Photoprogrammable circularly polarized phosphorescence switching of chiral helical polyacetylene thin films

3D printable organic room-temperature phosphorescent materials and printed real-time sensing and display devices

Polymer-based host-guest organic room-temperature phosphorescent (RTP) materials are promising candidates for new flexible electronic devices. Nowadays, the insufficient fabrication processes of polymeric RTP materials have hindered the development of these materials. Herein, we propose a strategy to realize 3D printable organic RTP materials and have successfully demonstrated real-time sensing and display devices through a Digital Light Processing (DLP) 3D printing process. We have designed and synthesized the molecules EtCzBP, PhCzBP and PhCzPM with A-D-A structures. The crucial role of strong intramolecular charge transfer (ICT) at the lowest triplet states in achieving bright photo-activated phosphorescence in polymer matrices has also been demonstrated. 3D printable RTP resins were manufactured by doping emissive guest molecules into methyl methacrylate (MMA). Based on these resins, a series of complex 3D structures and smart temperature responsive RTP performances were obtained by DLP 3D printing. Additionally, these RTP 3D structures have been applied in real-time temperature sensing and display panels for the first time. This work not only provides a guiding strategy for the design of emissive guest molecules to realize photo-activated RTP in poly(methyl methacrylate) (PMMA), but also paves the way for the development of 3D-printable real-time sensing structures and new-concept display devices.

Fluoride binding-modulated supramolecular chirality of urea-containing triarylamine and its photo-manifestation

In recent years, the regulation of anion-mediated chiral assemblies has gained significant interest. This study investigated the modulation of supramolecular chiroptical signals and chiral assembled structures in a triarylamine system containing a urea moiety through fluoride ion-urea bond interactions, aiming to understand the chiral sense amplification in supramolecular assemblies. Chiral triarylamine derivatives containing urea or amide units were synthesized and the self-assemblies were examined in the absence and presence of fluoride ions. The results revealed that the addition of F- led to an increase in the circular dichroism (CD) intensity for the triarylamine compounds containing urea, accompanied by a transformation of the nanofiber structure into chiral twists. Comparative studies with other anions confirmed the selective specificity for F-. Additionally, the combination of photo-induced triarylamine anion radicals allowed the F- in the system to be visualized through photoirradiation, resulting in distinct colour changes that were detectable by the naked eye. The research demonstrates that F- can selectively amplify supramolecular chirality through urea-F- interactions, which may have promising applications in the fields of sensing and chiroptical devices.

Helix-induced full-color circularly polarized luminescence films with multiple information encryption and multi-stimuli responsiveness

The development of full-color circularly polarized luminescence (CPL) materials is of great significance in the field of luminescent materials; however, it is difficult due to the limitations in the synthesis and preparation methods. Helical polymers, with their high optical activity and easy processability, offer a promising solution for the construction of high-performance CPL materials. In this study, we successfully prepared full-color CPL composite films using precisely synthesized polyisocyanide (PI) as chiral source, poly(methyl methacrylate) as the matrix, and commercially available fluorescein as fluorescence source. The introduction of PI not only improves the mechanical properties and fluorescence lifetime of the composite films but also facilitates recyclability through centrifugation after dissolving the composite films with the poor solvent of PI. Moreover, the use of spiropyran as a red fluorescein allows for dynamic responsiveness to light, heat, and acid-base stimuli, broadening the functionality of the CPL materials and constructs a multiple information encryption system. This work presents a low-cost, easily processable, and multi-stimuli responsive strategy for full-color fabrication of CPL materials based on helical PI.

Excitation-Dependent Circularly Polarized Luminescence Inversion Driven by Dichroic Competition of Achiral Dyes in Cholesteric Liquid Crystals

The development of stimuli-responsive chiral cholesteric liquid crystals (CLCs) materials holds significant potential for achieving three-dimensional (3D) anti-counterfeiting and multi-level information encryption. However, constructing phototunable CLCs systems with easy fabrication and fast response remains a great challenge. Herein, we exploit an excitation-dependent CLCs (ExD-CLCs) material by establishing dynamically photoresponsive dichroic competition between two achiral dyes: a negative dichroic dye (SP-COOH) and a positive dichroic dye (Nile Red, NR) within a CLCs medium. The ExD-CLCs exhibits a negative circularly polarized luminescence (CPL) signal (glum=-0.16) at 625 nm when excited at 365 nm. Remarkably, under excitation at 430 nm, the CPL signal is inverted, and the glum value increases to +0.26. Notably, the helical superstructure and handedness of the ExD-CLCs remain unchanged during this reversal process. The CPL signal reversal is driven by the dichroic competition between the SP-COOH dimer, which displays strong negative dichroism in its open-ring isomer form and silent negative dichroism in its closed-ring isomer form, and the NR dye, which exhibits static positive dichroism. Leveraging these excitation-dependent CPL properties, the quadruplex numerical anti-counterfeiting using ExD-CLCs is achieved.

New Concept on the Generation and Regulation of Circularly Polarized Luminescence

Circularly polarized luminescence (CPL) has attracted tremendous attention because of its significant application prospect across multiple fields of three-dimensional display, data storage, and information encryption. Chirality and luminescence are two necessary prerequisites for the generation of CPL. However, controlling these two factors simultaneously in a rational manner remains a challenge. Herein, we highlight the recent advances on the rational generation and regulation of CPL through the new concept, named matching rules, mainly including fluorescence-selective absorption, circularly polarized fluorescence energy transfer, and chiral communication between excited state and ground state. An important commonality among these strategies is that they need a good overlap of the corresponding spectra between the luminescent part (fluorescence, phosphorescence, or CPL) and the chiral part (organic, inorganic, or organic-inorganic hybrid materials), which can be contactless and separate. Different from most previous studies, no covalent or noncovalent interactions between the two parts are required, which makes them more facile and convenient. Finally, we summarize the main advantages of these strategies and the current challenges. We expect this concept to offer insightful and novel understanding and inspiration on CPL generation and regulation.

Triplet Exciplex Mediated Multi-Color Ultra-Long Afterglow Mate-rials

Organic long-lived phosphorescent materials demonstrating ultra-long photoluminescence have practical advantages owing to their flexible design and easy processability. However, the exact photophysical process underpinning the persistent-luminescent continues to elude full understanding, and the principles governing the compatibility of hosts and guests remain elusive. In this work, a new type of nonradiative energy transfer mechanism is proposed for the bi-component RTP system. Different from Förster resonance energy transfer or Dexter-type energy transfer, this energy transfer mechanism primarily relies on a triplet exciplex to exchange the electron. This facilitates the formation of triplet excitons that are otherwise difficult to excite directly. An evaluation methodology is devised to gauge the potential of a specific dopant-host combination toward generating pronounced afterglow. According to this framework, the enhancement of the afterglow is proportional to the decrease in the activation energy (ΔG≠) associated with the electron transfer reaction between the dopant and the host. Notably, when the ΔG≠ too larger, no observable afterglow occurs, as higher ΔG≠ values significantly impede the electron transfer reaction between the two components. Furthermore, the remarkable dependence of afterglow intensity on the dopant concentration renders the bi-component RTP system highly promising for applications requiring ultra-high sensitivity and broad-spectrum detection capabilities.

