Macromolecular ionophores. 1. Chiral recognition properties of poly[(1→6)‐2,5‐anhydro‐ D ‐glucitol] toward racemic amino acid ester

The chiral recognition property of poly[(1→6)‐2,5‐anhydro‐3,4‐di‐ O ‐alkyl‐D‐glucitol] ( 1 ) toward racemic RCH (CO 2 CH 3 )NH 3 + · PF 6 − ( 2 · HPF 6 ) has been studied using a transport system involving an aqueous source and receiving phases separated by a chloroform phase containing 1 . Transport rates for aromatic guests 2a (R = Ph) and 2b (R = CH 2 Ph) were faster than those for aliphatic guests, 2c (R = CH(CH 3 ) 2 ) and 2d (R = CH 2 CH(CH 3 ) 2 ), using the polymer substituted with methyl groups ( 1a ). The enantiomeric excess (e.e.) was 10.9% for 2a as a maximum value and decreased in the order of 2a > 2c > 2b = 2d . When the transport of 2a · HPF 6 was carried out using the polymers with 3,4‐di‐ O ‐methyl ( 1a ), ethyl ( 1b ), allyl ( 1c ), and pentyl ( 1d ) groups, the e.e. was 22.0% for 1d as a maximum value and increased in the order of 1a < 1b < 1c < 1d . The formation of a complex between 1a and 2a · HPF 6 was confirmed by 1 H and 13 C NMR spectral measurements. © 1995 Wiley‐Liss, Inc.