Multicolor Circularly Polarized Luminescence of a Single-Component System Revealing Multiple Information Encryption

Metal-free materials with multicolor tunable circularly polarized luminescence(CPL)are attractive because of their potential applications in information storage and encryption.Here,we designed two enantiomers composed of chiral dialkyl glutamides and achiral vibration-induced emission(VIE)moiety,which can switch on CPL after a simple gelation process.It is noteworthy that the CPL colors vary in different solvents,and this is attributed to various self-assembly-induced microstructures,in which the VIE moiety is restrained to different degrees.Accordingly,a multidimensional code system composed of a quick response code,a ultraviolet(UV)light-activated color code,and a CPL information figure was constructed.To our satisfaction,the system possesses multiple information-storage functions.The orthogonal anticounterfeiting and CPLenhanced encryption functions also improve the system information encryption ability.In brief,this study provides a practical example of CPL applied to information security and an effective approach to obtain a single-component color-tunable CPL material with multiple information storage and encryption functions as well.

Keto-form directed hierarchical chiral self-assembly of Schiff base derivatives with amplified circularly polarized luminescence

While enol-keto tautomerism has attracted great interest in Schiff bases and related compounds in solution and crystal states,the self-assembly of energy-unfavored keto form were scarcely investigated.Here,we report a keto-form directed self-assembly of a naphthalene-attached enantiomeric N-salicylideneanil analog L/DGG-Nap accompanied with a significantly amplified circularly polarized luminescence(CPL).It was found that LGG-Nap exists as a mixture of enol and keto form in monomer at a diluted toluene solution.The increment of the concentrations leads to the formation of predominated keto form,which subsequently triggers the self-assembly.Cryo-transmission electron microscopy(Cryo-TEM)revealed that a hierarchical assembly process happened upon increasing the concentration of LGG-Nap in toluene.Individual nanofibers formed at 1×10-4 mol/L and transferred into helical nanofiber bundles in 5×10-3 mol/L.Interestingly,while these is nearly no circular dichroism(CD)or CPL in the monomeric solution,the assembly showed strong CD and CPL.Remarkably,the dissymmetry factor(glum)was significantly amplified from zero in solution through the 0.005 in individual nanofiber to 0.1 in nanofiber bundles.This work demonstrates that the enol-keto tautomerism can be broken and trigger the self-assembly upon increasing the concentration,which can subsequently direct the chiral self-assembly and significantly amplify the dissymmetry factor of assembled CPL materials.

Upconverting and downshifting circularly polarized luminescence in a superstructural helix

The modulation of circularly polarized luminescence(CPL) has become an increasingly prominent area of research. In this study,we propose a unique “one-excitation-to-three-emissions” CPL system through the co-assembly of an upconversion system,incorporating one sensitizer(Pt(II) mesotetraphenyl tetrabenzoporphyrine, Pt TPBP) and two annihilators(R/S-DPA and R/SBDP) within liquid crystals. The chiral nature of the annihilators induces a transformation of the nematic liquid crystal into chiral nematic liquid crystals(N*LC), establishing an excellent chiral matrix. Upon the incorporation of the sensitizer Pt TPBP and subsequent excitation at 635 nm, the system demonstrates two independent triplet–triplet annihilation photon upconversion(TTA-UC) with the emission in blue and yellow, aided by thermally activated triplet–triplet energy transfer(TTET). This is accompanied by the simultaneous generation of upconverting circularly polarized luminescence(UC-CPL) and downshifting near-infrared circularly polarized luminescence(DS-CPL) originating from the residual luminescence of Pt TPBP. Remarkably,fine-tuning the ratio between the two annihilators allows the TTA-UC system to exhibit multicolor CPL emission with an amplified luminescence dissymmetry factor(glum, reaching up to 0.6). Our study unveils a previously unreported “one-excitation-to-three-emissions” system and provides a versatile strategy for modulating CPL emissions, surpassing conventional methodologies.