Activatable red/near-infrared aqueous organic phosphorescence probes for improved time-resolved bioimaging

Organic red/near-infrared (NIR) room-temperature phosphorescence (RTP) holds significant potential for autofluorescence-free bioimaging and biosensing due to its prolonged persistent luminescence and exceptional penetrability. However, achieving activatable red/NIR organic RTP probes with tunable emission in aqueous solution remains a formidable challenge. Here we report on aqueous organic RTP probes with red/NIR phosphorescence intensity and lifetime amplification. These probes consist of supramolecular assemblies comprising macrocyclic cucurbit[8]uril and amine-containing alkyl-bridged pyridiniums, exhibiting viscosity-activatable phosphorescence with enhanced quantum yield (≤20%) and lifetime. Notably, by utilizing this activatable organic RTP probe, we successfully achieve two-photon imaging of lysosomal viscosity and millisecond-scale time-resolved cell imaging. Moreover, intravital phosphorescence imaging by using an RTP probe enables the monitoring of viscosity variations in inflammatory mice, demonstrating a significantly improved signal-to-background ratio compared with fluorescence imaging. This activatable red/NIR supramolecular platform facilitates versatile high-resolution phosphorescence imaging for in vivo tracking of specific biomarkers and physiological events.

Dynamic Covalent Bonds-Mediated Color-Switchable Circularly Polarized Luminescence in Helical Assemblies of Achiral Liquid Crystal Block Copolymer Films

Circularly polarized luminescence (CPL) film attracted considerable attention in information storage and encryption, three-dimensional display, and chiral recognition. However, due to the limited molecular mobility within thin film, achieving a high asymmetry factor and non-contact modulation of CPL remain challenging. In this work, color-switchable homochiral CPL films with high luminescence asymmetry factor (glum~0.11) were constructed based on the co-assembly of a liquid crystal block copolymer (poly (ethylene oxide)-b-poly (methyl methacrylate) bearing cyanostilbene group) with axial chiral dinaphthalene diamine derivatives (R/S-DINBPA). Mechanistic investigation revealed that the efficient stacking of R/S-DINBPA with cyanostilbene groups and the liquid crystal field provide the driving force for chiral transfer and amplification. The dynamic covalent bonds of the cyanostilbene groups endow the film with chiral fixation ability and enable precise modulation of CPL luminescence bands under UV light irradiation, making it suitable for chiral patterned anti-counterfeit encryption. This facile strategy provides a general platform for designing intelligent chiroptical materials.

Triarylmethanol Derivatives with Ultralong Organic Room-Temperature Phosphorescence

Triphenylmethyl-based compounds such as rhodamines and fluoresceine representing an old and well-known class of triphenylmethane dyes, are widely used in fluorescent labeling of bioimaging. Inspired by ultralong room temperature phosphorescence of triphenylphosphine derivatives, herein we report a methoxy substituted triarylmethanol ((4-methoxyphenyl)diphenylmethanol, LJW-1) exhibits ultralong room temperature phosphorescence (RTP) under ambient condition with afterglows of about 7 seconds. Its multiple C-H ⋅ ⋅ ⋅ π intermolecular interactions, C-H ⋅ ⋅ ⋅ O intermolecular interactions, hydrogen bond and π-π interactions are beneficial for forming rigid environment in the aggregated state which is evidently an important factor in the appearance of excellent RTP. Different substituents on triarylmethanol result in compounds with different lifetimes varying from 7 μs to 818 ms. The substituent effects on the phosphorescence of triarylmethanol derivatives provide an efficient method for the design of organic RTP materials and may be enlightening the phosphorescence research of triarylmethanol derivatives.

Organic Circularly Polarized Room-Temperature Phosphorescence: Strategies, Applications and Challenges

Organic circularly polarized luminescence (CPL) plays crucial roles in chemistry and biology for the potential in chiral recognition, asymmetric catalysis, 3D displays, and biological probes. The long-lived luminescence, large Stokes shift, and unique chiroptical properties make organic circularly polarized room-temperature phosphorescence (CPP) a new research hotspot in recent years. Nevertheless, achieving high-performance organic CPP is still challenging due to the sensitivity and complexity of integrating triplet excitons and polarization within organic materials. This review summarizes the latest advances in organic CPP, ranging from design strategies and photophysical properties to underlying luminescence mechanisms and potential applications. Specifically, the design strategies for generating CPP are systemically categorized and discussed according to the interactions between chiral units and chromophores. The applications of organic CPP in organic light-emitting diodes, sensing, chiral recognition, afterglow displays, and information encryption are also illustrated. In addition, we present the current challenges and perspectives on developing organic CPP. We expect this review to provide some instructive design principles to fabricate high-performance organic CPP materials, offering an in-depth understanding of the luminescence mechanism and paving the way toward diverse practical applications.

Circularly Polarized Lasing from Helical Superstructures of Chiral Organic Molecules

Chiral supramolecular aggregates have the potential to explore circularly polarized lasing with large dissymmetry factors. However, the controllable assembly of chiral superstructures towards deterministic circularly polarized laser emission remains elusive. Here, we design a pair of chiral organic molecules capable of stacking into a pair of definite helical superstructures in microcrystals, which enables circularly polarized lasing with deterministic chirality and high dissymmetry factors. The microcrystals function as optical cavities and gain media simultaneously for laser oscillations, while the supramolecular helices endow the laser emission with strong and opposite chirality. As a result, the microcrystals of two enantiomers allow for circularly polarized laser emission with opposite chirality and high dissymmetry factors up to ~1.0. This work demonstrates the chiral supramolecular assemblies as an excellent platform for high-performance circularly polarized lasers.

Reversible Circularly Polarized Luminescence Inversion and Emission Color Switching in Photo-Modulated Supramolecular Polymer for Multi-Modal Information Encryption

Constructing circularly polarized luminescence (CPL) materials that exhibit dynamic handedness inversion and emissive color modulation for multimodal information encryption presents both a significant challenge and a compelling opportunity. Here, we have developed a pyridinethiazole acrylonitrile-cholesterol derivative (Z-PTC) that exhibits wavelength-dependent photoisomerization and photocyclization, enabling dynamic handedness inversion and emissive color modulation in supramolecular assemblies with decent CPL activity. Coordination with Ag+ ions form the Z-PTC Ag supramolecular polymer (SP1), which assembles into nanotubes displaying enhanced positive yellow-green CPL. Irradiation at 454 nm transforms SP1 into nanospheres of a mixture supramolecular polymer (SP2) of Z/E-PTC Ag, displaying inverted supramolecular chirality and emitting negative orange-yellow CPL. Reheating SP2 to 343 K restores the original nanotube structure via excellent reversible photoisomerization. Exposure to 365 nm light also induces CPL inversion from positive to negative and triggers morphological changes from SP1 to SP2. Prolonged irradiation causes further transformation into irregular supramolecular aggregate, shifting the emission color to blue and eliminating CPL. These dynamic properties of the multicolor CPL system, including reversible handedness inversion, can also be realized in the semisolid state, exhibiting promising potential for multimodal information encryption applications with enhanced security and complexity.

