Residual dipolar couplings as a tool in determining the structure of organic molecules

Macromolecular NMR spectroscopy for the non‐spectroscopist

“…This effect is normally averaged to zero by rapid molecular tumbling, although partial alignment of a macromolecule, as achieved by steric restriction using polyacrylamide gels, bacteriophage or other reagents [49,50], can recover the couplings. The magnitude of the coupling for each 1 H-15 N pair, for example, provides information on the orientation of all N-H bond vectors relative to a single molecular axis.…”

Variable angle NMR spectroscopy and its application to the measurement of residual chemical shift anisotropy

“…In this case, the magnitude of observed anisotropic parameters is scaled according to 3 2 cos 2 H À 1 2 . The same relation is valid for alignment induced by stretched gels, for which the angle of the stretching axis relative to B 0 then has to be varied.…”

“…In recent years NMR spectroscopy on partially oriented samples has significantly extended the possibilities for structure determination of small molecules [1][2][3][4]. The numerous applications range from improved assignment [5,6], discrimination of enantiomers [7][8][9][10][11][12][13][14][15], the indirect measurement of J-couplings [16], enhanced resolution by RDCs [17], relative configuration [18][19][20][21][22][23][24][25][26][27][28][29], and the 3D-conformation of molecules [30][31][32][33][34][35][36].…”

Synthesis and Conformational Analysis of Efrapeptins

“…This approach has been proven successful for aqueous solutions by using phages or bicelles, while liquid crystalline phases or stretched polymer gels are applicable to organic solvents. [55] To refine the conformational data obtained for efrapeptin C in DMSO, the NMR-based conformational analysis was repeated in dichloromethane, because no appropriate alignment media were known for DMSO at the time. The extracted residual dipolar coupling information was included besides NOE-based distances.…”