Decoupling residual dipolar coupling between 13C and14N spin pairs in CPMAS NMR

Effect of Encapsulating Arginine Containing Molecules on PLGA: A Solid-State NMR Study

“…Therefore this resonance was assigned to the ${\rm CH}_2^\delta$ site of the guanidine tail. Splitting in a 1:2 doublet due to the residual 13 C– 14 N dipolar coupling51–55 is observed for the resonance at 56.3 ppm which was ascribed to the CH α . This assignment is corroborated by 1 H– 13 C HETCOR spectrum (Fig.…”

“…Such splitting is not visible for the peaks at 56.3 and 43.1 ppm as the chemical environment around these sites in the nonequivalent molecules is probably very similar. The broadening of resonance at 43.1 ppm in comparison with the low frequency aliphatic doublet can be explained by the residual 13 C– 14 N dipolar coupling due to the presence of a bound 14 N atom 51–55. Therefore this resonance was assigned to the ${\rm CH}_2^\delta$ site of the guanidine tail.…”

13C CP MAS NMR of halogenated (Cl, Br, I) pharmaceuticals at ultrahigh magnetic fields

“…As mentioned above, the quadrupolar 14 N (I = 1) has the same effect on neighboring 13 suggested using 14 N decoupling. [25] Another more straightforward solution to this problem is to perform experiments at the highest available magnetic field, because residual 13 C-14 N dipolar interactions would also scale inversely with the field. Previously we have demonstrated the utility of this approach while studying crystal structures of caffeine polymorphs.…”

Ab-initio crystal structure analysis and refinement approaches of oligo p-benzamides based on electron diffraction data

“…The magnitude of such splitting, however, scales inversely with the static magnetic field strength of the NMR experiment and is thus fairly small at intermediate field strengths such as 11.7 T (Gan, 2006). In principle, line broadening due to 13 C-14 N RDCs can be either decoupled artificially via selective pulse irradiation employing a non-standard 14 N, 13 C and 1 H tripleresonance MAS NMR probe (Orr & Duer, 2006), or selfdecoupled due to sufficiently fast quadrupolar relaxation (Olivieri, 1989). A detailed analysis of the 14 N quadrupolar coupling tensor (e.g.…”