Tuning the circularly polarized phosphorescence of platinum(II) complexes through a chiral cation strategy

Circularly polarized phosphorescent (CPP) materials, especially chiral platinum(II) complexes, which combine the advantages of both circularly polarized luminescence (CPL) and phosphorescence, show broad potential applications in chiral optoelectronic devices. Developing CPP emitters with both excellent chiroptical properties and high yield is urgently needed. Here, a chiral cation strategy is employed to construct the CPP Pt(II) complexes R/S-ABA·[Pt(ppy)Cl2] and R/S-MBA·[Pt(ppy)Cl2] through a simple one-step reaction with almost 100% yield. The circular dichroism and CPL spectra confirm that the chirality was successfully transferred to the [Pt(ppy)Cl2]- anion. The luminescence asymmetry factors (glum) are +1.4/-1.8 × 10-3 for R/S-ABA·[Pt(ppy)Cl2] and +4.4/-2.8 × 10-3 for R/S-MBA·[Pt(ppy)Cl2]. The stronger chiroptical property of R/S-MBA·[Pt(ppy)Cl2] is attributed to the enhanced chiral structural deformation and better matched electric and magnetic transition dipole moments. This chiral cation strategy is confirmed to efficiently construct CPP Pt(II) complexes, which will accelerate the development of CPP emitters towards commercialization.

A Dynamic H-Bonding Network Enables Stimuli-Responsive Color-Tunable Chiral Afterglow Polymer for 4D Encryption

The development of stimuli-responsive and color-tunable chiral organic afterglow materials has attracted great attention but remains a daunting challenge. Here, a simple yet effective strategy through the construction of a dynamic H-bonding network is proposed to explore the multi-color stimuli-responsive chiral afterglow by doping a self-designed chiral phosphorescent chromophore into a polyvinyl alcohol matrix. A stimuli-responsive deep blue chiral afterglow system with a lifetime of up to 3.35 s, quantum yield of 25.0%, and luminescent dissymmetry factor of up to 0.05 is achieved through reversible formation and breakdown of the H-bonding network upon thermal-heating and water-fumigating. Moreover, multi-color stimuli-responsive chiral afterglow can be obtained by chiral and afterglow energy transfer, allowing the establishment of afterglow information displays and high-level 4D encryption. This work not only offers a facile platform to develop advanced stimuli-responsive materials but also opens a new avenue for developing next-generation optical information technology with enhanced functionality and responsiveness.

Xylan-based full-color room temperature phosphorescence materials enabled by imine chemistry

Developing sustainable matrix and efficient bonding mode for preparing room temperature phosphorescence (RTP) materials with full-color afterglows is attractive but still challenging. Here, xylan, a hemicellulose by-product from the paper mill, is used to construct full-color RTP materials based on imine bonds. Xylan is oxidation by periodate to introduce aldehyde groups to increase reaction sites; aromatic amines with different π conjugations can be readily anchored to dialdehyde xylan (DAX) by imine chemistry. The dual rigid environments were constructed by hydrogen bonding and imine covalent bonding, which can facilitate the triplet population and suppress non-radiative transitions, thus the xylan derivatives display satisfactory RTP performances. As the degree of conjugation of the chromophore increases, the afterglow colors can be changed from blue to green, yellow, and then to red. Thus, such a universal, facile, and eco-friendly strategy can be used to fabricate full-color RTP materials, which show a bright future in information encryption and advanced anti-counterfeiting. These results unambiguously state that the biodegradable paper mill waste-based RTP materials are convincingly expected to replace and surpass petroleum polymer-based counterparts.

Intense Circularly Polarized Luminescence Induced by Chiral Supramolecular Assembly: The Importance of Intermolecular Electronic Coupling

Herein we report on circularly polarized luminescence (CPL) emission originating from supramolecular chirality of organic microcrystals with a |glum| value up to 0.11. The microcrystals were prepared from highly emissive difluoroboron β-diketonate (BF2dbk) dyes R-1 or S-1 with chiral binaphthol (BINOL) skeletons. R-1 and S-1 exhibit undetectable CPL signals in solution but manifest intense CPL emission in their chiral microcrystals. The chiral superstructures induced by BINOL skeletons were confirmed by single-crystal XRD analysis. Spectral analysis and theoretical calculations indicate that intermolecular electronic coupling, mediated by the asymmetric stacking in the chiral superstructures, effectively alters excited-state electronic structures and facilitates electron transitions perpendicular to BF2bdk planes. The coupling increases cosθμ,m from 0.05 (monomer) to 0.86 (tetramer) and triggers intense optical activity of BF2bdk. The results demonstrate that optical activity of chromophores within assemblies can be regulated by both orientation and extent of intermolecular electronic couplings.

Polymeric Cholesteric Superhelix Induced by Chiral Helical Polymer for Achieving Full-Color Circularly Polarized Room-Temperature Phosphorescence with Ultra-High Dissymmetry Factor

Circularly polarized room-temperature phosphorescence (CPRTP) simultaneously featuring multiple colors and extremely high dissymmetry factor (glum) is crucial for increasing the complexity of optical characteristics and advancing further development, but such a type of CPRTP is still unprecedented. The present work develops an effective and universal strategy to achieve full-color CPRTP with ultra-high glum factors in a polymeric cholesteric superhelix network, which is constructed by cholesteric liquid crystal polymer and chiral helical polymer (CHP). Taking advantage of the high helical twisting power of CHP, the resulting polymeric cholesteric superhelix network exhibits remarkable optical activity. Significantly, by adopting a simple double-layered architectures consisting of the cholesteric superhelix film and phosphorescent films, blue-, green-, yellow-, and red-CPRTP emissions are successfully obtained, with maximum |glum| values up to 1.43, 1.39, 1.09 and 0.84, respectively. Further, a multilevel information encryption application is demonstrated based on the multidimensional optical characteristics of the full-color double-layered CPRTP architectures. This study offers new insights into fabricating polymeric cholesteric superhelix with considerable CPRTP performance in advanced photonic applications.

Stacking Transformation-Triggered Circularly Polarized Luminescence Reversion in γ-Cyclodextrins-Pyrene Co-Assembly

Considerable attention has been directed towards cyclodextrins (CDs) in the creation of co-assembled CPL-active materials, owing to their intrinsic chiral host cavities and synergistic host-guest interactions. However, achieving reversed CPL emission regulation with single-handedness CDs moiety poses a significant challenge. In this study, we have devised a series of γ-CD-based host-guest complexes comprising dual pyrene imidazolium derivatives with multiple linkers, which exhibit reversed circularly polarized emission. We have uncovered that the transformation of excimer stacking within γ-CD/pyrene complexes contributes to the inverted CPL emissions originating from a single-handed chiral host. This research elucidates the phenomenon of (+)- and (-)-circularly polarized excimer emission (CPEE) within γ-CD, arising from right- and left-handed stacking conformations, respectively.

Multiple Chirality Switching of a Dye-Grafted Helical Polymer Film Driven by Acid & Base

A stimuli-responsive multiple chirality switching material, which can regulate opposed chiral absorption characteristics, has great application value in the fields of optical modulation, information storage and encryption, etc. However, due to the rareness of effective functional systems and the complexity of material structures, developing this type of material remains an insurmountable challenge. Herein, a smart polymer film with multiple chirality inversion properties was fabricated efficiently based on a newly-designed acid & base-sensitive dye-grafted helical polymer. Benefited from the cooperative effects of various weak interactions (hydrogen bonds, electrostatic interaction, etc.) under the aggregated state, this polymer film exhibited a promising acid & base-driven multiple chirality inversion property containing record switchable chiral states (up to five while the solution showed three-state switching) and good reversibility. The creative exploration of such a multiple chirality switching material can not only promote the application progress of current chiroptical regulation technology, but also provide a significant guidance for the design and synthesis of future smart chiroptical switching materials and devices.

