Graphene Oxide‐Cyclopentylamine (GO‐d‐CP) Liquid Crystals as a Novel Alignment Medium for Anisotropic NMR with Analyte Recovery

AbstractIn this study, we present graphene oxide derivatized with cyclopentylamine (GO‐d‐CP) as a DMSO‐compatible liquid crystal alignment medium that is free from any background NMR signal for application in anisotropic NMR. This novel alignment medium facilitates optimal isotropic and anisotropic conditions within a single sample preparation, controlled by sonication, thereby enabling the measurement of anisotropic NMR parameters‐ residual dipolar couplings (RDC) and residual chemical shift anisotropy (RCSA). GO‐d‐CP offers several advantages, including ease of synthesis, isolation of solid GO‐d‐CP as a stable non‐hygroscopic material, and maintenance of the anisotropic state stability >30 days, allowing for prolonged and repetitive experiments. Notably, post the analysis it allows for easy recovery of valuable analytes as well as GO‐d‐CP for reuse, enabling the routine application of anisotropic NMR in structural analysis of small molecules. We demonstrate its efficacy by analyzing the relative stereochemistry of four compounds ‐ estrone, santonin, griseofulvin, and cinmethylin ‐ using anisotropic NMR data.