Helix-sense-selective radical polymerization of bulky styrenic monomers: chiral induction and liquid crystallinity

Turning off the majority-rules effect in two-dimensional hierarchical chiral assembly by introducing a chiral mismatch

Understanding the mechanism in chiral transmission from a single molecule to a supramolecular level is fundamentally important to decipher the nonlinear amplification effect in the two-dimensional (2D) chiral assembly process. In this contribution, we report on the dramatically different nonlinear amplification effect in the chiral co-adsorber induced homochiral assemblies constructed by a series of homologous achiral building blocks on the graphite surface under control of the majority-rules principle. Homologous hexagonal networks are formed for 5-(benzyloxy)-isophthalic acid (BIC) derivatives with different alkyl lengths. While globally homochiral monolayers of BIC-C6 or BIC-C16 can be obtained by using a mixture of chiral co-adsorber 2-octanol with a small enantiomeric excess, such majority-rules principle based nonlinear chiral amplification is inoperative for the assembly of BIC-C10. Molecular mechanistic analysis indicates that BIC-C10 assembly can accommodate a chiral mismatched motif to form long-range ordered but short-range disordered crystalline networks, leading to the co-adsorption of enantiomers without enantioselectivity. The present results shed important insights into the significance of chirality mismatch during chiral transmission and benefit the understanding of chiral communication in a surface monolayer.

Optically active helical vinylbiphenyl polymers with reversible thermally induced stereomutation

A series of novel chiral vinylbiphenyl monomers, (+)-2-[(S)-alkoxycarbonyl]-5-(4′-hexyloxyphenyl)styrene (S-(+)-I-Mm, m = 0, 1, 2, 3)/(−)-2-[(R)-sec-butyloxycarbonyl]-5-(4′-hexyloxyphenyl)styrene (R-(−)-I-M0), were designed and synthesized to search for new building blocks of optically active helical polymers.

Synthesis and properties of novel helical 3-vinylpyridine polymers containing proline moieties for asymmetric aldol reaction

Novel helical vinyl polymers bearing l/d-proline amide moieties were prepared to catalyze asymmetric aldol reactions, which afforded faster reaction rate but slightly poorer enantio-selectivity than the low molar mass counterparts.