Self‐Assembly of Helical Polymers and Oligomers to Create Liquid Crystalline Alignment for Anisotropic NMR Parameters

Abstract

The measurement of anisotropic residual dipolar couplings (RDCs) parameters for the structure elucidation of organic molecules relies on suitable alignment media. Employment of self‐assembled liquid crystalline systems to create anisotropic alignment can be an effective way to realize aligned samples and acquire RDCs. This Mini‐review highlights the recent advances on amino acid‐based helical polymers and supramolecular oligomers forming rigid, rod‐like structures that aggregate into ordered liquid crystalline phases, including amino acid‐based helical polyisocyanides, polyacetylenes, polypeptides, and oligopeptides assembled alignment media. The methodology for the determination of anisotropic liquid crystals is briefly discussed, and a summary of recent research progress in the enantiodifferentiation of helical polymers aligned media is followed. In addition, the self‐assembled mechanism of oligopeptides and their RDCs structural analysis are also described.

Synthesis of poly(3-hexylthiophene)-block-poly(phenylisocyanide) copolymers and their self-assembly in solution

“…Self-assembly is a useful method for preparing functional polymer soft materials and supramolecular assembly in pure solvent has attracted the interest of researchers because it results in the formation of lyotropic liquid crystals, which has potential applications as functional alignment medium for anisotropic NMR analyses. 53 Thus, 2 H NMR spectra were used to evaluate the occurrence of anisotropic phases because deuterium nuclei present a nuclear electric quadrupole moment. For poly( 1 20 - b - 5 150 ), a feeble quadrupolar splitting 2 H solvent signal was observed in CD 2 Cl 2 (Fig.…”

Anisotropic 1H STD‐NMR Spectroscopy: Exploration of Enantiomer‐Polypeptide Interactions in Chiral Oriented Environments

“…Establishing and then prioritizing the key molecular features governing the molecular shape recognition mechanisms involved in enantiodiscrimination phenomena in lyotropic CLCs is essential for two reasons: [51][52][53] i) optimize computational predictions (such as molecular dynamics simulation) of existing enantiodiscriminating helically-chiral polymers with the ultimate goal of solving the thorny challenge of absolute configuration determination, ii) design novel polymer-based effective enantiodiscriminating systems.…”

Light-Controlled Lyotropic Liquid Crystallinity of Polyaspartates Exploited as Photo-Switchable Alignment Medium

“…Polypeptides are one class of alignment media widely used. , Their rigid, helical secondary structures resemble rods that align parallelly to form a cholesteric LLC. , The anisotropic shape of the polypeptide is mandatory for the formation of an LLC and is a possible handle to control the alignment by external stimuli: If the anisotropic shape is lost as can be achieved by the addition of acids, the LLC becomes an isotropic solution. Usually, the amino acid determines and fixes the secondary structure of a polypeptide .…”