Traceless Chiral Shift Reagent Based on Nonbonding Interaction with Single-Handed Helical Poly(quinoxaline-2,3-diyl).

Abstract

Single-handed poly(quinoxaline-2,3-diyl)s (PQX) have been found to serve as a new chiral shift reagent (CSR) for determining the enantiomeric ratio by NMR. Even though there is no specific binding site in PQX, its nonbonding interaction with chiral analytes leads to a significant shift of the NMR chemical shift, allowing quantification of the enantiomeric ratio. The new CSR has the advantages of a wide scope of analytes including ethers, haloalkanes, and alkanes, easy tunability of the degree of chemical shifts by measurement temperature, and erasability of proton signals of CSR because of the short spin-spin (T2) relaxation of the macromolecular scaffold.