Adaptive Helical Chirality in Supramolecular Microcrystals for Circularly Polarized Lasing

Chiral organic molecules offer a promising platform for exploring circularly polarized lasing, which, however, faces a great challenge that the spatial separation of molecular chiral and luminescent centers limits chiroptical activity. Here we develop a helically chiral supramolecular system with completely overlapped chiral and luminescent units for realizing high-performance circularly polarized lasing. Adaptive helical chirality is obtained by incorporating chiral agents into organic microcrystals. Benefiting from the efficient coupling of stimulated emission with the adaptive helical chirality, the supramolecular microcrystals enable high-performance circularly polarized lasing emission with dissymmetry factors up to ~0.7. This work opens up the way to rational design of chiral organic materials for circularly polarized lasing.

Tunable circularly polarized luminescence behaviors caused by the structural symmetry of achiral pyrene-based emitters in chiral co-assembled systems

The regulation of circularly polarized luminescence (CPL) behavior is of great significance for practical applications. Herein, we deliberately designed three achiral pyrene derivatives (Py-1, Py-2, and Py-3) with different butoxy-phenyl substituents and the chiral binaphthyl-based inducer (R/S-B) with anchored dihedral angle to construct chiral co-assemblies, and explored their induced CPL behaviors. Interestingly, the resulting co-assemblies demonstrate tunable CPL emission behaviors caused by the structural symmetry effect of achiral pyrene-based emitters during the chiral co-assembly process. And in spin-coated films, the dissymmetry factor (gem) values were 9.1 × 10-3 for (R/S-B)1-(Py-1)10, 5.6 × 10-2 for (R/S-B)1-(Py-2)7, and 8.6 × 10-4 for (R/S-B)1-(Py-3)1, respectively. The strongest CPL emission (|gem| = 5.6 × 10-2, λem = 423 nm, QY = 34.8 %) was detected on (R/S-B)1-(Py-2)7 due to the formation of regular and ordered helical nanofibers through the strong π-π stacking interaction between the R/S-B and the achiral Py-2 emitter. The strategy presented here provides a creative approach for progressively regulating CPL emission behaviors in the chiral co-assembly process.

Unveiling the potential of triphenylphosphine salts in tuning organic room temperature phosphorescence

Triphenylphosphine (TPP) salt derivatives, with their rich chemistry of core-substitution, have emerged as promising candidates for ultralong room temperature phosphorescence (RTP) materials owing to their distinct molecular structures, high quantum efficiency and exceptional phosphorescence properties. This feature article highlights the vast potential of TPP salt derivatives in tunable RTP properties by exploring some factors such as the alkyl chains, halogen anions, through-space charge transfer states, etc., and recent advancements in multi-level information encryption, high-level anticounterfeiting tags and X-ray imaging applications. We anticipate that this article will assist in directing future analyses based on the mechanisms underlying the RTP behavior of TPP derivatives and offer guidance for the rational design of high-performance RTP materials.

Photoactivated room temperature phosphorescence from lignin

Sustainable photoactivated room temperature phosphorescent materials exhibit great potential but are difficult to obtain. Here, we develop photoactivated room temperature phosphorescent materials by covalently attaching lignin to polylactic acid, where lignin and polylactic acid are the chromophore and matrix, respectively. Initially the phosphorescence of the lignin is quenched by residual O2. However, the phosphorescence is switched on when the residual oxygen is consumed by the triplet excitons of lignin under continuous UV light irradiation. As such, the lifetime increases from 3.0 ms to 221.1 ms after 20 s of UV activation. Interestingly, the phosphorescence is quenched again after being kept under an atmosphere of air for 2 h in the absence of UV irradiation due to the diffusion of oxygen into the materials. Using these properties, as-developed material is successfully used as a smart anti-counterfeiting logo for a medicine bottle and for information recording.

Responsive circularly polarized ultralong room temperature phosphorescence materials with easy-to-scale and chiral-sensing performance

Circularly polarized room temperature phosphorescence materials represent a state-of-the-art frontier of optical materials and exhibit promising applications in various fields. Herein, we fabricate a series of full-color circularly polarized room temperature phosphorescence materials, based on anionic cellulose derivatives and achiral luminophores. The ionic achiral substituents promote the spontaneous formation of chiral helical structure of cellulose derivatives via the electrostatic repulsion effect. There are multiple interactions between anionic cellulose derivatives and the doped luminophores, thus the chirality is transferred to luminophores and the non-radiative transition is inhibited. The resultant materials can be easily processed into large-scale film and flexible 3D objects with repeatable folding and curling properties. In addition, their phosphorescence performance shows to be excitation-dependence, time-dependence, visible-light excitation, and multi-responsiveness to humidity, temperature as well as pH value. Importantly, they recognize many enantiomers in an instrument-free visual mode, including amino acids, hydroxyl acids, organic phosphate and hydrobenzoin. These results provide insights into design of advanced optical materials which can be applied in multilevel information handling and chiral sensing.

Visualization of Solvent Effect and Oxygen Content via a Red Room-Temperature Phosphorescent Material

The development of pure organic room-temperature phosphorescent (RTP) materials greatly facilitates the integrated application of luminescent materials. Herein, a type of photoactivated red RTP material was constructed by simply doping 4-(benzo[c][1,2,5]thiadiazol-5-ylthio)benzonitrile (p-NNS) into a poly(methyl methacrylate) (PMMA) matrix. The obtained film realized a controllable photoactivation process by regulation of diverse solvent levels, demonstrating potential advantages in optical anti-counterfeiting applications. Furthermore, luminescent properties of the doped film were utilized to detect oxygen content from 2.00% to 4.90%, which revealed the exact consumption of ambient oxygen under UV light. Every CIE point of the luminescence corresponds to a certain oxygen content, illustrating the visualization of oxygen content. The remarkable regulation of solvent effect and oxygen content in this work will provide competitive material for further optical applications.

Dynamic Near-Infrared Circularly Polarized Luminescence Encoded by Transient Supramolecular Chiral Assemblies

Circularly polarized luminescence (CPL) is promising for applications in many fields. However, most systems involving CPL are within the visible range; near-infrared (NIR) CPL-active materials, especially those that exhibit high glum values and can be controlled spatially and temporally, are rare. Herein, dynamic NIR-CPL with a glum value of 2.5×10-2 was achieved through supramolecular coassembly and energy-transfer strategies. The chiral assemblies formed by the coassembly between adenosine triphosphate (ATP) and a pyrene derivative exhibited a red CPL signal (glum of 10-3). The further introduction of sulfo-cyanine5 resulted in a energy-transfer process, which not only led to the NIR CPL but also increased the glum value to 10-2. Temporal control of these chiral assemblies was realized by introducing alkaline phosphatase to fabricate a biomimetic enzyme-catalyzed network, allowing the dynamic NIR CPL signal to be turned on. Based on these enzyme-regulated temporally controllable dynamic CPL-active chiral assemblies, a multilevel information encryption system was further developed. This study provides a pioneering example for the construction of dynamic NIR CPL materials with the ability to perform temporal control via the supramolecular assembly strategy, which is expected to aid in the design of supramolecular complex systems that more closely resemble natural biological systems.