In situ thermoresponsive supramolecular assembly for switchable circularly polarized luminescence

The dynamic regulation of circularly polarized luminescence(CPL)holds profound significance in various fields,such as highlevel information storage and encryption.Here we developed a chiral amphiphilic molecule,CPSB-GLU-PEG350(CGP),composed of aggregation-induced emission(AIE)chromophores(Z)-4-(1-cyano-2-phenylvinyl)benzoic acid(CPSB),a chiral linker Glutamic acid and polyethylene glycol(PEG)thermoresponsive segments.Within the self-assembled supramolecular system formed by CGP,we have achieved in-situ temperature-responsive chiral structures,facilitating the thermal control switch of the CPL signal.Molecular dynamics simulations demonstrate the distinct behaviors of AIE and PEG units during the temperature-variable assembly process.Furthermore,by co-assembling achiral dye molecules with CGP,we have expanded the color range of the temperature-responsive CPL assembly system in situ and confirmed the occurrence of circularly polarizedF?rster resonance energy transfer(C-FRET)phenomenon in this process,which successfully enriched the strategies for in-situ CPL control in aqueous phases.In addition,the contactless radiative energy transfer of CPL can also be realized in this system,exhibiting more flexible temperature regulation of the CPL signal.This study provides a convenient and universal strategy for the construction of dynamically smart chiroptical materials.

Enhancing the Circularly Polarized Luminescence of Self-assembled Cyanostilbenes through Extended π-Conjugation

Chiral supramolecular assembly of π-conjugated luminophores provides a promising avenue for enhancing circularly polarized luminescence.In this study,we shed light on the impact of π-conjugation length on circularly polarized luminescent performance of the resulting supramolecular assemblies,by designing a tetra-cyanostilbene monomeric compound alongside two dicyanostilbene control compounds.These cyanostilbene-based compounds possess the ability to form chiral supramolecular polymers in toluene,driven by a synergistic combination of intermolecular hydrogen bonding and π-stacking interactions.The extended π π-aromatic skeleton brings bathochromic-shifted fluorescence and enhanced intermolecular stacking capability for the tetra-cyanostilbene compound.Consequently,chiral supramolecular assemblies formed by the tetra-cyanostilbene compound demonstrate a remarkable two-fold increase in g_(lum) values relative to the assemblies formed by the dicyanostilbene compounds.Overall,this study provides valuable insights into the relationship between-conjugation length and the circularly polarized luminescent performance of π-conjugatedsupramolecularassemblies.

Regulation and application of supramolecular gel with circularly polarized luminescence

Supermolecular gel is a three-dimensional network structure assembled by small molecules or polymers in solvents through noncovalent interaction.The emergence of system complexity occurs spontaneously during the molecular self-assembly process.A multitude of chiral molecular self-assembly systems have been engineered,facilitating the achievement of circularly polarized luminescence(CPL)through the amalgamation of chiral entities with fluorophores.Hydrogen bonding,π-πstacking,and noncovalent forces,such as host-guest interactions and Van der Waals'forces,confer upon supramolecular gels the capacity to react to diverse stimuli.Due to the flexibility of supramolecular assembly,the CPL properties of supramolecular gels have rich controllability and can be used in various applications.In this review,we summarized the examples of CPL-active supramolecular gel assembly,and further summarized the assembly environment factors and external stimuli.Furthermore,the versatility of CPL applications in supramolecular gels is demonstrated,ranging from optical devices,information encryption,biosensing and chemical sensing,and other practical applications.In conclusion,the study provides insights into the multicultural factors influencing CPL in supramolecular gels,describes their applications in various domains,and presents future perspectives in the field.

Producing circularly polarized luminescence by radiative energy transfer from achiral metal-organic cage to chiral organic molecules

The development of circularly polarized luminescence(CPL)materials with high performance is signifi-cantly important.Herein,we develop a facial strategy for fabricating a CPL-active system by employing an achiral luminescent metal-organic cage(MOC)and chiral boron dipyrromethene(BODIPY)molecules.CPL is achieved by taking advantage of the radiative energy transfer process,in which BODIPY molecules act as energy acceptors and MOCs act as donors.The CPL performance(maximum luminescence dissymme-try factor up to±1.5×10^(−3))can be tuned by adjusting the ratio between MOCs and BODIPY.White-light emission with the CPL feature is obtained by using a ternary system including MOC,chiral BODIPY,and Rhodamine B.The present work provides a facile and universal strategy to construct a CPL-active system by integrating achiral luminophores and chiral molecules.

