CYCLCROP Mapping of ¹³ C Labelled Compounds: Perspectives in Polymer Science and Plant Physiology

Selective Determination of Elastomer Distribution in Multicomponent Systems Using Proton-Detected 13C Imaging

“…Figure presents the CYCLCROP spectra of PI in CDCl 3 solution and in the bulk using both MOIST and PRAWN methods for effecting cross-polarization. Spectra a and b in Figure reveal that both methods behave similarly in solution, in accordance with recent results of a CYCLCROP application in imaging of plants …”

“…Very short T ρ ,eff values would additionally explain the reduced enhancement (∼3) obtained in the CYCLCROP images compared to the theoretical maximum of 10 for a CH 2 spin system. Note that during cross-polarization both the 1 H and the 13 C nuclei are involved in the relaxation process, so one refers to an “effective” relaxation time T ρ ,eff in the rotating frame for the whole molecular 13 CH N group …”

“…Indirect 13 C detection methods of this sort in principle provide the sensitivity of proton NMR by assuming the same number of nuclei. − In the following, we refer to the cyclic cross-polarization (CYCLCROP) scheme ,− with the pathway 1 H → 13 C → 1 H. This method turned out to be particularly easy to implement and to be robust against artifacts. The variety of its applications have recently been demonstrated in studies of sugar metabolism in plants …”

1H Detected 13C Echo Planar Imaging

“…Using the cyclic J cross polarization (CYCLCROP) (2) technique, the 13 C nucleus can be detected with almost the same sensitivity as a comparable number of 1 H nuclei, leading to a theoretical increase of the signal of (γ 1H /γ 13C ) 3 = 64, as compared to a direct 13 C one-pulse experiment (3). Further gains in sensitivity per unit time may also be realized with this technique by taking advantage of the faster repetition rates allowed by the lower relaxation times of 1 H nuclei compared with those of 13 C. The improvement in sensitivity delivered by the CYCLCROP technique permits proton-detected 13 C-images to be acquired in much reduced times, even at natural abundance or at low 13 C enrichment (4). For example, the movement of 13 C-labeled metabolites has been mapped in small plants using CYCLCROP in conjunction with short-echo-time spin-warp imaging with a temporal resolution of 100 min and a voxel volume of 0.3 mm 3 at 9.4 T (5).…”