An Acrylonitrile‐Based Copolymer Gel as an NMR Alignment Medium for Extraction of Residual Dipolar Couplings of Small Molecules in Aqueous Solution

Abstract

An NMR weakly-aligning polymer gel has been prepared by copolymerization of acrylonitrile and 2-acrylamide-2-methyl-1propanesulfonic acid in the presence of 1,4-butanediol diacrylate as a cross-linker. The polymer readily swells in water in a large range of temperatures, although the swelling ratio is decreased in saline solutions. The swollen gel can be mechanically compressed, in a reversible way, generating anisotropy, as easily shown in 2 H NMR experiments, and allowing measure-ment of 1 D CH residual dipolar couplings (RDCs) through F1coupled HSQC experiments. The performance of this gel as a NMR alignment medium was evaluated in several water-soluble organic molecules and, while it provided RDCs of proper size for sucrose and even such as small molecule as 5-norbornen-2ol, in the case of azidothymidine and cefuroxime sodium salt the strong interaction of these molecules with the gel prevented successful extraction of the RDCs.

Residual dipolar couplings as a tool for structural analysis of ionic liquids

“…5 Following on from the original PMMA/CDCl 3 system, other combinations of polymers/solvents have been reported such as poly-DEGMEMA/CD 3 OD, 6 poly-HEMA/DMSO- d 6 , 7 and polyacrylonitrile (PAN)/DMSO- d 6 8 and even water compatible systems. 9,10…”

“…5 Following on from the original PMMA/CDCl 3 system, other combinations of polymers/solvents have been reported such as poly-DEGMEMA/CD 3 OD, 6 poly-HEMA/DMSO-d 6 , 7 and polyacrylonitrile (PAN)/DMSO-d 6 8 and even water compatible systems. 9,10 Ionic liquids (ILs) are a large and important family of solvents. They are room temperature molten organic salts, very often composed of an organic cation and an inorganic counterion.…”