Helical Assemblies of One-Dimensional Supramolecular Polymers Composed of Helical Macromolecules: Generation of Circularly Polarized Light Using an Infinitesimal Chiral Source

Abstract

We report the synthesis of one-dimensional supramolecular polymers composed of one-handed helical macromolecules bearing fluorescent pendant groups and the generation of circularly polarized light on the basis of hierarchical chiral amplification starting from a tiny amount of chiral substituent. Copolymerization of benzo­[1,2-b:4,5-b′]­dithiophene-appended achiral/chiral isocyanides (99:1, mol/mol) with a solid-state photoluminescence feature afforded submicrometer supramolecular fibers, in which almost perfect single-handed helical polyisocyanides were noncovalently connected end to end. The resulting helical supramolecular polymers were further helically assembled to form a cholesteric liquid crystal film with an intense circularly polarized luminescence (CPL) signal. Surprisingly, the supramolecular system containing only 0.01 mol % of the chiral monomer unit also emitted the observable circularly polarized light owing to multiple chiral amplification from an infinitesimal point chirality to helical chirality and then to supramolecular chirality. Furthermore, chiral information was efficiently transferred from the helically assembled supramolecular system containing 1 mol % of the chiral unit to achiral dye molecules blended in the film, allowing full-color tunable induced CPL with luminescence dissymmetry factors greater than 1.0 × 10–2. This unprecedentedly strong chiral amplification enables the creation of helical supramolecular polymers and chirally assembled systems with various chiral functions based solely on an infinitesimal chiral source.

Crystallization‐Driven Asymmetric Helical Assembly of Conjugated Block Copolymers and the Aggregation Induced White‐light Emission and Circularly Polarized Luminescence

“…[25][26][27] These studies not only explore the structures and functions of their natural counterparts,but also and more importantly,develop new functional materials with applications in, for example,c hiral resolution, [28] asymmetric catalysis, [29,30] chiral switch, [31,32] and circularly polarized luminescence (CPL). [33,34] Among them, CPL has lately attracted increasing attentions on account of their potentials in chemical sensors,biological probes,and three-dimensional displays. [35][36][37][38] Several kinds of CPL materials have been developed based on small organic molecules,l anthanide and transition metal complexes.…”

Strong‐Induced CPL Emission Promoted from Achiral Conjugated Polymer‐Containing Emissive Nematic Liquid Crystals (P‐N*‐LCs)

“…[ 33–35 ] Recently, Ikai's group reported that the helical supramolecular polymers were assembled as a cholesteric liquid crystal, strong chiral amplification effect, and intense CPL signal ( g em = 1.0 × 10 −2 ) were observed while adding infinitesimal achiral dyes into cholesteric LC to form N*‐LCs. [ 36 ] In 2019, Duan and co‐workers explored a new pathway to develop the novel CPL‐active LC material by dispersing chiral emitters and a triplet donor into N‐LCs, the g em of N*‐LCs could be amplified one order of magnitude up to about 0.04 through remarkable photon upconverted circularly polarized luminescence (UC‐CPL) mechanism. [ 37 ]…”

On the Optical Activity of Poly(l-lactic acid) (PLLA) Oligomers and Polymer: Detection of Multiple Cotton Effect on Thin PLLA Solid Film Loaded with Two Dyes

“…Thus, PLLA and PDLA are ideal polymers for the study of the extrinsic Cotton effect or induced Cotton effect involving the interaction of helical polymer structure in solution with a guest molecular chromophore hosted inside the spiral pitches or intercalated between the PLLA helices. The guest symmetric molecule without ORD signal, by interacting with the asymmetric helical structure of PLLA, gives rise to an induced ORD signal in correspondence of its electronic transition in the visible through the coupled oscillator mechanism or the one-electron mechanism or exciton coupling [21][22][23][24][25]. In other words, the electronic transition of the chromophore of the guest molecule has a spatial relationship with host macromolecule which is manifested as a dissymmetry in the ORD spectrum of the complex [21][22][23][24][25].…”

“…The guest symmetric molecule without ORD signal, by interacting with the asymmetric helical structure of PLLA, gives rise to an induced ORD signal in correspondence of its electronic transition in the visible through the coupled oscillator mechanism or the one-electron mechanism or exciton coupling [21][22][23][24][25]. In other words, the electronic transition of the chromophore of the guest molecule has a spatial relationship with host macromolecule which is manifested as a dissymmetry in the ORD spectrum of the complex [21][22][23][24][25]. The induced Cotton effect was indeed detected by ORD spectroscopy both in solutions of PLLA/iodine [26] and PLLA/C 60 fullerene [27], whereas a charge-transfer host-guest interaction was measured in both cases.…”