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Correlation between structures of chiral polymers and their efficiency for chiral resolution by crystallization
Author(s) -
Menahem Tali,
Pravda Martin,
Mastai Yitzhak
Publication year - 2009
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20724
Subject(s) - crystallization , chemistry , polymer , chiral resolution , random coil , enantiomer , copolymer , polyethylene glycol , circular dichroism , chirality (physics) , resolution (logic) , crystallography , polymer chemistry , stereochemistry , organic chemistry , chiral symmetry breaking , symmetry breaking , computer science , nambu–jona lasinio model , physics , quantum mechanics , artificial intelligence
In this work, we describe the correlation between chiral polymer structures, particularly α‐helical and random coil conformations, and their efficiency as chiral resolving agents in crystallization processes. A set of chiral block copolymers based on polyethylene oxide with chiral glutamic acid oligopeptide segments (PEG 113 ‐ b ‐(+)‐( S )‐Glu 20 ) were synthesized and employed as additives in the crystallization of rac ‐threonine. CD spectroscopy demonstrates that structures of chiral polymers could be switched between a helical and a disordered random coil by pH. The effect of these polymers at different conformations on the crystallization kinetics, crystal morphology, and chiral resolution of rac ‐threonine is reported. Our study demonstrates that only chiral polymers with α‐helical conformations of the chiral segment are effective as additives for chiral resolution throughout crystallization. Overall, our results provide useful guidelines for the selection and design of chiral polymer additives that will act efficiently for chiral resolution by crystallization. Chirality 2009. © 2009 Wiley‐Liss, Inc.