3D Printed Room Temperature Phosphorescence Materials Enabled by Edible Natural Konjac Glucomannan

Shaping room temperature phosphorescence (RTP) materials into 3D bodies is important for stereoscopic optoelectronic displays but remains challenging due to their poor processability and mechanical properties. Here, konjac glucomannan (KGM) is employed to anchor arylboronic acids with various π conjugations via a facile B─O covalent reaction to afford printable inks, using which full-color high-fidelity 3D RTP objects with high mechanical strength can be obtained via direct ink writing-based 3D printing and freeze-drying. The doubly rigid structure supplied by the synergy of hydrogen bonding and B─O covalent bonding can protect the triplet excitons; thus, the prepared 3D RTP object shows a striking lifetime of 2.14 s. The printed counterparts are successfully used for 3D anti-counterfeiting and can be recycled and reprinted nondestructively by dissolving in water. This success expands the scope of printable 3D luminescent materials, providing an eco-friendly platform for the additive manufacturing of sophisticated 3D RTP architectures.

Resonance-Induced Dynamic Triplet Exciton Population for Photoactivated Organic Ultralong Room Temperature Phosphorescence

Dynamically populating triplet excitons under external stimuli is desired to develop smart optoelectronic materials, but it remains a formidable challenge. Herein, we report a resonance-induced excited state regulation strategy to dynamically modulate the triplet exciton population by introducing a self-adaptive N-C═O structure to phosphors. The developed phosphors activated under high-power ultraviolet irradiation exhibited enhanced photoactivated organic ultralong room temperature phosphorescence (PA-OURTP) with lifetimes of up to ∼500 ms. The enhanced PA-OURTP was ascribed to activated N-C═O resonance variation-induced intersystem crossing to generate excess triplet excitons. The excellent PA-OURTP performance and ultralong deactivation time under ambient conditions of the developed materials could function as a reusable recorded medium for time-sensitive information encryption through optical printing. This study provides an effective approach to dynamically regulating triplet excitons and offers valuable guidance to develop high-performance PA-OURTP materials for security printing applications.

Circularly Polarized Room Temperature Phosphorescence through Twisting-Induced Helical Structures from Polyvinyl Alcohol-Based Fibers Containing Hydrogen-Bonded Dyes

Room temperature phosphorescence (RTP) materials have garnered significant attention owing to its distinctive optical characteristics and broad range of potential applications. However, the challenge remains in producing RTP materials with more simplicity, versatility, and practicality on a large scale, particularly in achieving chiral signals within a single system. Herein, we show that a straightforward and effective combination of wet spinning and twisting technique enables continuously fabricating RTP fibers with twisting-induced helical chirality. By leveraging the hydrogen bonding interactions between polyvinyl alcohol (PVA) and quinoline derivatives, along with the rigid microenvironment provided by PVA chains, typically, Q-NH2@PVA fiber demonstrates outstanding phosphorescent characteristics with RTP lifetime of 1.08 s and phosphorescence quantum yield of 24.6 %, and the improved tensile strength being 1.7 times than pure PVA fiber (172±5.82 vs 100±5.65 MPa). Impressively, the transformation from RTP to circularly polarized room temperature phosphorescence (CP-RTP) is readily achieved by imparting left- or right-hand helical structure through simply twisting, enabling large-scale production of chiral Q-NH2@PVA fiber with dissymmetry factor of 10-2. Besides, an array of displays and encryption patterns are crafted by weaving or seaming to exemplify the promising applications of these PVA-based fibers with outstanding adaptivity in cutting-edge anti-counterfeiting technology.

Recent Progress in Solid-State Room Temperature Afterglow Based on Pure Organic Small Molecules

Organic room temperature afterglow (ORTA) can be categorized into two key mechanisms: continuous thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), both of which involve a triplet excited state. However, triplet excited states are easily quenched by non-radiative transitions due to oxygen and molecular vibrations. Solid-phase systems provide a conducive environment for triplet excitons due to constrained molecular motion and limited oxygen permeation within closely packed molecules. The stimulated triplet state tends to release energy through radiative transitions. Despite numerous reports on RTP in solid-phase systems in recent years, the complexity of these systems precludes the formulation of a universal theory to elucidate the underlying principles. Several strategies for achieving ORTA luminescence in the solid phase have been developed, encompassing crystallization, polymer host-guest doping, and small molecule host-guest doping. Many of these systems exhibit luminescent responses to various physical stimuli, including light stimulation, mechanical stimuli, and solvent vapor exposure. The appearance of these intriguing luminescent phenomena in solid-phase systems underscores their significant potential applications in areas such as light sensing, biological imaging, and information security.

Zero-dimensional halide hybrid bulk glass exhibiting reversible photochromic ultralong phosphorescence

Dynamically responsive materials, capable of reversible changes in color appearance and/or photoemission upon external stimuli, have attracted substantial attention across various fields. This study presents an effective approach wherein switchable modulation of photochromism and ultralong phosphorescence can be achieved simultaneously in a zero-dimensional organic-inorganic halide hybrid glass doped with 4,4´-bipyridine. The facile fabrication of large-scale glasses is accomplished through a combined grinding-melting-quenching process. The persistent luminescence can be regulated through the photochromic switch induced by photo-generated radicals. Furthermore, the incorporation of the aggregation-induced chirality effect generates intriguing circularly polarized luminescence, with an optical dissymmetry factor (glum) reaching the order of 10-2. Exploiting the dynamic ultralong phosphorescence, this work further achieves promising applications, such as three-dimensional optical storage, rewritable photo-patterning, and multi-mode anti-counterfeiting with ease. Therefore, this study introduces a smart hybrid glass platform as a new photo-responsive switchable system, offering versatility for a wide array of photonic applications.

Photoactivated Circularly Polarized Luminescent Organic Radicals in Doped Amorphous Polymer

Luminescent organic radicals, especially those with photoactivated circularly polarized luminescence (CPL) features, hold great significance for cutting-edge optoelectronic applications, but their development still remains a challenge. In this study, we propose a novel strategy to achieve photoactivated CPL radicals by bonding two phosphine centers within an axial chiral system, yielding a compound of R/S-5,5-bis(diphenylphosphino)-4,4'-bibenzo[d][1,3]dioxole (R/S-BDP). The photoactivated R/S-BDP molecules in polymer matrix display a robust quantum yield of 19.8 % and a dissymmetry factor (glum) of 1.2×10-4, marking this work as the first example of photoactivated CPL radicals. Furthermore, the glum is improved to 1.0×10-2 by using a liquid crystal as host. Experimental and theoretical analyses reveal that R/S-BDP molecules, endowed with double phosphine cores in axial chirality, offer a direct way for intramolecular electron transfer upon photoirradiation. This leads to the generation of radical ionic pairs, which subsequently trigger the donor-acceptor arrangement through intermolecular electron transfer, thereby resulting in stable radical emission. The extended photoactivated BDP-F exhibits a remarkably high quantum efficiency of 57.8%. Ultimately, the distinctive photo-responsive CPL radical luminescence has been successfully used for information displays and anti-counterfeiting.

