Alignment Media Of Residual Dipolar Coupling Based On Derivated Graphene Oxide Liquid Crystal

Residual dipolar coupling(RDC)was an important parameter for organic molecular structure elucidation,which can reflect the spatial information in the organic molecules.It had attracted increasing attention in recent years.RDC could not be detected in isotropic solvent.The effectiveness of RDC measurements was limited by the shortage of alignment media compatible with widely used organic solvents.Herein,we presented the first liquid crystal(LC)based on alignment medium that was compatible with pure DMSO,thus enabling RDC measurements of polar and intermediate polarity molecules.Graphene oxide(GO)was synthesized from natural graphite powder using a modified Hummers method.Then,the GO was grafted by trifluoroethyl methacrylate(TFEMA)using free radical polymerization.The resulting products were characterized by FTIR,TGA,SEM.which could be formed liquid crystals in pure DMSO.Furthermore,to demonstrate the aligning properties of this LCs,Estrone,Dihydroartemisinin,L-Camphor,L-Boc-Tryptophan,Isopinocampheol were selected as analytes for RDC measurements.The linear relation plots showed an excellent linear relationship between the experimental and back-calculated RDC values from Mspin software.Moreover,to expand the derivatization graphene oxide application in other organic solvents,GO-g-GMA was also synthesised by using free radical polymerization,and could be formed LCs in pure acetonitrile.The aligning properties of GO-g-GMA LCs was demonstrated in the similar way of last chapter,the result indicated that the GO-g-GMA LCs couldextract residual dipolar coupling values accurately,and it was a very effective alignment medium.The resulting new media offered several advantages,such as absence of background signals,narrow line shapes,tunable alignment,and no ?-?stacking with ?-conjugated molecules.Importantly,the resulting anisotropic media had moderate alignment strength,which was a prerequisite for an accurate RDC measurement.