A New Chirality Invertible Photoswitch:Light-Driven Axially Chiral Hydrazone Enabling Dynamic Handedness Inversion of Self-Organized Helical Superstructure

Inspired by nature,dynamic self-organized helical superstructures are becoming attractive as building blocks in soft photonic crystals and advanced chiroptical devices.Herein,a chirality invertible hydrazone photoswitch,possessing high helical twisting power(HTP)was judiciously designed and synthesized.Due to the photoinduced configuration changes of the hydrazone photoswitch,it displayed superior thermal stability and strikingly reversible HTP changes.By incorporating a novel chiral hydrazone(CH)into the liquid crystal(LC)host,a handedness invertible cholesteric liquid crystal(CLC)helical superstructure with high thermal stability and light-modulated photonic bandgap was prepared.We inferred that the mechanism of chirality inversion of the novel CH photoswitch derived from changes in the dihedral angle between the two naphthalene rings induced by hydrazone isomerization.Therefore,the influence of chemical structures on its photoresponsiveness was explored.Finally,the potential applications of this advanced light-driven CLC in soft photonic crystals,showing erasable and rewritable colorful patterns and chiroptical templates to induce handedness invertible circularly polarized luminescence were illustrated.

Solvent and guest-binding-controlled chiroptical inversion of molecular devices based on pseudo[1]catenane-type pillar[5]arene derivatives

Four pillar[5]arene-based bicyclic compounds,so-called molecular universal joint(MUJ),were synthesized by incorporating a bisamide ring containing N,O,or S-heteroatom groups,which served as stimuli-responsive chiroptical molecular devices.The structure of MUJ was confirmed by 1H NMR spectra and single-crystal X-ray diffraction analysis,and their planar-chiral enantiomers were successfully separated.Chiroptical inversion behaviors from in to out configurations triggered by temperature,solvent,and guest complexation were investigated by circular dichroism spectra.Chiroptical inversion could be realized in the presence of adiponitrile in certain solvents due to the solvation effects on the side ring and the threading of the guest into the pillar[5]arene cavity.However,the stronger self-included interactions between the cavity and the inside ring of certain MUJs led to inhibition of the switching.

Sculpting the tunable mesoscopic helical chirality into poly(m-phenylenediamine)via Mn^(2+)coordination

Chiral conjugated polymers with controlled mesoscopic helicity are gaining attention for enantioseparation and asymmetric catalysis.However,achieving on-demand chirality and processability remain challenging.Herein,we exploit supramolecular coordination polymers formed by Mn^(2+)and chiral phenylglycine derivatives(L-/D-16PhgCOOH)as templates,using m-phenylenediamine as the monomer to synthesize chiral poly(m-phenylenediamine)(PMPD).In the Mn^(2+)-templated system,the PMPD’s handedness is opposite to the molecular chirality of L-/D-16PhgCOOH,while in the Mn^(2+)-free system,the PMPD handedness aligns with that of the template molecule.This method allows for helicity switching of chiral polymers within a single chirality template system.The introduction of Mn^(2+)is demonstrated to disrupt and reconstitute the supramolecular interactions in the co-assembly,influencing subsequent supramolecular stacking patterns.Carbonizing the resulting PMPDs directly produces chiroptical active nitrogen-doped carbonaceous nanomaterials that inherit the original helicity.Moreover,incorporating F-127 into the polymerization system enhances the aspect ratio of PMPDs,facilitating their delicate processing into chiral self-supporting two-dimensional films and three-dimensional foams.With abundant Lewis basic sites,these chiral polymers offer versatile platforms for novel chiral host-guest interactions.

Hierarchical Self-Assembly Promoted Circularly Polarized Luminescence Enhancement and Handedness Inversion of Metal–Organic Helicate

In-depth studies of hierarchical self-assembly with chirality inversion and asymmetry amplification are indispensable for understanding the chiral transfer rule in assembly systems and construction of circularly polarized luminescence(CPL)active materials.Herein,a coordination-driven primary assembly of pyrene-based chiral ligand and Zn(OTf)2 was employed for the construction of homochiral metal–organic helicate with a triple helix structure,tunable emission color,and significant chirality amplification.More excitingly,the metal–organic helicate further assembled into well-ordered hierarchical nanoarchitectures with the aid of C–H⋯πinteraction andπ–πstacking,showing significant CPL enhancement and unexpected handedness inversion.Thus,the|glum|increased from 5.20×10^(−5) to 5.60×10^(−2),and the|gabs|rose from 3.80×10^(−4) to 1.04×10^(−2) over the entire hierarchical self-assembly process.The multiple supramolecular interactions not only endowed the resultant metal–organic helicate with efficient chirality transmission and tunable emission color but also guided the(supra)molecular building block of metal–organic helicate organizing into the hierarchically chiral nanoarchitecture in a directional manner.This work provides insight into the metal–organic helicate-mediated hierarchical self-assembly and aids the development of CPLactive materials with dynamic chirality modulation and enhanced chiroptical performance.

