¹⁴N decoupled ¹H–¹⁹F HOESY with ROYALPROBE™ HFX

Measurements of ¹⁴N decoupling ¹H–¹⁹F HOESY

It often happens that ¹H NMR analysis is prevented with the severe line broadening of ¹H signal that is bound to ¹⁴N atom. In such a case, the ¹⁴N decoupling technique is useful. ¹H–¹⁹F 1D-HOESY spectra with and without ¹⁴N decoupling are shown in Fig.1. Selective excitation was done at F5 (Fig.1: upper) and F6 (Fig.1: bottom), respectively. The amide ¹H signal intensity in 1D-HOESY is increased by twice, compared to that measured without ¹⁴N decoupling. Since NOE measurements have generally difficulty in low sensitivity, the ¹⁴N decoupling technique is useful for observation of cross peaks with ¹H–¹⁴N signals. 2D-HOESY with ¹⁴N decoupling measurement is also available(Fig.2).

Fig.1 Comparison of amide ¹H signal intensities in 1D-HOESY spectra with or without ¹⁴N decoupling
(upper: selective excitation at F5; bottom: F6).

Fig.2 2D-HOESY spectrum of 1 under the ¹⁴N decoupling condition.

Sample: 36 mg fluorinated benzanilide in chloroform-d
Equipment: JNM-ECZ400S with ROYALPROBE™ HFX^※
※Special modification for ¹⁴N nuclei required.

References

G. N. Manjunatha Reddy, M. V. Vasantha Kumar, T. N. Guru Row, N. Suryaprakash, Phys. Chem. Chem. Phys., 12, 13232–13237 (2010).
L. E. Combettes, P. Clausen-Thue, M. A. King, B. Odell, A. L. Thompson, V. Gouverneur, T. D. W. Claridge, Chem. Eur. J., 18, 13133–13141 (2012).