Carbon-13 Nuclear Magnetic Resonance Studies of Creatine, Creatinine and some of their Analogs

Article abstract of DOI:10.1002/mrc.1270130202

Creatine (N-methyl-N-amidinoglycine), creatinine (1-methyl-2-aminoimidazolin-4-one) and a series of 38 of their close structural analogs have been examined using natural abundance 13C NMR spectroscopy at 25.16 MHz.Both proton-coupled and proton noise-decoupled spectra were recorded.Unequivocal assignments of the carbon resonances could be made in the vast majority of cases.Both 13C NMR chemical shifts and ¹J(CH) values can be used to characterize and to differentiate readily between analogs of creatine and analogs of creatinine.For example, the ¹J(CH) coupling constants for the α-carbons of the acyclic creatine analogs were all in the 140-142 Hz range, whereas the corresponding coupling constants for the related, cyclized creatinine analogs were all in the 150-152 Hz range.