Chirality Inversion of Assemblies of Bio-based Surfactant Triggered by Metal Ions

The utilization of biomass has attracted much attention during the last decade. Sorbitol is a kind of abundant biomass with multiple chiral centers in its skeleton, indicating an im- portant potential for helical architectures. Helical nanostruc- tures with switchable chirality are attracting much attention due to their crucial roles in many fields.

1,1’-Binaphthol annulated perylene diimides: Aggregation-induced emission enhancement and chirality inversion

Aggregation-induced emission enhancement and aggregation-induced chirality inversion are two individ-ual phenomena for the enantiomerically pure organic dyes in the aggregates.Herein we reported for the first time that these two interesting phenomena could be observed simultaneously in the aggregated states of enantiomerically pure S/R-1,1?-binaphthol annulated perylene diimides,in which two perylene diimides moieties were bridged by S/R-1,1?-binaphthol(BINOL)at the bay positions.Owing to the rotat-able C2 axes between two naphthol annulated perylene diimides moieties,both of them display intrinsic behaviors of aggregation-induced emission enhancements.At the same time,due to the steric hindrances in the imide and methoxy positions,the neighboring twoπ-systems of these two unique polycyclic aro-matic imides in poor solvents are preferable to adopt a cross-stacking mode and thus form helical X-aggregates of opposite chirality(M/P)with chirality inversion characteristics in their circular dichroism and circularly polarized luminescence spectroscopic studies.

Stable hydrazone-linked chiral covalent organic frameworks:Synthesis,modification,and chiral signal inversion from monomers

The designed synthesis of chiral covalent organic frameworks(COFs) featuring intriguing properties is fairly scant and remains a daunting synthetic challenge.Here we develop a de novo synthesis of an enantiomeric pair of 2 D hydroxyl-functionalized hydrazone-linked chiral COFs,(S)-and(R)-HthBta-OH COFs,using enantiopure 2,5-bis(2-hydroxypropoxy)terephthalohydrazide(Hth) as monomers.The fo rmation process of hydroxyl-functionalized chiral COFs was monitored using rigorous time-dependent PXRD,vibrational circular dichroism(VCD),and electronic circular dichroism(ECD) studies.Remarkably,VCD spectra indicated a unique chiral signal inversion from the positive Cotton effect of(S)-Hth monomer to the negative Cotton effect of(S)-HthBta-OH COF,which has never been reported in chiral COFs.Moreover,two unprecedented carboxyl-functionalized chiral COFs,(S)-and(R)-HthBta-COOH,were constructed by a post-synthetic modification of the corresponding hydroxyl chiral COFs with succinic anhydride.Notably,carboxyl-functionalized COFs retained homochirality and crystallinity without linker racemization and structural collapse after the chemical modification due to the chemically robust nature of pristine hydrazone-linked chiral COFs.

Chirality Transfer in Supramolecular Co-assembled Fibrous Material Enabling the Visual Recognition of Sucrose

Molecular recognition of simple sugars is crucial due to their essential roles in most living organisms.However,it remains extremely challenging to achieve a visual recognition of simple sugars like sucrose in water media under physiological conditions.In this article,the visual recognition of sucrose is accomplished by a chiral supramolecular hydrogel formation through the co-assembly of a two-component fibrous solution(l-phenylalanine based gelator co-diaminopyridine,LDAP)and sucrose.H-bonding between the amino group of LDAP and the hydroxyl group of sucrose facilitates the gelation by loading sucrose into the LDAP solution.The formed hydrogel showed an amplified inversion of circular dichroism(CD)signals as compared to the corresponding LDAP solution.In addition,the effective chirality transfer was accompanied by a bathochromic shift in UV-Vis and FL spectra of the gel.Such a simple and straightforward chiral co-assembled strategy to visually recognize sucrose will have the potential use of smart gelators in saccharides separation and proteomics to be further applied in medical diagnostics and cell imaging.

Solvent-mediated handedness inversed and amplified circularly polarized luminescence system based on camptothecin derivative

To realize the handedness controllable circularly polarized luminescence(CPL) system remains challenging. Herein, the solvent-mediated CPL inversion and amplification systems were successfully constructed by camptothecin derivative(CPT-A). Due to the planar structure of N,N-dimethylformamide, it could coassemble with CPT-A, resulting in the alteration of g_(lum) from –0.0082 to +0.0085 by increasing water content. While in the non-planar solvent(hexafluoroisopropanol), the g_(lum) was amplified to 0.034 with the increase in water content. Moreover, the CPT-A could react with the glutathione, resulting in the anticancer drug CPT to make it more toxic to the cancer cells. Overall, the handedness controllable CPL systems were realized by tuning the supramolecular self-assembly of a prodrug.