Compensating for variation in 1J(CH) coupling constants in HSQC spectra acquired on small organic molecules.
The HSQC sequence provides a sensitive way of determining the (13)C chemical shift of protonated carbons. It uses INEPT elements for magnetization transfer, which can only be optimized for one value of (1)J(CH), but small organic molecules contain a wide range of (1)J(CH) values. One popular method of compensating for (1)J(CH) variation is to incorporate adiabatic pulses into the INEPT elements. This article shows that this method fails for a significant subset of functional groups. It also shows that the effects of this failure can be reduced by avoiding refocusing delays and by using a J-compensated excitation element.
Howe
Peter W A
PW
Analytical Sciences, Syngenta, Jealott's Hill Research Centre, Bracknell RG42 6EY, UK. peter.howe@syngenta.com
D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D009930:Organic Chemicals / Q000737:chemistry*; D012015:Reference Standards
D002247:Carbon Isotopes; D009930:Organic Chemicals