Light-triggered fluorochromic cholesteric liquid crystal elastomer with hydrogen-bonded fluorescent switch: dualmodal-switchable circularly polarized luminescence

Solid materials with dynamically tunable circularly polarized luminescence(CPL) feature higher security levels and devicefriendly characteristics, showing great superiority in the field of information technology and anti-counterfeiting. To address the limited photoisomerization of fluorescent photoswitch in CPL-active solid materials, here a cholesteric liquid crystal elastomer(CLCE) containing a hydrogen-bonded(H-bonded) polymerizable fluorescent switch AHBA-PSD is prepared. Owing to the good flexibility and low glass-transition temperature of CLCE, AHBA-PSD shows a fast and fully reversible photocyclization/cycloreversion with fluorochromic behavior in CLCE. Further, by controlling the spectral overlapping area between the emission and reflection bands, the CLCE exhibits a strong CPL with a g_(lum) value of up to 0.76 accompanied by a reversible phototunable CPL signal. Meanwhile, the H-bond helps to stabilize the mechanical property, and the force-induced switching-off of CPL signal could be achieved due to the destroyed helical structures by external force. Finally, an automatically-recognized identification card with abundant chiroptical information is demonstrated.

Enhanced circularly polarized luminescence emission promoted by achiral dichroic oligomers of F8BT in cholesteric liquid crystal

In the exploration of circularly polarized luminescence(CPL)materials,doping cholesteric liquid crystals(CLCs)with achiral dyes is a common strategy.Conjugated polymers are favored as achiral dyes for their superior luminescent properties.In this study,a series of oligomers(M1-M3)and the conjugated polymer F8BT were synthesized to systematically assess the impact of the length of the conjugated backbone on CPL signals of CLCs doped with conjugated polymers.As the length rose from M1 to M3,CPL intensity concurrently increased(|g_(lum)|increased from 0.35 to 0.84),attributable to enhanced dichroism(order parameter,SFincreased from 0.20 to 0.56).In contrast,F8BT polymer resulted in diminished CPL intensity(|g_(lum)|=0.64)due to the reduced compatibility.Achieving a balance between dichroism and compatibility is crucial for optimizing CPL in conjugated polymer-doped CLCs.The guiding principle established here may have broad applicability in other CPL assemblies,offering a strategic avenue to engineer highperformance CPL materials with conjugated polymer.

Induced Absolute Configuration of Achiral Tetradentate Ligands in Metal–Organic Frameworks for Circularly Polarized Luminescence

The crystallization of chiral molecules is of great significance to understand the origin and evolution of hierarchical chirality and reveal the relationships between structural chirality and circularly polarized luminescence(CPL)activity.Here,we report two pairs of chiral metal–organic frameworks(MOFs)(DCF-17/LCF-17,DCF-18/LCF-18)by utilizing tetradentate ligands tetra(3-imidazoylphenyl)ethylene(TIPE)and 4,4'-[4',5'-bis[4-(4-pyridinyl)phenyl][1,1':2',1”-terphenyl]-4,4”-diyl]bis[pyridine](TPPP)as linkers.It can be observed that the spontaneous resolution of the achiral ligands is converted into the induced resolution,and the ligands form the absolute configuration by using enantiopure camphoric acid(cam)as chiral induced reagent(CIR).As a result,the racemate MOFs can be driven to generate absolute homochiral crystallization.Another two achiral MOFs[Cd(D-cam)(TPPP)_(0.5)](AF-1,AF=achiral framework)and[Cd(L-cam)(TPPP)_(0.5)](AF-2)were prepared.The position disorder of D/L-cam skeleton causes the generation of nonchiralization,further leading to disappearance of symmetry breaking of TPPP.For the perspective of structure,this is the first report which reveals the chiral transfer and nonchiralization between chiral induced agents and tetradentate ligands.Besides,DCF-17 and LCF-17 show CPL with luminescence dissymmetry factor(glum)of–1.0×10^(-2)and+9.2×10^(–3),respectively.This work provides the useful evidences to reveal the induced chiral crystallization and the construction of CPL-active crystalline materials.

Triple Aza[6]helicenes with Circularly Polarized Luminescence:N-Alkylation as a Tool to Tune the Chiroptical Properties

Recently,multiple helicenes have attracted enormous attention due to their exceptionally distorted conjugated architectures,appealing optical properties and unique spatial stacking patterns.The electronic and optical properties of multiple helicenes could be modulated by heteroatom doping.Herein,the first triple aza[6]helicene was reported by an intramolecular oxidation reaction,which exhibited highly distorted propeller-like geometry revealed by single crystal X-ray diffraction analysis.In comparison to the reported triple oxa[6]helicene,the triple aza[6]helicene demonstrated increased quantum yield(5.5%),and chiroptical properties with a|gabs|value of 0.012 and a|glum|value of 3.0×10^(-3).Furthermore,the stability and chiroptical properties of the triple aza[6]helicene could be enhanced by N-alkylation.

