Chiral recognition in molecular and macromolecular pairs of (S)- and (R)-1-cyano-2-methylpropyl-4?- {[4-(8-vinyloxyoctyloxy)benzoyl]oxy}biphenyl-4- carboxylate enantiomers

Abstract

S)-1-Cyano-2-methylpropyl-49-{(4-(8-vinyloxyoctyloxy)benzoyl)oxy}biphenyl- 4-carboxylate ((S)-11) and (R)-1-cyano-2-methylpropyl-49-{(4-(8-vinyloxyoctyloxy)- benzoyl)oxy}biphenyl-4-carboxylate ((R)-11) enantiomers, both greater than 99% enan- tiomeric excess, and their corresponding homopolymers, poly((S)-11) and poly((R)-11), with well-defined molecular weights and narrow molecular weight distributions were synthesized and characterized. The mesomorphic behaviors of (S)-11 and poly((S)-11) are identical to those of (R)-11 and poly((R)-11), respectively. Both (S)-11 and (R)-11 exhibit enantiotropic SA ,S *, and SX (unidentified smectic) phases. The corresponding homopolymers exhibit SA and S* C phases. The homopolymers with a degree of polymer- ization (DP) less than 6 also show a crystalline phase, whereas those with a DP greater than 10 exhibit a second SX phase. Phase diagrams were investigated for four different pairs of enantiomers, (S)-11/(R)-11, (S)-11/poly((R)-11), and poly((S)-11)/poly((R)-11), with similar and dissimilar molecular weights. In all cases, the structural units derived from the enantiomeric components are miscible and, therefore, isomorphic in the SA and S* phases over the entire range of enantiomeric composition. Chiral molecular recognition was observed in the SA and SX phases of the monomers but not in the SA phase of the polymers. In addition, a very unusual chiral molecular recognition effect was detected in the S* C phase of the monomers below their crystallization temperature and in the S* C phase of the polymers below their glass-transition temperature. In the S* C phase of the monomers above the melting temperature and of the polymers above the glass-transition temperature, nonideal solution behavior was observed. However, in the SA phase the monomer-polymer and polymer-polymer mixtures behave as an ideal solution. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3631-3655, 2000