J-modulated ADEQUATE (JM-ADEQUATE) experiment for accurate measurement of carbon-carbon coupling constants.
A new method for the accurate determination of carbon-carbon coupling constants is described. The method is based on a modified ADEQUATE experiment, where a J-modulated spin-echo sequence precedes the ADEQUATE pulse scheme. The J-modulation and scaling of carbon-carbon couplings is based on simultaneous incrementation of 13C chemical shift and coupling evolution periods. The time increment for the homonuclear carbon-carbon coupling evolution can be suitably scaled with respect to the corresponding increment for the chemical shift evolution. Typically a scaling factor of 2 to 3 is employed for the measurement of one-bond coupling constants, while multiplication by a factor of 10 to 15 is applied when small long-range couplings are determined. The same pulse scheme with coupling evolution period optimized for one-bond or long-range couplings allows the determination of the corresponding carbon-carbon coupling constants. The splittings of the ADEQUATE crosspeaks in the F1 dimension yield the appropriately multiplied coupling constants.
Kövér
Katalin E
KE
Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary. kover@tigris.klte.hu
Forgó
Péter
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D000465:Algorithms; D002244:Carbon / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry; D003461:Crystallography / Q000379:methods*; D005240:Feasibility Studies; D005947:Glucose / Q000031:analogs & derivatives* / Q000737:chemistry*; D008280:Magnetics; D008968:Molecular Conformation; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
D002247:Carbon Isotopes; C013844:benzylidene glucose; D002244:Carbon; D005947:Glucose