Helical Photonic Confinement of Metal Clusters Enables Switching and Imaging of Near-Infrared Circularly Polarized Light.

Tunable Multicolor Circularly Polarized Luminescence via Co-assembly of One Chiral Electron Acceptor with Various Donors

The ability to design halide perovskite nanocrystals (PNCs) with circularly polarized luminescence (CPL) offers exceptional potential in photonic technologies. Despite recent inspiring advances, the creation of PNCs with full-color tailorablity, outstanding CPL, and long-term stability remains a substantial challenge. Herein, a robust strategy to craft CPL-active PNCs is reported, exhibiting appealing full-color tunable wavelengths, enhanced CPL, and prolonged stability. In contrast to conventional methodologies, this strategy utilizes chiral nematic mesoporous silica (CNMS) as host to render in situ confined growth of diverse achiral PNCs. By strategically engineering photonic bandgap, adjusting loading amount of PNCs, and manipulating cations/anion compositions of PNCs, robust CPL responses with tunable wavelength and intensity are successfully obtained. The resulting PNCs-CNMS achieves stable CPL emissions with full-color tunability and impressive luminescent dissymmetric factors up to -0.17. Remarkably, silica-based hosts as a protective barrier confer exceptional resistance to humidity, photodegradation, and thermal stability, even up to 95 °C. Furthermore, the ability to achieve reversible CPL switching within PNCs-CNMS is attainable by leveraging the responsiveness of CNMS matrix or dynamic behavior of impregnated PNCs. Additionally, circularly polarized light-emitting diode devices based on PNCs-CNMS can be conveniently fabricated. This research affords a powerful platform for designing functional chiroptical materials.

Supramolecular Nanohelix Fabricated by Pillararene-Based Host–Guest System for Chirality Amplification, Transfer, and Circularly Polarized Luminescence in Water

Recently, near-infrared (NIR) circularly polarized luminescence (CPL) has emerged as a research hotspot owing to its unique application prospects. Atomic precision Au clusters (AuCs) have shown excellent biocompatibility and characteristic emission in the NIR region, and have found various applications in biosensing and imaging. Here, we achieve stable and highly dissymmetric CPL in both visible and NIR regions from cholesteric liquid crystals (CLCs) overlaid on a uniform AuCs film. The glum factors (Maximum 2) in the visible and the NIR regions reach 1.8 and 0.7, respectively. AuCs films are prepared by the anti-solvent precipitation method for the first time. By overlaying wide-band CLCs on the AuCs film, dual CPL is simultaneously realized in both visible and NIR regions. Based on the intrinsic properties of CLCs, electrically tunable, thermally reversible and optically tunable CPL from CLCs/AuCs composites are successfully demonstrated. These features of CLCs/AuCs composites offer possibilities for applications in cryptography and anti-counterfeiting.

Ultrastable Dual-Matrix meditated CsPbBr3 composites with enhanced photoluminescence quantum yield and robust circular polarization luminescence

Analogues of Shibasaki's complexes supported by enantiopure Spinol are synthesized and characterized. The tris(Spinol) LnIII complexes are generated either by ligand deprotonation followed by complexation with lanthanide triflate salts or by in situ deprotonation by Ln(N(SiMe3)2)3 salts in the presence of additional base. The resulting complexes are found to be luminescent and chiroptically active for both circular dichroism and circularly polarized luminescence (CPL), notably producing strong CPL with dissymmetry factors (glum) of up to 0.50, 0.53, and 0.53 for Sm, Tb, and Dy, respectively. The Sm complex is found to be CPL-active in the near-infrared (NIR) region at 980 nm, representing the first report of NIR CPL from Sm. Additionally, the Tb complex, due to efficient sensitization (Φ = 0.846 in tetrahydrofuran) coupled with strong dissymmetry factors, achieves a CPL brightness (BCPL) of 3760 M-1 cm-1, the highest reported for any CPL-active compound to date. These are rare examples of compounds that show simultaneous improvement of both CPL metrics (glum and BCPL). Solid-state structural analysis of the Spinolate complexes and comparisons to other CPL-active analogues of Shibasaki's complexes also suggest that nondistorted geometries should generate even stronger metrics.

