J-HMBC / Broadband XLOC
Sequences
J-HMBC and constant-time J-HMBC for measurement of long-range J(X,H) coupling constants
- 1 = ( 2×(Jmin + 0.070(Jmax - Jmin)))-1
- 2 = ( Jmax + Jmin)-1
- 3 = ( 2×(Jmax - 0.070(Jmax - Jmin)))-1
- i: duration of low-pass J filter (LPJF)
- : scaling factor for apparent upscaling of nJ(X,H)
- = × t1max
- tA = 0.5 × ( - i + t1max) -
- tB = 0.5 × ( + t1max - (1 + )×t1)
- tC = 0.5 × ( ×t1 + i) +
- = gradient delay
- Gradient ratios:
- LPJF: +7, -4, -2, -1
- Echo: +5.0 : -3.0
- Antiecho: -3.0 : +5.0
Broadband XLOC for measurement of J(H,H) coupling constants
- 1 = ( 2×(Jmin + 0.070(Jmax - Jmin)))-1
- 2 = ( Jmax + Jmin)-1
- 3 = ( 2×(Jmax - 0.070(Jmax - Jmin)))-1
- i: duration of low-pass J filter (LPJF)
- : Excitation delay
- = gradient delay
- Gradient ratios:
- LPJF: +7, -4, -2, -1
- Echo: +5.0 : -3.0
- Antiecho: -3.0 : +5.0
Results
Expansion of a constant-time J-HMBC spectrum of 15 µl of ethyl trans-cinnamate in 600 µl CDCl3 at 25° C. = 500 ms, = 22;F1 sections from J-HMBC spectra of 15 µl of ethyl trans-cinnamate in 600 µl CDCl3 at 25° C. = 500 ms and = 22 which results in an apparent splitting of the doublet components by J relative to the 13C chemical shifts.
Expansion from a Broadband XLOC spectrum of 15 µl of ethyl trans-cinnamate in 600 µl CDCl3 at 25° C. with F2traces suitable for measurement of J(H,H) coupling constants.
References
- Meissner, A. and Sorensen, O.W. Measurement of J(H,H) and long-range J(X,H) coupling constants in small molecules. Broadband XLOC and J-HMBC Magn.Reson.Chem. 39 49-522001
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