Long-range 1H-15N heteronuclear shift correlation across wide F1 spectral windows

Long‐range ¹H? ¹⁵N heteronuclear shift correlation experiments at natural abundance are becoming more routinely utilized in the characterization of unknown chemical structures from a diverse range of sources including natural products and pharmaceuticals. Apart from the inherent challenges of the low gyromagnetic ratio and natural abundance of ¹⁵N, investigators are also occasionally hampered by having to deal with the wide spectral range inherent to various nitrogen functional groups, which can exceed 500 ppm. Earlier triple resonance cryoprobe designs typically provided 90° ¹⁵N pulses in the range of 35–40 µs, which did not allow the uniform excitation of wide F₁ spectral ranges for ¹H? ¹⁵N GHMBC spectra. We report the results obtained with a newly designed Bruker 600 MHz triple resonance TCI Micro CryoProbe? using methyl orange as a model compound, in which the ¹⁵N resonances are separated by > 450 ppm. Copyright © 2010 John Wiley & Sons, Ltd.