It is essential to create organic compounds that exhibit circularly polarized luminescence (CPL) in the near-infrared (NIR) range. Helicene-type emitters possess appealing chiroptical features, however, such NIR molecules are scarce due to a paucity of synthetic strategies. Herein, we developed a series of helical β-isoindigo-based B-O-B bridged aza-BODIPY analogs that were synthesized conveniently. The reaction of diimino-β-isoindigo with a heteroaromatic amine produced a restricted ligand cavity, which triggered off the generation of a B-O-B bridge. The B-O-B bridge led to distorted conformations that satisfy the helical requirements, resulting in excellent spectroscopic and chiroptical properties. Tunable CPL with the highest luminescence dissymmetry factor (glum ) of 1.3×10-3 and a CPL brightness (BCPL =11.5 M-1 cm-1 ) in the NIR region was achieved. This synthetic approach is expected to offer a new opportunity to chiral chemistry and increase flexibility for chiroptical tuning.

It is essential to create organic compounds that exhibit circularly polarized luminescence (CPL) in the near‐infrared (NIR) range. Helicene‐type emitters possess appealing chiroptical features, however, such NIR molecules are scarce due to a paucity of synthetic strategies. Herein, we developed a series of helical β‐isoindigo‐based B−O−B bridged aza‐BODIPY analogs that were synthesized conveniently. The reaction of diimino‐β‐isoindigo with a heteroaromatic amine produced a restricted ligand cavity, which triggered off the generation of a B−O−B bridge. The B−O−B bridge led to distorted conformations that satisfy the helical requirements, resulting in excellent spectroscopic and chiroptical properties. Tunable CPL with the highest luminescence dissymmetry factor (glum) of 1.3×10−3and a CPL brightness (BCPL=11.5 M−1 cm−1) in the NIR region was achieved. This synthetic approach is expected to offer a new opportunity to chiral chemistry and increase flexibility for chiroptical tuning.

Carbon-based double helicates consisting of two anthracene-containing oligo(p-phenyleneethynylene) units and two flexible chiral 1,1'-binaphthyl units or two rigid chiral 9,9'-spirobifluorene units were developed. The curved oligo(p-phenyleneethynylene) fragments in the double helicates were successfully constructed by tin-mediated reductive aromatization. Helical oligo(p-phenyleneethynylene) double strands fixed by two rigid spirobifluorene units showed little structural change under photoirradiation, thereby emitting circularly polarized luminescence (CPL) in the visible region with a high quantum yield (ΦPL =0.93). In contrast, flexible binaphthyl units induced dynamic structural change of the oligo(p-phenyleneethynylene) luminophores under photoirradiation, leading to strong CPL (|glum |=1.1×10-2 ) in the near-infrared (NIR) region. UV/Vis, circular dichroism (CD), CPL and NMR spectroscopic analyses of the binaphthyl-hinged double helicate suggested excimer formation between two π-conjugated strands in the excited state. Theoretical calculations highlight the importance of the tightly interlocked excimer structure of the carbon-based double helicate in controlling the angle between the electric and magnetic transition dipole moments for strong NIR CPL generation.

Advances in near-infrared circularly polarized luminescence with organometallic and small organic molecules

A chiral‐switchable device for circularly polarized luminescence (CPL) is fabricated based on dynamic superstructure of cholesteric liquid crystals (N*‐LC) doped with light‐driven molecular motor (MM), which achieves simultaneous modulation of chirality and intensity of CPL. Functional MM, designed with the modification of alkyl chains on the rotor, allows for advanced chemical isomerization to be driven with light. The selective reflection band due to the N*‐LC is shifted upon UV irradiation so that the reflection band moves toward the emissive band of the luminescence dyes, yielding CPL with opposite handedness and high dissymmetry factor values. The geometric changes of the motor during the rotary steps finally cause a remarkable reversible handedness inversion of the N*‐LC, which also leads switchable chirality of CPL. The dynamic N*‐LC cell bearing the light‐controlled selective reflection is useful for generating CPL from fluorescent materials and for allowing light chirality‐switching in CPL signals, which presents new possibilities for optoelectronic and photonics applications.

