[Ph3C][B(C6F5)4]: A Highly Efficient Metal‐Free Single‐Component Initiator for the Helical‐Sense‐Selective Cationic Copolymerization of Chiral Aryl Isocyanides and Achiral Aryl Isocyanides

Inspired by the exquisite helices in Nature, fabrication of helical materials with controlled handedness has attracted considerable attention. Herein, we report on precis synthesis of single left‐ and right‐handed helical polyisocyanides through living polymerization of achiral monomers using chiral palladium catalysts under helix‐sense‐selective manner. Mechanism study revealed that the yielded helices with opposite handedness showed different activity of the living chain end. The helix with unfavored handedness was self‐terminated, while the one with favored handedness showed high activity and could undergo chain propagation to form a high molecular weight polymer with maintained single‐handed helicity.

Selective Synthesis of Single‐Handed Helical Polymers from Achiral Monomer and a Mechanism Study on Helix‐Sense‐Selective Polymerization

Zhou

Jiang

et al. 2020

Helicity‐ and Molecular‐Weight‐Driven Self‐Sorting and Assembly of Helical Polymers towards Two‐Dimensional Smectic Architectures and Selectively Adhesive Gels

Kang

et al. 2021

Self‐sorting plays a crucial role in living systems such as the selective assembly of DNA and specific folding of proteins. However, the self‐sorting of artificial helical polymers such as biomacromolecules has rarely been achieved. In this work, single‐handed helical poly(phenyl isocyanide)s bearing pyrene (Py) and naphthalene (Np) probes were prepared, which exhibited interesting self‐sorting properties driven by both helicity and molecular weight (Mn) in solution, solid state, gel, and on the gel surface as well. The polymers with the same helix sense and similar Mn can self‐sort and assemble into well‐defined two‐dimensional smectic architectures and form stable gels in organic solvents. In contrast, mixed polymers with opposite handedness or different Mn were repulsive to each other and did not aggregate. Moreover, the gels of helical polymers with the same handedness and similar Mn can recognize themselves and adhere together to form a gel.

Controlled Synthesis of Cyclic‐Helical Polymers with Circularly Polarized Luminescence

Gao

et al. 2022

Cyclic polymers attract attention because of their endless structure and unique properties, which differ from the linear analogs. However, the synthesis of cyclic polymers is difficult and prohibits their functions and applications. In this study, we reported chiral cyclic Pd II -catalysts that initiate a living ring-expansion polymerization of isocyanides, yielding a single-handed cyclic-helical poly(phenyl isocyanide), with predictable molecular weight (M n ) and low dispersity (M w /M n ), in good yield. Using this method, cyclic bottlebrush polymers were prepared via the grafting-onto strategy. The cyclic topology was confirmed using various spectroscopic data and atomic force microscope observation. Moreover, the cyclic polymer brushes, comprising of a one-handed helical backbone, showed interesting photoluminescence and circularly-polarized luminescence.