Achieving Efficient Dark Blue Room-Temperature Phosphorescence with Ultra-Wide Range Tunable-Lifetime

Tunable-lifetime room-temperature phosphorescence (RTP) materials have been widely studied due to their broad applications. However, only few reports have achieved wide-range lifetime modulation. In this work, ultra-wide range tunable-lifetime efficient dark blue RTP materials were realized by doping methyl benzoate derivatives into polyvinyl alcohol (PVA) matrix. The phosphorescence lifetimes of the doped films can be increased from 32.8 ms to 1925.8 ms. Such wide range of phosphorescence lifetime modulation is extremely rare in current reports. Moreover, the phosphorescence emission of the methyl 4-hydroxybenzoate-doped film is located in the dark blue region and the phosphorescence quantum yield reaches as high as 15.4 %, which broadens their applications in organic optoelectronic information. Further studies demonstrated that the reason for the tunable lifetime was that the magnitude of the electron-donating ability of the substituent group modulates the HOMO-LUMO and singlet-triplet energy gap of methyl benzoate derivatives, as well as the ability to non-covalent interactions with PVA. Moreover, the potential applications of luminescent displays and optical anti-counterfeiting of these high-performance dark blue RTP materials have been conducted.

"Matching Rule" for Generation, Modulation and Amplification of Circularly Polarized Luminescence

ConspectusCircularly polarized luminescence (CPL) generated by chiral luminescent systems has sparked enormous attention in multidisciplinary field as it brings infinite potential for applications, such as 3D optical displays, biological probes, and chiroptical sensors. Satisfying both the conditions of chirality and luminescence (including fluorescence or phosphorescence) is a prerequisite for constructing CPL materials. In this regard, whether in organic, inorganic, or hybrid systems, chiral and luminescent components generally involve effective coupling through covalent or noncovalent bonds. For covalent interactions, such as the copolymerization of chiral and luminescent monomers, although covalent bonds provide high stability for the system, they inevitably involve tedious preparation procedures that connect chirality and luminescence together. For noncovalent bonds, take supramolecular assembly as an example, chiral elements and achiral light-emitting units are chiral transferred through intermolecular interactions, and their advantages include the diversity of luminescent and chiral building blocks, the stimuli responsiveness brought by noncovalent bonds, as well as the potential amplification of CPL signals by coassembly. However, the stability of the assembly system may be poor, and the assembly chiroptical performance and morphology are difficult to predict. Gratifyingly, matching rule that do not rely on covalent together with noncovalent interactions allows for the effortless construction, modulation, as well as amplification of CPL systems.In this Account, we overview different strategies based on matching rule, including fluorescence-selective absorption, circularly polarized reflection, and circularly polarized fluorescence energy transfer (CPF-ET). Examples of these strategies are illustrated with a focus on helical polymers in light of their appealing structures and wide uses. For instance, for fluorescence-selective absorption, chiral helical polymers can convert racemic fluorescence light into a circularly polarized one with specific handedness by simply overlapping the helical polymer's circular dichroism (CD) spectra with the luminophore's emission spectra. For circularly polarized reflection, employing the selective reflection of certain handedness's circularly polarized light, the high helical twisting power (HTP) of the helical polymer in the cholesteric liquid crystals (N*-LCs) gives the system high glum. Additionally, for CPF-ET, only the emission spectrum of the donor and the absorption (or excitation) spectrum of the achiral acceptor are required to overlap, and no covalent or noncovalent interactions between the two are required. An outlook for the CPL materials related to matching rule which will avail the optimization and extension of this intriguing approach concludes the Account. We hope that the Account will offer insightful inspiration for the flourishing progress of chiroptical systems and present exciting opportunities.

Enabling robust blue circularly polarized organic afterglow through self-confining isolated chiral chromophore

Creating circularly polarized organic afterglow system with elevated triplet energy levels, suppressed non-radiative transitions, and effective chirality, which are three critical prerequisites for achieving blue circularly polarized afterglow, has posed a formidable challenge. Herein, a straightforward approach is unveiled to attain blue circularly polarized afterglow materials by covalently self-confining isolated chiral chromophore within polymer matrix. The formation of robust hydrogen bonds within the polymer matrix confers a distinctly isolated and stabilized molecular state of chiral chromophores, endowing a blue emission band at 414 nm, lifetime of 3.0 s, and luminescent dissymmetry factor of ~ 10-2. Utilizing the synergistic afterglow and chirality energy transfer, full-color circularly polarized afterglow systems are endowed by doping colorful fluorescent molecules into designed blue polymers, empowering versatile applications. This work paves the way for the streamlined design of blue circularly polarized afterglow materials, expanding the horizons of circularly polarized afterglow materials into various domains.

High-Resolution Afterglow Patterning Using Cooperative Vapo- and Photo-Stimulation

Bright afterglow room-temperature phosphorescence (RTP) soon after ceasing excitation is a promising technique for greatly increasing anti-counterfeiting capabilities. The development of a process for rapid high-resolution afterglow patterning of crystalline materials can improve both high-speed fabrication of anti-counterfeiting afterglow media and stable afterglow readout compared with those achieved with amorphous materials. Here, the high-resolution afterglow patterning of crystalline materials via cooperative organic vapo- and photo-stimulation is reported. A single crystal of (S)-(-)-2,2'-bis(diphenylphosphino)-5,5',6,6',7,7'8,8'-octahydro-1,1'-binaphthyl [(S)-H8-BINAP] doped with (S)-(-)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl [(S)-BINAP] shows green afterglow RTP. Crystals of (S)-BINAP-doped (S)-H8-BINAP changed to an amorphous state with no afterglow capability on weak continuous photoirradiation under dichloromethane (DCM) vapor. Photoirradiation induced oxidation of the (S)-H8-BINAP host molecule in the crystal. The oxidized (S)-H8-BINAP forms on the crystal surface strongly interacted with DCM molecules, which induces melting of the (S)-BINAP-doped (S)-H8-BINAP crystal and trigger formation of an amorphous state without an afterglow capability. High-resolution afterglow patterning of the crystalline film is rapidly achieved by using cooperative organic vapo- and photo-stimulation. In addition to the benefit of rapid afterglow patterning, the formed afterglow images of the crystalline film can be repeatedly read out under ambient conditions without DCM vapor.

Double-Model Decay Strategy Integrating Persistent Photogenic Radicaloids with Dynamic Circularly Polarized Doublet Radiance and Triplet Afterglow

Organic phosphors integrating circularly polarized persistent luminescence (CPPL) across the visible range are widespread for applications in optical information encryption, bioimaging, and 3D display, but the pursuit of color-tunable CPPL in single-component organics remains a formidable task. Herein, via in situ photoimplanting radical ion pairing into axial chiral crystals, we present and elucidate an unprecedented double-module decay strategy to achieve a colorful CPPL through a combination of stable triplet emission from neutral diphosphine and doublet radiance from photogenic radicals in an exclusive crystalline framework. Owing to the photoactivation-dependent doublet radiance component and an inherent triplet phosphorescence in the asymmetric environment, the CPL vision can be regulated by altering the photoactivation and observation time window, allowing colorful glow tuning from blue and orange to delayed green emission. Mechanism studies clearly reveal that this asymmetric electron migration environment and hybrid n-π* and π-π* instincts are responsible for the afterglow and radical radiance at ambient conditions. Moreover, we demonstrate the applications of colorful CPPL for displays and encryption via manipulation of both excitation and observation times.