Chiral induction and Sb3+doping in indium halides to trigger second harmonic generation and circularly polarized luminescence

Recently,organic-inorganic hybrid metal halides(HMHs)have attracted extensive attention as promis-ing multifunctional materials by virtue of their structural diversity and tunable photophysical properties.However,it remains a challenge to design HMHs with specific functions on demand.Herein,by introduc-ing R/S-methylbenzylamine(R/S-MBA)and doping Sb^(3+),we have achieved both second harmonic gen-eration(SHG)and circularly polarized luminescence(CPL)properties in lead-free indium halides.The introduction of chiral organic cations can break the symmetry and induce the indium halides to crys-tallize in the chiral space group.The Sb^(3+)with ns2 electronic configuration can serve as the dopants to promote the formation of self-trapped excitons,so as to activate highly efficient luminescence.As a re-sult,the as-prepared Sb3+doped(R/S-MBA)3 InCl6 show not only SHG responses but also CPL signals with luminescence dissymmetry factor of−5.3×10^(−3) and 4.7×10^(−3).This work provides a new inspiration for the exploitation of chiral multifunctional materials.

Engineering intelligent chiral silver cluster-assembled materials for temperature-triggered dynamic circularly polarized luminescence

The development of stimuli-responsive circularly polarized luminescence(CPL)materials is quite attractive but challenging.Here,a pair of atomically precise enan-tiomers R/S-Ag20 nanoclusters has been synthesized using chiral acid ligands.And then,stimuli-responsive CPL materials were developed by assembling the chiral silver nanoclusters with an achiral bridging ligand.The atomically precise silver cluster-assembled materials produce CPL with a dissymmetry factor(|glum|)of 1×10-3,through the high-efficiency chiral induction process.More interestingly,the single CPL band at room temperature could quickly transform into highly separated dual CPL emissions at low temperature.This study provides a new strategy for the rational functionalization of chiral silver clusters in preparing cluster-based CPL emitters and enriches the types of stimuli-responsive CPL materials.

Sequence Engineering in Tuning the Circularly Polarized Luminescence of Aggregation-Induced Emission-Active Hetero[3]rotaxanes

Based on a[2]rotaxane precursor with exchangeable pentafluorophenyl ester stoppers,a new wheelassembling approach has been successfully developed for the precise sequence control of hetero[3]rotaxanes,leading to the facile and efficient synthesis of both sequence isomers of hetero[3]rotaxanes.More importantly,taking advantage of the chirality retention along with the wheel-assembling process,corresponding sequence isomers of chiral AIEgenfunctionalized hetero[3]rotaxanes were further precisely synthesized.Impressively,the resultant hetero[3]rotaxanes revealed remarkable sequencedependent aggregation-induced emission(AIE)behavior and circularly polarized luminescence performance with large dissymmetry factors up to 0.012,highlighting the great power of the newly coined sequence engineering concept in developing novel AIE-active chiroptical materials.This proof-ofconcept study lays the foundation for investigation of the structure-property relationships of heterorotaxanes that can further direct the rational design and precise synthesis of sequence-defined heterorotaxanes with desirable properties for practical applications.

Circularly polarized luminescence from a common alkoxy pillar[5]arene and its co-aggregates withπ-conjugated rods

Cylinder-shaped macrocycles composed ofπ-panels have attracted special attention as one of the best platforms for the development of organic molecule-based chi-roptical materials.Pillar[n]arenes are a class of macrocycles with the advantage of easy preparation but have not been extensively investigated from the perspective of luminescent molecules.However,common alkoxy pillar[n]arenes arefluorescent in non-haloalkane solvents,showing potential to be used for molecule-based chi-roptical materials.In this work,circularly polarized luminescence(CPL)spectra are reported for a pillar[5]arene with stable planar chirality using tetrahydrofu-ran(THF)and cyclohexane as solvents,which has been missing for many years.The pillar[5]arene also forms co-aggregates with 1,4-bis(phenylethynyl)benzene and 1,4-bis[(pentafluorophenyl)ethynyl]benzene in THF/H2O mixtures,owing to a hydrophobic effect.The co-aggregates with thefluorinatedπ-rod display a new low-energy absorption peak and broad emission band as well as intense circular dichroism and CPL signals.Chiral information from the enantiopure pillar[5]arene core is efficiently transmitted to the co-aggregates with theπ-conjugated rod,lead-ing to the highest dissymmetry factor for CPL(2.9×10-2 at 472 nm)among pillar[n]arene-based CPL materials.

