We have found a simple and novel synthetic method for obtaining a chiral polymer from an achiral monomer by using a chiral catalytic system. The chirality of the polymer was caused only by a one-handed helical backbone, and the polymer had no other chiral structures in the side groups. In addition, the helical conformation was stable in solution by itself. This is the first example of helix-sense-selective polymerization of a substituted acetylene. The stability of the helicity was found to be caused by intramolecular hydrogen bonds.
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http://dx.doi.org/10.1021/ja021233o | DOI Listing |
Macromol Rapid Commun
October 2024
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin, 130012, China.
Polyallenes with appropriate pendants can form stable helices and exhibit significant optical activity. These helical polyallenes contain reactive double bonds that allow for further functionalization, making them a class of chiral functional materials with broad application prospects. This review article delves into the intricacies of synthesizing well-defined helical polyallenes through controlled synthetic methodologies, including helix-sense selective living polymerization, regioselective and asymmetric living polymerization, and one-pot block copolymerization of allenes with aryl monomers.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
Department of Molecular and Macromolecular Chemistry Graduate School of Engineering, Nagoya University Chikusa-ku, Nagoya, 464-8603, Japan.
We report the helix-sense-selective memory polymerization (HSMP) of achiral biphenylylacetylenes bearing carboxy and amino pendant groups in the presence of basic and acidic chiral guests in water, respectively. The HSMP proceeds in a highly helix-sense-selective manner driven by noncovalent chiral ionic interactions between the monomers and guests under kinetic control, producing the one-handed helical polymers with a static memory of helicity in one-pot during the polymerization in a very short time, accompanied by amplification of asymmetry. The carboxy-bound helicity-memorized polymer self-assembles into a cholesteric liquid crystal in concentrated water, in which a variety of basic achiral fluorophores further co-assembles to form supramolecular helical aggregates that exhibit an induced circularly polarized luminescence in a color tunable manner.
View Article and Find Full Text PDFChemistry
June 2024
Institute for Catalysis (ICAT) and Graduate School of Chemical Sciences and Engineering, Hokkaido University, N21 W10, Kita-ku, Sapporo, 001-0021, Japan.
ACS Catal
September 2023
Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States.
The synthesis of stereoregular polymers through ionic mechanisms using asymmetric ion-pairing (AIP) catalysis is emerging as an effective strategy to achieve differentiated material properties from readily available building blocks. Stereoselective cationic polymerization in particular is primed for advancement using AIP by leveraging the breadth of Brønsted and Lewis acid small-molecule catalysis literature; however, mechanistic studies that address polymer-specific phenomena are scarce and, as a result, the lack of mechanistic understanding has limited catalyst design. In a recent study, we demonstrated the only example of a stereoselective and helix-sense-selective cationic vinyl polymerization of -vinylcarbazole using chiral scandium-(oxazoline) Lewis acids.
View Article and Find Full Text PDFChem Commun (Camb)
April 2023
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China.
Optically active helical polycarbenes were constructed through the living and controlled helix-sense-selective polymerization (HSSP) of methyl salicylate modified diazoacetate monomer catalysed π-allylPdCl with chiral phosphine ligands. The obtained helical polycarbenes could undergo postpolymerization modification to afford functional polycarbenes efficiently.
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