Recent progress in ion-regulated organic room-temperature phosphorescence

Organic room-temperature phosphorescence (RTP) materials have attracted considerable attention for their extended afterglow at ambient conditions, eco-friendliness, and wide-ranging applications in bio-imaging, data storage, security inks, and emergency illumination. Significant advancements have been achieved in recent years in developing highly efficient RTP materials by manipulating the intermolecular interactions. In this perspective, we have summarized recent advances in ion-regulated organic RTP materials based on the roles and interactions of ions, including the ion-π interactions, electrostatic interactions, and coordinate interactions. Subsequently, the current challenges and prospects of utilizing ionic interactions for inducing and modulating the phosphorescent properties are presented. It is anticipated that this perspective will provide basic guidelines for fabricating novel ionic RTP materials and further extend their application potential.

Dynamically Modulating the Dissymmetry Factor of Circularly Polarized Organic Ultralong Room-Temperature Phosphorescence from Soft Helical Superstructures

Achieving circularly polarized organic ultralong room-temperature phosphorescence (CP-OURTP) with a high luminescent dissymmetry factor (glum ) is crucial for diverse optoelectronic applications. In particular, dynamically controlling the dissymmetry factor of CP-OURTP can profoundly advance these applications, but it is still unprecedented. This study introduces an effective strategy to achieve photoirradiation-driven chirality regulation in a bilayered structure film, which consists of a layer of soft helical superstructure incorporated with a light-driven molecular motor and a layer of room-temperature phosphorescent (RTP) polymer. The prepared bilayered film exhibits CP-OURTP with an emission lifetime of 805 ms and a glum value up to 1.38. Remarkably, the glum value of the resulting CP-OURTP film can be reversibly controlled between 0.6 and 1.38 over 20 cycles by light irradiation, representing the first example of dynamically controlling the glum in CP-OURTP.

Biobased and biodegradable films exhibiting circularly polarized room temperature phosphorescence

There is interest in developing sustainable materials displaying circularly polarized room-temperature phosphorescence, which have been scarcely reported. Here, we introduce biobased thin films exhibiting circularly polarized luminescence with simultaneous room-temperature phosphorescence. For this purpose, phosphorescence-active lignosulfonate biomolecules are co-assembled with cellulose nanocrystals in a chiral construct. The lignosulfonate is shown to capture the chirality generated by cellulose nanocrystals within the films, emitting circularly polarized phosphorescence with a 0.21 dissymmetry factor and 103 ms phosphorescence lifetime. By contrast with most organic phosphorescence materials, this chiral-phosphorescent system possesses phosphorescence stability, with no significant recession under extreme chemical environments. Meanwhile, the luminescent films resist water and humid environments but are fully biodegradable (16 days) in soil conditions. The introduced bio-based, environmentally-friendly circularly polarized phosphorescence system is expected to open many opportunities, as demonstrated here for information processing and anti-counterfeiting.

Boosting Circularly Polarized Luminescence from Alkyl-Locked Axial Chirality Scaffold by Restriction of Molecular Motions

Boosting the circularly polarized luminescence of small organic molecules has been a stubborn challenge because of weak structure rigidity and dynamic molecular motions. To investigate and eliminate these factors, here, we carried out the structure-property relationship studies on a newly-developed axial chiral scaffold of bidibenzo[b,d]furan. The molecular rigidity was finely tuned by gradually reducing the alkyl-chain length. The environmental factors were considered in solution, crystal, and polymer matrix at different temperatures. As a result, a significant amplification of the dissymmetry factor glum from 10-4 to 10-1 was achieved, corresponding to the situation from (R)-4C in solution to (R)-1C in polymer film at room temperature. A synergistic strategy of increasing the intramolecular rigidity and enhancing the intermolecular interaction to restrict the molecular motions was thus proposed to improve circularly polarized luminescence. The though-out demonstrated relationship will be of great importance for the development of high-performance small organic chiroptical systems in the future.

Disentangling optical effects in 3D spiral-like, chiral plasmonic assemblies templated by a dark conglomerate liquid crystal

Chiral thin films showing electronic and plasmonic circular dichroism (CD) are intensively explored for optoelectronic applications. The most studied chiral organic films are the composites exhibiting a helical geometry, which often causes entanglement of circular optical properties with unwanted linear optical effects (linearly polarized absorption or refraction). This entanglement limits tunability and often translates to a complex optical response. This paper describes chiral films based on dark conglomerate, sponge-like, liquid crystal films, which go beyond the usual helical type geometry, waiving the problem of linear contributions to chiroptical electronic and plasmonic properties. First, we show that purely organic films exhibit high electronic CD and circular birefringence, as studied in detail using Mueller matrix polarimetry. Analogous linear properties are two orders of magnitude lower, highlighting the benefits of using the bi-isotropic dark conglomerate liquid crystal for chiroptical purposes. Next, we show that the liquid crystal can act as a template to guide the assembly of chemically compatible gold nanoparticles into 3D spiral-like assemblies. The Mueller matrix polarimetry measurements confirm that these composites exhibit both electronic and plasmonic circular dichroisms, while nanoparticle presence is not compromising the beneficial optical properties of the matrix.

Circularly Polarized Phosphorescence of Benzils Achieved by Chiral Supramolecular Polymerization

In current approaches for circularly polarized phosphorescent materials, the crystallization of chiral phosphors suffers from poor processability, while integrating them into an amorphous polymer matrix results in unsatisfactory chiroptical signals due to the absence of chirality communication. Here, we have developed an innovative strategy through chiral supramolecular polymerization of benzil phosphors facilitated by intermolecular hydrogen bonds. The inherent film-forming capabilities of non-covalent supramolecular polymers obviate the need for an external polymer matrix. The pronounced helical asymmetry of benzil phosphors resulting from chiral supramolecular polymerization leads to enhanced circularly polarized phosphorescence compared to their non-hydrogen-bonded counterparts. The circularly polarized phosphorescent signals can be further modulated by varying the location of stereogenic centers or introducing halogen bonding to benzils. Incorporation of platinum(II) phosphor into the benzil supramolecular polymers induces both chirality and triplet-to-triplet energy transfer, leading to a change in circularly polarized phosphorescent color from yellow to red. In summary, chiral supramolecular polymerization of phosphors represents a novel and effective approach to circularly polarized phosphorescent materials.

Circularly Polarized Organic Ultralong Room-Temperature Phosphorescence with A High Dissymmetry Factor in Chiral Helical Superstructures

Long-lived room-temperature phosphorescence (RTP) of organic materials holds a significant potential for optical information. Circularly polarized organic ultralong room-temperature phosphorescence (CP-OURTP) with extremely high dissymmetry factor (glum ) values is even highly demanded and considerably challenging. Here, an effective strategy is introduced to realize CP-OURTP with an emission decay time of 735 ms and a glum value up to 1.49, which exceeds two orders of magnitude larger than previous records, through a system composed of RTP polymers and chiral helical superstructures. The system exhibits excellent stability under multiple cycles of photoirradiation and thermal treatment, and is further employed for information encryption based on optical multiplexing. The results are anticipated to lay the foundation for the development of CP-OURTP materials in advanced photonic applications.