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.

Large-scale chiral spherulites with controllable circularly polarized luminescence in liquid crystal block copolymers film

Macroscopic chiral spherulites prepared by hierarchical self-assembly have attracted considerable attention due to their excellent property as chiroptical materials.However,preparing controllable chiral spherulites in bulk film remains a challenge due to the absent knowledge of the evolution mechanism from the molecule to macroscopic crystal during chiral assembly.In this contribution,chiral macroscopic spherulites were constructed with controllable circularly polarized luminescence(CPL)using enantiomeric tartaric acid and rhodamine B co-assembled with liquid crystal block copolymers,poly(ethylene oxide)-b-poly(methyl methacrylate)bearing azobenzene group side chains.It was found that the chiral liquid crystal field induced by exogenous chiral molecules was closely related to the formation of macroscopic chiral spherulites.Moreover,the transformation of azobenzene cis-trans isomerization under photo-thermal endows films with adjustable CPL.This facile strategy provides a platform to design large-scale chiral structures for chiroptical switching,encryption,and memory storage materials.

Chirality transfer induced circularly polarized luminescence of achiral dye molecules by plasmonic nanohelicoid

Optical materials with circularly polarized luminescence(CPL)features have attracted a growing interest due to their crucial role in biological sensing,display,spintronics,information storage,and so forth.However,CPL emissions in hybrid nanoparticle systems,in particular,chirality transfer induced CPL from chiral plasmonic nanoparticles,have rarely been explored due to a lack of effective bottom-up synthesis method.Herein,we creatively take advantage of the newly introduced chiral plasmonic nanoparticles-gold nanohelicoid(GNH)to excite the CPL of achiral Rhodamine 6G(R6G).The fabricated GNH@R6G-SiO_(2)shows obvious CPL signals with|g_(lum)|up to 0.014.Compared with the single GNH,the photoluminescence(PL)dissymmetry factor of the single GNH@R6G-SiO_(2)is similar,but with 25 folds higher PL intensities under different circular polarization.Our research not only offers an effective and feasible method to fabricate single-particle level CPL-active materials,but also provides guidelines on how to regulate the CPL of achiral luminophores from chiral plasmonic nanostructures,thereby enlarging the category and quantity of CPL-active materials that can be applied for photonic technologies and visualization biosensing,especially some intracellular chirality related detection.

Flexible Organic Crystal with Two-Dimensional Elastic Bending and Recoverable Plastic Twisting for Circularly Polarized Luminescence

Multidimensional mechanical flexible organic crystals with tunable optoelectronic properties hold significant promise for practical application in complicated environmental conditions.Herein,based on a newly designed“flexible”Schiff base small molecule with chirality,we presented a compatibly bendable and twistable organic single crystal with circularly polarized luminescence for the first time.First,the twodimensional elastic bending of the chiral crystal was realized at both room and liquid nitrogen temperatures,along with recoverable plastic twisting at room temperature.Besides,circular dichroism and circularly polarized luminescence spectroscopy were employed to characterize the chiral enantiomer in solution and the solid state.Our design strategy provides a new perspective for the future construction of chiroptical flexible crystal materials.

A new strategy to achieve enhanced upconverted circularly polarized luminescence in chiral perovskite nanocrystals

Achieving large luminescence dissymmetry factors(pium)is challenging in the research field of circularly polarized luminescence(CPL).While various approaches have been developed to construct organic systems with CPL activity,there is still a lack of effective methods for fabricating CPL active inorganic materials.Herein,we propose an approach for endowing upconversion nanoparticles(UCNPs)and perovskite nanocrystal(PKNC)hybrid nanomaterials with upconverted circularly polarized luminescence(UC-CPL)activity.Chiral cesium lead bromides(CsPbBr_(3))PKNCs were synthesized by a chiral-ligand-assistant method.Meanwhile,UCNP could be embedded into the chiral PKNC,enabling a photon upconvesion feature to the PKNC.The embedded UCNPs in PKNCs were confirmed by electron tomography.Consequently,various CPL activities,including prompt CPL,UC-CPL,and energy transfer enhanced circularly polarized luminescence(ET-CPL),were realized.The chiral perovskite nanocrystals could reabsorb the chiral energy generated from UCNPs,showing energy transfer enhanced CPL activity with four times magnification of the circular polarization.These findings provide a meaningful strategy for designing chiral photon upconversion inorganic nanomaterials with highly efficient UC-CPL activity.