Residual dipolar couplings (RDC) emerged to be an important structural parameter for organic and biomolecules. Herein, a new helical polyisocyanopeptide (l,l-PIAF-OBn) that forms lyotropic liquid crystals (LLC) in CDCl is proposed as a novel weakly orienting medium for acquiring residual dipolar couplings (RDCs) of organic molecules. We demonstrate its application for the structural elucidation of strychnine and triptolide.

Residual dipolar couplings (RDCs) have attracted attention in light of their great impact on the structural elucidation of organic molecules. However, the effectiveness of RDC measurements is limited by the shortage of alignment media compatible with widely used organic solvents, such as DMSO. Herein, we present the first liquid crystal (LC) based alignment medium that is compatible with pure DMSO, thus enabling RDC measurements of polar and intermediate polarity molecules. The liquid crystals were obtained by grafting polymer brushes onto graphene oxide (GO) using free radical polymerization. The resulting new medium offers several advantages, such as absence of background signals, narrow line shapes, and tunable alignment. Importantly, this medium is compatible with π-conjugated molecules. Moreover, sonication-induced fragmentation can reduce the size of GO sheets. The resulting anisotropic medium has moderate alignment strength, which is a prerequisite for an accurate RDC measurement.

Enantiopure diphenylprolinols have been developed as effective and practical NMR chiral solvating agents for the enantiodiscrimination of diverse α-carboxylic acids.

MaterialsGraphite powder (4μm) was purchased from Qingdao Henglide Graphite Co. Ltd.. Trifluoroethyl methacrylate was bought from Aladdin without purification.2,2'-azobis-(2-methyl-propionitrile). (AIBN) was bought from Aladdin and employed after twice recrystallization. All other regents such as DMF and DMSO were purchased from Aladdin and employed without purification. Estrone and dihydroartemisinin were purchased from J&K China Chemical Ltd. without purification. InstrumentationScanning Electron Microscopy (SEM): Scanning electron microscopy (SEM) images were recorded on a Hitachi S4800 field emission SEM system to verify the morphology of GO and GO-g-TFEMA.Fourier-Transform Infrared (FTIR): IR spectra were recorded on a Bruker EQUINOX55 instrument with 16 scans.Thermal Gravimetric Analysis (TGA): TGA was measured on a Perkin-Elmer S II TGA instrument with a heating rate of 5 o C/min from 100°C to 550 o Synthesis of GO-g-TFEMAC under a 100.0 mL/min nitrogen flow.Small-angle X-ray scattering (SAXS)：SAXS experiments were performed by the Shanghai Synchrotron Radiation Facility, using a fixed wavelength of 1.03 nm, a sample-to-detector distance of 5 m and an exposure time of 20 s.

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