N,¹³C] HDF at 18°C in acetonitrile-d₃. HSQC (black contour lines) and H2BC (gray contour lines) are superimposed. H2BC is based on two-bond ¹H-¹³C correlations allowing for sequential assignment using both ¹H and ¹³C resonances. To illustrate sequential assignment, important correlation peaks are connected with lines and labeled according to the ¹H and ¹³C resonances associated with the atom numbering.