Analytical Instrument Documents

Application note NM260006
Product used: Nuclear Magnetic Resonance (NMR)

Fluorinated organic molecules exhibit complex and often unusually large carbon-fluorine coupling constraints (J_CF) that differ markedly from the coupling patterns observed in proton-based systems. Accurate measurement of these couplings is essential for structural elucidation, conformational analysis, and validation of computational models in fluorine-rich chemical environments. This application note demonstrates a streamlined approach for determining both one-bond and long-range JCF values using 1D ¹³C NMR with selective ¹⁹F decoupling, enabled by the high ¹³C sensitivity and ¹H&¹⁹F dual-channel decoupling capabilities of the SuperCOOL MARVEL HFX Duo probe. The method leverages the wide chemical shift dispersion of ¹⁹F nuclei, which allows highly selective decoupling with minimal off-target excitation. A 53 mg sample of perfluoroaromatic model compound N,N-dimethylamino-2,5,6-trifluoro-3,4-phthalonitrile was used to illustrate the workflow using 500 MHz SuperCOOL MARVEL HFX Duo probe.