Full-Color Circularly Polarized Luminescence of Supramolecular Polymers with Handedness Inversion Regulated by Anion and Temperature

Constructing full-color circularly polarized luminescence (CPL) materials with switchable handedness in the solid state is an appealing yet considerably challenging task, especially for supramolecular polymer films assembled from homochiral monomers. Herein, supramolecular polymers with full-color CPL and inverted handedness are realized through the coassembly of a homochiral cholesterol derivative (PVPCC), metal ions (Zn2+), and achiral fluorescent dyes. The obtained coassembled systems show anion-directed supramolecular chirality inversion by exchanging the anions of NO3-, ClO4-, BF4-, and Cl-. For instance, the negative CD and right-handed CPL are detected in the PVPCC/Zn(NO3)2 aggregates, which convert into positive CD and left-handed CPL after introducing Cl-, corresponding to the transformation from nanorods to nanofibers. Furthermore, the tunable CPL color and handedness inversion of the coassembly system of PVPCC/Zn(NO3)2 and achiral fluorescent dyes can be established by alternately changing the assembling temperature of 298 and 273 K. Importantly, the full-color CPL polymeric materials are then constructed by doping the PVPCC/Zn(NO3)2/dyes complexes into poly(methyl methacrylate) (PMMA) film, which maintains the handedness inversion and shows the enhanced CPL performance. The work not only deepens the understanding of chirality inversion in supramolecular chemistry but also helps to construct full-color CPL materials with switchable handedness from homochiral building blocks in materials science.

Stimulus-responsive polymer materials toward multi-mode and multi-level information anti-counterfeiting: recent advances and future challenges

Information storage and security is one of the perennial hot issues in society, while the further advancements of related chemical anti-counterfeiting systems remain a formidable challenge. As emerging anti-counterfeiting materials, stimulus-responsive polymers (SRPs) have attracted extensive attention due to their unique stimulus-responsiveness and charming discoloration performance. At the same time, single-channel decryption technology with low-security levels has been unable to effectively prevent information from being stolen or mimicked. As a result, it would be of great significance to develop SRPs with multi-mode and multi-level anti-counterfeiting characteristics. This study summarizes the latest achievements in advance anti-counterfeiting strategies based on SRPs, including multi-mode anti-counterfeiting (static information) and multi-level anti-counterfeiting (dynamic information). In addition, the promising applications of such materials in anti-counterfeiting labels, identification platforms, intelligent displays, and others are briefly reviewed. Finally, the challenges and opportunities in this emerging field are discussed. This review serves as a useful resource for manipulating SRP-based anti-counterfeiting materials and creating cutting-edge information security and encryption systems.

A Photoactivatable Luminescent Motif through Ring-Flipping Isomerization for Multiple Photopatterning

Photoactivatable luminescent materials have garnered enormous attention in the field of intelligent responsive materials, yet their design and applications remain challenging due to the limited variety of photoactivatable motifs. In the work described herein, we discovered a new photoactivatable luminescent motif that underwent ring-flipping isomerization under UV irradiation. The emission of this motif exhibited a rapid transformation from dark yellow to bright green, accompanied by a significant enhancement of quantum yield from 1.9% to 34.2%. Experimental and theoretical studies revealed that the effective intramolecular motion (EIM) was crucial to the distinct luminescence performance between two isomers. In addition, polymers containing this motif were achieved through a one-pot alkyne polymerization, exhibiting both photofluorochromic and photo-cross-linking properties. Furthermore, multiple types of photopatterning, including luminescent encryption, fluorescent grayscale imaging, and high-resolution photolithographic patterns, were realized. This work developed a new photoactivatable luminescent motif and demonstrated its potential applications in both small molecules and macromolecules, which will help in the future design of photoactivatable luminescent materials.

Enhancing Circularly Polarized Luminescence in Quantum Dots through Chiral Coordination-Mediated Growth at the Liquid/Liquid Interface

Here, we develop a novel methodology for synthesizing chiral CdSe@ZnS quantum dots (QDs) with enhanced circularly polarized luminescence (CPL) by incorporating l-/d-histidine (l-/d-His) ligands during ZnS shell growth at the water/oil interface. The resulting chiral QDs exhibit exceptional absolute photoluminescence quantum yield of up to 67.2%, surpassing the reported limits of 40.0% for chiral inorganic QDs, along with absorption dissymmetry factor (|gabs|) and luminescence dissymmetry factor (|glum|) values of 10-2, exceeding the range of 10-5-10-3 and 10-4-10-2, respectively. Detailed investigations of the synthetic pathway reveal that the interface, as a binary synthetic environment, facilitates the coordinated ligand exchange and shell growth mediated by chiral His-Zn2+ coordination complexes, leading to a maximum fluorescent brightness and chiroptical activities. The growth process, regulated by the His-Zn2+ coordination complex, not only reduces trap states on the CdSe surface, thereby enhancing the fluorescence intensity, but also significantly promotes the orbital hybridization between QDs and chiral ligands, effectively overcoming the shielding effect of the wide bandgap shell and imparting pronounced chirality. The proposed growth pathway elucidates the origin of chirality and provides insights into the regulation of the CPL intensity in chiral QDs. Furthermore, the application of CPL QDs in multilevel anticounterfeiting systems overcomes the limitations of replication in achiral fluorescence materials and enhances the system's resistance to counterfeiting, thus opening new opportunities for chiral QDs in optical anticounterfeiting and intelligent information encryption.

Recyclable soft photonic crystal film with overall improved circularly polarized luminescence

Existing circularly polarized luminescence materials can hardly satisfy the requirements of both large luminescence dissymmetry factor and high luminescent quantum yield, which hinders their practical applications. Here, we present a soft photonic crystal film embedded with chiral nanopores that possesses excellent circularly polarized luminescence performance with a high luminescence dissymmetry factor as well as a large luminescent quantum yield when loaded with various luminescent dyes. Benefitting from the retention of chiral nanopores imprinted from a chiral liquid crystal arrangement, the chiral soft photonic crystal film can not only endow dyes with chiral properties, but also effectively avoid severe aggregation of guest dye molecules. More importantly, the soft photonic crystal film can be recycled many times by loading and eluting guest dye molecules while retaining good stability as well as circularly polarized luminescence performance, enabling various applications, including smart windows, multi-color circularly polarized luminescence and anticounterfeiting.

Solvent-Directed Hierarchical Self-Assembly of Tetraphenylpyrazine-Cholesterol with Amplified Circularly Polarized Luminescence

It is important to identify the effect of assembly and aggregation on the chirality transfer and energy transmission in supramolecular polymer system, since the unordered aggregation is insufficient to promote luminescence enhancement and chirality transfer, even causing the negative effect. Another key issue is to identify the solvent effect on hierarchically chiral self-assembly. Herein, we designed an AIE-core based building block, tetraphenylpyrazine-cholesterol (TPP-Chol), to explore how the solvent component influences chirality transfer and energy transmission of its aggregates and/or assemblies. Interestingly, the hierarchical assembly behavior was realized in the mixture of MeOH/CHCl3 highly dependent on the MeOH content. During the solvent-directed hierarchical assembly, the morphologic transformations, such as nanoribbons with a width of 150 nm, twisted nanoribbons with helical pitch of 420 nm, nanoribbon clusters, and microflowers with an average diameter of 5.5 μm, were realized with obvious chirality amplification for both circular dichroism (CD) and circularly polarized luminescence (CPL) measurements. The hierarchical assembly of TPP-Chol was also demonstrated by a time-dependent CD test. The work points out the complexity and dynamic of hierarchically chiral self-assembly regulated by the solvent effect, which would be helpful for the development of supramolecular materials with enhanced CPL performance and dynamic chirality.