Stretched Poly(vinyl acetate) Gels as NMR Alignment Media for the Measurement of Residual Dipolar Couplings in Polar Organic Solvents

摘要

Residual dipolar couplings (RDCs) have revolutionized the NMR-based structure determination of large biomolecules[1]-[4] and lately demonstrated their potential in the field of small molecules.[5]-[12] The measurement of RDCs relies on the partial orientation of the molecule of interest, for which a so-called alignment medium is necessary. In aqueous solution a variety of alignment media are known, for example, bicelles,[13] filamentous phage,[14] liquid-crystalline phases,[15] or stretched polyacrylamide-based gels.[16], [17] For relatively apolar organic solvents, liquid crystals such as poly--benzyl-L-glutamate (PBLG)[5]-[7], [18] or deuterated 4-n-pentyl-4-cyanobiphenyl (PCBP)[19] as well as stretched polystyrene (PS)[11] and polydimethylsiloxane (PDMS)[12] gels are used to obtain structural information from RDCs. For polar organic solvents such as methanol or DMSO, however, no alignment medium is available yet. Herein we propose the use of stretched poly(vinyl acetate) (PVAC) gels for partial orientation of molecules dissolved in polar organic solvents.