Helicity Control of π‐Stacked Assemblies of Oligo(para‐phenylene) Derivatives Using Photoresponsive Chiral Moieties at Terminal Sites

Abstract

Oligo(para‐phenylene) (OPP) derivatives bearing photoresponsive chiral dithienylethene (DE*) terminal moieties that induce chirality in the OPP main chain are synthesized. In the assembled state, the photoisomerization of the chiral DE* terminal moieties prior to assembly, from the open to the closed form, leads to a change in the helicity of the π‐stacked structures. The circular dichroism spectra of mixed solvent solutions and cast films of the OPP assemblies exhibit bisignate Cotton effects in the absorption region associated with the oligomer main chain: these features indicate the presence of helically π‐stacked structures. Furthermore, the chiral transcription of racemic poly(bithiophenethiophene) (PBTT) by chiral OPP in the assembled state is demonstrated. The chirally transcribed PBTT shows a change in helicity upon the photoisomerization of the chiral DE* terminal moieties of OPP. To the best of our knowledge, this is the first report of helicity control of a helically π‐stacked conjugated oligomer through the photoisomerization of a chiral photoresponsive moiety. Such assemblies could be attractive for use in optoelectronic devices and optical memory systems.

Inverse Evolution of Helicity from the Molecular to the Macroscopic Level Based on N-Terminal Aromatic Amino Acids

“…Helicity defined as an entity with an axis yet not superimposable on its mirror image has emerged as the most common phenomenon in supramolecular chiral systems . Helicity can be expressed on wide scales from molecular to nanoscale and to macroscopic scale. − At an observable scale by electron microscopy or atomic force microscopy, one-dimensional objects exhibit either M - or P -handed helicity. , Such helical structures at the macroscopic level have been developed with vital importance in recognizing supramolecular chirality, , asymmetrical synthesis, , a matrix for circularly polarized luminescence, − and other chiroptical applications. − Rational control of the emergence, transfer, inversion, amplification, and manipulation of macroscopic helicity is a key in realizing these applications. , …”

“…4−6 At an observable scale by electron microscopy or atomic force microscopy, onedimensional objects exhibit either M-or P-handed helicity. 7,8 Such helical structures at the macroscopic level have been developed with vital importance in recognizing supramolecular chirality, 9,10 asymmetrical synthesis, 11,12 a matrix for circularly polarized luminescence, 13−15 and other chiroptical applications. 16−18 Rational control of the emergence, transfer, inversion, amplification, and manipulation of macroscopic helicity is a key in realizing these applications.…”

Biphenyl-Induced Superhelix in l -Phenylalanine-Based Supramolecular Self-Assembly with Dynamic Morphology Transitions

“…6,7 The conformational misfolding or disorders in coiled-coil super-helical structures of proteins may disrupt normal cellular metabolism and increase the risk of some diseases including Alzheimer's or Parkinson's diseases. 8,9 Despite the transformation of chiral structures has been modulated in some supramolecular assembled systems via external stimuli such as light, 10,11 pH, 12,13 ions, 14,15 temperature, 16,17 and solvent, 18,19 the involved helical structures are only with simple helix due to rigorous molecular packing mode required for transition from one-dimensional (1D) helical assemblies to higher-order super-helical structures. 20 Therefore, it is a great challenge to fabricate higher level super-helical assemblies and accomplish reversible transformation between initial assemblies and super-helical structures, which is the key to really mimic complex chiral structures related to diverse biological functions.…”

Hierarchically Evolved Supramolecular Chirality Mediated by Arene-Perfluoroarene Interaction

“…In contrast, supramolecular chirality is formed by the ordered packing of chiral or achiral entities, which has expressed great potential in chiroptical materials, asymmetrical synthesis, sensing, and devices . Supramolecular chirality is reflected at hierarchical levels, from sub-1 nm to micrometer helix, facilitated by the hierarchical coassemblies of either single or multiple-constituent species. − Precise and rational control over supramolecular chirality across multiple scales is promising in materials design, which however remains considerably challenging. For instance, the supramolecular tilt chirality and 2 1 columnar chirality found in the crystal phase is considered as the smallest helix with sub-1 nm diameter and pitch. , Its evolution to micrometer-scale spiral fibers or spiral tubes with a diameter of about tens to hundreds of nanometers − provides a diversified and facile method to regulate chiroptical activity and other performances.…”