Self-assembly, as a typical bottom-up strategy for the fabrication of functional materials, has been applied to fabricate chiral materials with subtle chiral nanostructures. The chiral nanostructures exhibit great potential in asymmetric catalysis, chiral sensing, chiral electronics, photonics, and even the realization of several biological functions. According to existing studies, the supramolecular chirality transfer process combined with hierarchical self-assembly plays a vital role in the fabrication of multiscale chiral structures. This progress report focuses on the hierarchical self-assembly of chiral or achiral molecules that aggregate with asymmetric spatial structures such as twisted bands, helices, and superhelices in different environments. Herein, recent studies on the chirality transfer induced self-assembly based on a variety of supramolecular interactions are summarized. In addition, the influence of different environments and the states of systems including solutions, condensed states, gel systems, interfaces on the asymmetric hierarchical self-assembly, and the expression of chirality are explored. Moreover, both the driving forces that facilitate chiral bias and the supramolecular interactions that play an important role in the expression, transfer, and amplification of the chiral sense are correspondingly discussed.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202002132

Supramolecular Chirality Transfer toward Chiral Aggregation: Asymmetric Hierarchical Self-Assembly

The first example of luminescent monosubstituted polyacetylenes (mono-PAs) is presented, based on a contracted cis-cisoid polyene backbone. It has an excellent circularly polarized luminescence (CPL) performance with a high dissymmetric factor (up to the order of 10-1 ). The luminescence stems from the helical cis-cisoid PA backbone, which is tightly fixed by the strong intramolecular hydrogen bonds, thereby reversing the energy order of excited states and enabling an emissive energy dissipation. CPL switches are facilely achieved by the solvent and temperature through reversible conformational transition. By taking advantages of fast response and high sensitivity, the thin film of mono-PAs could be used as a CPL-based probe for quantitative detection of trifluoroacetic acid with a wider linear dynamic range than those of photoluminescence and circular dichroism. This work opens a new avenue to develop novel smart CPL materials through modulating conformational transition.

Brightening up Circularly Polarized Luminescence of Monosubstituted Polyacetylene by Conformation Control: Mechanism, Switching, and Sensing

Allostery can regulate protein self-assembly which further affects biological activities, and achieving precise control over the chiral suprastructures during self-assembly remains challenging Herein, to mimic the allosterical nature of proteins, the poly(phenylacetylene) block copolymers PPA-b-PsmNap with the dynamic helical backbone were synthesized to investigate their conformational-transition-induced self-assembly As the helical conformation of the block PsmNap spontaneously transforms from cis-transiod to cis-cisoid, the decreasing solubility of PsmNap blocks in THF induced self-assembly of PPA-b-PsmNap The self-assembly structures of copolymers can sequentially evolve from vesicles to nanobelts to helical strands during the process of conformation transformation The screw sense of final helical strands was strictly correlated to the helicity of the block PsmNap This is helpful to understand the mechanism of allostery-modulated self-assembly

Allostery‐Mimicking Self‐assembly of Helical Poly(phenylacetylene) Block Copolymers and the Chirality Transfer

Nature has developed unique strategies to refine and optimise structural performance. Using surfaces designed at multiple length scales, from micro to nano levels, combined with complex chemistries...

https://www.tandfonline.com/doi/pdf/10.1080/09506608.2021.1995112

Mimicking nature to control bio-material surface wetting and adhesion

In the past few decades, the enantioseparations techniques have been quickly developed in order to meet the needs of single enantiomers in many fields. Polyacetylene derivatives have attracted considerable attention due to their rigid conjugated backbone with high stereoregularity that can be readily induced into a regular helical conformation by the chiral bias covalently or non-covalently bonding to the backbone. Macromolecular helicity plays an important role in enhancing the enantioseparation ability, and the controllable and stereoregular helical structure of the polyacetylenes affords them a wide variety of potential applications, which are promising candidates for enantioseparation. In this review, the discovery and development of helical polyacetylene derivatives and the enantioseparations using helical polyacetylene derivatives as chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC), optical resolution membranes, enantioselective adsorbents and chiral additives for enantioselective crystallization will be described.

Enantioseparation using helical polyacetylene derivatives

A pair of enantiomeric cis-poly(phenylacetylene)s (PPAs) substituted at the meta-positions of pendant phenyl rings by an achiral methoxycarbonyl group and a chiral 1-methylpropyloxycarbonyl group (i.e., sP-Me-C4/rP-Me-C4) as well as two cis-PPAs bearing either just a methoxycarbonyl (i.e., m-aP-Me) or a 1-methylpropyloxycarbonyl (i.e., m-sP-C4) meta substituent were synthesized under the catalysis of [Rh(nbd)Cl]2 (nbd = norbornadiene). Various techniques including 1H NMR, FTIR, Raman, UV–vis, CD, DSC, STM, DLS/SLS, and computer calculation were applied to characterize the helical structures of these polymers in both solution and solid states. sP-Me-C4/rP-Me-C4 adopted contracted cis-cisoid helical conformations in THF, toluene, CH2Cl2, and ClCH2CH2Cl but cis-transoid ones in CHCl3 and Cl2CHCHCl2. The cis-cisoid helices were considered to be stabilized by the existence of six n → π* interaction bands along the polyene backbones between vicinal carbonyl groups. Such interactions were insensitive to the diel...

Cis-Cisoid Helical Structures of Poly(3,5-disubstituted phenylacetylene)s Stabilized by Intramolecular n → π* Interactions

The cis-trans isomerization of amides plays a vital role in all kinds of structural changes and biological activities, involving protein folding, protein misfolding, and even protein molecular reco...

Xiaoyan Guan

Papers

Brightening up Circularly Polarized Luminescence of Monosubstituted Polyacetylene by Conformation Control: Mechanism, Switching, and Sensing

Cis-Cisoid Helical Structures of Poly(3,5-disubstituted phenylacetylene)s Stabilized by Intramolecular n → π* Interactions

Thermoswitching of Helical Inversion of Dynamic Polyphenylacetylenes through cis-trans Isomerization of Amide Pendants

Hydrogen bonds driven conformation autoregulation and sol-gel transition of poly(3,5-disubstituted phenylacetylene)s

Synthesis and thermo-responsive behavior of helical polyacetylenes derived from proline