Near infrared (NIR) circularly polarized organic afterglow are highly attractive for information encryption, bio‐imaging/sensing. However, achieving both NIR afterglow and high optical asymmetry remains challenging. Here, a pure‐organic afterglow film with circularly polarized NIR emission is achieved through co‐assembly of chromophores with cellulose nanocrystals (CNCs). The film exhibits a strong NIR afterglow with a lifetime of 0.38 s at 808 nm and a high g lum of ‐0.15, 1–2 orders higher than reported performance. The CNCs matrix not only stabilizes triplet excitons via hydrogen bonding, facilitating phosphorescence from 1‐naphthylboronic acid, but also provides a cholesteric surrounding to enable circularly polarized luminescence (CPL). Further employing an intermediate dye, Rhodamine B (RB), and a NIR dye, Cyanine7, the CPL is extended from visible to NIR range via a two‐step Förster resonance energy transfer. Moreover, the film demonstrates dynamic switch of the NIR circularly polarized afterglow by modulating the pH‐responsive intermediate RB, showing potential for multi‐channel information encryption, bio‐imaging, and sensing.

Preparing multi‐color and multi‐stimuli‐responsive circularly polarized luminescence (CPL) materials and understanding the evolution of chirality through the visualized mode is still a challenge. Here, an encapsulation engineering approach of chiral metal‐organic frameworks (MOFs) is proposed to confine guest emitters to realize multi‐color and multi‐stimuli‐responsive CPL. Based on triplet‐triplet energy transfer (TTET), white CPL and near‐infrared circularly polarized room temperature phosphorescence (NIR‐CPRTP) can be obtained by introducing the pyrene derivatives. With the introduction of the guest containing vinylpyrene group, the light‐ and thermal‐responsive CPL with the signal inversion can be realized through the reversible [2+2] cycloaddition reaction between the ligand and guest triggered by visible light/ultraviolet light or heating. Furthermore, the excitation‐dependent CPL is successfully achieved with the incorporation of excited state intramolecular proton transfer (ESIPT) molecules into nanopores. Importantly, the chirality magnification can be greatly enhanced through the chiral spatial confinement, the accurate host‐guest single crystal structures of FLT@DCF‐12 and FLT@LCF‐12 provide the visualized mode to understand the mechanism of chirality transfer, amplification and responsiveness. White LED and multiple information display and encryption are further demonstrated. This breakthrough provides a new perspective to guest‐encapsulated chiral MOFs and contributes to the construction of stimuli‐responsive CPL‐active materials.

The practical application of the circularly polarized luminescence (CPL) emitted from chiral substances faces significant hurdles, primarily due to the small luminescence dissymmetry factor (glum) and low photoluminescence quantum yield (PLQY). Herein, we demonstrate a hierarchical system in which metal clusters exhibit excellent CPL performance, with both excellent glum factors and high PLQYs, thereby triggering enantioselective photopolymerization. Their CPL activities are sequentially amplified in different assembly forms induced by liquid crystals (LCs), and the maximum glum factor is increased by 1240 times, reaching a value of 1.24. The PLQYs of the metal clusters in different assembled states are sharply enhanced compared to that in the discrete state. Benefiting from the CPL performance of the metal clusters, their CPL was used to remotely regulate enantioselective polymerization, thus realizing light-to-matter chirality transfer. Impressively, upon incorporation of achiral luminophores, the polymer system is endowed with CPL through sequential chirality transfer. These innovative achievements open new avenues for the design and cutting-edge application of CPL-active metal clusters.

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.