Dear All,
We have a set of H-1, C-13, HSQC, and HMBC data on a small molecule. The data were acquired on our 600 with CryoProbes. The HSQC data showed perfect line-up with the H-1 and C-13 1D data, with a cross peak at 5.14ppm/69.2ppm. But on the HMBC spectrum, the two one-bond HC cross peaks for H-1 resonance at 5.14 ppm were at 61.8 ppm on C-13 dimension, not at 69.2 ppm as we expected. There was no C-13 resonance signal at 61.8 ppm on C-13 1D data. All other HMBC cross peaks, for multiple bonds as well as one-bond cross peaks matched perfectly with HSQC and 1D's data. We are totally at a loss on this 8 ppm difference on C-13 dimension for this C-13 resonance on HMBC. Have anyone of you observed such discrepancy in any of your data before? Or have any explanation for this?
Many thanks in advance for your kind help.
Best,
Dee
Dee-Hua Huang, Ph.D., Director
Research Services NMR Facility
The Scripps Research Institute
10550 N. Torrey Pines Rd.
La Jolla, CA 92037
(858) 784-2329
Received on Mon Nov 21 2016 - 15:12:24 MST