Investigation of Peptoid Chiral Stationary Phases Terminated withN′‐Substituted Phenyl‐L‐proline/leucine Amide

Abstract

AbstractEight peptoid chiral stationary phases (CSPs) terminated withN′‐substituted phenyl‐L‐proline orL‐leucine amide were prepared and evaluated under normal phase mode. With 59 racemic analytes, we compared the enantiomeric separations on CSPs terminated withp‐methylphenyl,p‐chlorophenyl and unsubstituted phenyl. For short peptoid selectors containing only oneS‐N‐(1‐phenylethyl) glycine (Nspe) unit, the terminalp‐methyl substituent did not affect chiral recognition abilities significantly. InL‐proline amide terminated CSPs,p‐chloro substituent resulted in obviously inferior selectivity while inL‐leucine amide terminated CSPs, it worked much better. Longer peptoid selectors containing two moreNspe units generally performed much better than the shorter ones, due to the great contributions of peptoid chain to chiral recognition. Meanwhile, the effects of the terminal substituent on selectivity were found changed on these CSPs. For CSPs terminated withL‐leucine amide, the terminalp‐chloro substituent in longer selector no longer produced the best recognition ability; the CSP with unsubstituted phenyl instead performed best. Comparison of these peptoid CSPs varied in terminal substituents and chain length was conducted to gain a better understanding of the chiral recognition mechanism of this type CSP and promote the development of more useful CSPs.